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Sample records for high flow priapism

  1. High-flow priapism in acute lymphatic leukaemia

    Energy Technology Data Exchange (ETDEWEB)

    Mentzel, Hans-Joachim; Vogt, Susanna; Kaiser, Werner A. [Institute of Diagnostic and Interventional Radiology, Department of Pediatric Radiology, Friedrich-Schiller-Universitaet Jena, Bachstrasse 18, 07740, Jena (Germany); Kentouche, Karim; Doerfel, Claus; Zintl, Felix [Department of Paediatrics, University of Jena (Germany)

    2004-07-01

    Priapism is defined as prolonged and persistent erection of the penis without sexual stimulation. It is associated with excessive hyperleukocytosis (e.g. in acute or chronic leukaemia); however, this complication is rarely seen in the pediatric population. We report a 12-year-old boy suffering from acute leukaemia presenting with, at first intermittent, but increasingly persistent erection. Doppler US revealed signs of high-flow priapism. MRI excluded intrapelvic tumour masses, and three-dimensional contrast-enhanced MR angiography could not demonstrate an arteriovenous fistula or thrombosis. Cavernosal blood-gas measurement was in agreement with high-flow priapism. On the basis of the imaging findings, invasive therapeutic management was avoided in our patient with a successful outcome. (orig.)

  2. High-flow priapism in acute lymphatic leukaemia

    International Nuclear Information System (INIS)

    Mentzel, Hans-Joachim; Vogt, Susanna; Kaiser, Werner A.; Kentouche, Karim; Doerfel, Claus; Zintl, Felix

    2004-01-01

    Priapism is defined as prolonged and persistent erection of the penis without sexual stimulation. It is associated with excessive hyperleukocytosis (e.g. in acute or chronic leukaemia); however, this complication is rarely seen in the pediatric population. We report a 12-year-old boy suffering from acute leukaemia presenting with, at first intermittent, but increasingly persistent erection. Doppler US revealed signs of high-flow priapism. MRI excluded intrapelvic tumour masses, and three-dimensional contrast-enhanced MR angiography could not demonstrate an arteriovenous fistula or thrombosis. Cavernosal blood-gas measurement was in agreement with high-flow priapism. On the basis of the imaging findings, invasive therapeutic management was avoided in our patient with a successful outcome. (orig.)

  3. Percutaneous Direct Puncture Embolization with N-butyl-cyanoacrylate for High-flow Priapism

    Energy Technology Data Exchange (ETDEWEB)

    Tokue, Hiroyuki, E-mail: tokue@s2.dion.ne.jp; Shibuya, Kei [Gunma University Hospital, Department of Diagnostic and Interventional Radiology (Japan); Ueno, Hiroyuki [Isesaki Municipal Hospital, Department of Radiology (Japan); Tokue, Azusa; Tsushima, Yoshito [Gunma University Hospital, Department of Diagnostic and Interventional Radiology (Japan)

    2016-09-15

    There are many treatment options in high-flow priapism. Those mentioned most often are watchful waiting, Doppler-guided compression, endovascular highly selective embolization, and surgery. We present a case of high-flow priapism in a 57-year-old man treated by percutaneous direct puncture embolization of a post-traumatic left cavernosal arteriovenous fistula using N-butyl-cyanoacrylate. Erectile function was preserved during a 12-month follow-up. No patients with percutaneous direct puncture embolization for high-flow priapism have been reported previously. Percutaneous direct puncture embolization is a potentially useful and safe method for management of high-flow priapism.

  4. Erectie bij een kleuter door "high-flow" -priapisme: spoedgeval.

    NARCIS (Netherlands)

    Donker, G.A.

    2005-01-01

    A healthy 5-year-old child was brought to the general practitioner with priapism that had been observed for a few days, without any other symptoms. Angiography revealed an arteriovenous fistula originating from the left A. dorsalis penis, which was successfully embolised. The diagnosis was ‘high

  5. Conversion of Low-Flow Priapism to High-Flow State Using T-Shunt with Tunneling.

    Science.gov (United States)

    Mistry, Neil A; Tadros, Nicholas N; Hedges, Jason C

    2017-01-01

    Introduction . The three types of priapism are stuttering, arterial (high-flow, nonischemic), and venoocclusive (low-flow, ischemic). These are usually distinct entities and rarely occur in the same patient. T-shunts and other distal shunts are frequently combined with tunneling, but a seldom recognized potential complication is conversion to a high-flow state. Case Presentation . We describe 2 cases of men who presented with low-flow priapism episodes that were treated using T-shunts with tunneling that resulted with both men having recurrent erections shortly after surgery that were found to be consistent with high-flow states. Case 1 was a 33-year-old male with sickle cell anemia and case 2 was a 24-year-old male with idiopathic thrombocytopenic purpura. In both cases the men were observed over several weeks and both men returned to normal erectile function. Conclusions . Historically, proximal shunts were performed only in cases when distal shunts failed and carry a higher risk of serious complications. T-shunts and other distal shunts combined with tunneling are being used more frequently in place of proximal shunts. These cases illustrate how postoperative erections after T-shunts with tunneling can signify a conversion from low-flow to high-flow states and could potentially be misdiagnosed as an operative failure.

  6. Penile angiography and superselective embolization therapy in arterial priapism; Penisangiographie und superselektive Embolisationstherapie bei high-flow Priapismus

    Energy Technology Data Exchange (ETDEWEB)

    Dinkel, H.P.; Triller, J. [Inst. fuer Diagnostische Radiologie, Inselspital, Univ. Bern (Switzerland); Hochreiter, W. [Urologische Klinik, Inselspital, Univ. Bern (Switzerland)

    2003-08-01

    Purpose: To report feasibility, benefit and complications of penile angiography and superselective penile embolization in arterial priapism. Materials and Methods: Four consecutive patients (aged 28, 29, 40 and 49 years), who underwent penile angiography for arterial priapism (high-flow priapism) within a four-year period, were identified by a keyword search of our radiology information system. One patient had sustained a direct penile trauma (severe blow to the erected penis) and three patients suffered from recurrent spontaneous priapism. All patients had previously undergone corporeal aspiration and noradrenaline injection to achieve detumescence. Two patients had one or several unsuccessful spongiocavernous shunt procedures. Results: In three of the four patients, superselective pudendal and penile angiography demonstrated pathologic arteriocavernous shunting. In two of the three patients, superselective embolization using a coaxial micro-catheter was attempted. In one of the two patients, the cavernous artery became spastic before embolization material was actually injected, inducing immediate and lasting detumescence. In the other patient, unilateral Gelfoam embolization led to immediate detumescence but the priapism recurred 12 hours after the procedure. A subsequent contralateral Gelfoam embolization was successful. Erectile function was preserved in all cases. No procedure-related complications occurred. Conclusion: Our experience supports the prevailing opinion found in the current literature that superselective coaxial embolization constitutes the treatment of choice in patients with high-flow priapism. Prognosis is good with high probability of preserving the erectile function. (orig.) [German] Ziel: Untersuchung der Interventionsmoeglichkeiten bei arteriellem (high-flow) Priapismus durch endovaskulaere superselektive Embolisation der Penisarterien. Methode: Alle innerhalb eines Vierjahreszeitraums (1/99-5/2002) wegen Priapismus zur Angiographie

  7. Clinical Management of Priapism: A Review

    Directory of Open Access Journals (Sweden)

    Kazuyoshi Shigehara

    2016-04-01

    Full Text Available Priapism is defined as a persistent and painful erection lasting longer than four hours without sexual stimulation. Based on episode history and pathophysiology, priapism is classified into three subtypes: ischemic (low-flow, non-ischemic (high-flow, and stuttering priapism. Ischemic priapism is characterized by a persistent, painful erection with remarkable rigidity of the corpora cavernosa caused by a disorder of venous blood outflow from this tissue mass, and is similar to penile compartment syndrome. Stuttering priapism is characterized by a self-limited, recurrent, and intermittent erection, frequently occurring in patients with sickle cell disease. Non-ischemic priapism is characterized by a painless, persistent nonsexual erection that is not fully rigid and is caused by excess arterial blood flow into the corpora cavernosa. Because ischemic and non-ischemic priapism differ based on emergency status and treatment options, appropriate discrimination of each type of priapism is required to initiate adequate clinical management. The goal of management of priapism is to achieve detumescence of the persistent penile erection and to preserve erectile function after resolution of the priapism. To achieve successful management, urologists should address this emergency clinical condition. In the present article, we review the diagnosis and clinical management of the three types of priapism.

  8. Management of Low-Flow Priapism Using the Winter Procedure: A Case Report

    Directory of Open Access Journals (Sweden)

    Chung-Chin Chen

    2003-02-01

    Full Text Available Priapism is a prolonged penile erection that is unrelated to sexual stimulation. Low-flow priapism has been associated with sickle cell disease and other hemoglobinopathies, neoplastic syndrome, anticoagulant therapy, psychotropic medication, and idiopathic causes. We report the successful treatment of idiopathic low-flow priapism using the Winter procedure. Initial treatment consisted of aspiration and intracavernous irrigation with iced saline and a vasoconstrictive agent, but in vain. We then performed the Winter procedure, in which fistulas between the corpora cavernosa and the glans penis were created. This resulted in the simultaneous detumescence of the penis, without complication. The erectile function of the penis was normal 1 year after the procedure. This case shows that idiopathic low-flow priapism can be successfully treated using the Winter procedure when conservative treatment fails.

  9. The Winter Procedure as Management for Prolonged Low-Flow Priapism: A Case Report

    Directory of Open Access Journals (Sweden)

    Hsi-Lin Hsiao

    2007-10-01

    Full Text Available Priapism is a prolonged penile erection that is not associated with sexual stimulation. Although the time course has not been formally defined, it is usually considered to be one that lasts for more than 4–6 hours. Low-flow (ischemic priapism is usually associated with sickle cell disease, hemoglobinopathies, neoplastic syndrome, anticoagulant therapy, psychotropic medication or idiopathic causes. Here, we report a case of prolonged low-flow priapism lasting for 2 weeks, which was successfully treated with the Winter procedure after several attempts of conservative treatment. Although the potency remains unclear and the patient needs a longer period of follow-up, the case reported here still shows that prolonged low-flow priapism can be successfully treated with the Winter procedure when conservative treatments fail.

  10. One month priapism in a 39 year old man with chronic myeloid ...

    African Journals Online (AJOL)

    Background: Priapism is an involuntary prolonged erection unrelated to sexual stimulation and unrelieved by ejaculation. There are two types of priapism ; low flow (ischaemic ) and high flow priapism. It presents with engorgement of corpora carvernosa sparing the copora spongiosum and glans penis, and can be ...

  11. Interventional management of low-flow priapism: A protocol proposal

    Directory of Open Access Journals (Sweden)

    Herney Andrés García-Perdomo

    2018-01-01

    Full Text Available Priapism is an involuntary prolonged erection that lasts for more than 4 h. Although several interventions have been proposed to manage the condition, these strategies are based on expert panel opinions, and little evidence exists regarding prognosis and outcomes. To synthetize information about interventions to treat priapism and to make evidence-based recommendations, we performed a literature search of Medline via Ovid, Scopus (including Embase and Lilacs from 1980 to the current day with the following keywords: ischemic priapism, erectile function, drainage, and shunt. The length of the ischemic priapism is an important variable for the prognosis because of the pathophysiology of this condition. Here, we propose a step-by-step approach based on the time and invasiveness of the intervention. However, it is important to note that we could not find any clinical trial that supports this approach, and more research is needed for the future statements.

  12. Priapism: etiology, pathophysiology and management

    Directory of Open Access Journals (Sweden)

    Van Der Horst C.

    2003-01-01

    Full Text Available The understanding of erectile physiology has improved the prompt diagnosis and treatment of priapism. Priapism is defined as prolonged and persistent erection of the penis without sexual stimulation and failure to subside despite orgasm. Numerous etiologies of this condition are considered. Among others a disturbed detumescence mechanism, which may due to excess release of contractile neurotransmitters, obstruction of draining venules, malfunction of the intrinsic detumescence mechanism or prolonged relaxation of intracavernosal smooth muscle are postulated. Treatment of priapism varies from a conservative medical to a drastic surgical approach. Two main types of priapism; veno-occlusive low flow (ischemic and arterial high flow (non-ischemic, must be distinguished to choose the correct treatment option for each type. Patient history, physical examination, penile hemodynamics and corporeal metabolic blood quality provides distinction between a static or dynamic pathology. Priapism can be treated effectively with intracavernous vasoconstrictive agents or surgical shunting. Alternative options, such as intracavernous injection of methylene blue (MB or selective penile arterial embolization (SPEA, for the management of high and low flow priapism are described and a survey on current treatment modalities is given.

  13. [Prophylaxis of recurring low-flow priapism : Experimental botulinum neurotoxin injection into the ischiocavernosus muscle].

    Science.gov (United States)

    Reichel, G; Stenner, A

    2018-01-01

    The treatment of recurring low-flow priapism with the usual medications is still unsatisfactory. The case of an otherwise healthy young man experiencing low-flow priapism at the age of 31 is presented. A reason for his condition could not be identified. Over the course of several months, he required emergency urological treatment more than ten times. Treatment with cyproterone acetate (Androcur® 50 mg/day) stopped the spontaneous erections, but resulted in erectile impotence, reduced motivation, decreased interest in sex, weight gain of 10 kg, breast enlargement combined with touch sensitivity on both sides, and hair loss on both legs. In addition, the patient complained about painful cramps in his pelvic muscles. After appropriate explanations he agreed to try botulinum neurotoxin injections into both ischiocavernosus muscles. The objective was to reduce muscle tone in order to improve venous drainage of blood from the penis. The latest relapse of priapism occurred more than 6 months ago.

  14. Successful Management of Psychotropics Induced Stuttering Priapism with Pseudoephedrine in a Patient with Schizophrenia.

    Science.gov (United States)

    Thippaiah, Srinagesh Mannekote; Nagaraja, Soumya; Birur, Badari; Pandurangi, Ananda

    2018-02-05

    Stuttering Priapism is a recurrent, persistent penile erection in the absence of sexual desire due to altered genital hemodynamics, affecting the arterial component (high flow, non-ischemic) or the veno-occlusive mechanism (low flow, ischemic). Both typical and atypical antipsychotics increase the risk for priapism with greater implications in typicals than atypicals. Prompt recognition and treatment are important as 40% to 50% of patients with stuttering priapism may develop an erectile dysfunction if left untreated. There are several case reports in the literature about the association between psychotropic agents and priapism. However, there are no reports of successfully treating stuttering priapism using pseudoephedrine (sudafed) in the adult population. Here we present successful management of psychotropics induced stuttering priapism with pseudoephedrine in a male patient with schizophrenia.

  15. Airborne Priapism: A Case of Nonischemic Priapism After Military Static-Line Parachute Injury.

    Science.gov (United States)

    Charny, Grigory; Booms, Zachary; McDonough, Patrick; Schauer, Steven

    2015-07-01

    We report the case of a 21-year-old active duty U.S. Army soldier with painful and nonresolving priapism following blunt pelvic and lower extremity trauma from military static-line parachute injury during training. The patient's condition was initially managed with corporal aspiration and intracavernosal injections of phenylephrine that provided temporary relief but recurrence soon after. Referral to Urology at the site of the patient's injury yielded a diagnosis of penile hematoma. On subsequent evaluation by Urology on return to the patient's home duty station (over 96 hours after injury, with symptoms persisting), the corpora cavernosa were rigid, the corpus spongiosum was soft, and corporal blood gas drawn by the emergency department consistent with arterial blood. Penile duplex ultrasound revealed an isolated arterial-cavernosal fistula within the proximal left corporal body. The patient underwent percutaneous embolization of the fistula with successful resolution of his condition and return of normal erectile function. We discuss this unique case of high-flow priapism occurring after blunt trauma from military parachute injury and review suggested management in a stepwise fashion. The case is significant in that extensive literature review yields no previously described case of priapism following trauma from military parachute injury. Reprint & Copyright © 2015 Association of Military Surgeons of the U.S.

  16. Aripiprazole-induced priapism

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    Satya K Trivedi

    2016-01-01

    Full Text Available Priapism is a urologic emergency representing a true disorder of penile erection that persists beyond or is unrelated to sexual interest or stimulation. A variety of psychotropic drugs are known to produce priapism, albeit rarely, through their antagonistic action on alpha-1 adrenergic receptors. We report such a case of priapism induced by a single oral dose of 10 mg aripiprazole, a drug with the least affinity to adrenergic receptors among all atypical antipsychotics. Polymorphism of alpha-2A adrenergic receptor gene in schizophrenia patients is known to be associated with sialorrhea while on clozapine treatment. Probably, similar polymorphism of alpha-1 adrenergic receptor gene could contribute to its altered sensitivity and resultant priapism. In future, pharmacogenomics-based approach may help in personalizing the treatment and effectively prevent the emergence of such side effects.

  17. Successful management of stuttering priapism using home self-injections of the alpha-agonist metaraminol

    Directory of Open Access Journals (Sweden)

    Mcdonald Michael

    2004-01-01

    Full Text Available Low-flow priapism can result in impotence if treatment is delayed, yet patients with recurrent priapism often suffer delay before therapy. We describe management of recurrent priapism using self-administered injections of intracavernosal metaraminol (Aramine™, Merck, a long-acting vasoconstricting amine that is considered safer than epinephrine. The patient injects as often as once daily using 5-10 mg of drug. Our patient reports rapid detumescence and has not required emergency room visits since starting injections. He denies complications. Treatment of priapism using metaraminol has been suggested in the hospital setting; however, this is the first report of successful home self-administration of the drug.

  18. Recurrent Priapism from Therapeutic Quetiapine

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    Omeed Saghafi

    2014-02-01

    Full Text Available Priapism is rarely related to use of non-erectile related medications. The objective was to educate about the multiple possible causes of priapism and to provide treatment recommendations for the different types of priapism. We present the case of a 43 year-old African American male with a history of schizoaffective disorder who presented to our emergency department multiple times over a three year period with priapism, each episode related to the ingestion of quetiapine. Following penile aspiration and intercavernosal injection of phenylephrine, this patient had resolution of his priapism. This case demonstrates an unusual case of recurrent priapism. [West J Emerg Med. 2014;15(1:114–116.

  19. Emergency department management of priapism [digest].

    Science.gov (United States)

    Podolej, Gregory S; Babcock, Christine; Kim, Jeremy

    2017-01-22

    Priapism is a genitourinary emergency that demands a thorough, time-sensitive evaluation. There are 3 types of priapism: ischemic, nonischemic, and recurrent ischemic priapism; ischemic priapism accounts for 95% of cases. Ischemic priapism must be treated within 4 to 6 hours to minimize morbidity, including impotence. The diagnosis of ischemic priapism relies heavily on the history and physical examination and may be facilitated by penile blood gas analysis and penile ultrasound. This issue reviews current evidence regarding emergency department treatment of ischemic priapism using a stepwise approach that begins with aspiration of cavernosal blood, cold saline irrigation, and penile injection with sympathomimetic agents. Evidence-based management and appropriate urologic follow-up of nonischemic and recurrent ischemic priapism maximizes patient outcomes and resource utilization. [Points & Pearls is a digest of Emergency Medicine Practice].

  20. Malignant Priapism Due to Metastatic Papillary Renal Cell Carcinoma : A Case Report

    OpenAIRE

    望月, 拓; 伊藤, 悠城; 栗田, 華代; 石垣, 華子; 林, 博文; 堀田, 綾子; 齋藤, 生朗; 平井, 耕太郎

    2012-01-01

    A 70-year-old man presented in December, 2010 with priapism persistent for over a month. The patient had no history of medications for erectile dysfunction, penis trauma, or traumatic sexual activities. A blood gas measurement of the cavernosum was performed, but only fibrosis tissue was aspirated and no blood was obtained. Color-flow Doppler imaging of the penis revealed blood flow in the corpora cavernosa of the penis, suggesting the occurrence of nonischemic priapism. Enhanced chest and ab...

  1. Barry shunt for treatment of a 76-hour stuttering priapism without subsequent erectile dysfunction

    Directory of Open Access Journals (Sweden)

    Osmonov DK

    2014-07-01

    Full Text Available Daniar Kurmanbekovich Osmonov, Aleksey Aksenov, Andrea Nathaly Guerra Sandoval, Almut Kalz, Klaus Peter Juenemann Department of Urology and Pediatric Urology, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany Introduction: This paper reports treatment of a 76-hour low-flow priapism with a shunting procedure that was first described by Barry in 1976. We were able to observe the preservation of erectile function despite the long period of ischemia. A review of the literature shows that there are few reports of erectile function recovery after a priapism of similar duration. Materials and methods: A 42-year-old patient presented with a 76-hour priapism, probably caused by consumption of alcohol and illegal drugs. A Barry Shunt procedure was performed. The erectile function of the patient was assessed by means of International Index of Erectile Function score over a follow-up period of 30 months. Moreover, we reviewed different surgical options for treatment of priapism in the literature. Results: Partial return of erection without sexual arousal occurred on two occasions during the 10-day hospitalization, but was treated by manipulation of the penis, ie, by milking the tumescence into the shunt. After 3 months, the shunt was still palpable as a subcutaneous swelling. Six months postoperatively, the residual swelling had disappeared. The International Index of Erectile Function score was of 21 without phosphodiesterase type 5 inhibitors after a follow-up of 2.5 years. Conclusion: Barry shunt is an effective alternative surgical option for the treatment of low-flow priapism. In the case of our patient, it was also effective after a 76-hour-lasting priapism. Keywords: low flow priapism, erectile function, cavernovenous shunt, surgical treatment of stuttering priapism

  2. Malignant priapism: a case report.

    LENUS (Irish Health Repository)

    Ellanti, P

    2011-12-01

    Metastatic involvement of the penis is most commonly from a primary malignant genitourinary tumour. It is a rare phenomenon usually reflecting disseminated malignancy associated with a poor prognosis. Metastasis to the penis mimicking priapism is extremely rare, particularly in the absence of disseminated disease.

  3. Nonischemic Priapism in Childhood: A Case Series and Review of Literature.

    Science.gov (United States)

    Hacker, Hans-Walter; Schwoebel, Marcus G; Szavay, Philipp O

    2018-06-01

     Nonischemic priapism (NIP) in childhood is a very rare affection. In the literature, patients with NIP are described mainly incidental after perineal trauma. Many of them underwent embolization of either internal pudendal artery or bulbocavernosal arteries.  We report on six boys between 4 and 13 years of age with NIP, treated at our institution between 2008 and 2014. Color Doppler ultrasound (CDU) was performed in all patients as emergency diagnostic evaluation. Patients were treated conservatively, including bed rest, local cooling, and perineal compression. History, etiological factors, clinical findings, diagnostics, and follow-up are presented.  Out of the six patients, only one boy had a history of perineal injury with subsequent arteriocavernosal fistula, revealed in CDU. Five patients were circumcised, and one of them suffered from thalassemia minor, but no other underlying disease or etiological factors could be found. In all patients, normal to high blood flow velocities were detected in the cavernosal arteries. Detumescence started with nonoperative treatment within 24 hours in five boys and in one patient with recurrent priapism after 1 week. All six patients remained painless without evidence for an ischemic priapism. None of them suffered from relapse and further erections were observed during follow-up from 3 to 87 months.  In contrast to the literature, five out of six boys developed NIP without a previous perineal trauma. The etiology of idiopathic NIP in childhood remains unclear; however, circumcision may play a role as a conditional factor. One etiological thesis could be the release of the neurotransmitter nitric oxide after stimulation of the corpora cavernosa. Conservative treatment proved to be successful in all six patients. During a median follow-up of 55 months (3-87 months), none of the patients showed signs of erectile dysfunction. Georg Thieme Verlag KG Stuttgart · New York.

  4. Priapism caused by 'Tribulus terrestris'.

    Science.gov (United States)

    Campanelli, M; De Thomasis, R; Tenaglia, R L

    2016-01-01

    A 36-year-old Caucasian man was diagnosed with a 72-h-lasting priapism that occurred after the assumption of a Herbal supplement based on Tribulus terrestris, which is becoming increasingly popular for the treatment of sexual dysfunction. The patient underwent a cavernoglandular shunt (Ebbehoj shunt) in order to obtain complete detumescence, from which derived negative post-episode outcomes on sexual function. All patients consuming non-FDA-approved alternative supplements such as Tribulus terrestris should be warned about the possible serious side effects.

  5. Medical management of ischemic stuttering priapism: a contemporary review of the literature.

    Science.gov (United States)

    Levey, Helen R; Kutlu, Omer; Bivalacqua, Trinity J

    2012-01-01

    Priapism is defined as a prolonged and persistent erection of the penis without sexual stimulation. This is a poorly understood disease process with little information on the pathophysiology of this erectile disorder. Complications from this disorder are devastating due to the irreversible erectile damage and resultant erectile dysfunction (ED). Stuttering priapism, though relatively rare, affects a high prevalence of men with sickle-cell disease (SCD) and presents a challenging problem with guidelines for treatment lacking or resulting in permanent ED. The mechanisms involved in the development of priapism in this cohort are poorly characterized; therefore, medical management of priapism represents a therapeutic challenge to urologists. Additional research is warranted, so we can effectively target treatments for these patients with prevention as the goal. This review gives an introduction to stuttering priapism and its clinical significance, specifically with regards to the patient with SCD. Additionally, the proposed mechanisms behind its pathophysiology and a summary of the current and future targets for medical management are discussed.

  6. Homocysteinemia: A rare cause of priapism

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    Jaisukh Kalathia

    2016-01-01

    Full Text Available Priaprism is a persistent painful erection that continuous beyond or is unrelated to sexual stimulation. Majority of cases are idiopathic (46%, alcohol and drug related (21%, perineal trauma (12%, sickle cell anemia and hypercoagualable state related (11%. We report case of priapism caused by hyperhomocysteinemia with favorable outcome with only few cases so far reported in the literature to the best of our knowledge. A 31 year-old male referred to our institution with non resolving priaprism for the last 6 days. Immediate distal shunt (Al-ghorab was created but it could not achieve the detumescence. The penile Doppler showed no flow into the corpora, so a proximal shunt (Quackels was made which achieved satisfactory detumescence. On thorough evaluation for the cause of priaprism, only homocysteine level was found to be significantly raised (40.46 µmol/L, being the unusual and rare cause for priaprism. The patient was discharged on homocheck. In the follow-up the patient is on vacuum assisted device for the erectile dysfunction and has been advised for the penile implant. Priaprism being a urological emergency should be thoroughly evaluated even for the rare causes and should be timely intervened to avoid the unavoidable consequences of permanent erectile dysfunction.

  7. Recurring priapism may be a symptom of voiding dysfunction – case report and literature review

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    Lisieux Eyer de Jesus

    2016-04-01

    Full Text Available ABSTRACT Recurring priapism is rare in pre-pubertal children and may be attributed to multiple causes. We propose that voiding dysfunction (VD may also justify this symptom and detail a clinical case of recurring stuttering priapism associated to overactive bladder that completely resolved after usage of anticholinergics and urotherapy. Sacral parasympathetic activity is responsible for detrusor contraction and for spontaneous erections and a relationship between erections and bladder status has been proved in healthy subjects (morning erections and models of medullar trauma. High bladder pressures and/or volumes, voiding incoordination and posterior urethritis can potentially trigger reflex erections.

  8. Penile Gangrene: An Unusual Complication of Priapism in a Patient ...

    African Journals Online (AJOL)

    3. 13. Badmus TA, Adediran IA, Adesunkanmi AR, Katung IA. Priapism in southwestern Nigeria. East Afr Med J 2003;80:518-24. 14. Ajape AA, Kuranga IS, Babata AL, Abiola OO, Obiano SK, Sanni MA, et al. Priapism as an initial presentation of ...

  9. Is Priapism Really A Surgical Emergency? | Adetayo | Nigerian ...

    African Journals Online (AJOL)

    Fifty-six (56) patients with 60 episodes of priapism treated surgically over a 14 year period were studied. The aim was to determine whether this condition is a surgical emergency or not. The mean age of the patients was 23.6+8.7 years. All the patients who had their priapism relieved within 24 hours (one day) of onset were ...

  10. Chronic myeloid leukaemia presenting with priapism as the only ...

    African Journals Online (AJOL)

    Objective: There have been few reports of priapism as complications of various haematological malignancies. Delays in establishing the cause and late institution of appropriate intervention in patients suffering from priapism could result in long-term complications, especially erectile dysfunction. We present here a case of ...

  11. Prognostic factors and outcome of management of ischemic priapism in Zaria, Nigeria

    Directory of Open Access Journals (Sweden)

    Muhammed Ahmed

    2017-01-01

    Full Text Available Objectives: The objective of this study was to determine the nuances of management, prognostic factors, and outcome of ischemic priapism in patients seen at Ahmadu Bello University Teaching Hospital, Zaria, Nigeria. Patients and Methods: We retrospectively studied the case notes of all patients managed for ischemic priapism in the Ahmadu Bello University Teaching Hospital, Zaria, over a period of 10 years (2006–2015. The data extracted included patients' age, occupation, duration of painful penile erection, and previous episodes. Addition information including precipitating factors, hemoglobin genotype, treatment, and complications was also retrieved. Data obtained were analyzed using SPSS version 20. Results: The records of a total of forty patients managed for priapism over the period under review were retrieved. Thirty-three (82.5% of these patients had an operative intervention. The mean age was 23.7 years with a range of 8–53 years. Sixty percent of patients were young adults in their third decade of life. The minimum duration of erection at presentation was 18 h and a maximum period of 10 days with a mean of 105.5 h (4 days. Thirty-three patients (82.5% had sickle cell anemia (HbSS. Erectile dysfunction (ED accounted for 60% of all forms of postpriapism complications. Five patients (12.5% had residual tumescence from fibrosis, and three patients had recurrence outside the immediate postoperative period. Duration of symptoms before surgical intervention, SSA and previous episodes were the most important prognostic factors. Conclusion: Priapism is a disease of the young, mostly sickle cell anemic patients. Late presentation remains the norm in our environment, hence a higher incidence of ED. The distal penile shunt is an effective means of achieving detumescence even with failed conservative management. Favorable outcome is highly dependent on the duration of erection and early intervention.

  12. Priapism in Sickle Cell Disease: A Hematologist’s Perspective

    Science.gov (United States)

    Kato, Gregory J.

    2011-01-01

    Introduction Priapism is a familiar problem to hematologists, well known for its association with sickle cell disease. It also occurs in a variety of other hematological illnesses, nearly all forms of congenital hemolytic anemia, including other hemoglobinopathies and red blood cell membranopathies and enzymopathies. Aim Provide urologists with a comprehensive review of priapism in sickle cell disease, with an emphasis on the perspective of a practicing hematologist. Methods Medline searches through July 2010 were conducted using the terms priapism, erectile dysfunction, and sickle cell. Main Outcome Measure Expert opinion was based on review of the medical literature related to this subject matter. Results In men with sickle cell disease, large epidemiological studies have linked the risk of priapism to clinical markers of the severity of intravascular hemolysis. Extracellular hemoglobin and arginase released during hemolysis has been implicated in reducing nitric oxide bioavailability, although the relevance of hemolysis to vascular dysfunction has been challenged by some scientists. Consistent with the role of impairment of the nitric oxide axis, mice genetically deficient in nitric oxide production have also been shown to develop priapic activity. Provocative new data indicates that hemolysis-linked dysregulation of adenosine signaling in the penis contributes to priapism in sickle cell mice. Serious questions have arisen regarding the efficacy of mainstays of textbook dogma for treatment of acute severe priapism, including intravenous fluids, alkalinization and exchange transfusion, and there is increasing acceptance for early aspiration and irrigation of the corpus cavernosum. Conclusions For sickle cell patients with recurrent priapism, there is very limited evidence for a medical prophylaxis role for hydroxyurea, etilefrine, pseudoephedrine, leuprolide, sildenafil, and other agents. Recent publications have highlighted nitric oxide and adenosine signal

  13. Malignant priapism: Penile metastasis originating on a primary prostate adenocarcinoma

    Directory of Open Access Journals (Sweden)

    Sandro Roberto da Silva Gaspar

    2015-01-01

    Full Text Available Malignant priapism is a definition invented in 1938 by Peacock, defined as a persistent erection, not related with sexual activity, caused by cavernous sinus and associated venous systems invasion with malignant cells. Penile secondary lesions are rare entities. Primary locations are usually the pelvic cavity organs, namely the prostate and the bladder as the most common ones. Priapism as a first manifestation of these kinds of lesions is even rarer. The aim was to present a 52-year-old patient harboring a penile metastasis that originated in the primary prostate adenocarcinoma, manifesting itself as a "common" priapism. The patient referred to the emergency room presenting with a priapism and nodules at the coronal sulcus, without previous similar episodes. His evolution until properly diagnosed was catastrophic with multiple lymph nodes, bone and organ involvement, and with his demise soon after from serious bleeding and congestive heart failure, almost 2 months after he first came to the emergency room. We review the literature concerning malignant priapism, diagnosis, and current treatment and survival perspectives.

  14. Hematological parameters in sick cell anemia patients with and without priapism

    International Nuclear Information System (INIS)

    Ahmed, Sagir G.; Ibrahim, Umma A.; Hassan, Abba W.

    2006-01-01

    Priapism was associated with certain hematological parameters in sickle cell anemia (SCA) patients in one report but not in another. We studied differences haematological parameters between SCA patients with and without priapism. Eighteen patients with SCA who presented with acute priapism during the years 2001-2004 were compared with age-and sex-matched SCA patients without priapism with respect to hematocrit, reticulocyte count, level of irreversibly sickled cells (ISC), percentage of haemoglobin (Hb F), total leukocyte and platelet counts. SCA patients with priapism had a mean hematocrit of 0.28 L/L, which was significantly higher than mean hematocrit value of 0.24 L/L (P<0.05) in patients without priapism. The mean reticulocyte count of 8% in patients with priapism was siginificantly lower than mean reticulocyte count of 12% (P<0.05) in patients without priapism. The level of ISC of 3% in patients with priapism was significantly lower than the level of 6.5% (P<0.05) in patients without priapism. There was no statistically significant difference in the mean levels of Hb F (7% vs. 6%). Patients with priapism had a mean leukocyte count that did not significantly differ from values in patients without priapism. SCA patients with priapism had a lower rate of hemolysis resulting in a higher hematocrit and greater blood viscosity, which increased the risk of corpora cavernosal sickling and blockade. Hence, a relatively higher hematocrit is risk factor for the development priapism in patients with sickle cell anemia. (author)

  15. Penile fracture in a patient with stuttering priapism | Badmus | West ...

    African Journals Online (AJOL)

    Penile fracture commonly results from trauma of sexual intercourse or masturbation. It is common in the Middle East and America, but rare in Nigeria and sub-Sahara Africa. We present a case of penile fracture, an uncommon urologic emergency, complicating priapism, another urologic emergency; precipitated in an ...

  16. Priapisme induit par la chlorpromazine: A propos de deux cas

    African Journals Online (AJOL)

    I. Marrag

    We report here two cases of priapism associated with chlorpromazine. The first one ... who was admitted for a manic episode in the context of bipolar disorder. The second ... comportement à type d'hétéroagressivité verbale et physique envers.

  17. Priapisme induit par la chlorpromazine: A propos de deux cas

    Directory of Open Access Journals (Sweden)

    I. Marrag

    2016-06-01

    Le priapisme veineux est une urgence urologique. Il constitue un des effets secondaires des neuroleptiques parmi les quels la chlorpromazine. Cet effet iatrogène, qui est rare mais grave, doit être connu par les cliniciens afin d’être mieux prévenu pour éviter les séquelles érectiles.

  18. Effects of cigarette smoking on priapism induced by quetiapine: a case report

    Directory of Open Access Journals (Sweden)

    Hosseini Seyed

    2012-10-01

    Full Text Available Abstract Priapism is defined as an unwanted, prolonged, and painful erection which is unrelated to sexual stimulation. Some case studies suggest that priapism is an adverse effect of antipsychotic medications. In our case study a 30 year-old Iranian male with schizophrenia was experiencing recurrent priapism associated with quetiapine use. There are three interesting facts about this case: Firstly, the patient suffered priapism after even low dose consumption of quetiapine. Secondly, this case had experienced priapism with risperidone, olanzapine, and even clozapine in the past, suggesting a possible pharmacodynamic interaction of antipsychotics and inner biological traits in this particular case. Thirdly, priapism induced by low dose quetiapine was resolved after cigarette smoking.

  19. Refractory priapism associated with ingestion of yohimbe extract

    OpenAIRE

    Myers, Amy; Barrueto, Fermin

    2009-01-01

    Extracts of the bark of the central African treePausinystalia yohimbe contain yohimbine, an indole alkaloid, which is used to treat erectile dysfunction. The reported side effects of over-the-counter preparations of yohimbine include gastrointestinal upset, anxiety, increased blood pressure, headache, agitation, rash, tachycardia, and frequent urination. In this report, we describe a severe case of intractable priapism associated with the ingestion of yohimbe extract. Management required inse...

  20. Refractory priapism associated with ingestion of yohimbe extract.

    Science.gov (United States)

    Myers, Amy; Barrueto, Fermin

    2009-12-01

    Extracts of the bark of the central African tree Pausinystalia yohimbe contain yohimbine, an indole alkaloid, which is used to treat erectile dysfunction. The reported side effects of over-the-counter preparations of yohimbine include gastrointestinal upset, anxiety, increased blood pressure, headache, agitation, rash, tachycardia, and frequent urination. In this report, we describe a severe case of intractable priapism associated with the ingestion of yohimbe extract. Management required insertion of a proximal cavernosal spongiosum shunt (Quackles shunt) in the operating room.

  1. Poorly Controlled Homocystinuria: A Rare Cause of Ischemic Priapism?

    OpenAIRE

    Mark Johnson, BSc, MBChB; Elaine Murphy, MRCP, FRCPath; Amr Raheem, MB BCh, PhD; David Ralph, BSc, MS FRCS(Urol)

    2018-01-01

    We report on the 1st case of ischemic priapism secondary to poorly controlled homocystinuria. Homocystinuria is a rare, autosomal recessive, inherited disorder of metabolism that is caused by a deficiency of cystathionine synthase, leading to marked hyperhomocysteinemia. Arterial and/or venous thromboemboli are a major cause of mortality and morbidity in patients with homocystinuria. Untreated patients have a 50% chance of having a vascular event by 30 years of age. Increased homocysteine lev...

  2. Priapism associated with lumbar stenosis in a dog.

    Science.gov (United States)

    Payan-Carreira, R; Colaço, B; Rocha, C; Albuquerque, C; Luis, M; Abreu, H; Pires, M A

    2013-08-01

    Priapism, a persistent long-lasting involuntary erection of the penis, is uncommon in dogs. In this report, the case of a 13-year-old male Pointer, referred to our services due to persistent exposition of the penis, is described. This condition was consecutive to an intermittent priapism situation lasting for several days, which has been initially attributed to the inflammation and haematoma associated with a perianal bite. The owners became unable to retract the penis into the prepuce. At presentation, the dog was anorectic for 48 h, intolerant to manipulation, and showed poor body condition and unsteady locomotion. During physical evaluation, a marked engorgement of the local vessels in the prepuce and penis was found. An abdominal X-ray was asked under the suspicion of a neurogenic origin for the clinical situation, which showed evidences of spondylosis. After discussion of the clinical condition, the owners asked for euthanasia. The necropsy confirmed the engorgement of the regional vessels deriving from the pudendal arteries and blood accumulation within all the cavernous spaces, accompanied by congestion and thrombosis within the erectile structures of the penis. No significant changes were observed in the pelvic organs that could be at the origin of priapism. The lumbar-sacral spinal regions were carefully inspected and evidenced signs of L7-S1 stenosis due to spondylosis. The case presented herein is a rare situation of priapism of neurogenic origin in a dog. Necropsy findings suggest that it was consecutive to cauda equina compression due to lumbar spinal stenosis. © 2013 Blackwell Verlag GmbH.

  3. Priapism Followed by Discontinuation of Methadone: A rare Case Report

    Directory of Open Access Journals (Sweden)

    Seyed-Ali Mostafavi

    2015-10-01

    Full Text Available Objective: Priapism is defined by persistent, painful penile erection which occurs without sexual stimulation. Methadone is used as an analgesic and is also used in detoxification and maintenance protocol for opioid dependence treatment. Here we will report a case of a male with priapism after rapid discontinuation doses of methadone.Case presentation: The case was a young married male who referred to a psychiatry clinic due to long-time spontaneous erections. The patient had no history of mental disorders, trauma or sickle cell anemia. He used to smoke opium for five years and used methadone for four years at a dose of 17 cc daily, which he abruptly discontinued. Then he often experienced spontaneous and painful erections without physical or mental stimulation that caused him shame and embarrassment .Conclusion: In this case, chronology indicates that rapid discontinuation of methadone was possibly responsible for the occurrence of priapism. This may have happened due to a compensatory reaction to methadone side effect of erectile dysfunction, followed by its rapid withdrawal.

  4. TREATMENT OF PRIAPISM BY INJECTION OF ADRENALINE INTO THE CORPORA CAVERNOSA PENIS

    NARCIS (Netherlands)

    VANDRIEL, MF; MOOIBROEK, JJ; MENSINK, HJA

    1991-01-01

    Intracavernous papaverine injection has gained widespread acceptance in the treatment of erectile impotence. The opposite problem-priapism -can be treated with the same technique using a vasoconstrictive drug such as adrenaline. We report on eight patients successfully treated for priapism by

  5. Priapism in paediatric patients with sickle cell disease - a report of ...

    African Journals Online (AJOL)

    Results: Of the 185 SCD cases, three (1.6%) had priapism. They were adolescents aged 17years, 11years and 10 years 9months respectively. Two patients had never attended a sickle cell clinic, never been on routine drugs nor received advice on oral liberal fluids intake. One patient had stuttering priapism, 24hours before ...

  6. Pattern and management of priapism in a tertiary hospital of North ...

    African Journals Online (AJOL)

    Three patients (11.5%) developed erectile dysfunction. Conclusion: Sickle cell disease is the commonest cause of ischaemic priapism in our practice. Late presentation is common and is usually associated with the development of erectile dysfunction. Keywords: priapism, sickle cell disease, aphrodisiacs, erectile ...

  7. Semi-rigid penile prosthesis as a salvage management of idiopathic ischemic stuttering priapism

    Directory of Open Access Journals (Sweden)

    Faddan AA

    2015-09-01

    Full Text Available Amr A Faddan, Alexey V Aksenov, Carsten M Naumann, Klaus P Jünemann, Daniar K Osmonov Department of Urology and Pediatric Urology, University Hospital Schleswig-Holstein, Kiel, Germany Introduction: Priapism is the persistent erection resulting from dysfunction of the mechanisms that regulate penile swelling, stiffness, and sagging. It is a full or partial erection that persists for a period more than 4 hours beyond sexual stimulation and/or orgasm or is unrelated to sexual stimulation. Ischemic priapism should be managed in a step-by-step fashion. Objective: To demonstrate step-by-step management of stuttering refractory ischemic priapism. We report a case of stuttering refractory ischemic priapism. Moreover, we reviewed different approaches to priapism management in the literature. Case presentation: A 53-year-old male presented with a painful erection of 29 hours’ duration, probably caused by consumption of alcohol. The penile blood gas showed a pH of 7.08, PCO2 of 75 mmHg and PO2 of 39 mmHg. Aspiration was followed by irrigation of an α-adrenergic, Winter and T-shunt operations were preformed, and finally a semi-rigid penile prosthesis was implanted to overcome the refractory stuttering ischemic priapism. Conclusion: In case of stuttering refractory ischemic priapism, immediate implantation of a penile prosthesis is a simple and effective procedure that manages both the acute episode and the inevitable erectile dysfunction that would otherwise occur, while preserving penile length. Keywords: priapism, stuttering priapism, shunting operation, penile prosthesis 

  8. Recent advances in the management of priapism [version 1; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Asif Muneer

    2018-01-01

    Full Text Available Priapism is an uncommon urological emergency that can lead to permanent impotence if prompt presentation and medical intervention is not performed. It is a breakdown of the usual physiological mechanisms controlling penile tumescence and detumescence, leading to a prolonged penile erection (>4 hours that is unrelated to sexual stimulation. Currently, there are three accepted subtypes: ischaemic, non-ischaemic, and stuttering priapism, which is also known as recurrent ischemic priapism. The aim of treatment is the immediate resolution of the painful erection and the preservation of cavernosal smooth muscle function in order to prevent cavernosal fibrosis, which can lead to penile shortening and permanent erectile dysfunction.

  9. High flow ceramic pot filters.

    Science.gov (United States)

    van Halem, D; van der Laan, H; Soppe, A I A; Heijman, S G J

    2017-11-01

    Ceramic pot filters are considered safe, robust and appropriate technologies, but there is a general consensus that water revenues are limited due to clogging of the ceramic element. The objective of this study was to investigate the potential of high flow ceramic pot filters to produce more water without sacrificing their microbial removal efficacy. High flow pot filters, produced by increasing the rice husk content, had a higher initial flow rate (6-19 L h -1 ), but initial LRVs for E. coli of high flow filters was slightly lower than for regular ceramic pot filters. This disadvantage was, however, only temporarily as the clogging in high flow filters had a positive effect on the LRV for E. coli (from below 1 to 2-3 after clogging). Therefore, it can be carefully concluded that regular ceramic pot filters perform better initially, but after clogging, the high flow filters have a higher flow rate as well as a higher LRV for E. coli. To improve the initial performance of new high flow filters, it is recommended to further utilize residence time of the water in the receptacle, since additional E. coli inactivation was observed during overnight storage. Although a relationship was observed between flow rate and LRV of MS2 bacteriophages, both regular and high flow filters were unable to reach over 2 LRV. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Pattern and Management of Priapism in a Tertiary Hospital of North ...

    African Journals Online (AJOL)

    ADMIN

    COSECSA/ASEA Publication --East & Central African Journal of Surgery 2017; Vol. 22 (1) ... Hospital of North- Western Nigeria ... In Western world, ischaemic priapism is .... This difference can be accounted for by the late presentation in.

  11. Oral phosphodiesterase type 5 inhibitors alleviate recurrent priapism complicating thalassemia intermedia: a case report

    NARCIS (Netherlands)

    Tzortzis, Vassilios; Mitrakas, Lampros; Gravas, Stavros; Mamoulakis, Charalampos; Meissner, Andreas; Kyriakou, Despina; Melekos, Michael D.

    2009-01-01

    Recurrent ischemic priapism still remains a serious and difficult to treat complication of certain hematological disorders. Elucidation of the underlying pathophysiologic mechanisms and application of new effective prophylactic treatments are needed. To present the efficacy of phosphodiesterase type

  12. Is there a relation between priapism occurring after penile doppler ultrasonography and international erectile function index score and erection hardness score levels?

    Science.gov (United States)

    Sönmez, Mehmet Giray; Öztürk, Ahmet

    2017-12-01

    The relation between Erection Hardness Score (EHS) and The International Erectile Function Index (IIEF) Questionnaire- Erectile Function Domain Score (IIEF-EF score) used in erectile dysfunction (ED) evaluation and the prevalence of priapism after penile Doppler ultrasonography (PDU) was examined in this study. A total of 62 patients who had PDU were included in the study. Patients were divided into two groups; there were 33 patients in IIEF-EF score ≤10, EHS 10, EHS ≥2 group (Group 2). The two groups separated according to their scores were compared for age, body mass index (BMI), prevalence of priapism, vascular comorbidities and duration of erection. When compared to Group 2, median age, rate of vascular comorbidities rate and BMI were detected to be higher in Group 1 with IIEF-EF score ≤10 and EHS 10 and EHS ≥2 (p<0.001, p=0.027, p=0.049 respectively). High IIEF-EF and EHS scores, younger ages and lower rates of vascular comorbidities in patients from whom PDU was demanded increase the prevalence of priapism.

  13. Megalophallus as a sequela of priapism in sickle cell anemia: use of blood oxygen level-dependent magnetic resonance imaging.

    Science.gov (United States)

    Kassim, A A; Umans, H; Nagel, R L; Fabry, M E

    2000-09-01

    Priapism is a common complication of sickle cell anemia. We report a little known sequela of priapism: painless megalophallus, with significant penile enlargement. The patient had had an intense episode of priapism 9 years previously and his penis remained enlarged. Blood oxygen level-dependent magnetic resonance imaging revealed enlarged, hypoxic corpora cavernosa. Megalophallus probably resulted from permanent loss of elasticity of the tunica albuginea due to severe engorgement during the episode of priapism. This sequela needs to be recognized by physicians because no intervention is necessary and sexual function seems to remain intact.

  14. High flow ceramic pot filters

    OpenAIRE

    van Halem, D.; van der Laan, H.; Soppe, A. I.A.; Heijman, S.G.J.

    2017-01-01

    Ceramic pot filters are considered safe, robust and appropriate technologies, but there is a general consensus that water revenues are limited due to clogging of the ceramic element. The objective of this study was to investigate the potential of high flow ceramic pot filters to produce more water without sacrificing their microbial removal efficacy. High flow pot filters, produced by increasing the rice husk content, had a higher initial flow rate (6–19 L h−1), but initial LRVs for E. coli o...

  15. Management of priapism with a trial of exercise in the emergency department.

    Science.gov (United States)

    Gravel, Jonathan; LeBlanc, Constance; Varner, Catherine

    2018-03-16

    Priapism is characterized by persistent penile erection in the absence of sexual arousal or desire that does not subside with orgasm. Although relatively uncommon, it is a genitourinary emergency that necessities prompt work-up and appropriate management, as there is a time-dependent relationship between total duration of erection and an increasing risk of permanent erectile dysfunction. Confirming the type of priapism is key to proper management, but the majority of cases presenting to the emergency department are ischemic in nature. Conservative management strategies for ischemic priapism are sparsely described in the literature but generally include ice pack application to the area, cold showers, masturbation and rarely, exercise. These strategies lack sound evidence, but the risks of attempting them are minimal as long as access to more definitive treatment is not delayed. Lower-limb exercise as a first-line treatment warrants further study in the undifferentiated emergency department priapism population. The case we present and discuss here illustrates the potential benefits of a trial of acute lower-limb exercise, specifically stair climbing, as a treatment for medication-induced priapism. If effective, this simple non-invasive management strategy may decrease the time to effective treatment, requires minimal resource utilization, and ultimately, avoids the need for more invasive treatment.

  16. Grain Flow at High Stresses

    Science.gov (United States)

    McSaveney, M. J.

    2015-12-01

    The transport mechanism of rapid long-runout rock avalanches was a hotly debated topic when I came on the scene in 1967. So how come it is still debated today? My explanation is that it is the expected outcome of peer review, poor comprehension, and technological advances outpacing intellectual advances. Why think about the problem when we can model it! So let us think about the problem. Shreve thought that rock avalanches fell upon and trapped a layer of air. What physics was he thinking about? It is how feathers and tissue papers fall. When my rock avalanches fly, they fly like unlubricated bricks using the physics of projectiles and ballistics. But the main transport mechanism is not flight. The dominant impression from watching a rock avalanche in motion is of fluid flow, as Heim described it in 1882. A rock avalanche is a very large grain flow. Bagnold studied dispersive grain flows, but why should one assume that rock avalanches are dispersive grain flows as many do. The more common grain flow type is a dense grain flow and rock avalanches are dense grain flows in which the weight can and does generate very high stresses at grain contacts. Brittle rock deforms elastically up to its compressive strength, whereupon it breaks, releasing elastic strain as transient elastic strain (seismic energy to a seismologist, acoustic energy to a physicist). Melosh and others have shown that acoustic energy can fluidize a grain mass. There is no exotic physics behind grain flow at high stress. When grains break, the released elastic strain has to go somewhere, and it goes somewhere principally by transmission though grain contacts. Depending on the state of stress at the grain contact, the contact will pass the stress or will slip at conventional values of Coulomb friction. Enough thinking! A physical model of the entire process is too big for any laboratory. So whose numerical model will do it?

  17. Priapism associated with the use of stimulant medications and atomoxetine for attention-deficit/hyperactivity disorder in children.

    Science.gov (United States)

    Eiland, Lea S; Bell, Edward A; Erramouspe, John

    2014-10-01

    To review the association of priapism with stimulant medications and atomoxetine commonly used in the treatment of attention-deficit/hyperactivity disorder (ADHD). A comprehensive literature search was conducted through PubMed (1966-May 15, 2014) using the search terms priapism, methylphenidate, amphetamine, atomoxetine, attention-deficit disorder with hyperactivity, and pediatrics. Google Scholar, Scopus, and the Food and Drug Administration (FDA) Web site were also searched. References from identified literature were also reviewed. All identified literature focused on ADHD treatment. Literature regarding priapism caused by methylphenidate, amphetamines, and atomoxetine were included. Stimulant medications and atomoxetine have been linked to the occurrence of priapism in children. Specifically, methylphenidate has been implicated in a recent FDA safety announcement warning as a result of 15 case reports (mean age = 12.5 years), and thus, the drug label and medication guides have been updated to reflect this concern. Prolonged erections and priapism occurred with immediate- and long-acting products, dose increases, and drug withdrawal periods. Priapism has also occurred in 4 patients taking amphetamines and one 11-year-old patient taking atomoxetine for ADHD. Priapism has been associated with stimulants, amphetamines, and atomoxetine use for ADHD in children. Providers and health care practitioners should educate male patients prescribed these ADHD medications as well as caregivers regarding the signs, symptoms, and complications with priapism. Discontinuation and evaluation of the medication is warranted if this adverse drug reaction occurs. Depending on the priapism subtype, other products may be initiated or medications not associated with priapism may be utilized. © The Author(s) 2014.

  18. High flow ceramic pot filters

    NARCIS (Netherlands)

    van Halem, D.; van der Laan, H.; Soppe, A. I.A.; Heijman, S.G.J.

    2017-01-01

    Ceramic pot filters are considered safe, robust and appropriate technologies, but there is a general consensus that water revenues are limited due to clogging of the ceramic element. The objective of this study was to investigate the potential of high flow ceramic pot filters to produce more

  19. Daily tadalafil for the chronic phase of stuttering priapism: a case report.

    Science.gov (United States)

    Massenio, Paolo; D'Altilia, Nicola; Sanguedolce, Francesca; Carrieri, Giuseppe; Cormio, Luigi

    2018-05-31

    Recurrent (stuttering) ischemic priapism is a challenging clinical condition. Frequent recurrences result in frequent hospital admissions whereas treatment with a shunting procedure often results in erectile dysfunction. A 22-year-old man with stuttering idiopathic priapism developed erectile dysfunction (IIEF-5 score 12) following a Winter's shunt; he was given tadalafil, 5 mg/daily, for 6 months. This treatment resulted in progressive restoration of erectile function in the 6 months following the shunt as well as in preventing recurrence of priapic episodes over a 24-month follow-up. This is the first report in literature of chronic treatment of stuttering priapism with a phosphodiesterase-5 inhibitor being able not only to prevent recurrent priapic episodes but also to restore erectile function following a Winter's shunt.

  20. Malignant priapism due to penile metastases: Case series and literature review

    Directory of Open Access Journals (Sweden)

    Francesco De Luca

    2016-07-01

    Full Text Available Malignant priapism secondary to penile metastases is a rare condition. This term was originally used by Peacock in 1938 to describe a condition of painful induration and erection of the penis due to metastatic infiltration by a neoplasm. In the current literature there are 512 case reports. The primary tumor sites are bladder, prostate and rectum. The treatment has only palliative intent and consists of local tumor excision, penectomy, radiotherapy and chemotherapy. We present one case of malignant priapism originated from prostate cancer, and two from urothelial carcinoma of the bladder. Different approaches in diagnosis and therapy were performed. The entire three patient reported a relief of the pain following the treatment, with an improvement of their quality of life, even though it was only temporary as a palliative. Malignant priapism is a rare medical emergency. Penile/pelvis magnetic resonance imaging (MRI scan and corporal biopsies are considered an effective method of diagnosis of the primary organ site.

  1. Testosterone Replacement Therapy in Adolescents With Sickle Cell Disease Reverses Hypogonadism Without Promoting Priapism: A Case Report

    Directory of Open Access Journals (Sweden)

    Belinda F. Morrison

    2015-11-01

    Full Text Available Delayed puberty secondary to hypogonadism is commonly seen in sickle cell disease (SCD, affecting normal growth and development. The condition is rarely treated in SCD for fear of inducing priapism episodes. We present a case report of an Afro-Jamaican adolescent male at 16 years of age who presented with symptoms of delayed puberty as well as frequent stuttering priapism episodes. Endocrinological assessment revealed low serum total testosterone levels. Treatment was commenced monthly with testosterone enanthate which resulted in improved symptoms of delayed puberty, improvement in anthropometric parameters while apparently ameliorating priapism episodes.

  2. Prise en charge du priapisme à bas débit vue tardivement : à propos ...

    African Journals Online (AJOL)

    Introduction: Priapism is a rare condition, affecting young adults and is defined as a prolonged and painful erection of the corpora cavernosa, without ejaculation and with absence of sexual desire or local stimulation. The delay of care can affect sexuality with significant psychological impact. The objective is to study clinical, ...

  3. Priapism in type II Diabetes Mellitus: A case report | Muthuuri | East ...

    African Journals Online (AJOL)

    Priapism in type II diabetes mellitus is an uncommon event. A case of this condition in an adult male is presented. More common precipitating factors such as use of medications like sildenafil or use of an intracarvenosal vasodilator was absent, although diagnostic investigations postulated the cause as thrombotic factors in ...

  4. The possible protective effects of dipyridamole on ischemic reperfusion injury of priapism

    Directory of Open Access Journals (Sweden)

    Ersagun Karaguzel

    2016-02-01

    Full Text Available ABSTRACT Purpose To investigate the protective effects against ischemia reperfusion injury of dipyridamole in a model of induced priapism in rats. Materials and Methods Twenty-four male Sprague-Dawley rats were divided into four groups, control, P/R, P/R+DMSO and P/R+D. 3ml blood specimens were collected from vena cava inferior in order to determine serum MDA, IMA, TAS, TOS and OSI values, and penile tissue was taken for histopathological examination in control group. Priapism was induced in P/R group. After 1h, priapism was concluded and 30 min reperfusion was performed. In P/R+DMSO group 1ml/kg DMSO was administered intraperitoneally 30 min before reperfusion, while in P/R+D group 10mg/kg dipyridamole was administered intraperitoneally 30 min before reperfusion. Blood and penis specimens were collected after the end of 30 min reperfusion period. Sinusoidal area (µm2, tears in tunica albuginea and injury parameters in sinusoidal endothelium of penis were investigated. Results Histopathological examination revealed no significant changes in term of sinusoidal area. A decrease in tears was observed in P/R+D group compared to P/R group (p0.05. There were no significant differences in MDA and IMA values between groups. A significant increase in TOS and OSI values was observed in P/R+D group compared to P/R group. A significant decrease in TAS levels was observed in P/R+D group compared to the P/R group. Conclusions The administration of dipyridamole before reperfusion in ischemic priapism model has a potential protective effect against histopathological injury of the penis.

  5. Selective Embolization of Bilateral Arterial Cavernous Fistulas for Posttraumatic Penile Arterial Priapism

    International Nuclear Information System (INIS)

    Lazinger, Maxwell; Beckmann, Carl F.; Cossi, Alda; Roth, Robert A.

    1996-01-01

    A 22-year-old man suffered a hiking accident with perineal trauma and developed a nonpainful priapism secondary to bilateral arterial-cavernosal fistulas. To minimize the risk of impotence in this young patient, successive selective embolizations with autologous blood clot were performed to close the fistulas. This led to an uncomplicated full recovery. No fistula was detectable on Doppler ultrasonography at 1-year follow-up. Review of the literature confirms the safety of embolization with autologous clot

  6. Interventional therapy for priapism caused by arteriovenous fistula of penis: the nursing experience in two patients

    International Nuclear Information System (INIS)

    Peng Jinxia; Liu Ping; Jia Hongtao

    2010-01-01

    Objective: To discuss the perioperative nursing measures for interventional treatment of priapism caused by arteriovenous fistula of penis in order to reduce the operation-related complications and to promote rehabilitation. Methods: A series of nursing steps were carried out in 2 patients who suffered from priapism caused by arteriovenous fistula of penis and received interventional therapy. The nursing measures included preoperative psychological nursing,routine preoperative examinations, promotion of friendly relations between nurse and patient, preparation for the operation method, the preparation of skin, postoperative nursing of patient's position, observation of penis erection and vital signs, postoperative psychological nursing, and the health guidance at the time of discharge. Results: After the interventional therapy two patients were successfully cured at the time of discharge. No complications related to the operation occurred. Three months after the operation the erect function of the penis remained normal. Conclusion: The interventional therapy is a safe and reliable technique for priapism caused by arteriovenous fistula of penis. The proper and effective perioperative and postoperative nursing measures can surely improve the successful rate of interventional treatment as well as prevent the occurrence of complications. (authors)

  7. Investigations on high speed MHD liquid flow

    International Nuclear Information System (INIS)

    Yamasaki, Takasuke; Kamiyama, Shin-ichi.

    1982-01-01

    Lately, the pressure drop problem of MHD two-phase flow in a duct has been investigated theoretically and experimentally in conjunction with the problems of liquid metal MHD two-phase flow power-generating cycle or of liquid metal boiling two-phase flow in the blanket of a nuclear fusion reactor. Though many research results have been reported so far for MHD single-phase flow, the hydrodynamic studies on high speed two-phase flow are reported only rarely, specifically the study dealing with the generation of cavitation is not found. In the present investigation, the basic equation was derived, analyzing the high speed MHD liquid flow in a diverging duct as the one-dimensional flow of homogeneous two-phase fluid of small void ratio. Furthermore, the theoretical solution for the effect of magnetic field on cavitation-generating conditions was tried. The pressure distribution in MHD flow in a duct largely varies with load factor, and even if the void ratio is small, the pressure distribution in two-phase flow is considerably different from that in single-phase flow. Even if the MHD two-phase flow in a duct is subsonic flow at the throat, the critical conditions may be achieved sometimes in a diverging duct. It was shown that cavitation is more likely to occur as magnetic field becomes more intense if it is generated downstream of the throat. This explains the experimental results qualitatively. (Wakatsuki, Y.)

  8. Compressibility, turbulence and high speed flow

    CERN Document Server

    Gatski, Thomas B

    2013-01-01

    Compressibility, Turbulence and High Speed Flow introduces the reader to the field of compressible turbulence and compressible turbulent flows across a broad speed range, through a unique complimentary treatment of both the theoretical foundations and the measurement and analysis tools currently used. The book provides the reader with the necessary background and current trends in the theoretical and experimental aspects of compressible turbulent flows and compressible turbulence. Detailed derivations of the pertinent equations describing the motion of such turbulent flows is provided and an extensive discussion of the various approaches used in predicting both free shear and wall bounded flows is presented. Experimental measurement techniques common to the compressible flow regime are introduced with particular emphasis on the unique challenges presented by high speed flows. Both experimental and numerical simulation work is supplied throughout to provide the reader with an overall perspective of current tre...

  9. Prise en charge du priapisme à bas débit vue tardivement : à propos de 28 cas

    Directory of Open Access Journals (Sweden)

    K. Kamel

    2016-12-01

    Conclusion: Le priapisme doit être considéré comme une urgence andrologique majeure dont le traitement s’impose sans délai. Le pronostic dépend essentiellement de l’âge des malades et du délai de leur prise en charge. Dans notre étude le priapisme idiopathique semble avoir le meilleur pronostic. Enfin, le traitement des facteurs de risque et la prise en charge précoce sont les meilleurs moyens pour éviter cette infirmité.

  10. Prise en charge du priapisme à bas débit vue tardivement : à propos ...

    African Journals Online (AJOL)

    K. Kamel

    de ce travail est d'étudier les particularités cliniques, thérapeutiques et évolutives ... Patients et Méthodes : Etude rétrospective portant sur une série de 28 cas de priapisme à bas débit vus .... on complétait par un frotti sanguin à la recherche de drépanocyte et ... consultation un mois après pour évaluer la fonction érectile.

  11. Modelling of high-enthalpy, high-Mach number flows

    International Nuclear Information System (INIS)

    Degrez, G; Lani, A; Panesi, M; Chazot, O; Deconinck, H

    2009-01-01

    A review is made of the computational models of high-enthalpy flows developed over the past few years at the von Karman Institute and Universite Libre de Bruxelles, for the modelling of high-enthalpy hypersonic (re-)entry flows. Both flows in local thermo-chemical equilibrium (LTE) and flows in thermo-chemical non-equilibrium (TCNEQ) are considered. First, the physico-chemical models are described, i.e. the set of conservation laws, the thermodynamics, transport phenomena and chemical kinetics models. Particular attention is given to the correct modelling of elemental (LTE flows) and species (chemical non-equilibrium-CNEQ-flows) transport. The numerical algorithm, based on a state-of-the-art finite volume discretization, is then briefly described. Finally, selected examples are included to illustrate the capabilities of the developed solver. (review article)

  12. Wake flow characteristics at high wind speed

    DEFF Research Database (Denmark)

    Aagaard Madsen, Helge; Larsen, Torben J.; Larsen, Gunner Chr.

    2016-01-01

    Wake flow characteristic at high wind speeds is the main subject of this paper. Although the wake losses decrease at high wind speeds it has been found in a recent study that for multiple wake inflow the increase in loading due to wake effects are substantial even at wind speeds well above rated ...

  13. Numerical modelling of flow pattern for high swirling flows

    Directory of Open Access Journals (Sweden)

    Parra Teresa

    2015-01-01

    Full Text Available This work focuses on the interaction of two coaxial swirling jets. High swirl burners are suitable for lean flames and produce low emissions. Computational Fluid Dynamics has been used to study the isothermal behaviour of two confined jets whose setup and operating conditions are those of the benchmark of Roback and Johnson. Numerical model is a Total Variation Diminishing and PISO is used to pressure velocity coupling. Transient analysis let identify the non-axisymmetric region of reverse flow. The center of instantaneous azimuthal velocities is not located in the axis of the chamber. The temporal sampling evidences this center spins around the axis of the device forming the precessing vortex core (PVC whose Strouhal numbers are more than two for Swirl numbers of one. Influence of swirl number evidences strong swirl numbers are precursor of large vortex breakdown. Influence of conical diffusers evidence the reduction of secondary flows associated to boundary layer separation.

  14. Partial Cavity Flows at High Reynolds Numbers

    Science.gov (United States)

    Makiharju, Simo; Elbing, Brian; Wiggins, Andrew; Dowling, David; Perlin, Marc; Ceccio, Steven

    2009-11-01

    Partial cavity flows created for friction drag reduction were examined on a large-scale. Partial cavities were investigated at Reynolds numbers up to 120 million, and stable cavities with frictional drag reduction of more than 95% were attained at optimal conditions. The model used was a 3 m wide and 12 m long flat plate with a plenum on the bottom. To create the partial cavity, air was injected at the base of an 18 cm backwards-facing step 2.1 m from the leading edge. The geometry at the cavity closure was varied for different flow speeds to optimize the closure of the cavity. Cavity gas flux, thickness, frictional loads, and cavity pressures were measured over a range of flow speeds and air injection fluxes. High-speed video was used extensively to investigate the unsteady three dimensional cavity closure, the overall cavity shape and oscillations.

  15. Numerical models for high beta magnetohydrodynamic flow

    International Nuclear Information System (INIS)

    Brackbill, J.U.

    1987-01-01

    The fundamentals of numerical magnetohydrodynamics for highly conducting, high-beta plasmas are outlined. The discussions emphasize the physical properties of the flow, and how elementary concepts in numerical analysis can be applied to the construction of finite difference approximations that capture these features. The linear and nonlinear stability of explicit and implicit differencing in time is examined, the origin and effect of numerical diffusion in the calculation of convective transport is described, and a technique for maintaining solenoidality in the magnetic field is developed. Many of the points are illustrated by numerical examples. The techniques described are applicable to the time-dependent, high-beta flows normally encountered in magnetically confined plasmas, plasma switches, and space and astrophysical plasmas. 40 refs

  16. Boiling curve in high quality flow boiling

    International Nuclear Information System (INIS)

    Shiralkar, B.S.; Hein, R.A.; Yadigaroglu, G.

    1980-01-01

    The post dry-out heat transfer regime of the flow boiling curve was investigated experimentally for high pressure water at high qualities. The test section was a short round tube located downstream of a hot patch created by a temperature controlled segment of tubing. Results from the experiment showed that the distance from the dryout point has a significant effect on the downstream temperatures and there was no unique boiling curve. The heat transfer coefficients measured sufficiently downstream of the dryout point could be correlated using the Heineman correlation for superheated steam, indicating that the droplet deposition effects could be neglected in this region

  17. Steroids, drugs and stuttering priapism; the rock-and-roll lifestyle of a 24-year-old man.

    Science.gov (United States)

    Evans, Lloyd; Larsen, Matt; Cox, Adam; Skyrme, Rob

    2016-01-28

    The authors present a case of a 24-year-old, poorly controlled insulin-dependent type 1 diabetic Caucasian man who presented to the emergency department, with a painful erection of 36 h duration that had failed to resolve with conservative management. This was the patient's seventh priapism, with his most recent attendance 1 week previously for which he underwent a distal cavernosal shunt. He admitted to taking several recreational drugs, including marijuana and cocaine, during the preceding few days, in addition to the long-term use of the oral anabolic steroid oxandrolone. He had no family history of sickle cell disease or trait. On examination, a tensely erect penis was noted. A diagnosis of stuttering priapism was made and 750 mL of blood subsequently drained via a distal corporoglandular shunt resulting in successful detumescence. 2016 BMJ Publishing Group Ltd.

  18. Men with Sickle Cell Anemia and Priapism Exhibit Increased Hemolytic Rate, Decreased Red Blood Cell Deformability and Increased Red Blood Cell Aggregate Strength.

    Directory of Open Access Journals (Sweden)

    Kizzy-Clara Cita

    Full Text Available To investigate the association between priapism in men with sickle cell anemia (SCA and hemorheological and hemolytical parameters.Fifty-eight men with SCA (median age: 38 years were included; 28 who had experienced priapism at least once during their life (priapism group and 30 who never experienced this complication (control group. Twenty-two patients were treated with hydroxycarbamide, 11 in each group. All patients were at steady state at the time of inclusion. Hematological and biochemical parameters were obtained through routine procedures. The Laser-assisted Optical Rotational Cell Analyzer was used to measure red blood cell (RBC deformability at 30 Pa (ektacytometry and RBC aggregation properties (laser backscatter versus time. Blood viscosity was measured at a shear rate of 225 s-1 using a cone/plate viscometer. A principal component analysis was performed on 4 hemolytic markers (i.e., lactate dehydrogenase (LDH, aspartate aminotransferase (ASAT, total bilirubin (BIL levels and reticulocyte (RET percentage to calculate a hemolytic index.Compared to the control group, patients with priapism exhibited higher ASAT (p = 0.01, LDH (p = 0.03, RET (p = 0.03 levels and hemolytic indices (p = 0.02. Higher RBC aggregates strength (p = 0.01 and lower RBC deformability (p = 0.005 were observed in patients with priapism compared to controls. After removing the hydroxycarbamide-treated patients, RBC deformability (p = 0.01 and RBC aggregate strength (p = 0.03 were still different between the two groups, and patients with priapism exhibited significantly higher hemolytic indices (p = 0.01 than controls.Our results confirm that priapism in SCA is associated with higher hemolytic rates and show for the first time that this complication is also associated with higher RBC aggregate strength and lower RBC deformability.

  19. Homogenization of High-Contrast Brinkman Flows

    KAUST Repository

    Brown, Donald L.

    2015-04-16

    Modeling porous flow in complex media is a challenging problem. Not only is the problem inherently multiscale but, due to high contrast in permeability values, flow velocities may differ greatly throughout the medium. To avoid complicated interface conditions, the Brinkman model is often used for such flows [O. Iliev, R. Lazarov, and J. Willems, Multiscale Model. Simul., 9 (2011), pp. 1350--1372]. Instead of permeability variations and contrast being contained in the geometric media structure, this information is contained in a highly varying and high-contrast coefficient. In this work, we present two main contributions. First, we develop a novel homogenization procedure for the high-contrast Brinkman equations by constructing correctors and carefully estimating the residuals. Understanding the relationship between scales and contrast values is critical to obtaining useful estimates. Therefore, standard convergence-based homogenization techniques [G. A. Chechkin, A. L. Piatniski, and A. S. Shamev, Homogenization: Methods and Applications, Transl. Math. Monogr. 234, American Mathematical Society, Providence, RI, 2007, G. Allaire, SIAM J. Math. Anal., 23 (1992), pp. 1482--1518], although a powerful tool, are not applicable here. Our second point is that the Brinkman equations, in certain scaling regimes, are invariant under homogenization. Unlike in the case of Stokes-to-Darcy homogenization [D. Brown, P. Popov, and Y. Efendiev, GEM Int. J. Geomath., 2 (2011), pp. 281--305, E. Marusic-Paloka and A. Mikelic, Boll. Un. Mat. Ital. A (7), 10 (1996), pp. 661--671], the results presented here under certain velocity regimes yield a Brinkman-to-Brinkman upscaling that allows using a single software platform to compute on both microscales and macroscales. In this paper, we discuss the homogenized Brinkman equations. We derive auxiliary cell problems to build correctors and calculate effective coefficients for certain velocity regimes. Due to the boundary effects, we construct

  20. Sultan - forced flow, high field test facility

    International Nuclear Information System (INIS)

    Horvath, I.; Vecsey, G.; Weymuth, P.; Zellweger, J.

    1981-01-01

    Three European laboratories: CNEN (Frascati, I) ECN (Petten, NL) and SIN (Villigen, CH) decided to coordinate their development efforts and to install a common high field forced flow test facility at Villigen Switzerland. The test facility SULTAN (Supraleiter Testanlage) is presently under construction. As a first step, an 8T/1m bore solenoid with cryogenic periphery will be ready in 1981. The cryogenic system, data acquisition system and power supplies which are contributed by SIN are described. Experimental feasibilities, including cooling, and instrumentation are reviewed. Progress of components and facility construction is described. Planned extension of the background field up to 12T by insert coils is outlined. 5 refs

  1. High Flow Nasal Cannulae in preterm infants

    Directory of Open Access Journals (Sweden)

    F. Ciuffini

    2013-06-01

    Full Text Available Despite of improved survival of premature infants, the incidence of long term pulmonary complications, mostly associated with ventilation-induced lung injury, remains high. Non invasive ventilation (NIV is able to reduce the adverse effects of mechanical ventilation. Although nasal continuous positive airway pressure (NCPAP is an effective mode of NIV, traumatic nasal complications and intolerance of the nasal interface are common. Recently high flow nasal cannula (HFNC is emerging as an efficient, better tolerated form of NIV, allowing better access to the baby’s face, which may improve nursing, feeding and bonding. The aim of this review is to discuss the available evidence of effectiveness and safety of HFNC in preterm newborns with respiratory distress syndrome (RDS. It is known that distending pressure generated by HFNC increases with increasing flow rate and decreasing infant size and varies according to the amount of leaks by nose and mouth. The effects of HFNC on lung mechanics, its clinical efficacy and safety are still insufficiently investigated. In conclusion, there is a growing evidence of the feasibility of HFNC as an alternative mode of NIV. However, further larger randomized trials are required, before being able to recommend HFNC in the treatment of moderate respiratory distress of preterm infants.

  2. High flow concrete 2; Koryudo konkurito 2

    Energy Technology Data Exchange (ETDEWEB)

    Naruse, Hiroyasu [Mitsubishi Materials Corp., Tokyo (Japan)

    1998-09-10

    Hashimoto et al. compared U-type repletion test that evaluation method of the consistency in design of mix of high workable concrete was proposed as a repletion test with the box test, and it was examined, and it had clarified the difference between the behavior in the test by the analysis of the shearing strain speed by the visualization as the technique, and the important proposal was done, when the evaluation method would be divided in future. Anchors showed that it analyzed it in order to quantitatively evaluate separating resistance-ness of the coarse aggregate, with model and proposes the analysis method on separating resistance-ness of high workable concrete according to the original model, and that the correlation is high. In the future, further examination was carried out on aggregate shapes and lees aggregate amount, etc. and intended to propose the technique which could be analyzed more high-precise. Branch pines examined the effect of the fineness modulus in addition to factors such as real width rate and particle size of a fine aggregate in the technique in which researchers have proposed the setting of class aggregate amount in the top in search of the optimum value. It can be expected that it is future effectively utilized, because it is a proposed equation which sufficiently added characteristics of the Tsumugi aggregate. Temple areas found and proposed that viscosity and of the optimum mortar minute in design of mix in high workable concrete for the dam for the downward flow hour differed from the case in which the 20 mm aggregate was used on the design of mix technique in using the 40 mm aggregate. It is the research which considered the application of high workable concrete to the concrete for the dam, and it seems to be very much useful to future popularization. (translated by NEDO)

  3. Compressibility, turbulence and high speed flow

    CERN Document Server

    Gatski, Thomas B

    2009-01-01

    This book introduces the reader to the field of compressible turbulence and compressible turbulent flows across a broad speed range through a unique complimentary treatment of both the theoretical foundations and the measurement and analysis tools currently used. For the computation of turbulent compressible flows, current methods of averaging and filtering are presented so that the reader is exposed to a consistent development of applicable equation sets for both the mean or resolved fields as well as the transport equations for the turbulent stress field. For the measurement of turbulent compressible flows, current techniques ranging from hot-wire anemometry to PIV are evaluated and limitations assessed. Characterizing dynamic features of free shear flows, including jets, mixing layers and wakes, and wall-bounded flows, including shock-turbulence and shock boundary-layer interactions, obtained from computations, experiments and simulations are discussed. Key features: * Describes prediction methodologies in...

  4. High Reynolds Number Liquid Flow Measurements

    Science.gov (United States)

    1988-08-01

    25. .n Fig. 25, the dotted line represents data taken from Eckelmann’s study in the thick viscous sublaver of an oil channel. Scatter in the...measurements of the fundamental physical quantities are not only an essencial part in an understanding of multiphase flows but also in the measurement process...technique. One of the most yloei’ used techniques, however, is some form of flow visualization. This includes the use o: tufts, oil paint films

  5. A High-Current, Stable Nonaqueous Organic Redox Flow Battery

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Xiaoliang; Duan, Wentao; Huang, Jinhua; Zhang, Lu; Li, Bin; Reed, David; Xu, Wu; Sprenkle, Vincent; Wang, Wei

    2016-10-14

    Nonaqueous redox flow batteries are promising in pursuit of high-energy storage systems owing to the broad voltage window, but currently are facing key challenges such as poor cycling stability and lack of suitable membranes. Here we report a new nonaqueous all-organic flow chemistry that demonstrates an outstanding cell cycling stability primarily because of high chemical persistency of the organic radical redox species and their good compatibility with the supporting electrolyte. A feasibility study shows that Daramic® and Celgard® porous separators can lead to high cell conductivity in flow cells thus producing remarkable cell efficiency and material utilization even at high current operations. This result suggests that the thickness and pore size are the key performance-determining factors for porous separators. With the greatly improved flow cell performance, this new flow system largely addresses the above mentioned challenges and the findings may greatly expedite the development of durable nonaqueous flow batteries.

  6. High flow nasal cannula for respiratory support in preterm infants.

    LENUS (Irish Health Repository)

    Wilkinson, Dominic

    2011-01-01

    High flow nasal cannulae (HFNC) are small, thin, tapered cannulae used to deliver oxygen or blended oxygen and air at flow rates of > 1 L\\/min. HFNC can be used to provide high concentrations of oxygen and may deliver positive end-expiratory pressure.

  7. High Reynolds number flows using liquid and gaseous helium

    International Nuclear Information System (INIS)

    Donnelly, R.J.

    1991-01-01

    Consideration is given to liquid and gaseous helium as test fluids, high Reynolds number test requirements in low speed aerodynamics, the measurement of subsonic flow around an appended body of revolution at cryogenic conditions in the NTF, water tunnels, flow visualization, the six component magnetic suspension system for wind tunnel testing, and recent aerodynamic measurements with magnetic suspension systems. Attention is also given to application of a flow visualization technique to a superflow experiment, experimental investigations of He II flows at high Reynolds numbers, a study of homogeneous turbulence in superfluid helium, and thermal convection in liquid helium

  8. Global flow of glasma in high energy nuclear collisions

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Guangyao; Fries, Rainer J., E-mail: rjfries@comp.tamu.edu

    2013-06-25

    We discuss the energy flow of the classical gluon fields created in collisions of heavy nuclei at collider energies. We show how the Yang–Mills analog of Faraday's Law and Gauss' Law predicts the initial gluon flux tubes to expand or bend. The resulting transverse and longitudinal structure of the Poynting vector field has a rich phenomenology. Besides the well-known radial and elliptic flow in transverse direction, classical quantum chromodynamics predicts a rapidity-odd transverse flow that tilts the fireball for non-central collisions, and it implies a characteristic flow pattern for collisions of non-symmetric systems A+B. The rapidity-odd transverse flow translates into a directed particle flow v{sub 1} which has been observed at RHIC and LHC. The global flow fields in heavy ion collisions could be a powerful check for the validity of classical Yang–Mills dynamics in high energy collisions.

  9. Experimental investigation on a high subsonic compressor cascade flow

    Directory of Open Access Journals (Sweden)

    Zhang Haideng

    2015-08-01

    Full Text Available With the aim of deepening the understanding of high-speed compressor cascade flow, this paper reports an experimental study on NACA-65 K48 compressor cascade with high subsonic inlet flow. With the increase of passage pressurizing ability, endwall boundary layer behavior is deteriorated, and the transition zone is extended from suction surface to the endwall as the adverse pressure gradient increases. Cross flow from endwall to midspan, mixing of corner boundary layer and the main stream, and reversal flow on the suction surface are caused by corner separation vortex structures. Passage vortex is the main corner separation vortex. During its movement downstream, the size grows bigger while the rotating direction changes, forming a limiting circle. With higher incidence, corner separation is further deteriorated, leading to higher flow loss. Meanwhile, corner separation structure, flow mixing characteristics and flow loss distribution vary a lot with the change of incidence. Compared with low aspect-ratio model, corner separation of high aspect-ratio model moves away from the endwall and is more sufficiently developed downstream the cascade. Results obtained present details of high-speed compressor cascade flow, which is rare in the relating research fields and is beneficial to mechanism analysis, aerodynamic optimization and flow control design.

  10. Highly simplified lateral flow-based nucleic acid sample preparation and passive fluid flow control

    Science.gov (United States)

    Cary, Robert E.

    2015-12-08

    Highly simplified lateral flow chromatographic nucleic acid sample preparation methods, devices, and integrated systems are provided for the efficient concentration of trace samples and the removal of nucleic acid amplification inhibitors. Methods for capturing and reducing inhibitors of nucleic acid amplification reactions, such as humic acid, using polyvinylpyrrolidone treated elements of the lateral flow device are also provided. Further provided are passive fluid control methods and systems for use in lateral flow assays.

  11. Highly simplified lateral flow-based nucleic acid sample preparation and passive fluid flow control

    Energy Technology Data Exchange (ETDEWEB)

    Cary, Robert B.

    2018-04-17

    Highly simplified lateral flow chromatographic nucleic acid sample preparation methods, devices, and integrated systems are provided for the efficient concentration of trace samples and the removal of nucleic acid amplification inhibitors. Methods for capturing and reducing inhibitors of nucleic acid amplification reactions, such as humic acid, using polyvinylpyrrolidone treated elements of the lateral flow device are also provided. Further provided are passive fluid control methods and systems for use in lateral flow assays.

  12. High speed digital holographic interferometry for hypersonic flow visualization

    Science.gov (United States)

    Hegde, G. M.; Jagdeesh, G.; Reddy, K. P. J.

    2013-06-01

    Optical imaging techniques have played a major role in understanding the flow dynamics of varieties of fluid flows, particularly in the study of hypersonic flows. Schlieren and shadowgraph techniques have been the flow diagnostic tools for the investigation of compressible flows since more than a century. However these techniques provide only the qualitative information about the flow field. Other optical techniques such as holographic interferometry and laser induced fluorescence (LIF) have been used extensively for extracting quantitative information about the high speed flows. In this paper we present the application of digital holographic interferometry (DHI) technique integrated with short duration hypersonic shock tunnel facility having 1 ms test time, for quantitative flow visualization. Dynamics of the flow fields in hypersonic/supersonic speeds around different test models is visualized with DHI using a high-speed digital camera (0.2 million fps). These visualization results are compared with schlieren visualization and CFD simulation results. Fringe analysis is carried out to estimate the density of the flow field.

  13. High energy density redox flow device

    Science.gov (United States)

    Chiang, Yet-Ming; Carter, William Craig; Duduta, Mihai; Limthongkul, Pimpa

    2014-05-13

    Redox flow devices are described including a positive electrode current collector, a negative electrode current collector, and an ion-permeable membrane separating said positive and negative current collectors, positioned and arranged to define a positive electroactive zone and a negative electroactive zone; wherein at least one of said positive and negative electroactive zone comprises a flowable semi-solid composition comprising ion storage compound particles capable of taking up or releasing said ions during operation of the cell, and wherein the ion storage compound particles have a polydisperse size distribution in which the finest particles present in at least 5 vol % of the total volume, is at least a factor of 5 smaller than the largest particles present in at least 5 vol % of the total volume.

  14. High-temperature counter-flow recuperator

    Science.gov (United States)

    Rudloff, F.

    1981-05-01

    The commercial potential of a helical recuperator design in recovering waste heat from industrial furnaces is reported. The helical recuperator concept consists of a cylindrical column with an interior helical interface which separates the preheat air and the combustion gas. The column operates in a teer flow mode and is formed from modular sections. The material evaluation consisted of exposing material samples to a soda-lime glass furnace environment for a fifteen week period. ECP-3, X-81, and Unichrome were the best suited for use in a soda-lime environment and ECP-3 was the best candidate with respect to manufacturing. Two potential design modifications were identified: a finned design and a double helix design. For materials that showed the greatest potential for use in the glass environment, the double helix design made from ECP-3 was the most economical producing payback periods of 6 to 14 years.

  15. High temperature flow behaviour of SiC reinforced lithium

    Indian Academy of Sciences (India)

    The compressive flow behaviour of lithium aluminosilicate (LAS) glass, with and without SiC particulate reinforcements, was studied. The LAS glass crystallized to spodumene during high-temperature testing. The flow behaviour of LAS glass changed from Newtonian to non-Newtonian due to the presence of crystalline ...

  16. Modeling of high speed micro rotors in moderate flow confinement

    NARCIS (Netherlands)

    Dikmen, E.; van der Hoogt, Peter; Aarts, Ronald G.K.M.; Sas, P.; Bergen, B.

    2008-01-01

    The recent developments in high speed micro rotating machinery lead to the need for multiphysical modeling of the rotor and the surrounding medium. In this study, thermal and flow induced effects on rotor dynamics of geometries with moderate flow confinement are studied. The structure is modeled via

  17. High Frame Rate Synthetic Aperture 3D Vector Flow Imaging

    DEFF Research Database (Denmark)

    Villagómez Hoyos, Carlos Armando; Holbek, Simon; Stuart, Matthias Bo

    2016-01-01

    , current volumetric ultrasonic flow methods are limited to one velocity component or restricted to a reduced field of view (FOV), e.g. fixed imaging planes, in exchange for higher temporal resolutions. To solve these problems, a previously proposed accurate 2-D high frame rate vector flow imaging (VFI...

  18. High definition graphics application in fluid flow simulations

    International Nuclear Information System (INIS)

    Bancroft, G.; Merritt, F.; Buning, P.; Watson, V.

    1987-01-01

    NASA Ames is using high spatial/color-resolution computer graphics to interactively visualize flow fields generated by supercomputer solutions for the flow about such vehicles as the Space Shuttle. The scientist's viewing position in three-dimensional space can be interactively changed while the fluid flow is either frozen or moving in time. Animated sequences can then be made for workstation viewing with the aid of specialized software that allows easy editing and automatic tweening of the sequences. Attention is presently given to the software generating the three-dimensional flow field displays, as well as that for creating the animation sequences

  19. High Pressure Reverse Flow APS Engine

    Science.gov (United States)

    Senneff, J. M.

    1972-01-01

    A design and test demonstration effort was undertaken to evaluate the concept of the reverse flow engine for the APS engine application. The 1500 lb (6672 N) thrust engine was designed to operate on gaseous hydrogen and gaseous oxygen propellants at a mixture ratio of 4 and to achieve the objective performance of 435 sec (4266 Nsec/kg) specific impulse. Superimposed durability requirements called for a million-cycle capability with 50 hours duration. The program was undertaken as a series of tasks including the initial preliminary design, design of critical test components and finally, the design and demonstration of an altitude engine which could be used interchangeably to examine operating parameters as well as to demonstrate the capability of the concept. The program results are reported with data to indicate that all of the program objectives were met or exceeded within the course of testing on the program. The analysis effort undertaken is also reported in detail and supplemented with test data in some cases where prior definitions could not be made. The results are contained of these analyses as well as the test results conducted throughout the course of the program. Finally, the test data and analytical results were combined to allow recommendations for a flight weight design. This preliminary design effort is also detailed.

  20. Core surface flow modelling from high-resolution secular variation

    DEFF Research Database (Denmark)

    Holme, R.; Olsen, Nils

    2006-01-01

    -flux hypothesis, but the spectrum of the SV implies that a conclusive test of frozen-flux is not possible. We parametrize the effects of diffusion as an expected misfit in the flow prediction due to departure from the frozen-flux hypothesis; at low spherical harmonic degrees, this contribution dominates...... the expected departure of the SV predictions from flow to the observed SV, while at high degrees the SV model uncertainty is dominant. We construct fine-scale core surface flows to model the SV. Flow non-uniqueness is a serious problem because the flows are sufficiently small scale to allow flow around non......-series of magnetic data and better parametrization of the external magnetic field....

  1. Rat muscle blood flows during high-speed locomotion

    International Nuclear Information System (INIS)

    Armstrong, R.B.; Laughlin, M.H.

    1985-01-01

    We previously studied blood flow distribution within and among rat muscles as a function of speed from walking (15 m/min) through galloping (75 m/min) on a motor-driven treadmill. The results showed that muscle blood flows continued to increase as a function of speed through 75 m/min. The purpose of the present study was to have rats run up to maximal treadmill speeds to determine if blood flows in the muscles reach a plateau as a function of running speed over the animals normal range of locomotory speeds. Muscle blood flows were measured with radiolabeled microspheres at 1 min of running at 75, 90, and 105 m/min in male Sprague-Dawley rats. The data indicate that even at these relatively high treadmill speeds there was still no clear evidence of a plateau in blood flow in most of the hindlimb muscles. Flows in most muscles continued to increase as a function of speed. These observed patterns of blood flow vs. running speed may have resulted from the rigorous selection of rats that were capable of performing the high-intensity exercise and thus only be representative of a highly specific population of animals. On the other hand, the data could be interpreted to indicate that the cardiovascular potential during exercise is considerably higher in laboratory rats than has normally been assumed and that inadequate blood flow delivery to the muscles does not serve as a major limitation to their locomotory performance

  2. Evaporation of polydispersed droplets in a highly turbulent channel flow

    Energy Technology Data Exchange (ETDEWEB)

    Cochet, M.; Bazile, Rudy; Ferret, B.; Cazin, S. [INPT, UPS, IMFT (Institut de Mecanique des Fluides de Toulouse), Universite de Toulouse (France)

    2009-09-15

    A model experiment for the study of evaporating turbulent two-phase flows is presented here. The study focuses on a situation where pre-atomized and dispersed droplets vaporize and mix in a heated turbulent flow. The test bench consists in a channel flow with characteristics of homogeneous and isotropic turbulence where fluctuations levels reach very high values (25% in the established zone). An ultrasonic atomizer allows the injection of a mist of small droplets of acetone in the carrier flow. The large range diameters ensure that every kind of droplet behavior with regards to turbulence is possible. Instantaneous concentration fields of the vaporized phase are extracted from fluorescent images (PLIF) of the two phase flow. The evolution of the mixing of the acetone vapor is analyzed for two different liquid mass loadings. Despite the high turbulence levels, concentration fluctuations remain significant, indicating that air and acetone vapor are not fully mixed far from the injector. (orig.)

  3. High order Poisson Solver for unbounded flows

    DEFF Research Database (Denmark)

    Hejlesen, Mads Mølholm; Rasmussen, Johannes Tophøj; Chatelain, Philippe

    2015-01-01

    This paper presents a high order method for solving the unbounded Poisson equation on a regular mesh using a Green’s function solution. The high order convergence was achieved by formulating mollified integration kernels, that were derived from a filter regularisation of the solution field....... The method was implemented on a rectangular domain using fast Fourier transforms (FFT) to increase computational efficiency. The Poisson solver was extended to directly solve the derivatives of the solution. This is achieved either by including the differential operator in the integration kernel...... the equations of fluid mechanics as an example, but can be used in many physical problems to solve the Poisson equation on a rectangular unbounded domain. For the two-dimensional case we propose an infinitely smooth test function which allows for arbitrary high order convergence. Using Gaussian smoothing...

  4. Topics in the numerical simulation of high temperature flows

    International Nuclear Information System (INIS)

    Cheret, R.; Dautray, R.; Desgraz, J.C.; Mercier, B.; Meurant, G.; Ovadia, J.; Sitt, B.

    1984-06-01

    In the fields of inertial confinement fusion, astrophysics, detonation, or other high energy phenomena, one has to deal with multifluid flows involving high temperatures, high speeds and strong shocks initiated e.g. by chemical reactions or even by thermonuclear reactions. The simulation of multifluid flows is reviewed: first are Lagrangian methods which have been successfully applied in the past. Then we describe our experience with newer adaptive mesh methods, originally designed to increase the accuracy of Lagrangian methods. Finally, some facts about Eulerian methods are recalled, with emphasis on the EAD scheme which has been recently extended to the elasto-plastic case. High temperature flows is then considered, described by the equations of radiation hydrodynamics. We show how conservation of energy can be preserved while solving the radiative transfer equation via the Monte Carlo method. For detonation, some models, introduced to describe the initiation of detonation in heterogeneous explosives. Finally we say a few words about instability of these flows

  5. Close-Spaced High Temperature Knudsen Flow.

    Science.gov (United States)

    1986-07-15

    radiant heat source assembly was substituted for the brazed molybdenum one in order to achieve higher radiant heater temperatures . 2.1.4 Experimental...at very high temperature , and ground flat. The molybdenum is then chemically etched to the desired depth using an etchant which does not affect...RiB6 295 -CLSE PCED HIGH TEMPERATURE KNUDSEN FLOU(U) RASOR I AiASSOCIATES INC SUNNYVALE CA J 8 MCVEY 15 JUL 86 NSR-224 AFOSR-TR-87-1258 F49628-83-C

  6. Subarachnoid hemorrhage as complication of phenylephrine injection for the treatment of ischemic priapism in a sickle cell disease patient.

    Science.gov (United States)

    Davila, Hugo H; Parker, Justin; Webster, J Christopher; Lockhart, Jorge L; Carrion, Rafael E

    2008-04-01

    Ischemic priapism (IP) is a urologic condition, which necessitates prompt management. Intracavernosal injection of phenylephrine is a usual treatment modality utilized for the management of these patients. Aim. We present a case of subarachnoid hemorrhage following intracavernosal injection of phenylephrine for IP in a patient with sickle cell disease. We analyzed the degree of subarachnoid hemorrhage in our patient after intracavernosal injection of phenylephrine. The patient had an acute rise in blood pressure during corporal irrigation. This was followed by the onset of severe headache. Computed tomography (CT) scan confirmed the diagnosis of a subarachnoid hemorrhage. Subarachnoid hemorrhage associated with intracavernosal injection of phenylephrine. Result. A 23-year-old African American male with a history of sickle cell disease presented with a painful penile erection. The patient was started on intravenous fluids, oxygen by nasal canula, and analgesic medication. After this, a blood gas was obtained from his left corpora cavernosa. This was followed by normal saline irrigation and injection of phenylephrine. The patient complained of a sudden, severe "terrible headache" immediately following the last injection, and noncontrast CT scan of the head was obtained and a subarachnoid hemorrhage was noted. The patient was admitted for observation and no significant changes were noted. Intracavernosal injection of phenylephrine for the management of IP can be associated with several possible complications. We present our single case complicated with the formation of a subarachnoid hemorrhage. The patient was treated conservatively and had no long-term neurologic sequelae. Davila HH, Parker J, Webster JC, Lockhart JL, and Carrion RE. Subarachnoid hemorrhage as complication of phenylephrine injection for the treatment of ischemic priapism in a sickle cell disease patient.

  7. The flow field structure of highly stabilized partially premixed flames in a concentric flow conical nozzle burner with coflow

    KAUST Repository

    Elbaz, Ayman M.; Zayed, M.F.; Samy, M.; Roberts, William L.; Mansour, Mohy S.

    2015-01-01

    The stability limits, the stabilization mechanism, and the flow field structure of highly stabilized partially premixed methane flames in a concentric flow conical nozzle burner with air co-flow have been investigated and presented in this work

  8. Topologically protected loop flows in high voltage AC power grids

    International Nuclear Information System (INIS)

    Coletta, T; Delabays, R; Jacquod, Ph; Adagideli, I

    2016-01-01

    Geographical features such as mountain ranges or big lakes and inland seas often result in large closed loops in high voltage AC power grids. Sizable circulating power flows have been recorded around such loops, which take up transmission line capacity and dissipate but do not deliver electric power. Power flows in high voltage AC transmission grids are dominantly governed by voltage angle differences between connected buses, much in the same way as Josephson currents depend on phase differences between tunnel-coupled superconductors. From this previously overlooked similarity we argue here that circulating power flows in AC power grids are analogous to supercurrents flowing in superconducting rings and in rings of Josephson junctions. We investigate how circulating power flows can be created and how they behave in the presence of ohmic dissipation. We show how changing operating conditions may generate them, how significantly more power is ohmically dissipated in their presence and how they are topologically protected, even in the presence of dissipation, so that they persist when operating conditions are returned to their original values. We identify three mechanisms for creating circulating power flows, (i) by loss of stability of the equilibrium state carrying no circulating loop flow, (ii) by tripping of a line traversing a large loop in the network and (iii) by reclosing a loop that tripped or was open earlier. Because voltages are uniquely defined, circulating power flows can take on only discrete values, much in the same way as circulation around vortices is quantized in superfluids. (paper)

  9. Turbulent behaviour of non-cohesive sediment gravity flows at unexpectedly high flow density

    Science.gov (United States)

    Baker, Megan; Baas, Jaco H.; Malarkey, Jonathan; Kane, Ian

    2016-04-01

    Experimental lock exchange-type turbidity currents laden with non-cohesive silica-flour were found to be highly dynamic at remarkably high suspended sediment concentrations. These experiments were conducted to produce sediment gravity flows of volumetric concentrations ranging from 1% to 52%, to study how changes in suspended sediment concentration affects the head velocities and run-out distances of these flows, in natural seawater. Increasing the volumetric concentration of suspended silica-flour, C, up to C = 46%, within the flows led to a progressive increase in the maximum head velocity. This relationship suggests that suspended sediment concentration intensifies the density difference between the turbulent suspension and the ambient water, which drives the flow, even if almost half of the available space is occupied by sediment particles. However, from C = 46% to C = 52% a rapid reduction in the maximum head velocity was measured. It is inferred that at C = 46%, friction from grain-to-grain interactions begins to attenuate turbulence within the flows. At C > 46%, the frictional stresses become progressively more dominant over the turbulent forces and excess density, thus producing lower maximum head velocities. This grain interaction process started to rapidly reduce the run-out distance of the silica-flour flows at equally high concentrations of C ≥ 47%. All flows with C tank, but the head velocities gradually reduced along the tank. Bagnold (1954, 1963) estimated that, for sand flows, grain-to-grain interactions start to become important in modulating turbulence at C > 9%. Yet, the critical flow concentration at which turbulence modulation commenced for these silica-flour laden flows appeared to be much higher. We suggest that Bagnold's 9% criterion cannot be applied to flows that carry fine-grained sediment, because turbulent forces are more important than dispersive forces, and frictional forces start to affect the flows only at concentrations just

  10. Close-Spaced High Temperature Knudsen Flow.

    Science.gov (United States)

    1984-06-15

    study of discharge processes in Knudsen mode (collisionless), thermionic energy converters. Areas of research involve mechanism for reducing the...The mechanisms we have chosen to study are: reduction of space-charge through a very close inter- electrode gap (less than 10 microns); transport and...AD-AI4U 471 :NNTIM R~ A Rl M ,i; ,11 , i J)W R8 1070 1 I~ "i E~Hhhh IIt Ll ~ : RASOR ASSOCIATES, INC.- AFOSR.TR. 84-1070 NSR-22-2 CLOSE -SPACED HIGH

  11. Autoinflation Leading to Failure of Two-Piece Ambicor Implantable Penile Prosthesis: An Outcome from a Methodical Treatment of Recalcitrant Stuttering Priapism

    Directory of Open Access Journals (Sweden)

    R. Charles Welliver

    2014-01-01

    Full Text Available Introduction. We present the case of a patient who received a two-piece Ambicor penile prosthesis for idiopathic recurrent “stuttering” priapism refractory to other treatment options. The patient returned unable to deflate the device due to an interesting anatomically induced mechanical failure. Aims. To describe the method and findings of this inflatable prosthesis failure. Results. Prosthesis failure occurred due to restrictive corporal diameter and the unique characteristics of fluid reservoir location in the two-piece inflatable prosthesis. The patient was successfully converted to a semirigid prosthesis with resolution of the pain that was due to his prosthesis autoinflation. Conclusion. Stuttering priapism remains a challenging clinical problem. Penile implantation is a reasonable long-term solution in a patient refractory to less invasive options. In patients with fibrotic corpora, a malleable device should be considered (at least temporarily if unable to dilate comfortably to 13 mm.

  12. Sildenafil citrate-restored eNOS and PDE5 regulation in sickle cell mouse penis prevents priapism via control of oxidative/nitrosative stress.

    Science.gov (United States)

    Bivalacqua, Trinity J; Musicki, Biljana; Hsu, Lewis L; Berkowitz, Dan E; Champion, Hunter C; Burnett, Arthur L

    2013-01-01

    Sildenafil citrate revolutionized the practice of sexual medicine upon its federal regulatory agency approval approximately 15 years ago as the prototypical phosphodiesterase type 5 inhibitor indicated for the treatment of male erectile dysfunction. We now provide scientific support for its alternative use in the management of priapism, a clinical disorder of prolonged and uncontrolled penile erection. Sildenafil administered continuously to sickle cell mice, which show a priapism phenotype, reverses oxidative/nitrosative stress effects in the penis, mainly via reversion of uncoupled endothelial nitric oxide synthase to the functional coupled state of the enzyme, which in turn corrects aberrant signaling and function of the nitric oxide/cyclic GMP/protein kinase G/phosphodiesterase type 5 cascade. Priapism tendencies in these mice are reverted partially toward normal neurostimulated erection frequencies and durations after sildenafil treatment in association with normalized cyclic GMP concentration, protein kinase G activity and phosphodiesterase type 5 activity in the penis. Thus, sildenafil exerts pleiotropic effects in the penis that extend to diverse erection disorders.

  13. Sildenafil citrate-restored eNOS and PDE5 regulation in sickle cell mouse penis prevents priapism via control of oxidative/nitrosative stress.

    Directory of Open Access Journals (Sweden)

    Trinity J Bivalacqua

    Full Text Available Sildenafil citrate revolutionized the practice of sexual medicine upon its federal regulatory agency approval approximately 15 years ago as the prototypical phosphodiesterase type 5 inhibitor indicated for the treatment of male erectile dysfunction. We now provide scientific support for its alternative use in the management of priapism, a clinical disorder of prolonged and uncontrolled penile erection. Sildenafil administered continuously to sickle cell mice, which show a priapism phenotype, reverses oxidative/nitrosative stress effects in the penis, mainly via reversion of uncoupled endothelial nitric oxide synthase to the functional coupled state of the enzyme, which in turn corrects aberrant signaling and function of the nitric oxide/cyclic GMP/protein kinase G/phosphodiesterase type 5 cascade. Priapism tendencies in these mice are reverted partially toward normal neurostimulated erection frequencies and durations after sildenafil treatment in association with normalized cyclic GMP concentration, protein kinase G activity and phosphodiesterase type 5 activity in the penis. Thus, sildenafil exerts pleiotropic effects in the penis that extend to diverse erection disorders.

  14. Flow field design for high-pressure PEM electrolysis cells

    DEFF Research Database (Denmark)

    Olesen, Anders Christian; Kær, Søren Knudsen

    -water distributes. Water not only serves a reactant, it also aids in cooling due to its high specific heat capacity. The movement of liquid water at the anode is difficult to model, since it is highly coupled to the formation of gas bubbles. To capture the complex two-phase flow behaviour that takes place within...... micro-channels and porous media, our research group has developed an Euler-Euler model in the computational fluid dynamics modelling framework of ANSYS CFX. In addition to two-phase flow, the model accounts for turbulence, species transport in the gas phase, heat transport in all three phases (i.......e. solid, gas and liquid), as well as charge transport of electrons and ions. Our recent improvements have focused on the models ability to account for phase change and electrochemistry as well as the modelling of two-phase flow regimes. For comparison, an interdigitated and parallel channel flow field...

  15. Signatures of collective flow in high multiplicity pp collisions

    CERN Document Server

    Kisiel, Adam

    2011-01-01

    A blast-wave parametrization, including a full set of hadronic resonances, is used to model a small system, with total particle multiplicity comparable to the one measured in the high-multiplicity pp collisions at the LHC. Calculations are preformed for three cases: with negligible, regular and strong radial flow on the blast-wave hypersurface. We investigate the effects of flow on inclusive p_T spectra as well as on 1D and 3D femtoscopic radii for pions. Special emphasis is put on the role of pions from resonance decays. In particular we show that they magnify the flow effects present in the blast-wave stage and significantly influence the shape of the correlation functions. A specific observable, the R^E_out/R^G_side ratio is proposed as a sensitive probe of the collective effects. Model results for the high multiplicity pp collisions, for scenarios with small and large radial flow are compared.

  16. Holography as a highly efficient RG flow I: Rephrasing gravity

    OpenAIRE

    Behr, Nicolas; Kuperstein, Stanislav; Mukhopadhyay, Ayan

    2015-01-01

    We investigate how the holographic correspondence can be reformulated as a generalisation of Wilsonian RG flow in a strongly interacting large $N$ quantum field theory. We firstly define a \\textit{highly efficient RG flow} as one in which the Ward identities related to local conservation of energy, momentum and charges preserve the same form at each scale -- to achieve this it is necessary to redefine the background metric and external sources at each scale as functionals of the effective sin...

  17. Self-flowing underwater concrete mixtures for high rise structures

    International Nuclear Information System (INIS)

    Yousri, K.M.

    2005-01-01

    Placement of conventional concrete mixtures in underwater construction results in a high percentage of material loss due to washout of cement paste. This paper presents the influence of anti washout admixture (AWA) on various properties of concrete. Eleven self-flowing concrete (SFC) mixtures using type II cement were proportioned. A combination of low water cement (w/c), high cement contents, anti washout admixtures, fly ash, and silica fume were used to enhance the resistance of fresh concrete to washout. The concrete mixtures proportioned to be highly flow able, self-leveling and cohesive. The water-cementitious materials ratios ranged between 0.356 and 0.392 which correspond a typical underwater concrete mixture. The concrete mixtures were tested for slump, slump flow, washout resistance and compressive strength. The compressive strength of each concrete mixture cast underwater was determined at 3, 7, 28 days and compared with the compressive strength of the same concrete mixture cast in normal condition (in air). Test results indicated that the use of an AWA facilitates the production of flow able concrete mixtures with the added benefit of lower washout loss. Concrete mixture proportioned using Type II cement and fly ash at level of replacement of 15% was found to develop self flowing concrete with better fresh and hardened properties and more resistant to washout. The self-flowing underwater concretes developed a 28-day compressive strengths ranging from 20 to 28 MPa

  18. Channel Geometry and Flood Flows: Quantifying over-bank flow dynamics during high-flow events in North Carolina's floodplains

    Science.gov (United States)

    Lovette, J. P.; Duncan, J. M.; Vimal, S.; Band, L. E.

    2015-12-01

    Natural riparian areas play numerous roles in the maintenance and improvement of stream water quality. Both restoration of riparian areas and improvement of hydrologic connectivity to the stream are often key goals of river restoration projects. These management actions are designed to improve nutrient removal by slowing and treating overland flow delivered from uplands and by storing, treating, and slowly releasing streamwater from overbank inundation during flood events. A major question is how effective this storage of overbank flow is at treating streamwater based on the cumulative time stream discharge at a downstream location has spent in shallower, slower overbank flow. The North Carolina Floodplain Mapping Program maintains a detailed statewide Flood Risk Information System (FRIS) using HEC-RAS modeling, lidar, and detailed surveyed river cross-sections. FRIS provides extensive information regarding channel geometry on approximately 39,000 stream reaches (a slightly coarser spatial resolution than the NHD+v2 dataset) with tens of cross-sections for each reach. We use this FRIS data to calculate volume and discharge from floodplain riparian areas separately from in-channel flow during overbank events. Preliminary results suggest that a small percentage of total annual discharge interacts with the full floodplain extent along a stream reach due to the infrequency of overbank flow events. However, with the significantly different physical characteristics of the riparian area when compared to the channel itself, this overbank flow can provide unique services to water quality. Our project aims to use this information in conjunction with data from the USGS SPARROW program to target non-point source hotspots of Nitrogen and Phosphorus addition and removal. By better understanding the flow dynamics within riparian areas during high flow events, riparian restoration projects can be carried out with improved efficacy.

  19. Plasma-Assisted Chemistry in High-Speed Flow

    International Nuclear Information System (INIS)

    Leonov, Sergey B.; Yarantsev, Dmitry A.; Napartovich, Anatoly P.; Kochetov, Igor V.

    2007-01-01

    Fundamental problems related to the high-speed combustion are analyzed. The result of plasma-chemical modeling is presented as a motivation of experimental activity. Numerical simulations of the effect of uniform non-equilibrium discharge on the premixed hydrogen and ethylene-air mixture in supersonic flow demonstrate an advantage of such a technique over a heating. Experimental results on multi-electrode non-uniform discharge maintenance behind wallstep and in cavity of supersonic flow are presented. The model test on hydrogen and ethylene ignition is demonstrated at direct fuel injection to low-temperature high-speed airflow

  20. High frequency flow-structural interaction in dense subsonic fluids

    Science.gov (United States)

    Liu, Baw-Lin; Ofarrell, J. M.

    1995-01-01

    Prediction of the detailed dynamic behavior in rocket propellant feed systems and engines and other such high-energy fluid systems requires precise analysis to assure structural performance. Designs sometimes require placement of bluff bodies in a flow passage. Additionally, there are flexibilities in ducts, liners, and piping systems. A design handbook and interactive data base have been developed for assessing flow/structural interactions to be used as a tool in design and development, to evaluate applicable geometries before problems develop, or to eliminate or minimize problems with existing hardware. This is a compilation of analytical/empirical data and techniques to evaluate detailed dynamic characteristics of both the fluid and structures. These techniques have direct applicability to rocket engine internal flow passages, hot gas drive systems, and vehicle propellant feed systems. Organization of the handbook is by basic geometries for estimating Strouhal numbers, added mass effects, mode shapes for various end constraints, critical onset flow conditions, and possible structural response amplitudes. Emphasis is on dense fluids and high structural loading potential for fatigue at low subsonic flow speeds where high-frequency excitations are possible. Avoidance and corrective measure illustrations are presented together with analytical curve fits for predictions compiled from a comprehensive data base.

  1. The Relationship between High Flow Nasal Cannula Flow Rate and Effort of Breathing in Children.

    Science.gov (United States)

    Weiler, Thomas; Kamerkar, Asavari; Hotz, Justin; Ross, Patrick A; Newth, Christopher J L; Khemani, Robinder G

    2017-10-01

    To use an objective metric of effort of breathing to determine optimal high flow nasal cannula (HFNC) flow rates in children flow rates of 0.5, 1.0, 1.5, and 2.0 L/kg/minute. For a subgroup of patients, 2 different HFNC delivery systems (Fisher & Paykel [Auckland, New Zealand] and Vapotherm [Exeter, New Hampshire]) were compared. Twenty-one patients (49 titration episodes) were studied. The most common diagnoses were bronchiolitis and pneumonia. Overall, there was a significant difference in the percent change in PRP from baseline (of 0.5 L/kg/minute) with increasing flow rates for the entire cohort (P flow rates were increased (P = .001) than patients >8 kg. The optimal HFNC flow rate to reduce effort of breathing in infants and young children is approximately 1.5-2.0 L/kg/minute with more benefit seen in children ≤8 kg. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. High energy density Z-pinch plasmas using flow stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Shumlak, U., E-mail: shumlak@uw.edu; Golingo, R. P., E-mail: shumlak@uw.edu; Nelson, B. A., E-mail: shumlak@uw.edu; Bowers, C. A., E-mail: shumlak@uw.edu; Doty, S. A., E-mail: shumlak@uw.edu; Forbes, E. G., E-mail: shumlak@uw.edu; Hughes, M. C., E-mail: shumlak@uw.edu; Kim, B., E-mail: shumlak@uw.edu; Knecht, S. D., E-mail: shumlak@uw.edu; Lambert, K. K., E-mail: shumlak@uw.edu; Lowrie, W., E-mail: shumlak@uw.edu; Ross, M. P., E-mail: shumlak@uw.edu; Weed, J. R., E-mail: shumlak@uw.edu [Aerospace and Energetics Research Program, University of Washington, Seattle, Washington, 98195-2250 (United States)

    2014-12-15

    The ZaP Flow Z-Pinch research project[1] at the University of Washington investigates the effect of sheared flows on MHD instabilities. Axially flowing Z-pinch plasmas are produced that are 100 cm long with a 1 cm radius. The plasma remains quiescent for many radial Alfvén times and axial flow times. The quiescent periods are characterized by low magnetic mode activity measured at several locations along the plasma column and by stationary visible plasma emission. Plasma evolution is modeled with high-resolution simulation codes – Mach2, WARPX, NIMROD, and HiFi. Plasma flow profiles are experimentally measured with a multi-chord ion Doppler spectrometer. A sheared flow profile is observed to be coincident with the quiescent period, and is consistent with classical plasma viscosity. Equilibrium is determined by diagnostic measurements: interferometry for density; spectroscopy for ion temperature, plasma flow, and density[2]; Thomson scattering for electron temperature; Zeeman splitting for internal magnetic field measurements[3]; and fast framing photography for global structure. Wall stabilization has been investigated computationally and experimentally by removing 70% of the surrounding conducting wall to demonstrate no change in stability behavior.[4] Experimental evidence suggests that the plasma lifetime is only limited by plasma supply and current waveform. The flow Z-pinch concept provides an approach to achieve high energy density plasmas,[5] which are large, easy to diagnose, and persist for extended durations. A new experiment, ZaP-HD, has been built to investigate this approach by separating the flow Z-pinch formation from the radial compression using a triaxial-electrode configuration. This innovation allows more detailed investigations of the sheared flow stabilizing effect, and it allows compression to much higher densities than previously achieved on ZaP by reducing the linear density and increasing the pinch current. Experimental results and

  3. Void fraction in horizontal bulk flow boiling at high flow qualities

    International Nuclear Information System (INIS)

    Collado, Fancisco J.; Monne, Carlos; Pascau, Antonio

    2008-01-01

    In this work, a new thermodynamic prediction of the vapor void fraction in bulk flow boiling, which is the core process of many energy conversion systems, is analyzed. The current heat balance is based on the flow quality, which is closely related to the measured void fraction, although some correlation for the vapor-liquid velocity ratio is needed. So here, it is suggested to work with the 'static' or thermodynamic quality, which is directly connected to the void fraction through the densities of the phases. Thus, the relation between heat and the mixture enthalpy (here based on the thermodynamic quality instead of the flow one) should be analyzed in depth. The careful void fraction data taken by Thom during the 'Cambridge project' for horizontal saturated flow boiling with high flow qualities (≤0.8) have been used for this analysis. As main results, first, we have found that the applied heat and the increment of the proposed thermodynamic enthalpy mixture throughout the heated duct do not agree, and for closure, a parameter is needed. Second, it has been checked that this parameter is practically equal to the classic velocity ratio or 'slip' ratio, suggesting that it should be included in a true thermodynamic heat balance. Furthermore, it has been clearly possible to improve the 'Cambridge project' correlations for the 'slip' ratio, here based on inlet pressure and water velocity, and heat flux. The calculated void fractions compare quite well with the measured ones. Finally, the equivalence of the suggested new heat balance with the current one through the 'slip' ratio is addressed. Highlighted is the same new energetic relation for saturated flow boiling that has been recently confirmed by the authors for Knights data, also taken during the 'Cambridge project', which include not only horizontal but also vertical upwards flows with moderate outlet flow quality (≤0.2)

  4. Void fraction in horizontal bulk flow boiling at high flow qualities

    Energy Technology Data Exchange (ETDEWEB)

    Collado, Fancisco J.; Monne, Carlos [Dpto. de Ingenieria Mecanica, Universidad de Zaragoza-CPS, Maria de Luna 3, 50018-Zaragoza (Spain); Pascau, Antonio [Dpto. de Ciencia de los Materiales y Fluidos, Universidad de Zaragoza-CPS, Maria de Luna 3, 50018-Zaragoza (Spain)

    2008-04-15

    In this work, a new thermodynamic prediction of the vapor void fraction in bulk flow boiling, which is the core process of many energy conversion systems, is analyzed. The current heat balance is based on the flow quality, which is closely related to the measured void fraction, although some correlation for the vapor-liquid velocity ratio is needed. So here, it is suggested to work with the 'static' or thermodynamic quality, which is directly connected to the void fraction through the densities of the phases. Thus, the relation between heat and the mixture enthalpy (here based on the thermodynamic quality instead of the flow one) should be analyzed in depth. The careful void fraction data taken by Thom during the 'Cambridge project' for horizontal saturated flow boiling with high flow qualities ({<=}0.8) have been used for this analysis. As main results, first, we have found that the applied heat and the increment of the proposed thermodynamic enthalpy mixture throughout the heated duct do not agree, and for closure, a parameter is needed. Second, it has been checked that this parameter is practically equal to the classic velocity ratio or 'slip' ratio, suggesting that it should be included in a true thermodynamic heat balance. Furthermore, it has been clearly possible to improve the 'Cambridge project' correlations for the 'slip' ratio, here based on inlet pressure and water velocity, and heat flux. The calculated void fractions compare quite well with the measured ones. Finally, the equivalence of the suggested new heat balance with the current one through the 'slip' ratio is addressed. Highlighted is the same new energetic relation for saturated flow boiling that has been recently confirmed by the authors for Knights data, also taken during the 'Cambridge project', which include not only horizontal but also vertical upwards flows with moderate outlet flow quality ({<=}0.2). (author)

  5. Characterization of non equilibrium effects on high quality critical flows

    International Nuclear Information System (INIS)

    Camelo, E.; Lemonnier, H.; Ochterbeck, J.

    1995-01-01

    The appropriate design of various pieces of safety equipment such as relief systems, relies on the accurate description of critical flow phenomena. Most of the systems of industrial interest are willing to be described by one-dimensional area-averaged models and a large fraction of them involves multi-component high gas quality flows. Within these circumstances, the flow is very likely to be of an annular dispersed nature and its description by two-fluid models requires various closure relations. Among the most sensitive closures, there is the interfacial area and the liquid entrained fraction. The critical flowrate depends tremendously on the accurate description of the non equilibrium which results from the correctness of the closure equations. In this study, two-component flows are emphasized and non equilibrium results mainly form the differences in the phase velocities. It is therefore of the utmost importance to have reliable data to characterize non equilibrium phenomena and to assess the validity of the closure models. A comprehensive description of air-water nozzle flows, with emphasis on the effect of the nozzle geometry, has been undertaken and some of the results are presented here which helps understanding the overall flow dynamics. Besides the critical flowrate, the presented material includes pressure profiles, droplet size and velocity, liquid film flowrate and liquid film thickness

  6. Measurements of granular flow dynamics with high speed digital images

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jingeol [Univ. of Florida, Gainesville, FL (United States)

    1994-01-01

    The flow of granular materials is common to many industrial processes. This dissertation suggests and validates image processing algorithms applied to high speed digital images to measure the dynamics (velocity, temperature and volume fraction) of dry granular solids flowing down an inclined chute under the action of gravity. Glass and acrylic particles have been used as granular solids in the experiment. One technique utilizes block matching for spatially averaged velocity measurements of the glass particles. This technique is compared with the velocity measurement using an optic probe which is a conventional granular flow velocity measurement device. The other technique for measuring the velocities of individual acrylic particles is developed with correspondence using a Hopfield network. This technique first locates the positions of particles with pattern recognition techniques, followed by a clustering technique, which produces point patterns. Also, several techniques are compared for particle recognition: synthetic discriminant function (SDF), minimum average correlation energy (MACE) filter, modified minimum average correlation energy (MMACE) filter and variance normalized correlation. The author proposes an MMACE filter which improves generalization of the MACE filter by adjusting the amount of averaged spectrum of training images in the spectrum whitening stages of the MACE filter. Variance normalized correlation is applied to measure the velocity and temperature of flowing glass particles down the inclined chute. The measurements are taken for the steady and wavy flow and qualitatively compared with a theoretical model of granular flow.

  7. Characterization of non equilibrium effects on high quality critical flows

    Energy Technology Data Exchange (ETDEWEB)

    Camelo, E.; Lemonnier, H.; Ochterbeck, J. [Commissariat a l Energie Atomique, Grenoble (France)] [and others

    1995-09-01

    The appropriate design of various pieces of safety equipment such as relief systems, relies on the accurate description of critical flow phenomena. Most of the systems of industrial interest are willing to be described by one-dimensional area-averaged models and a large fraction of them involves multi-component high gas quality flows. Within these circumstances, the flow is very likely to be of an annular dispersed nature and its description by two-fluid models requires various closure relations. Among the most sensitive closures, there is the interfacial area and the liquid entrained fraction. The critical flowrate depends tremendously on the accurate description of the non equilibrium which results from the correctness of the closure equations. In this study, two-component flows are emphasized and non equilibrium results mainly form the differences in the phase velocities. It is therefore of the utmost importance to have reliable data to characterize non equilibrium phenomena and to assess the validity of the closure models. A comprehensive description of air-water nozzle flows, with emphasis on the effect of the nozzle geometry, has been undertaken and some of the results are presented here which helps understanding the overall flow dynamics. Besides the critical flowrate, the presented material includes pressure profiles, droplet size and velocity, liquid film flowrate and liquid film thickness.

  8. Mixing of high density solution in vertical upward flow

    International Nuclear Information System (INIS)

    Kumamaru, Hiroshige; Hosogi, Nobuyoshi; Komada, Toshiaki; Fujiwara, Yoshiki

    1999-01-01

    Experimental and analytical studies have been performed in order to provide fundamental data and a numerical calculation model on the mixing of boric acid solution, injected from the standby liquid control system (SLCS), under a low natural circulation flow during an ATWS in a BWR. First, fundamental experiments on the mixing of high-density solution in vertically-upward water flow have been performed by using a small apparatus. Mixing patterns observed in the experiments have been classified to two groups, i.e. complete mixing (entrainment) and incomplete mixing (entrainment). In the complete mixing, the injected high-density solution is mixed (entrained) completely into the vertically-upward water flow. From the experiments, the minimum water flow rates in which the complete mixing (entrainment) is achieved have been obtained for various solution densities and solution injection rates. Secondly, two-dimensional numerical calculations have been performed. A continuity equation for total fluid, momentum equations in two directions and a continuity equation for solute are solved by using the finite difference method for discretization method and by following the MAC method for solution procedure. The calculations have predicted nearly the minimum water flow rate in which the complete mixing is achieved, while the calculations have been performed only for one combination of the solution density and solution injection rate until now. (author)

  9. High-resolution flow structure measurements in a rod bundle

    Energy Technology Data Exchange (ETDEWEB)

    Ylönen, A. T.

    2013-07-01

    Flow behaviour inside a rod bundle has been an active research topic since the early days of the nuclear power industry. Of particular interest in previous studies have been topics such as flow mixing, two-phase flow structure and mapping of two-phase flow transitions. The optimisation of fuel element design can only be achieved by truly understanding the nature of flow. The ultimate goal in this research is to enhance the heat transfer and increase the critical heat flux, which would improve the fuel economy. A better understanding of the flow would also improve nuclear safety as departure from nucleate boiling (DNB) can be predicted more accurately. The motivation for the current project (SUBFLOW) was to increase knowledge of the complex flow phenomena inside a rod bundle. A dedicated sub-channel flow test facility was designed and constructed at the Paul Scherrer Institut (PSI), Villigen, Switzerland. An adiabatic test loop has an up-scaled (1:2.6) vertical fuel rod bundle model with a 4 × 4 geometry. For the very first time, the wire-mesh sensor measurement technique was implemented in a rod bundle as two 64×64 conductivity wire-mesh sensors were installed in the upper part of the test section. The measurement technique enables one to study single- and two-phase flow behaviour with high spatial and temporal resolution. The research topics addressed in this thesis cover a wide range of flow conditions with and without a spacer grid in a rod bundle. The experimental campaign was started by studying natural mixing of a passive scalar to characterise the development of turbulent diffusion in an injection sub-channel and, later on, cross-mixing between adjacent sub-channels. The results were also used in comparison with the in-house CFD code PSI-Boil that is being developed at PSI. The code could estimate the mixing inside the sub-channel and the transition to cross-mixing with a good accuracy. As a natural transition, the SUBFLOW experiments were continued by

  10. High-resolution flow structure measurements in a rod bundle

    International Nuclear Information System (INIS)

    Ylönen, A. T.

    2013-01-01

    Flow behaviour inside a rod bundle has been an active research topic since the early days of the nuclear power industry. Of particular interest in previous studies have been topics such as flow mixing, two-phase flow structure and mapping of two-phase flow transitions. The optimisation of fuel element design can only be achieved by truly understanding the nature of flow. The ultimate goal in this research is to enhance the heat transfer and increase the critical heat flux, which would improve the fuel economy. A better understanding of the flow would also improve nuclear safety as departure from nucleate boiling (DNB) can be predicted more accurately. The motivation for the current project (SUBFLOW) was to increase knowledge of the complex flow phenomena inside a rod bundle. A dedicated sub-channel flow test facility was designed and constructed at the Paul Scherrer Institut (PSI), Villigen, Switzerland. An adiabatic test loop has an up-scaled (1:2.6) vertical fuel rod bundle model with a 4 × 4 geometry. For the very first time, the wire-mesh sensor measurement technique was implemented in a rod bundle as two 64×64 conductivity wire-mesh sensors were installed in the upper part of the test section. The measurement technique enables one to study single- and two-phase flow behaviour with high spatial and temporal resolution. The research topics addressed in this thesis cover a wide range of flow conditions with and without a spacer grid in a rod bundle. The experimental campaign was started by studying natural mixing of a passive scalar to characterise the development of turbulent diffusion in an injection sub-channel and, later on, cross-mixing between adjacent sub-channels. The results were also used in comparison with the in-house CFD code PSI-Boil that is being developed at PSI. The code could estimate the mixing inside the sub-channel and the transition to cross-mixing with a good accuracy. As a natural transition, the SUBFLOW experiments were continued by

  11. Thermal Mechanisms for High Amplitude Aerodynamic Flow Control (YIP 2012)

    Science.gov (United States)

    2016-04-15

    transport aircraft , much less cruise. The search for a perfect actuator continues, but progress has been limited by the often proprietary nature these...wave generation as a mechanism for high amplitude, high bandwidth actuation has been demonstrated, but the fundamental physics of how this...moving forward with such a definition. 15. SUBJECT TERMS active flow control, energy deposition, plasma actuation 16. SECURITY CLASSIFICATION OF: 17

  12. Flow visualization in models of high speed centrifugal separators

    International Nuclear Information System (INIS)

    Lagerstedt, T.; Nabo, O.

    1987-01-01

    The modern centrifugal separator is a fluid machine where the high ''G'' forces set up by rotation are utilized to separate phases of different densities. The fluid dynamics of the separator is complex and poorly known. Hundred years of (practical) experience has, however, turned the separator into an efficient machine. The present report shows how straight forward visualization experiments in model rigs provide valuable information on the flow inside the separator. The report concentrates on describing the flow between the closely spaced discs in a separator disc stack

  13. Computation of high Reynolds number internal/external flows

    Science.gov (United States)

    Cline, M. C.; Wilmoth, R. G.

    1981-01-01

    A general, user oriented computer program, called VNAP2, was developed to calculate high Reynolds number, internal/ external flows. The VNAP2 program solves the two dimensional, time dependent Navier-Stokes equations. The turbulence is modeled with either a mixing-length, a one transport equation, or a two transport equation model. Interior grid points are computed using the explicit MacCormack Scheme with special procedures to speed up the calculation in the fine grid. All boundary conditions are calculated using a reference plane characteristic scheme with the viscous terms treated as source terms. Several internal, external, and internal/external flow calculations are presented.

  14. Computation of high Reynolds number internal/external flows

    International Nuclear Information System (INIS)

    Cline, M.C.; Wilmoth, R.G.

    1981-01-01

    A general, user oriented computer program, called VNAP2, has been developed to calculate high Reynolds number, internal/external flows. VNAP2 solves the two-dimensional, time-dependent Navier-Stokes equations. The turbulence is modeled with either a mixing-length, a one transport equation, or a two transport equation model. Interior grid points are computed using the explicit MacCormack scheme with special procedures to speed up the calculation in the fine grid. All boundary conditions are calculated using a reference plane characteristic scheme with the viscous terms treated as source terms. Several internal, external, and internal/external flow calculations are presented

  15. Automation in high-content flow cytometry screening.

    Science.gov (United States)

    Naumann, U; Wand, M P

    2009-09-01

    High-content flow cytometric screening (FC-HCS) is a 21st Century technology that combines robotic fluid handling, flow cytometric instrumentation, and bioinformatics software, so that relatively large numbers of flow cytometric samples can be processed and analysed in a short period of time. We revisit a recent application of FC-HCS to the problem of cellular signature definition for acute graft-versus-host-disease. Our focus is on automation of the data processing steps using recent advances in statistical methodology. We demonstrate that effective results, on par with those obtained via manual processing, can be achieved using our automatic techniques. Such automation of FC-HCS has the potential to drastically improve diagnosis and biomarker identification.

  16. Initial angular momentum and flow in high energy nuclear collisions

    Science.gov (United States)

    Fries, Rainer J.; Chen, Guangyao; Somanathan, Sidharth

    2018-03-01

    We study the transfer of angular momentum in high energy nuclear collisions from the colliding nuclei to the region around midrapidity, using the classical approximation of the color glass condensate (CGC) picture. We find that the angular momentum shortly after the collision (up to times ˜1 /Qs , where Qs is the saturation scale) is carried by the "β -type" flow of the initial classical gluon field, introduced by some of us earlier. βi˜μ1∇iμ2-μ2∇iμ1 (i =1 ,2 ) describes the rapidity-odd transverse energy flow and emerges from Gauss's law for gluon fields. Here μ1 and μ2 are the averaged color charge fluctuation densities in the two nuclei, respectively. Interestingly, strong coupling calculations using anti-de Sitter/conformal field theory (AdS/CFT) techniques also find an energy flow term featuring this particular combination of nuclear densities. In classical CGC the order of magnitude of the initial angular momentum per rapidity in the reaction plane, at a time 1 /Qs , is |d L2/d η |≈ RAQs-3ɛ¯0/2 at midrapidity, where RA is the nuclear radius, and ɛ¯0 is the average initial energy density. This result emerges as a cancellation between a vortex of energy flow in the reaction plane aligned with the total angular momentum, and energy shear flow opposed to it. We discuss in detail the process of matching classical Yang-Mills results to fluid dynamics. We will argue that dissipative corrections should not be discarded to ensure that macroscopic conservation laws, e.g., for angular momentum, hold. Viscous fluid dynamics tends to dissipate the shear flow contribution that carries angular momentum in boost-invariant fluid systems. This leads to small residual angular momentum around midrapidity at late times for collisions at high energies.

  17. High speed motion neutron radiography of two-phase flow

    International Nuclear Information System (INIS)

    Robinson, A.H.; Wang, S.L.

    1983-01-01

    Current research in the area of two-phase flow utilizes a wide variety of sensing devices, but some limitations exist on the information which can be obtained. Neutron radiography is a feasible alternative to ''see'' the two-phase flow. A system to perform neutron radiographic analysis of dynamic events which occur on the order of several milliseconds has been developed at Oregon State University. Two different methods have been used to radiograph the simulated two-phase flow. These are pulsed, or ''flash'' radiography, and high speed movie neutron radiography. The pulsed method serves as a ''snap-shot'' with an exposure time ranging from 10 to 20 milliseconds. In high speed movie radiography, a scintillator is used to convert neutrons into light which is enhanced by an optical intensifier and then photographed by a high speed camera. Both types of radiography utilize the pulsing capability of the OSU TRIGA reactor. The principle difficulty with this type of neutron radiography is the fogging of the image due to the large amount of scattering in the water. This difficulty can be overcome by using thin regions for the two-phase flow or using heavy water instead of light water. The results obtained in this paper demonstrate the feasibility of using neutron radiography to obtain data in two-phase flow situations. Both movies and flash radiographs have been obtained of air bubbles in water and boiling from a heater element. The neutron radiographs of the boiling element show both nucleate boiling and film boiling. (Auth.)

  18. Efficient Unsteady Flow Visualization with High-Order Access Dependencies

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jiang; Guo, Hanqi; Yuan, Xiaoru

    2016-04-19

    We present a novel high-order access dependencies based model for efficient pathline computation in unsteady flow visualization. By taking longer access sequences into account to model more sophisticated data access patterns in particle tracing, our method greatly improves the accuracy and reliability in data access prediction. In our work, high-order access dependencies are calculated by tracing uniformly-seeded pathlines in both forward and backward directions in a preprocessing stage. The effectiveness of our proposed approach is demonstrated through a parallel particle tracing framework with high-order data prefetching. Results show that our method achieves higher data locality and hence improves the efficiency of pathline computation.

  19. Void fraction measurement system for high temperature flows

    Energy Technology Data Exchange (ETDEWEB)

    Teyssedou, A; Aube, F; Champagne, P [Montreal Univ., PQ (Canada). Institut de Genie Energetique

    1992-05-01

    A {gamma}-ray absorption technique has been developed for measuring the axial distribution of the void fraction for high-temperature and high-pressure two-phase flows. The system is mounted on a moving platform driven by a high-power stepping motor. A personal computer (IBM AT) connected to a data acquisition system is used to control the displacement of the {gamma} source and detector, and to read the response of the detector. All the measurement procedures are carried out automatically by dedicated software developed for this purpose. (Author).

  20. Characteristics of Multiplexed Grooved Nozzles for High Flow Rate Electrospray

    International Nuclear Information System (INIS)

    Kim, Kyoung Tae; Kim, Woo Jin; Kim, Sang Soo

    2007-01-01

    The electrospray operated in the cone-jet mode can generate highly charged micro droplets in an almost uniform size at flow rates. Therefore, the multiplexing system which can retain the characteristics of the cone-jet mode is inevitable for the electrospray application. This experiment reports the multiplexed grooved nozzle system with the extractor. The effects of the grooves and the extractor on the performance of the electrospray were evaluated through experiments. Using the grooved nozzle, the stable cone-jet mode can be achieved at the each groove in the grooved mode. Furthermore, the number of nozzles per unit area is increased by the extractor. The multiplexing density is 12 jets per cm 2 at 30 mm distance from the nozzle tip to the ground plate. The multiplexing system for the high flow rate electrospray is realized with the extractor which can diminish the space charge effect without sacrificing characteristics of the cone-jet mode

  1. Lithium-Based High Energy Density Flow Batteries

    Science.gov (United States)

    Bugga, Ratnakumar V. (Inventor); West, William C. (Inventor); Kindler, Andrew (Inventor); Smart, Marshall C. (Inventor)

    2014-01-01

    Systems and methods in accordance with embodiments of the invention implement a lithium-based high energy density flow battery. In one embodiment, a lithium-based high energy density flow battery includes a first anodic conductive solution that includes a lithium polyaromatic hydrocarbon complex dissolved in a solvent, a second cathodic conductive solution that includes a cathodic complex dissolved in a solvent, a solid lithium ion conductor disposed so as to separate the first solution from the second solution, such that the first conductive solution, the second conductive solution, and the solid lithium ionic conductor define a circuit, where when the circuit is closed, lithium from the lithium polyaromatic hydrocarbon complex in the first conductive solution dissociates from the lithium polyaromatic hydrocarbon complex, migrates through the solid lithium ionic conductor, and associates with the cathodic complex of the second conductive solution, and a current is generated.

  2. Vortex Generator Induced Flow in a High Re Boundary Layer

    DEFF Research Database (Denmark)

    Velte, Clara Marika; Braud, C.; Coudert, S.

    2014-01-01

    Stereoscopic Particle Image Velocimetry measurements have been conducted in cross-planes behind three different geometries of Vortex Generators (VGs) in a high Reynolds number boundary layer. The VGs have been mounted in a cascade producing counter-rotating vortices and the downstream flow...... development was examined. Three VG geometries were investigated: rectangular, triangular and cambered. The various VG geometries tested are seen to produce different impacts on the boundary layer flow. Helical symmetry of the generated vortices is confirmed for all investigated VG geometries in this high...... Reynolds number boundary layer. From the parameters resulting from this analysis, it is observed at the most upstream measurement position that the rectangular and triangular VGs produce vortices of similar size, strength and velocity induction whilst the cambered VGs produce smaller and weaker vortices...

  3. Vortex Generator Induced Flow in a High Re Boundary Layer

    DEFF Research Database (Denmark)

    Velte, Clara Marika; Braud, C.; Coudert, S.

    2012-01-01

    Stereoscopic Particle Image Velocimetry measurements have been conducted in cross-planes behind three different geometries of Vortex Generators (VGs) in a high Reynolds number boundary layer. The VGs have been mounted in a cascade producing counter-rotating vortices and the downstream flow...... development was examined. Three VG geometries were investigated: rectangular, triangular and cambered. The various VG geometries tested are seen to produce different impacts on the boundary layer flow. Helical symmetry of the generated vortices is confirmed for all investigated VG geometries in this high...... Reynolds number boundary layer. From the parameters resulting from this analysis, it is observed at the most upstream measurement position that the rectangular and triangular VGs produce vortices of similar size, strength and velocity induction whilst the cambered VGs produce smaller and weaker vortices...

  4. Krohne Flow Indicator and High Flow Alarm - Local Indicator and High Flow Alarm of Helium Flow from the SCHe Purge Lines C and D to the Process Vent

    International Nuclear Information System (INIS)

    MISKA, C.R.

    2000-01-01

    Flow Indicators/alarms FI/FSH-5*52 and -5*72 are located in the process vent lines connected to the 2 psig SCHe purge lines C and D. They monitor the flow from the 2 psig SCHe purge going to the process vent. The switch/alarm is non-safety class GS

  5. Miniaturized heat flux sensor for high enthalpy plasma flow characterization

    International Nuclear Information System (INIS)

    Gardarein, Jean-Laurent; Battaglia, Jean-Luc; Lohlec, Stefan; Jullien, Pierre; Van Ootegemd, Bruno; Couzie, Jacques; Lasserre, Jean-Pierre

    2013-01-01

    An improved miniaturized heat flux sensor is presented aiming at measuring extreme heat fluxes of plasma wind tunnel flows. The sensor concept is based on an in-depth thermocouple measurement with a miniaturized design and an advanced calibration approach. Moreover, a better spatial estimation of the heat flux profile along the flow cross section is realized with this improved small sensor design. Based on the linearity assumption, the heat flux is determined using the impulse response of the sensor relating the heat flux to the temperature of the embedded thermocouple. The non-integer system identification (NISI) procedure is applied that allows a calculation of the impulse response from transient calibration measurements with a known heat flux of a laser source. The results show that the new sensor leads to radially highly resolved heat flux measurement for a flow with only a few centimetres in diameter, the so far not understood non-symmetric heat flux profiles do not occur with the new sensor design. It is shown that this former effect is not a physical effect of the flow, but a drawback of the classical sensor design. (authors)

  6. Development and Application of Plasma Actuators for Active Control of High-Speed and High Reynolds Number Flows

    Science.gov (United States)

    Sammy, Mo

    2010-01-01

    Active flow control is often used to manipulate flow instabilities to achieve a desired goal (e.g. prevent separation, enhance mixing, reduce noise, etc.). Instability frequencies normally scale with flow velocity scale and inversely with flow length scale (U/l). In a laboratory setting for such flow experiments, U is high, but l is low, resulting in high instability frequency. In addition, high momentum and high background noise & turbulence in the flow necessitate high amplitude actuation. Developing a high amplitude and high frequency actuator is a major challenge. Ironically, these requirements ease up in application (but other issues arise).

  7. Treatment of High-Flow Vascular Malformations by Venous Embolization Aided by Flow Occlusion Techniques

    International Nuclear Information System (INIS)

    Jackson, James E.; Mansfield, Averil O.; Allison, David J.

    1996-01-01

    Purpose: Transvenous embolization techniques may be helpful as alternatives to the arterial route when treating high-flow vascular malformations. We present our experience using these techniques in four patients. Methods: In one patient the venous portion of the arteriovenous malformation (AVM) was punctured directly; in the other three patients it was catheterized via a retrograde venous approach. Flow occlusion techniques were utilized in all patients during embolization, which was performed with absolute alcohol or N-butyl-2-cyanoacrylate.Results: Excellent clinical and angiographic results were obtained, with obliteration of arteriovenous shunting in all patients. There were no complications.Conclusion: The embolization of certain AVMs using a venous approach is a safe and effective treatment

  8. Transient flow characteristics of a high speed rotary valve

    Science.gov (United States)

    Browning, Patrick H.

    were experimentally mapped as a function of valve speed, inter-cylinder pressure ratios and volume ratios and the results were compared to compressible flow theoretical models. Specifically, the transient behavior suggested a short-lived loss-mode initiation closely resembled by shock tube theory followed by a quasi-steady flow regime resembling choked flow behavior. An empirical model was then employed to determine the useful range of the CCV design as applied to a four-stroke CIBAI engine cycle modeled using a 1-D quasi-steady numerical method, with particular emphasis on the cyclic timing of the CCV opening. Finally, a brief discussion of a high-temperature version of the CCV design is presented.

  9. High-speed solar wind flow parameters at 1 AU

    International Nuclear Information System (INIS)

    Feldman, W.C.; Asbridge, J.R.; Bame, S.J.; Gosling, J.T.

    1976-01-01

    To develop a set of constraints for theories of solar wind high-speed streams, a detailed study was made of the fastest streams observed at 1 AU during the time period spanning March 1971 through July 1974. Streams were accepted for study only if (1) the maximum speed exceeded 650 km s -1 ; (2) effects of stream-stream dynamical interaction on the flow parameters could be safely separated from the intrinsic characteristics of the high-speed regions; (3) the full width at half maximum (FWHM) of the stream when mapped back to 20 solar radii by using a constant speed approximation was greater than 45degree in Carrington longitude; and (4) there were no obvious solar-activity-induced contaminating effects. Nineteen streams during this time interval satisfied these criteria. Average parameters at 1 AU for those portions of these streams above V=650 km s -1 are given.Not only is it not presently known why electrons are significantly cooler than the protons within high-speed regions, but also observed particle fluxes and convected energy fluxes for speed greater than 650 km s -1 are substantially larger than those values predicted by any of the existing theories of solar wind high-speed streams. More work is therefore needed in refining present solar wind models to see whether suitable modifications and/or combinations of existing theories based on reasonable coronal conditions can accommodate the above high-speed flow parameters

  10. Computational Study of Nonequilibrium Chemistry in High Temperature Flows

    Science.gov (United States)

    Doraiswamy, Sriram

    Recent experimental measurements in the reflected shock tunnel CUBRC LENS-I facility raise questions about our ability to correctly model the recombination processes in high enthalpy flows. In the carbon dioxide flow, the computed shock standoff distance over the Mars Science Laboratory (MSL) shape was less than half of the experimental result. For the oxygen flows, both pressure and heat transfer data on the double cone geometry were not correctly predicted. The objective of this work is to investigate possible reasons for these discrepancies. This process involves systematically addressing different factors that could possibly explain the differences. These factors include vibrational modeling, role of electronic states and chemistry-vibrational coupling in high enthalpy flows. A state-specific vibrational model for CO2, CO, O2 and O system is devised by taking into account the first few vibrational states of each species. All vibrational states with energies at or below 1 eV are included in the present work. Of the three modes of vibration in CO2 , the antisymmetric mode is considered separately from the symmetric stretching mode and the doubly degenerate bending modes. The symmetric and the bending modes are grouped together since the energy transfer rates between the two modes are very large due to Fermi resonance. The symmetric and bending modes are assumed to be in equilibrium with the translational and rotational modes. The kinetic rates for the vibrational-translation energy exchange reactions, and the intermolecular and intramolecular vibrational-vibrational energy exchange reactions are based on experimental data to the maximum extent possible. Extrapolation methods are employed when necessary. This vibrational model is then coupled with an axisymmetric computational fluid dynamics code to study the expansion of CO2 in a nozzle. The potential role of low lying electronic states is also investigated. Carbon dioxide has a single excited state just below

  11. Supersonic plasma flow between high latitude conjugate ionospheres

    International Nuclear Information System (INIS)

    Roesler, G.

    1975-01-01

    The polar wind problem has been investigated for closed field lines in situations where one of the two conjugate ionospheric regions is fully illuminated by the sun and the other darkness (solstices at high latitudes). A supersonic flow between hemispheres is possible; the magnetospheric part of this flow must be symmetric with respect to the equator. The daytime fluxes are proportional to the neutral hydrogen density. Fluxes of the order of 10 8 cm -2 sec -1 are only possible with density considerably higher than given by CIRA models. For stationary solutions higher flow speeds are needed on the dark side than provided from the illuminated side. It is concluded that shock waves with upward velocities of about 5 km/sec would form above the dark ionosphere. This implies a reduction by a factor of 3 to 5 of the plasma influx into the dark hemisphere, whereby F-layer densities of only up to 2 x 10 4 cm -3 can be maintained. (orig.) [de

  12. High energy electron disinfection of sewage wastewater in flow systems

    Energy Technology Data Exchange (ETDEWEB)

    Miyata, T; Arai, H; Hosono, M; Tokunaga, O; Machi, S [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment; Kondoh, M; Minemura, T; Nakao, A; Seike, Y [Sumitomo Heavy Industries Ltd., Tokyo (Japan)

    1990-01-01

    The disinfection of effluent municipal wastewaters by high-energy electrons in flow systems was studied using an experimental apparatus which has the maximum treatment capacity of 10.8 m{sup 3}/h. An electron accelerator with an accelerating voltage of 2 MV was used. The electron beam current was controlled to deliver the desired doses ranging from 0.05 to 1 kGy. Treatment times were in the range from 0.0022 to 0.051 s. Preliminary experiments with batch system using Petri dish of 100 ml showed that the effectiveness of electron irradiation on inactivation of coliforms was not influenced significantly by factors such as pH, SS, COD, DO and irradiation temperature. The dose required to produce 99.9% kill in the total population presented in wastewater were markedly affected by the thickness of water exposure to electron irradiation; that is, 0.39, 0.4 and 0.44 kGy for the depth of 5, 6 and 7 mm, respectively. The data obtained after a suitable correction for the doses due to the depth dose distribution showed no deviation from an experimental survival curve. Experiments with flow system indicated no measureable effect of the flow rate of wastewaters on the efficiency of disinfection in the range from 0.5 to 3.5 m/s. (author).

  13. High urinary flow in women with stress incontinence: corrected flow-age nomogram evaluation after a transobturator tape procedure.

    Science.gov (United States)

    Kitagawa, Yasuhide; Narimoto, Kazutaka; Urata, Satoko; Kawaguchi, Shohei; Kuribayashi, Masato; Namiki, Mikio

    2016-07-01

    We noninvasively compared urinary flow in both pre- and post-transobturator tape (TOT) procedures in stress urinary incontinence (SUI) patients using previously reported corrected flow-age nomograms in healthy women. This retrospective cohort study included patients who underwent a successful TOT procedure to treat SUI. Non-instrumented uroflowmetry was performed before and 3 months after surgery. Corrected maximum flow rate (cQmax) and average flow rate (cQave) were calculated using Qmax/√voided volume (VV) and Qave/√VV respectively. The ratio of corrected flow to age-adjusted corrected flow in healthy women was calculated in each patient. Each parameter was compared against pre-TOT and 3-months post-TOT values. Sixty-two patients were eligible for study inclusion. All urinary flow parameters were significantly higher pre-TOT than at 3 months post-TOT. The number of patients with cQmax and cQave over mean flow-age nomogram, compared with healthy women, before the TOT procedure decreased 3 months post-TOT; however, in many patients, cQmax and cQave were higher than in the corrected flow-age nomogram post-TOT. No significant difference in the ratio of cQmax to age-adjusted cQmax between pre- and post-TOT in the normal urinary flow group was observed, but significantly decreased in the high urinary flow group 3 months after TOT. Urinary flow rates were higher in SUI patients compared with age-matched controls and successful TOT procedures normalized urinary flows in patients with high urinary flow. A simple evaluation of urinary flow using a corrected flow-age nomogram may be clinically useful in SUI patients.

  14. In-Vivo High Dynamic Range Vector Flow Imaging

    DEFF Research Database (Denmark)

    Villagómez Hoyos, Carlos Armando; Stuart, Matthias Bo; Jensen, Jørgen Arendt

    2015-01-01

    example with a high dynamic velocity range. Velocities with an order of magnitude apart are detected on the femoral artery of a 41 years old healthy individual. Three distinct heart cycles are captured during a 3 secs acquisition. The estimated vector velocities are compared against each other within...... the heart cycle. The relative standard deviation of the measured velocity magnitude between the three peak systoles was found to be 5.11% with a standard deviation on the detected angle of 1.06◦ . In the diastole, it was 1.46% and 6.18◦ , respectively. Results proves that the method is able to estimate flow...

  15. A high-precision algorithm for axisymmetric flow

    Directory of Open Access Journals (Sweden)

    A. Gokhman

    1995-01-01

    Full Text Available We present a new algorithm for highly accurate computation of axisymmetric potential flow. The principal feature of the algorithm is the use of orthogonal curvilinear coordinates. These coordinates are used to write down the equations and to specify quadrilateral elements following the boundary. In particular, boundary conditions for the Stokes' stream-function are satisfied exactly. The velocity field is determined by differentiating the stream-function. We avoid the use of quadratures in the evaluation of Galerkin integrals, and instead use splining of the boundaries of elements to take the double integrals of the shape functions in closed form. This is very accurate and not time consuming.

  16. The Granular Blasius Problem: High inertial number granular flows

    Science.gov (United States)

    Tsang, Jonathan; Dalziel, Stuart; Vriend, Nathalie

    2017-11-01

    The classical Blasius problem considers the formation of a boundary layer through the change at x = 0 from a free-slip to a no-slip boundary beneath an otherwise steady uniform flow. Discrete particle model (DPM) simulations of granular gravity currents show that a similar phenomenon exists for a steady flow over a uniformly sloped surface that is smooth upstream (allowing slip) but rough downstream (imposing a no-slip condition). The boundary layer is a region of high shear rate and therefore high inertial number I; its dynamics are governed by the asymptotic behaviour of the granular rheology as I -> ∞ . The μ(I) rheology asserts that dμ / dI = O(1 /I2) as I -> ∞ , but current experimental evidence is insufficient to confirm this. We show that `generalised μ(I) rheologies', with different behaviours as I -> ∞ , all permit the formation of a boundary layer. We give approximate solutions for the velocity profile under each rheology. The change in boundary condition considered here mimics more complex topography in which shear stress increases in the streamwise direction (e.g. a curved slope). Such a system would be of interest in avalanche modelling. EPSRC studentship (Tsang) and Royal Society Dorothy Hodgkin Fellowship (Vriend).

  17. High temperature, high pressure gas loop - the Component Flow Test Loop (CFTL)

    International Nuclear Information System (INIS)

    Gat, U.; Sanders, J.P.; Young, H.C.

    1984-01-01

    The high-pressure, high-temperature, gas-circulating Component Flow Test Loop located at Oak Ridge National Laboratory was designed and constructed utilizing Section III of the ASME Boiler and Pressure Vessel Code. The quality assurance program for operating and testing is also based on applicable ASME standards. Power to a total of 5 MW is available to the test section, and an air-cooled heat exchanger rated at 4.4 MW serves as heat sink. The three gas-bearing, completely enclosed gas circulators provide a maximum flow of 0.47 m 3 /s at pressures to 10.7 MPa. The control system allows for fast transients in pressure, power, temperature, and flow; it also supports prolonged unattended steady-state operation. The data acquisition system can access and process 10,000 data points per second. High-temperature gas-cooled reactor components are being tested

  18. High throughput analysis of samples in flowing liquid

    Energy Technology Data Exchange (ETDEWEB)

    Ambrose, W. Patrick (Los Alamos, NM); Grace, W. Kevin (Los Alamos, NM); Goodwin, Peter M. (Los Alamos, NM); Jett, James H. (Los Alamos, NM); Orden, Alan Van (Fort Collins, CO); Keller, Richard A. (White Rock, NM)

    2001-01-01

    Apparatus and method enable imaging multiple fluorescent sample particles in a single flow channel. A flow channel defines a flow direction for samples in a flow stream and has a viewing plane perpendicular to the flow direction. A laser beam is formed as a ribbon having a width effective to cover the viewing plane. Imaging optics are arranged to view the viewing plane to form an image of the fluorescent sample particles in the flow stream, and a camera records the image formed by the imaging optics.

  19. High-Fidelity Aerodynamic Shape Optimization for Natural Laminar Flow

    Science.gov (United States)

    Rashad, Ramy

    To ensure the long-term sustainability of aviation, serious effort is underway to mitigate the escalating economic, environmental, and social concerns of the industry. Significant improvement to the energy efficiency of air transportation is required through the research and development of advanced and unconventional airframe and engine technologies. In the quest to reduce airframe drag, this thesis is concerned with the development and demonstration of an effective design tool for improving the aerodynamic efficiency of subsonic and transonic airfoils. The objective is to advance the state-of-the-art in high-fidelity aerodynamic shape optimization by incorporating and exploiting the phenomenon of laminar-turbulent transition in an efficient manner. A framework for the design and optimization of Natural Laminar Flow (NLF) airfoils is developed and demonstrated with transition prediction capable of accounting for the effects of Reynolds number, freestream turbulence intensity, Mach number, and pressure gradients. First, a two-dimensional Reynolds-averaged Navier-Stokes (RANS) flow solver has been extended to incorporate an iterative laminar-turbulent transition prediction methodology. The natural transition locations due to Tollmien-Schlichting instabilities are predicted using the simplified eN envelope method of Drela and Giles or, alternatively, the compressible form of the Arnal-Habiballah-Delcourt criterion. The boundary-layer properties are obtained directly from the Navier-Stokes flow solution, and the transition to turbulent flow is modeled using an intermittency function in conjunction with the Spalart-Allmaras turbulence model. The RANS solver is subsequently employed in a gradient-based sequential quadratic programming shape optimization framework. The laminar-turbulent transition criteria are tightly coupled into the objective and gradient evaluations. The gradients are obtained using a new augmented discrete-adjoint formulation for non-local transition

  20. Study on flow regimes of high-pressure and dense-phase pneumatic conveying

    International Nuclear Information System (INIS)

    Lu Peng; Chen Xiaoping; Liang Cai; Pu Wenhao; Zhou Yun; Xu Pan; Zhao Changsui

    2009-01-01

    High-pressure and dense-phase pneumatic conveying of pulverized coal is a key technology in the field of large-scale entrained bed coal gasification. Flow regime plays an important role in two-phase flow because it affects not only flow behavior and safety operation, but also the reliability of practical processes. Few references and experiences in high-pressure and dense-phase conveying are available, especially for the flow regimes. And because of the high stickiness and electrostatic attraction of pulverized coal to the pipe wall, it is very difficult to make out the flow regimes in the conveying pipe by visualization method. Thus quartz powder was chosen as the conveyed material to study the flow regime. High-speed digital video camera was employed to photograph the flow patterns. Experiments were conducted on a pilot scale experimental setup at the pressure up to 3.6MPa. With the decrease in superficial gas velocity, three distinguishable flow regimes were observed: stratified flow, dune flow and plug flow. The characteristics of pressure traces acquired by high frequency response pressure transmitter and their EMD (Empirical Mode Decomposition) characteristics were correlated strongly with the flow regimes. Combining high-speed photography and pressure signal analysis together can make the recognition of flow patterns in the high-pressure and dense-phase pneumatic conveying system more accurate. The present work will lead to better understanding of the flow regime transition under high-pressure.

  1. High angle of attack aerodynamics subsonic, transonic, and supersonic flows

    CERN Document Server

    Rom, Josef

    1992-01-01

    The aerodynamics of aircraft at high angles of attack is a subject which is being pursued diligently, because the modern agile fighter aircraft and many of the current generation of missiles must perform well at very high incidence, near and beyond stall. However, a comprehensive presentation of the methods and results applicable to the studies of the complex aerodynamics at high angle of attack has not been covered in monographs or textbooks. This book is not the usual textbook in that it goes beyond just presenting the basic theoretical and experimental know-how, since it contains reference material to practical calculation methods and technical and experimental results which can be useful to the practicing aerospace engineers and scientists. It can certainly be used as a text and reference book for graduate courses on subjects related to high angles of attack aerodynamics and for topics related to three-dimensional separation in viscous flow courses. In addition, the book is addressed to the aerodynamicist...

  2. High-flow nasal cannula therapy for adult patients

    Science.gov (United States)

    Zhang, Jian; Lin, Ling; Pan, Konghan; Zhou, Jiancang

    2016-01-01

    High-flow nasal cannula (HFNC) oxygen therapy has several physiological advantages over traditional oxygen therapy devices, including decreased nasopharyngeal resistance, washing out of the nasopharyngeal dead space, generation of positive pressure in the pharynx, increasing alveolar recruitment in the lungs, humidification of the airways, increased fraction of inspired oxygen and improved mucociliary clearance. Recently, the use of HFNC in treating adult critical illness patients has significantly increased, and it is now being used in many patients with a range of different disease conditions. However, there are no established guidelines to direct the safe and effective use of HFNC for these patients. This review article summarizes the available published literature on the positive physiological effects, mechanisms of action, and the clinical applications of HFNC, compared with traditional oxygen therapy devices. The available literature suggests that HFNC oxygen therapy is an effective modality for the early treatment of critically adult patients. PMID:27698207

  3. Interventional management of high-flow vascular malformations.

    Science.gov (United States)

    Rosen, Robert J; Nassiri, Naiem; Drury, Jennifer E

    2013-03-01

    High-flow vascular malformations are among the most challenging lesions in the field of interventional radiology. For an optimal long-term result, the clinician must have a full understanding of the types of lesions, their natural history, appropriate diagnostic studies, indications for treatment, and all the treatment options, including surgery, embolization, laser, and pharmacotherapy. Surgery should, in general, be used primarily for lesions that are completely resectable or are so bulky that embolization would not provide a satisfactory result. Embolization techniques are directed at elimination of the nidus of the lesion, using a variety of penetrating embolic agents both by direct puncture and transcatheter approaches. This paper reviews the principles and techniques primarily involving embolization for lesions occurring in various parts of the body, emphasizing the lessons learned in treating more than 2000 patients over a 30-year period. Copyright © 2013 Elsevier Inc. All rights reserved.

  4. Flux flow and flux dynamics in high-Tc superconductors

    International Nuclear Information System (INIS)

    Bennett, L.H.; Turchinskaya, M.; Swartzendruber, L.J.; Roitburd, A.; Lundy, D.; Ritter, J.; Kaiser, D.L.

    1991-01-01

    Because high temperature superconductors, including BYCO and BSSCO, are type 2 superconductors with relatively low H(sub c 1) values and high H(sub c 2) values, they will be in a critical state for many of their applications. In the critical state, with the applied field between H(sub c 1) and H(sub c 2), flux lines have penetrated the material and can form a flux lattice and can be pinned by structural defects, chemical inhomogeneities, and impurities. A detailed knowledge of how flux penetrates the material and its behavior under the influence of applied fields and current flow, and the effect of material processing on these properties, is required in order to apply, and to improve the properties of these superconductors. When the applied field is changed rapidly, the time dependence of flux change can be divided into three regions, an initial region which occurs very rapidly, a second region in which the magnetization has a 1n(t) behavior, and a saturation region at very long times. A critical field is defined for depinning, H(sub c,p) as that field at which the hysteresis loop changes from irreversible to reversible. As a function of temperature, it is found that H(sub c,p) is well described by a power law with an exponent between 1.5 and 2.5. The behavior of H(sub c,p) for various materials and its relationship to flux flow and flux dynamics are discussed

  5. From "E-flows" to "Sed-flows": Managing the Problem of Sediment in High Altitude Hydropower Systems

    Science.gov (United States)

    Gabbud, C.; Lane, S. N.

    2017-12-01

    The connections between stream hydraulics, geomorphology and ecosystems in mountain rivers have been substantially perturbed by humans, for example through flow regulation related to hydropower activities. It is well known that the ecosystem impacts downstream of hydropower dams may be managed by a properly designed compensation release or environmental flows ("e-flows"), and such flows may also include sediment considerations (e.g. to break up bed armor). However, there has been much less attention given to the ecosystem impacts of water intakes (where water is extracted and transferred for storage and/or power production), even though in many mountain systems such intakes may be prevalent. Flow intakes tend to be smaller than dams and because they fill quickly in the presence of sediment delivery, they often need to be flushed, many times within a day in Alpine glaciated catchments with high sediment yields. The associated short duration "flood" flow is characterised by very high sediment concentrations, which may drastically modify downstream habitat, both during the floods but also due to subsequent accumulation of "legacy" sediment. The impacts on flora and fauna of these systems have not been well studied. In addition, there are no guidelines established that might allow the design of "e-flows" that also treat this sediment problem, something we call "sed-flows". Through an Alpine field example, we quantify the hydrological, geomorphological, and ecosystem impacts of Alpine water transfer systems. The high sediment concentrations of these flushing flows lead to very high rates of channel disturbance downstream, superimposed upon long-term and progressive bed sediment accumulation. Monthly macroinvertebrate surveys over almost a two-year period showed that reductions in the flushing rate reduced rates of disturbance substantially, and led to rapid macroinvertebrate recovery, even in the seasons (autumn and winter) when biological activity should be reduced

  6. Aspects of magnetohydrodynamic duct flow at high magnetic Reynolds number

    International Nuclear Information System (INIS)

    Turner, R.B.

    1973-07-01

    The thesis is concerned with the performance of a flow coupler, which consists of an MHD generator coupled to an MHD pump so that one stream of fluid is induced to move by the motion of another. The flow coupler investigations include: the effects caused by eddy currents on the applied magnetic field and electric potential distribution, the velocity perturbation which occurs as a liquid flows through a magnetic field, devices in which large currents flow through a moving conductor and through an external circuit, and the movement of two conductors through the gap of a magnet. The expected performance of a flow coupler is calculated. (U.K.)

  7. High volume tidal or current flow harnessing system

    Energy Technology Data Exchange (ETDEWEB)

    Gorlov, A.M.

    1984-08-07

    Apparatus permitting the utilization of large volumes of water in the harnessing and extracting of a portion of the power generated by the rise and fall of ocean tides, ocean currents, or flowing rivers includes the provision of a dam, and a specialized single cavity chamber of limited size as compared with the water head enclosed by the dam, and an extremely high volume gating system in which all or nearly all of the water between the high and low levels on either side of the dam is cyclically gated through the single chamber from one side of the dam to the other so as to alternately provide positive air pressure and a partial vacuum within the single chamber. In one embodiment, the specialized chamber has a barrier at the bottom which divides the bottom of the chamber in half, large ports at the bottom of the chamber to permit inflow and outflow of high volumes of water, and ganged structures having a higher total area than that of corresponding ports, in which the structures form sluice gates to selectively seal off and open different sets of ports. In another embodiment, a single chamber is used without a barrier. In this embodiment, vertical sluice gates are used which may be activated automatically by pressures acting on the sluice gates as a result of ingested and expelled water.

  8. The flow field structure of highly stabilized partially premixed flames in a concentric flow conical nozzle burner with coflow

    KAUST Repository

    Elbaz, Ayman M.

    2015-08-29

    The stability limits, the stabilization mechanism, and the flow field structure of highly stabilized partially premixed methane flames in a concentric flow conical nozzle burner with air co-flow have been investigated and presented in this work. The stability map of partial premixed flames illustrates that the flames are stable between two extinction limits. A low extinction limit when partial premixed flames approach non-premixed flame conditions, and a high extinction limit, with the partial premixed flames approach fully premixed flame conditions. These two limits showed that the most stable flame conditions are achieved at a certain degree of partial premixed. The stability is improved by adding air co-flow. As the air co-flow velocity increases the most stable flames are those that approach fully premixed. The turbulent flow field of three flames at 0, 5, 10 m/s co-flow velocity are investigated using Stereo Particle Image Velocimetry (SPIV) in order to explore the improvement of the flame stability due to the use of air co-flow. The three flames are all at a jet equivalence ratio (Φj) of 2, fixed level of partial premixing and jet Reynolds number (Rej) of 10,000. The use of co-flow results in the formation of two vortices at the cone exit. These vortices act like stabilization anchors for the flames to the nozzle tip. With these vortices in the flow field, the reaction zone shifts toward the reduced turbulence intensity at the nozzle rim of the cone. Interesting information about the structure of the flow field with and without co-flow are identified and reported in this work.

  9. Internal Flow of a High Specific-Speed Diagonal-Flow Fan (Rotor Outlet Flow Fields with Rotating Stall

    Directory of Open Access Journals (Sweden)

    Norimasa Shiomi

    2003-01-01

    Full Text Available We carried out investigations for the purpose of clarifying the rotor outlet flow fields with rotating stall cell in a diagonal-flow fan. The test fan was a high–specific-speed (ns=1620 type of diagonal-flow fan that had 6 rotor blades and 11 stator blades. It has been shown that the number of the stall cell is 1, and its propagating speed is approximately 80% of its rotor speed, although little has been known about the behavior of the stall cell because a flow field with a rotating stall cell is essentially unsteady. In order to capture the behavior of the stall cell at the rotor outlet flow fields, hot-wire surveys were performed using a single-slant hotwire probe. The data obtained by these surveys were processed by means of a double phase-locked averaging technique, which enabled us to capture the flow field with the rotating stall cell in the reference coordinate system fixed to the rotor. As a result, time-dependent ensemble averages of the three-dimensional velocity components at the rotor outlet flow fields were obtained. The behavior of the stall cell was shown for each velocity component, and the flow patterns on the meridional planes were illustrated.

  10. Characteristics of high gradient insulators for accelerator and high power flow applications

    International Nuclear Information System (INIS)

    Elizondo, J.M.; Krogh, M.L.; Smith, D.

    1997-07-01

    The high gradient insulator has been demonstrated to operate at levels comparable or better than special geometry or coated insulators. Some patented insulator configurations allow for sophisticated accelerator structures, high power flow interfaces, and microwave applications not previously possible. Sophisticated manufacturing techniques available at AlliedSignal FM and T made this development possible. Bipolar and high power flow applications are specially suited for present insulator designs. The insulator shows a beneficial effect when used under RF fields or RF structures. These insulators can be designed, to a first approximation, from simple electron flight path equations. With a recently developed model of surface flashover physics the authors completed a set of design calculations that include effects such as layer density and dielectric/metal thickness. Experimental data, obtained in the last few years of development, is presented and reviewed. Several insulator fabrication characteristics, indicating critical design parameters, are also presented

  11. Flow visualization of bubble behavior under two-phase natural circulation flow conditions using high speed digital camera

    Energy Technology Data Exchange (ETDEWEB)

    Lemos, Wanderley F.; Su, Jian, E-mail: wlemos@con.ufrj.br, E-mail: sujian@lasme.coppe.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Faccini, Jose L.H., E-mail: faccini@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Lab. de Termo-Hidraulica Experimental

    2013-07-01

    The The present work aims at identifying flow patterns and measuring interfacial parameters in two-phase natural circulation by using visualization technique with high-speed digital camera. The experiments were conducted in the Natural Circulation Circuit (CCN), installed at Nuclear Engineering Institute/CNEN. The thermo-hydraulic circuit comprises heater, heat exchanger, expansion tank, the pressure relief valve and pipes to interconnect the components. A glass tube is installed at the midpoint of the riser connected to the heater outlet. The natural circulation circuit is complemented by acquisition system of values of temperatures, flow and graphic interface. The instrumentation has thermocouples, volumetric flow meter, rotameter and high-speed digital camera. The experimental study is performed through analysis of information from measurements of temperatures at strategic points along the hydraulic circuit, besides natural circulation flow rates. The comparisons between analytical and experimental values are validated by viewing, recording and processing of the images for the flows patterns. Variables involved in the process of identification of flow regimes, dimensionless parameters, the phase velocity of the flow, initial boiling point, the phenomenon of 'flashing' pre-slug flow type were obtained experimentally. (author)

  12. Flow visualization of bubble behavior under two-phase natural circulation flow conditions using high speed digital camera

    International Nuclear Information System (INIS)

    Lemos, Wanderley F.; Su, Jian; Faccini, Jose L.H.

    2013-01-01

    The The present work aims at identifying flow patterns and measuring interfacial parameters in two-phase natural circulation by using visualization technique with high-speed digital camera. The experiments were conducted in the Natural Circulation Circuit (CCN), installed at Nuclear Engineering Institute/CNEN. The thermo-hydraulic circuit comprises heater, heat exchanger, expansion tank, the pressure relief valve and pipes to interconnect the components. A glass tube is installed at the midpoint of the riser connected to the heater outlet. The natural circulation circuit is complemented by acquisition system of values of temperatures, flow and graphic interface. The instrumentation has thermocouples, volumetric flow meter, rotameter and high-speed digital camera. The experimental study is performed through analysis of information from measurements of temperatures at strategic points along the hydraulic circuit, besides natural circulation flow rates. The comparisons between analytical and experimental values are validated by viewing, recording and processing of the images for the flows patterns. Variables involved in the process of identification of flow regimes, dimensionless parameters, the phase velocity of the flow, initial boiling point, the phenomenon of 'flashing' pre-slug flow type were obtained experimentally. (author)

  13. Computations of ideal and real gas high altitude plume flows

    Science.gov (United States)

    Feiereisen, William J.; Venkatapathy, Ethiraj

    1988-01-01

    In the present work, complete flow fields around generic space vehicles in supersonic and hypersonic flight regimes are studied numerically. Numerical simulation is performed with a flux-split, time asymptotic viscous flow solver that incorporates a generalized equilibrium chemistry model. Solutions to generic problems at various altitude and flight conditions show the complexity of the flow, the equilibrium chemical dissociation and its effect on the overall flow field. Viscous ideal gas solutions are compared against equilibrium gas solutions to illustrate the effect of equilibrium chemistry. Improved solution accuracy is achieved through adaptive grid refinement.

  14. PDF methods for combustion in high-speed turbulent flows

    Science.gov (United States)

    Pope, Stephen B.

    1995-01-01

    This report describes the research performed during the second year of this three-year project. The ultimate objective of the project is extend the applicability of probability density function (pdf) methods from incompressible to compressible turbulent reactive flows. As described in subsequent sections, progress has been made on: (1) formulation and modelling of pdf equations for compressible turbulence, in both homogeneous and inhomogeneous inert flows; and (2) implementation of the compressible model in various flow configurations, namely decaying isotropic turbulence, homogeneous shear flow and plane mixing layer.

  15. Modeling of High-Velocity Flows in ITAM Impulse Facilities

    Science.gov (United States)

    2010-04-01

    were performed within the framework of the ISTC project Nos. 2109 and 3550 with direct participation of Dr. Jean-Claude Paulat [17, 18]. The ARES...the flow character in the boundary layer, namely, caused the laminar flow transition to the turbulent one. This work was sponsored by ISTC within

  16. Dust mobilization by high-speed vapor flow under LOVA

    International Nuclear Information System (INIS)

    Matsuki, K.; Suzuki, S.; Ebara, S.; Yokomine, T.; Shimizu, A.

    2006-01-01

    In the safety analysis on the International Thermonuclear Experimental Reactor (ITER), the ingress of coolant (ICE) event and the loss of vacuum (LOVA) event are considered as one of the most serious accident. On the assumption of LOVA occurring after ICE, it is inferable that activated dusts are under the wet condition. Transport behavior of in-vessel activated dusts under the wet condition is not well understood in comparison with the dry case. In this study, we experimentally investigated the entrainment behavior of dust under LOVA after ICE. We measured dust entrainment by high-speed humid airflow with phase change. Graphite dusts and glass beads are used as substitutions for mobile inventory. The relations among the relative humidity, the entrainment of particles in the exhaust gas flow and the adhesion rate of dust particles on the pipe wall have been made clear, as has the distribution profile of dust deposition on the pipe wall. The entrainment ratio decreased as the relative humidity increased and increased as the initial pressure difference increased

  17. Geometry of power flows and convex-relaxed power flows in distribution networks with high penetration of renewables

    DEFF Research Database (Denmark)

    Huang, Shaojun; Wu, Qiuwei; Zhao, Haoran

    2016-01-01

    Renewable energies are increasingly integrated in electric distribution networks and will cause severe overvoltage issues. Smart grid technologies make it possible to use coordinated control to mitigate the overvoltage issues and the optimal power flow (OPF) method is proven to be efficient...... in the applications such as curtailment management and reactive power control. Nonconvex nature of the OPF makes it difficult to solve and convex relaxation is a promising method to solve the OPF very efficiently. This paper investigates the geometry of the power flows and the convex-relaxed power flows when high...

  18. Theoretical and numerical study of highly anisotropic turbulent flows

    NARCIS (Netherlands)

    Biferale, L.; Daumont, I.; Lanotte, A.; Toschi, F.

    2004-01-01

    We present a detailed numerical study of anisotropic statistical fluctuations in stationary, homogeneous turbulent flows. We address both problems of intermittency in anisotropic sectors, and the relative importance of isotropic and anisotropic fluctuations at different scales on a direct numerical

  19. High Reynolds number liquid layer flow with flexible walls

    Indian Academy of Sciences (India)

    School of Mathematics, University of Manchester, Manchester, M13 9PL, UK ... tions have potential application to aerodynamic and marine flows. .... Next, assume that the displacement of the free-surface induces a transverse pressure gradient.

  20. High-Confidence Flow Accelerated Corrosion Screening Technique

    International Nuclear Information System (INIS)

    Ryu, Kyung Ha; Kim, Ji Hak; Hwang, Il Soon; Lee, Na Young; Kim, Ji Hyun

    2008-01-01

    All carbon steel pipes with fluid traveling through it could potentially be threatened by flowing fluid have a potential threat of Flow Accelerated Corrosion (FAC). FAC in a nuclear power plant (NPP) could cause not only pipe failure leading but fatalities sometimes. It is almost impossible to inspect all carbon steel pipes in NPPs, and FAC prediction programs such as CHECWORKS, WATHEC, and BRT-CICERO have limited capability to in predicting FAC area

  1. Electronic Instability at High Flux-Flow Velocities in High-Tc Superconducting Films

    DEFF Research Database (Denmark)

    Doettinger, S. G.; Huebener, R. P.; Gerdemann, R.

    1994-01-01

    At high flux-flow velocities in type-II superconductors the nonequilibrium distribution of the quasiparticles leads to an electronic instability and an aburpt switching into a state with higher electric resistivity, as predicted by Larkin and Ovchinnikow (LO). We report the first obervation...... of this effect in a high-temperature superconductor, namely in epitaxial c-axis oriented films of YBa(2)Cu3O(7)-(delta). Using the LO therory, we have extracted from out results the inelastic quasiparticle scattering rare tau(in)(-1), which strongly decreases with decreasing temperature below T-c...

  2. Microfluidic Impedance Flow Cytometry Enabling High-Throughput Single-Cell Electrical Property Characterization

    Science.gov (United States)

    Chen, Jian; Xue, Chengcheng; Zhao, Yang; Chen, Deyong; Wu, Min-Hsien; Wang, Junbo

    2015-01-01

    This article reviews recent developments in microfluidic impedance flow cytometry for high-throughput electrical property characterization of single cells. Four major perspectives of microfluidic impedance flow cytometry for single-cell characterization are included in this review: (1) early developments of microfluidic impedance flow cytometry for single-cell electrical property characterization; (2) microfluidic impedance flow cytometry with enhanced sensitivity; (3) microfluidic impedance and optical flow cytometry for single-cell analysis and (4) integrated point of care system based on microfluidic impedance flow cytometry. We examine the advantages and limitations of each technique and discuss future research opportunities from the perspectives of both technical innovation and clinical applications. PMID:25938973

  3. High anisotropy of flow-aligned bicellar membrane systems

    KAUST Repository

    Kogan, Maxim

    2013-10-01

    In recent years, multi-lipid bicellar systems have emerged as promising membrane models. The fast orientational diffusion and magnetic alignability made these systems very attractive for NMR investigations. However, their alignment was so far achieved with a strong magnetic field, which limited their use with other methods that require macroscopic orientation. Recently, it was shown that bicelles could be aligned also by shear flow in a Couette flow cell, making it applicable to structural and biophysical studies by polarized light spectroscopy. Considering the sensitivity of this lipid system to small variations in composition and physicochemical parameters, efficient use of such a flow-cell method with coupled techniques will critically depend on the detailed understanding of how the lipid systems behave under flow conditions. In the present study we have characterized the flow alignment behavior of the commonly used dimyristoyl phosphatidylcholine/dicaproyl phosphatidylcholine (DMPC/DHPC) bicelle system, for various temperatures, lipid compositions, and lipid concentrations. We conclude that at optimal flow conditions the selected bicellar systems can produce the most efficient flow alignment out of any lipid systems used so far. The highest degree of orientation of DMPC/DHPC samples is noticed in a narrow temperature interval, at a practical temperature around 25 C, most likely in the phase transition region characterized by maximum sample viscosity. The change of macroscopic orientation factor as function of the above conditions is now described in detail. The increase in macroscopic alignment observed for bicelles will most likely allow recording of higher resolution spectra on membrane systems, which provide deeper structural insight and analysis into properties of biomolecules interacting with solution phase lipid membranes. © 2013 Elsevier Ireland Ltd.

  4. High frequency lateral flow affinity assay using superparamagnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Lago-Cachón, D., E-mail: dlagocachon@gmail.com [Dpto. de Física, Universidad de Oviedo, Edificio Departamental Este, Campus de Viesques, 33204 Gijón (Spain); Rivas, M., E-mail: rivas@uniovi.es [Dpto. de Física, Universidad de Oviedo, Edificio Departamental Este, Campus de Viesques, 33204 Gijón (Spain); Martínez-García, J.C., E-mail: jcmg@uniovi.es [Dpto. de Física, Universidad de Oviedo, Edificio Departamental Este, Campus de Viesques, 33204 Gijón (Spain); Oliveira-Rodríguez, M., E-mail: oliveiramyriam@uniovi.es [Dpto. de Química Física y Analítica, Universidad de Oviedo, C/Julián Clavería 8, 33006 Oviedo (Spain); Blanco-López, M.C., E-mail: cblanco@uniovi.es [Dpto. de Química Física y Analítica, Universidad de Oviedo, C/Julián Clavería 8, 33006 Oviedo (Spain); García, J.A., E-mail: joseagd@uniovi.es [Dpto. de Física, Universidad de Oviedo, Escuela de Marina, Campus de Viesques, 33204 Gijón (Spain)

    2017-02-01

    Lateral flow assay is one of the simplest and most extended techniques in medical diagnosis for point-of-care testing. Although it has been traditionally a positive/negative test, some work has been lately done to add quantitative abilities to lateral flow assay. One of the most successful strategies involves magnetic beads and magnetic sensors. Recently, a new technique of superparamagnetic nanoparticle detection has been reported, based on the increase of the impedance induced by the nanoparticles on a RF-current carrying copper conductor. This method requires no external magnetic field, which reduces the system complexity. In this work, nitrocellulose membranes have been installed on the sensor, and impedance measurements have been carried out during the sample diffusion by capillarity along the membrane. The impedance of the sensor changes because of the presence of magnetic nanoparticles. The results prove the potentiality of the method for point-of-care testing of biochemical substances and nanoparticle capillarity flow studies. - Highlights: • A method for quantification of Lateral Flow Assays is proposed. • MNP induce an increase of the impedance on a RF-current carrying copper sensor. • Magnetic nanoparticles (MNP) can be detected flowing over the sensing element.

  5. High frequency lateral flow affinity assay using superparamagnetic nanoparticles

    International Nuclear Information System (INIS)

    Lago-Cachón, D.; Rivas, M.; Martínez-García, J.C.; Oliveira-Rodríguez, M.; Blanco-López, M.C.; García, J.A.

    2017-01-01

    Lateral flow assay is one of the simplest and most extended techniques in medical diagnosis for point-of-care testing. Although it has been traditionally a positive/negative test, some work has been lately done to add quantitative abilities to lateral flow assay. One of the most successful strategies involves magnetic beads and magnetic sensors. Recently, a new technique of superparamagnetic nanoparticle detection has been reported, based on the increase of the impedance induced by the nanoparticles on a RF-current carrying copper conductor. This method requires no external magnetic field, which reduces the system complexity. In this work, nitrocellulose membranes have been installed on the sensor, and impedance measurements have been carried out during the sample diffusion by capillarity along the membrane. The impedance of the sensor changes because of the presence of magnetic nanoparticles. The results prove the potentiality of the method for point-of-care testing of biochemical substances and nanoparticle capillarity flow studies. - Highlights: • A method for quantification of Lateral Flow Assays is proposed. • MNP induce an increase of the impedance on a RF-current carrying copper sensor. • Magnetic nanoparticles (MNP) can be detected flowing over the sensing element.

  6. Adapting high-level language programs for parallel processing using data flow

    Science.gov (United States)

    Standley, Hilda M.

    1988-01-01

    EASY-FLOW, a very high-level data flow language, is introduced for the purpose of adapting programs written in a conventional high-level language to a parallel environment. The level of parallelism provided is of the large-grained variety in which parallel activities take place between subprograms or processes. A program written in EASY-FLOW is a set of subprogram calls as units, structured by iteration, branching, and distribution constructs. A data flow graph may be deduced from an EASY-FLOW program.

  7. High resolution solutions of the Euler equations for vortex flows

    International Nuclear Information System (INIS)

    Murman, E.M.; Powell, K.G.; Rizzi, A.; Tel Aviv Univ., Israel)

    1985-01-01

    Solutions of the Euler equations are presented for M = 1.5 flow past a 70-degree-swept delta wing. At an angle of attack of 10 degrees, strong leading-edge vortices are produced. Two computational approaches are taken, based upon fully three-dimensional and conical flow theory. Both methods utilize a finite-volume discretization solved by a pseudounsteady multistage scheme. Results from the two approaches are in good agreement. Computations have been done on a 16-million-word CYBER 205 using 196 x 56 x 96 and 128 x 128 cells for the two methods. A sizable data base is generated, and some of the practical aspects of manipulating it are mentioned. The results reveal many interesting physical features of the compressible vortical flow field and also suggest new areas needing research. 16 references

  8. High Flow Nasal Cannula Therapy for Improving Obstructive Sleep Apnea: A Case Report

    Directory of Open Access Journals (Sweden)

    Se Joong Kim

    2015-06-01

    Full Text Available Although continuous positive airway pressure is the treatment of choice for obstructive sleep apnea, its compliance is low. Therefore, alternative therapeutic strategies are often required. High flow nasal cannula therapy uses an air compressor to deliver a constant flow of oxygen via the nasal cannula at a maximum of 60 L/m. It can produce positive end expiratory pressure and increase end expiratory pharyngeal pressure, which can help to alleviate upper airway obstruction. This is a case report of high flow nasal cannula therapy for a 71 year-old man. He had an obstructive sleep apnea and severe desaturation but failed to use continuous positive airway pressure. He underwent titration with high flow nasal cannula under polysomnography. Using high flow nasal cannula at an airflow of 45 L/m, his apnea-hypopnea, respiratory arousal and oxygen desaturation were improved. Importantly, he is very compliant with high flow nasal cannula therapy.

  9. Particle deposition in low-speed, high-turbulence flows

    DEFF Research Database (Denmark)

    Reck, Mads; Larsen, Poul Scheel; Ullum, U.

    2002-01-01

    The experimental and numerical study considers the concentration of airborne particulate contaminants, such as spores of spoilage fungi, and their deposition on a surface, in a petri dish, and on a warm box-shaped product placed in a food-processing environment. Field measurements by standard...... field measurements. Particle deposition is shown to be associated with near-wall coherent structures. Flow reversal, simulated by impulsive start, is shown to give higher deposition rates than steady mean flows. Key word index: Spoilage fungi; spores; food processing plant; deposition flux; large eddy...

  10. The use of high-flow nasal cannula in the pediatric emergency department

    Directory of Open Access Journals (Sweden)

    Katherine N. Slain

    Full Text Available Abstract Objectives: To summarize the current literature describing high-flow nasal cannula use in children, the components and mechanisms of action of a high-flow nasal cannula system, the appropriate clinical applications, and its role in the pediatric emergency department. Sources: A computer-based search of PubMed/MEDLINE and Google Scholar for literature on high-flow nasal cannula use in children was performed. Data summary: High-flow nasal cannula, a non-invasive respiratory support modality, provides heated and fully humidified gas mixtures to patients via a nasal cannula interface. High-flow nasal cannula likely supports respiration though reduced inspiratory resistance, washout of the nasopharyngeal dead space, reduced metabolic work related to gas conditioning, improved airway conductance and mucociliary clearance, and provision of low levels of positive airway pressure. Most data describing high-flow nasal cannula use in children focuses on those with bronchiolitis, although high-flow nasal cannula has been used in children with other respiratory diseases. Introduction of high-flow nasal cannula into clinical practice, including in the emergency department, has been associated with decreased rates of endotracheal intubation. Limited prospective interventional data suggest that high-flow nasal cannula may be similarly efficacious as continuous positive airway pressure and more efficacious than standard oxygen therapy for some patients. Patient characteristics, such as improved tachycardia and tachypnea, have been associated with a lack of progression to endotracheal intubation. Reported adverse effects are rare. Conclusions: High-flow nasal cannula should be considered for pediatric emergency department patients with respiratory distress not requiring immediate endotracheal intubation; prospective, pediatric emergency department-specific trials are needed to better determine responsive patient populations, ideal high-flow nasal cannula

  11. Differential impact of flow and mouth leak on oropharyngeal humidification during high-flow nasal cannula: a neonatal bench study.

    Science.gov (United States)

    Ullrich, Tim Leon; Czernik, Christoph; Bührer, Christoph; Schmalisch, Gerd; Fischer, Hendrik Stefan

    2018-03-09

    Heated humidification is paramount during neonatal high-flow nasal cannula (HFNC) therapy. However, there is little knowledge about the influence of flow rate and mouth leak on oropharyngeal humidification and temperature. The effect of the Optiflow HFNC on oropharyngeal gas conditioning was investigated at flow rates of 4, 6 and 8 L min -1 with and without mouth leak in a bench model simulating physiological oropharyngeal air conditions during spontaneous breathing. Temperature and absolute humidity (AH) were measured using a digital thermo-hygrosensor. Without mouth leak, oropharyngeal temperature and AH increased significantly with increasing flow (P < 0.001). Mouth leak did not affect this increase up to 6 L min -1 , but at 8 L min -1 , temperature and AH plateaued, and the effect of mouth leak became statistically significant (P < 0.001). Mouth leak during HFNC had a negative impact on oropharyngeal gas conditioning when high flows were applied. However, temperature and AH always remained clinically acceptable.

  12. High pressure axial flow fans for modern coal power stations

    Energy Technology Data Exchange (ETDEWEB)

    Cyrus, Vaclav [AHT Energetika s.r.o., Praha (Czech Republic); Koci, Petr [ZVVZ Milevsko a.s. (Czech Republic)

    2008-07-01

    Brown coal fired power stations, located in Northern Bohemia, have mostly older boiler blocks with an output of 110 and 200 MWe. Flue gases are cleaned by the desulphurization plants installed between 1993 and 1997. Usually, each boiler block has two air fans and one to three flue gas fans. Flue gas fans operate in severe conditions; fan blades should be resistant to the flue gases containing sulphur and acid drops with the operating temperature at 170 C to 190 C. Additionally, flue gas also often contains ash particles. Currently, some boiler blocks are gradually being refurbished. New blocks with an electrical power output of 600 to 700 MWe are at the design stage. Submitted paper shows our design study of one stage axial flow fan for the new blocks. Results from the new aerodynamic research of the axial flow stages were used in the fan design. (orig.)

  13. High-Fidelity Numerical Modeling of Compressible Flow

    Science.gov (United States)

    2015-11-01

    using exact flux Jacobians. The data-parallel line relaxation (DPLR) method, based on the Gauss - Seidel line relaxation method of MacCormack,29 is...then employed to solve the resulting linear system. To improve performance on parallel systems, the DPLR method replaces the Gauss - Seidel sweeps with a...boundary-layer height and edge velocity), but that higher-moments, like secondary flow, required more iterations to converge . Since the medium and fine grids

  14. Study of flux flow in high Tc superconductors

    International Nuclear Information System (INIS)

    Takacs, S.; Gomory, F.

    1989-01-01

    The magnetic field distribution and the hysteresis losses in superconductors with very large viscous forces are calculated for field amplitudes below and above the penetration field. Both the magnetic field and frequency dependence of the losses are changing with respect to the critical state model. The results are qualitatively confirmed by AC susceptibility measurements on YBaCuO superconductors, but the quantitative differences indicate that the flux flow effects are not so strong as expected and supposed by some theories

  15. A high performance magnetorheological valve with a meandering flow path

    International Nuclear Information System (INIS)

    Imaduddin, Fitrian; Amri Mazlan, Saiful; Azizi Abdul Rahman, Mohd; Zamzuri, Hairi; Ubaidillah; Ichwan, Burhanuddin

    2014-01-01

    The huge developments in the field of magnetorheological (MR) fluid-based devices will have a great influence on the future of mechatronic applications due to the ease of interfacing between electronic controls and the mechanical components that they provide. Among various MR fluid-based devices, an MR valve would be particularly significant for the development of other devices, if it could be successfully achieved. One of the most challenging obstacles to MR valve development is the difficulty of achieving device miniaturization while, at the same time, improving the achievable performance. This study demonstrates a novel design for an MR valve, using the meandering flow path approach in order to increase the effective area so that the MR fluid can be regulated within a small-sized valve. The meandering flow path is formed by combining multiple annular, radial and orifice flow channels. In order to analyze the valve performance, a mathematical model of the proposed MR valve is derived and combined with numerical simulation using the finite element method, with the intention of predicting the achievable pressure drop that can be generated by the valve. The predicted MR valve performances are then experimentally evaluated using an oscillation-disturbed bypass hydraulic cylinder. The simulation results show that the proposed MR valve design could yield substantial pressure drop improvement, which is confirmed by the experiment

  16. On the possibility of high-dispersed composite material obtaining in impulsive high-enthalpy flow

    International Nuclear Information System (INIS)

    Blinkov, I.V.; Brodyagin, A.G.; Ivanov, A.V.

    1987-01-01

    Thermodynamic possibility for the formation of TiC-Mo composite dispersed material in 1200-2800 K temperature interval and effect of H/Cl, C/Ti relation on the composite material composition are demonstrated. Investigation into the plasmo-chemical process of producing high-dispersed composite material in the pulsed regime has pointed out to a possibility of the product chemical composition regulation by changing the energy, flow-rate parameters and by conditions of component introduction into the plasmochemical reactor. Molybdenum-carbide composition powders produced are characterized by the particle size of ∼ 10 nm and high Mo and TiC distribution steadyness which allows one to exclude the stage of a long-term component mixing under the composition production

  17. Modeling Highly Buoyant Flows in the Castel Giorgio

    OpenAIRE

    Volpi, Giorgio; Magri, Fabien; Colucci, Francesca; Fisher, Thomas; De Caro, Mattia; Crosta, Giovanni B.

    2018-01-01

    The Castel Giorgio-Torre Alfina (CG-TA, central Italy) is a geothermal reservoir whose fluids are hosted in a carbonate formation at temperatures ranging between 120°C and 210°C. Data from deep wells suggest the existence of convective flow. We present the 3D numerical model of the CG-TA to simulate the undisturbed natural geothermal field and investigate the impacts of the exploitation process. The open source finite-element code OpenGeoSys is applied to solve the coupled systems of partial ...

  18. Analysis of impact of mixing flow on the pebble bed high temperature reactor

    International Nuclear Information System (INIS)

    Hao Chen; Li Fu; Guo Jiong

    2014-01-01

    The impact of the mixing flow in the pebble flow on pebble bed high temperature gas cooled reactor (HTR) was analyzed in the paper. New code package MFVSOP which can simulate the mixing flow was developed. The equilibrium core of HTR-PM was selected as reference case, the impact of the mixing flow on the core parameters such as core power peak factor, power distribution was analyzed with different degree of mixing flow, and uncertainty analysis was carried out. Numerical results showed that the mixing flow had little impact on key parameters of pebble bed HTR, and the multiple-pass-operation-mode in pebble bed HTR can reduce the uncertainty arouse from the mixing flow. (authors)

  19. Hybrid RANS/LES method for high Reynolds numbers, applied to atmospheric flow over complex terrain

    DEFF Research Database (Denmark)

    Bechmann, Andreas; Sørensen, Niels N.; Johansen, Jeppe

    2007-01-01

      The use of Large-Eddy Simulation (LES) to predict wall-bounded flows has presently been limited to low Reynolds number flows. Since the number of computational grid points required to resolve the near-wall turbulent structures increase rapidly with Reynolds number, LES has been unattainable...... for flows at high Reynolds numbers. To reduce the computational cost of traditional LES a hybrid method is proposed in which the near-wall eddies are modelled in a Reynolds-averaged sense. Close to walls the flow is treated with the RANS-equations and this layer act as wall model for the outer flow handled...... by LES. The wellknown high Reynolds number two-equation k - ǫ turbulence model is used in the RANS layer and the model automatically switches to a two-equation k - ǫ subgrid-scale stress model in the LES region. The approach can be used for flow over rough walls. To demonstrate the ability...

  20. High resolution measurement of the velocity profiles of channel flows using the particle image velocimetry technique

    International Nuclear Information System (INIS)

    Nor Azizi Mohamed

    2000-01-01

    The high resolution velocity profiles of a uniform steady channel flow and a flow beneath waves were obtained using the particle image velocimetry (PIV) technique. The velocity profiles for each flow were calculated for both components. It is shown that the profiles obtained are very precise, displaying the point velocities from a few millimeters from the bottom of the channel up to the water surface across the water depth. In the case of the wave-induced flow, the profiles are shown under the respective wave phases and given in a plane representation. High resolution measurement of point velocities in a flow is achievable using PIV and invaluable when applied to a complex flow. (Author)

  1. Structure of the radial electric field and toroidal/poloidal flow in high temperature toroidal plasma

    International Nuclear Information System (INIS)

    Ida, Katsumi

    2001-01-01

    The structure of the radial electric field and toroidal/poloidal flow is discussed for the high temperature plasma in toroidal systems, tokamak and Heliotron type magnetic configurations. The spontaneous toroidal and poloidal flows are observed in the plasma with improved confinement. The radial electric field is mainly determined by the poloidal flow, because the contribution of toroidal flow to the radial electric field is small. The jump of radial electric field and poloidal flow are commonly observed near the plasma edge in the so-called high confinement mode (H-mode) plasmas in tokamaks and electron root plasma in stellarators including Heliotrons. In general the toroidal flow is driven by the momentum input from neutral beam injected toroidally. There is toroidal flow not driven by neutral beam in the plasma and it will be more significant in the plasma with large electric field. The direction of these spontaneous toroidal flows depends on the symmetry of magnetic field. The spontaneous toroidal flow driven by the ion temperature gradient is in the direction to increase the negative radial electric field in tokamak. The direction of spontaneous toroidal flow in Heliotron plasmas is opposite to that in tokamak plasma because of the helicity of symmetry of the magnetic field configuration. (author)

  2. Non-darcy flow behavior mean high-flux injection wells in porous and fractured formations

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yu-Shu

    2003-04-25

    This paper presents a study of non-Darcy fluid flow through porous and fractured rock, which may occur near wells during high-flux injection of waste fluids into underground formations. Both numerical and analytical models are used in this study. General non-Darcy flow is described using the Forchheimer equation, implemented in a three-dimensional, multiphase flow reservoir simulator. The non-Darcy flow through a fractured reservoir is handled using a general dual continuum approach, covering commonly used conceptual models, such as double porosity, dual permeability, explicit fracture, etc. Under single-phase flow conditions, an approximate analytical solution, as an extension of the Warren-Root solution, is discussed. The objectives of this study are (1) to obtain insights into the effect of non-Darcy flow on transient pressure behavior through porous and fractured reservoirs and (2) to provide type curves for well test analyses of non-Darcy flow wells. The type curves generated include various types of drawdown, injection, and buildup tests with non-Darcy flow occurring in porous and fractured reservoirs. In addition, non-Darcy flow into partially penetrating wells is also considered. The transient-pressure type curves for flow in fractured reservoirs are based on the double-porosity model. Type curves provided in this work for non-Darcy flow in porous and fractured reservoirs will find their applications in well test interpretation using a type-curve matching technique.

  3. Development of an Active Flow Control Technique for an Airplane High-Lift Configuration

    Science.gov (United States)

    Shmilovich, Arvin; Yadlin, Yoram; Dickey, Eric D.; Hartwich, Peter M.; Khodadoust, Abdi

    2017-01-01

    This study focuses on Active Flow Control methods used in conjunction with airplane high-lift systems. The project is motivated by the simplified high-lift system, which offers enhanced airplane performance compared to conventional high-lift systems. Computational simulations are used to guide the implementation of preferred flow control methods, which require a fluidic supply. It is first demonstrated that flow control applied to a high-lift configuration that consists of simple hinge flaps is capable of attaining the performance of the conventional high-lift counterpart. A set of flow control techniques has been subsequently considered to identify promising candidates, where the central requirement is that the mass flow for actuation has to be within available resources onboard. The flow control methods are based on constant blowing, fluidic oscillators, and traverse actuation. The simulations indicate that the traverse actuation offers a substantial reduction in required mass flow, and it is especially effective when the frequency of actuation is consistent with the characteristic time scale of the flow.

  4. The impact of Indian Ocean high pressure system on rainfall and stream flow

    International Nuclear Information System (INIS)

    Rehman, S.; Nasir, H.; Zia, S.S.; Ansari, W.A.; Salam, K.; Tayyab, N.

    2012-01-01

    Centre of Action approach is very useful in getting insight of rainfall and stream flow variability of specific region. Hameed et al. showed that Inter-annual variability of Gulf Stream north wall is influenced by low Icelandic pressure system and has more statistically significant correlation than North Atlantic Oscillation (NAO) with longitude of Icelandic low. This study also aims to explore possible relationships between rainfall and stream flow in Collie river catchment in Southwest Western Australia (SWWA) with Indian Ocean high pressure dynamics. The relationship between rainfall and stream flow with Indian Ocean high pressure system have been investigated using correlation analysis for early winter season (MJJA), lag correlation for MJJA versus SOND rainfall and stream flow are also calculated and found significant at 95% confidence level. By investigating the relationship between COA indices with rainfall and stream flow over the period 1976-2008, significant correlations suggests that rainfall and stream flow in Collie river basin is strongly influenced by COA indices. Multiple correlations between rainfall and stream flow with Indian Ocean high pressure (IOHPS and IOHLN) is 0.7 and 0.6 respectively. Centers of Action (COA) indices explain 51% and 36% of rainfall and stream flow respectively. The correlation between rainfall and stream flow with IOHPS is -0.4 and -0.3 whereas, with IOHLN is -0.47 and -0.52 respectively. (author)

  5. High-Reynolds Number Viscous Flow Simulations on Embedded-Boundary Cartesian Grids

    Science.gov (United States)

    2016-05-05

    AFRL-AFOSR-VA-TR-2016-0192 High- Reynolds Number Viscous Flow Simulations on Embedded-Boundary Cartesian Grids Marsha Berger NEW YORK UNIVERSITY Final...TO THE ABOVE ORGANIZATION. 1. REPORT DATE (DD-MM-YYYY) 30/04/2016 2. REPORT TYPE Final 3. DATES COVERED (From - To) High- Reynolds 4. TITLE AND...SUBTITLE High- Reynolds Number Viscous Flow Simulations on Embedded-Boundary Cartesian Grids 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9550-13-1

  6. TEMPO-based catholyte for high-energy density nonaqueous redox flow batteries.

    Science.gov (United States)

    Wei, Xiaoliang; Xu, Wu; Vijayakumar, Murugesan; Cosimbescu, Lelia; Liu, Tianbiao; Sprenkle, Vincent; Wang, Wei

    2014-12-03

    A TEMPO-based non-aqueous electrolyte with the TEMPO concentration as high as 2.0 m is demonstrated as a high-energy-density catholyte for redox flow battery applications. With a hybrid anode, Li|TEMPO flow cells using this electrolyte deliver an energy efficiency of ca. 70% and an impressively high energy density of 126 W h L(-1) . © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. High Fidelity Simulations for Unsteady Flow Through the Orbiter LH2 Feedline Flowliner

    Science.gov (United States)

    Kiris, Cetin C.; Kwak, Dochan; Chan, William; Housman, Jeffrey

    2005-01-01

    High fidelity computations were carried out to analyze the orbiter M2 feedline flowliner. Various computational models were used to characterize the unsteady flow features in the turbopump, including the orbiter Low-Pressure-Fuel-Turbopump (LPFTP) inducer, the orbiter manifold and a test article used to represent the manifold. Unsteady flow originating from the orbiter LPFTP inducer is one of the major contributors to the high frequency cyclic loading that results in high cycle fatigue damage to the gimbal flowliners just upstream of the LPFTP. The flow fields for the orbiter manifold and representative test article are computed and analyzed for similarities and differences. An incompressible Navier-Stokes flow solver INS3D, based on the artificial compressibility method, was used to compute the flow of liquid hydrogen in each test article.

  8. A low-power high-flow shape memory alloy wire gas microvalve

    International Nuclear Information System (INIS)

    Gradin, Henrik; Braun, Stefan; Stemme, Göran; Van der Wijngaart, Wouter; Clausi, Donato; Peirs, Jan; Reynaerts, Dominiek

    2012-01-01

    In this paper the use of shape memory alloy (SMA) wire actuators for high gas flow control is investigated. A theoretical model for effective gas flow control is presented and gate microvalve prototypes are fabricated. The SMA wire actuator demonstrates the robust flow control of more than 1600 sccm at a pressure drop of 200 kPa. The valve can be successfully switched at over 10 Hz and at an actuation power of 90 mW. Compared to the current state-of-the-art high-flow microvalves, the proposed solution benefits from a low-voltage actuator with low overall power consumption. This paper demonstrate that SMA wire actuators are well suited for high-pressurehigh-flow applications. (paper)

  9. A case of atherosclerotic inferior mesenteric artery aneurysm secondary to high flow state.

    Science.gov (United States)

    Troisi, Nicola; Esposito, Giovanni; Cefalì, Pietro; Setti, Marco

    2011-07-01

    Inferior mesenteric artery aneurysms are very rare and they are among the rarest of visceral artery aneurysms. Sometimes, the distribution of the blood flow due to chronic atherosclerotic occlusion of some arteries can establish an increased flow into a particular supplying district (high flow state). A high flow state in a stenotic inferior mesenteric artery in compensation for a mesenteric occlusive disease can produce a rare form of aneurysm. We report the case of an atherosclerotic inferior mesenteric aneurysm secondary to high flow state (association with occlusion of the celiac trunk and severe stenosis of the superior mesenteric artery), treated by open surgical approach. Copyright © 2011 Society for Vascular Surgery. Published by Mosby, Inc. All rights reserved.

  10. A new modified-serpentine flow field for application in high temperature polymer electrolyte fuel cell

    DEFF Research Database (Denmark)

    Singdeo, Debanand; Dey, Tapobrata; Gaikwad, Shrihari

    2017-01-01

    field design is proposed and its usefulness for the fuel cell applications are evaluated in a high-temperature polymer electrolyte fuel cell. The proposed geometry retains some of the features of serpentine flow field such as multiple bends, while modifications are made in its in-plane flow path...

  11. Advancement and Application of Multi-Phase CFD Modeling to High Speed Supercavitating Flows

    Science.gov (United States)

    2013-08-13

    October 2008 - December 2013 4. TITLE AND SUBTITLE Advancement and Application of Multi-Phase CFD Modeling to High Speed Supercavitating Flows...influence cavity hysteresis behavior. These observations are used to guide improved supercavitating -vehicle analyses including numerical predictions...experiments, and modeling 15. SUBJECT TERMS supercavitation , computational fluid dynamics, multiphase flow 16. SECURITY CLASSIFICATION OF: a

  12. Flow Control Research at NASA Langley in Support of High-Lift Augmentation

    Science.gov (United States)

    Sellers, William L., III; Jones, Gregory S.; Moore, Mark D.

    2002-01-01

    The paper describes the efforts at NASA Langley to apply active and passive flow control techniques for improved high-lift systems, and advanced vehicle concepts utilizing powered high-lift techniques. The development of simplified high-lift systems utilizing active flow control is shown to provide significant weight and drag reduction benefits based on system studies. Active flow control that focuses on separation, and the development of advanced circulation control wings (CCW) utilizing unsteady excitation techniques will be discussed. The advanced CCW airfoils can provide multifunctional controls throughout the flight envelope. Computational and experimental data are shown to illustrate the benefits and issues with implementation of the technology.

  13. The roles of testicular nuclear receptor 4 (TR4 in male fertility-priapism and sexual behavior defects in TR4 knockout mice

    Directory of Open Access Journals (Sweden)

    Bao Bo-Ying

    2011-10-01

    Full Text Available Abstract Background Successful reproductive efforts require the establishment of a situation favorable for reproduction that requires integration of both behavior and internal physiological events. TR4 nuclear receptor is known to be involved in male fertility via controlling spermatogenesis, yet its roles in regulating other biological events related to reproduction have not been completely revealed. Methods Male TR4 knockout (TR4-/- and wild type mice were used for the sexual behavior and penile dysfunction studies. Mice were sacrificed for histological examination and corresponding genes profiles were analyzed by quantitative RT-PCR. Reporter gene assays were performed. Results We describe an unexpected finding of priapism in TR4-/- mice. As a transcriptional factor, we demonstrated that TR4 transcriptionally modulates a key enzyme regulating penis erection and neuronal nitric oxide synthese NOS (nNOS. Thereby, elimination of TR4 results in nNOS reduction in both mRNA and protein levels, consequently may lead to erectile dysfunction. In addition, male TR4-/- mice display defects in sexual and social behavior, with increased fear or anxiety, as well as reduced mounting, intromission, and ejaculation. Reduction of ER alpha, ER beta, and oxytocin in the hypothalamus may contribute to defects in sexual behavior and stress response. Conclusions Together, these results provide in vivo evidence of important TR4 roles in penile physiology, as well as in male sexual behavior. In conjunction with previous finding, TR4 represents a key factor that controls male fertility via regulating behavior and internal physiological events.

  14. Qualifying Elbow Meters for High Pressure Flow Measurements in an Operating Nuclear Power Plant

    International Nuclear Information System (INIS)

    Chan, A.M.; Maynard, K.J.; Ramundi, J.; Wiklung, E.

    2006-01-01

    To support the installation and use of elbow meters to measure the high pressure emergency coolant injection flow in an operating nuclear station, a test program was performed to qualify: (i) the 'hot' tapping procedure for field application and (ii) the use of elbow meters for accurate flow measurements over the full range of station ECI flow conditions. This paper describes the design conditions and major components of a flow loop used for the elbow meter calibrations. Typical test results are presented and discussed. (authors)

  15. A high-flow holweck pump for fusion applications

    International Nuclear Information System (INIS)

    Iseli, M.; Dinner, P.J.; Murdoch, D.K.

    1995-01-01

    Present concepts for power reactors require high pumping speed for the torus exhaust (10 5 -10 6 1/s) with low tritium inventories. Conventional approaches using Compound Cryopumps necessitate high tritium inventories and Turbomolecular pumps require large scale-up in throughput and are sensitive to eddy current heating of the rotor and sudden venting thrust. Cooling the gas to low temperature (20K) increases the gas density at the pump-entrance enough to obtain high throughputs from compact mechanical devices such as molecular drag pumps. A numerical model of such a pump and experimental results confirm the high pumping speed achievable with this concept. The model is used for extrapolation and optimisation of the design of a prototype. (orig.)

  16. High-Speed Thermal Characterization of Cryogenic Flows, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Luna proposes to continue development on a high-speed fiber optic sensor and readout system for cryogenic temperature measurements in liquid oxygen (LOX) and liquid...

  17. Cigarette smoke extract counteracts atheroprotective effects of high laminar flow on endothelial function

    Directory of Open Access Journals (Sweden)

    Sindy Giebe

    2017-08-01

    Full Text Available Tobacco smoking and hemodynamic forces are key stimuli in the development of endothelial dysfunction and atherosclerosis. High laminar flow has an atheroprotective effect on the endothelium and leads to a reduced response of endothelial cells to cardiovascular risk factors compared to regions with disturbed or low laminar flow. We hypothesize that the atheroprotective effect of high laminar flow could delay the development of endothelial dysfunction caused by cigarette smoking. Primary human endothelial cells were stimulated with increasing dosages of aqueous cigarette smoke extract (CSEaq. CSEaq reduced cell viability in a dose-dependent manner. The main mediator of cellular adaption to oxidative stress, nuclear factor erythroid 2-related factor 2 (NRF2 and its target genes heme oxygenase (decycling 1 (HMOX1 or NAD(PH quinone dehydrogenase 1 (NQO1 were strongly increased by CSEaq in a dose-dependent manner. High laminar flow induced elongation of endothelial cells in the direction of flow, activated the AKT/eNOS pathway, increased eNOS expression, phosphorylation and NO release. These increases were inhibited by CSEaq. Pro-inflammatory adhesion molecules intercellular adhesion molecule-1 (ICAM1, vascular cell adhesion molecule-1 (VCAM1, selectin E (SELE and chemokine (C-C motif ligand 2 (CCL2/MCP-1 were increased by CSEaq. Low laminar flow induced VCAM1 and SELE compared to high laminar flow. High laminar flow improved endothelial wound healing. This protective effect was inhibited by CSEaq in a dose-dependent manner through the AKT/eNOS pathway. Low as well as high laminar flow decreased adhesion of monocytes to endothelial cells. Whereas, monocyte adhesion was increased by CSEaq under low laminar flow, this was not evident under high laminar flow.This study shows the activation of major atherosclerotic key parameters by CSEaq. Within this process, high laminar flow is likely to reduce the harmful effects of CSEaq to a certain degree. The

  18. High bias gas flows increase lung injury in the ventilated preterm lamb.

    Directory of Open Access Journals (Sweden)

    Katinka P Bach

    Full Text Available BACKGROUND: Mechanical ventilation of preterm babies increases survival but can also cause ventilator-induced lung injury (VILI, leading to the development of bronchopulmonary dysplasia (BPD. It is not known whether shear stress injury from gases flowing into the preterm lung during ventilation contributes to VILI. METHODS: Preterm lambs of 131 days' gestation (term = 147 d were ventilated for 2 hours with a bias gas flow of 8 L/min (n = 13, 18 L/min (n = 12 or 28 L/min (n = 14. Physiological parameters were measured continuously and lung injury was assessed by measuring mRNA expression of early injury response genes and by histological analysis. Control lung tissue was collected from unventilated age-matched fetuses. Data were analysed by ANOVA with a Tukey post-hoc test when appropriate. RESULTS: High bias gas flows resulted in higher ventilator pressures, shorter inflation times and decreased ventilator efficiency. The rate of rise of inspiratory gas flow was greatest, and pulmonary mRNA levels of the injury markers, EGR1 and CTGF, were highest in lambs ventilated with bias gas flows of 18 L/min. High bias gas flows resulted in increased cellular proliferation and abnormal deposition of elastin, collagen and myofibroblasts in the lung. CONCLUSIONS: High ventilator bias gas flows resulted in increased lung injury, with up-regulation of acute early response genes and increased histological lung injury. Bias gas flows may, therefore, contribute to VILI and BPD.

  19. Turbulent Scalar Transport Model Validation for High Speed Propulsive Flows, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This effort entails the validation of a RANS turbulent scalar transport model (SFM) for high speed propulsive flows, using new experimental data sets and...

  20. High Performance Redox Flow Batteries: An Analysis of the Upper Performance Limits of Flow Batteries Using Non-aqueous Solvents

    International Nuclear Information System (INIS)

    Sun, C.-N.; Mench, M.M.; Zawodzinski, T.A.

    2017-01-01

    Redox Flow Batteries (RFBs) are a promising technology for grid-scale electrochemical energy storage. In this work, we use a recently achieved high-performance flow battery performance curve as a basis to assess the maximum achievable performance of a RFB employing non-aqueous solutions as active materials. First we show high performance in a vanadium redox flow battery (VRFB), specifically a limiting situation in which the cell losses are ohmic in nature and derive from electrolyte conductance. Based on that case, we analyze the analogous limiting behavior of non-aqueous (NA) systems using a series of calculations assuming similar ohmic losses, scaled by the relative electrolyte resistances, with a higher voltage redox couple assumed for the NA battery. The results indicate that the NA battery performance is limited by the low electrolyte conductivity to a fraction of the performance of the VRFB. Given the narrow window in which the NARFB offers advantages, even for the most generous limiting assumptions related to performance while ignoring the numerous other disadvantageous aspects of these systems, we conclude that this technology is unlikely under present circumstances to provide practical large-scale energy storage solutions.

  1. Flux flow in high-Tc Josephson junctions

    DEFF Research Database (Denmark)

    Filatrella, G.; Pedersen, Niels Falsig

    1993-01-01

    The possibility of achieving fluxon nucleation in nonhysteretic high-T(c) Josephson junctions due to the presence of inhomogeneities is investigated numerically. For a large range of parameters the I- V characteristics in presence of such discontinuities show a strong similarity with those obtain...

  2. Energy flow in high speed perforation and cutting

    International Nuclear Information System (INIS)

    van Thiel, M.

    1980-01-01

    It is demonstrated that effects of long rod penetrators on targets can be modeled by introducing a high pressure (energy) column on the penetration path in place of the projectile. This energy can be obtained from the kinetic energy of the penetrator; the equations of state of the materials used and a Bernoulli penetration condition. The model is supported by detailed hydro calculations

  3. Discussion of various flow calculation methods in high-speed centrifuges

    International Nuclear Information System (INIS)

    Louvet, P.; Cortet, C.

    1979-01-01

    The flow in high-speed centrifuges for the separation of uranium isotopes has been studied in the frame of linearized theory for long years. Three different methods have been derived for viscous compressible flow with small Ekman numbers and high Mach numbers: - numerical solution of flow equation by finite element method and Gaussian elimination (Centaure Code), - boundary layer theory using matched asymptotic expansions, - the so called eigenfunction method slightly modified. The mathematical assumptions, the easiness and the accuracy of the computations are compared. Numerical applications are performed successively for thermal countercurrent centrifuges with or without injections

  4. Phase-measuring laser holographic interferometer for use in high speed flows

    Science.gov (United States)

    Yanta, William J.; Spring, W. Charles, III; Gross, Kimberly Uhrich; McArthur, J. Craig

    Phase-measurement techniques have been applied to a dual-plate laser holographic interferometer (LHI). This interferometer has been used to determine the flowfield densities in a variety of two-dimensional and axisymmetric flows. In particular, LHI has been applied in three different experiments: flowfield measurements inside a two-dimensional scramjet inlet, flow over a blunt cone, and flow over an indented nose shape. Comparisons of experimentally determined densities with computational results indicate that, when phase-measurement techniques are used in conjunction with state-of-the-art image-processing instrumentation, holographic interferometry can be a diagnostic tool with high resolution, high accuracy, and rapid data retrieval.

  5. On the peculiarities of LDA method in two-phase flows with high concentrations of particles

    Science.gov (United States)

    Poplavski, S. V.; Boiko, V. M.; Nesterov, A. U.

    2016-10-01

    Popular applications of laser Doppler anemometry (LDA) in gas dynamics are reviewed. It is shown that the most popular method cannot be used in supersonic flows and two-phase flows with high concentrations of particles. A new approach to implementation of the known LDA method based on direct spectral analysis, which offers better prospects for such problems, is presented. It is demonstrated that the method is suitable for gas-liquid jets. Owing to the progress in laser engineering, digital recording of spectra, and computer processing of data, the method is implemented at a higher technical level and provides new prospects of diagnostics of high-velocity dense two-phase flows.

  6. The Characteristics of Turbulence in Curved Pipes under Highly Pulsatile Flow Conditions

    Science.gov (United States)

    Kalpakli, A.; Örlü, R.; Tillmark, N.; Alfredsson, P. Henrik

    High speed stereoscopic particle image velocimetry has been employed to provide unique data from a steady and highly pulsatile turbulent flow at the exit of a 90 degree pipe bend. Both the unsteady behaviour of the Dean cells under steady conditions, the so called "swirl switching" phenomenon, as well as the secondary flow under pulsations have been reconstructed through proper orthogonal decomposition. The present data set constitutes - to the authors' knowledge - the first detailed investigation of a turbulent, pulsatile flow through a pipe bend.

  7. High-frequency counter-flow plasma synthetic jet actuator and its application in suppression of supersonic flow separation

    Science.gov (United States)

    Wang, Hongyu; Li, Jun; Jin, Di; Tang, Mengxiao; Wu, Yun; Xiao, Lianghua

    2018-01-01

    We come up with a control strategy for suppression of supersonic flow separation based on high-frequency Counter-flow Plasma Synthetic Jet Actuator (CPSJA). The main purpose of this investigation is to verify if its control authority can be enhanced by the jet/shock interaction. We use a blunt nose to generate a bow shock, a step on a flat plate to introduce a massive separation in a Mach 2 wind tunnel, and the CPSJA to generate Plasma Synthetic Jet (PSJ). In this study, pulsed capacitive discharge is provided for an array of CPSJAs, which makes the actuation (discharge) frequency f1 = 1 kHz, f2 = 2 kHz and f3 = 3 kHz. We use the high-speed schlieren imaging and fast response pressure transducers as well as a numerical simulation to investigate the quiescent PSJ properties, the interaction between the jet and bow shock, and its disturbance effect on the downstream separated region. The schlieren images show that PSJ is characterized by a succession of vortex rings; the jet strength weakens with the increase of frequency. A 4.5 mN jet thrust is found for all the frequencies. The simulation results show that jet/shock interaction produces vorticity in the vortex ring of the jet, enhancing turbulent mixing in PSJ so that a great deal of momentum is produced into the flow. We found the downstream flow is significantly disturbed by the enhanced actuation. Actuation with frequency of f2, f3 which is close to the natural frequency fn of the separation bubble suppresses the separation with the upstream laminar boundary layer being periodically attenuated, which has a better control effect than f1. The control effect is sensitive to the position where PSJ interacts with the shear layer, but the amount of energy deposited in one pulse is not crucial in a separation reduction in the experiment.

  8. Technical Evaluation Report, Part A - Vortex Flow and High Angle of Attack

    Science.gov (United States)

    Luckring, James M.

    2003-01-01

    A symposium entitled Vortex Flow and High Angle of Attack was held in Loen, Norway, from May 7 through May 11, 2001. The Applied Vehicle Technology (AVT) panel, under the auspices of the Research and Technology Organization (RTO), sponsored this symposium. Forty-eight papers, organized into nine sessions, addressed computational and experimental studies of vortex flows pertinent to both aircraft and maritime applications. The studies also ranged from fundamental fluids investigations to flight test results, and significant results were contributed from a broad range of countries. The principal emphasis of this symposium was on "the understanding and prediction of separation-induced vortex flows and their effects on military vehicle performance, stability, control, and structural design loads." It was further observed by the program committee that "separation- induced vortex flows are an important part of the design and off-design performance of conventional fighter aircraft and new conventional or unconventional manned or unmanned advanced vehicle designs (UAVs, manned aircraft, missiles, space planes, ground-based vehicles, and ships)." The nine sessions addressed the following topics: vortical flows on wings and bodies, experimental techniques for vortical flows, numerical simulations of vortical flows, vortex stability and breakdown, vortex flows in maritime applications, vortex interactions and control, vortex dynamics, flight testing, and vehicle design. The purpose of this paper is to provide brief reviews of these papers along with some synthesizing perspectives toward future vortex flow research opportunities. The paper includes the symposium program. (15 refs.)

  9. Statistical study of high-latitude plasma flow during magnetospheric substorms

    Directory of Open Access Journals (Sweden)

    G. Provan

    2004-11-01

    Full Text Available We have utilised the near-global imaging capabilities of the Northern Hemisphere SuperDARN radars, to perform a statistical superposed epoch analysis of high-latitude plasma flows during magnetospheric substorms. The study involved 67 substorms, identified using the IMAGE FUV space-borne auroral imager. A substorm co-ordinate system was developed, centred on the magnetic local time and magnetic latitude of substorm onset determined from the auroral images. The plasma flow vectors from all 67 intervals were combined, creating global statistical plasma flow patterns and backscatter occurrence statistics during the substorm growth and expansion phases. The commencement of the substorm growth phase was clearly observed in the radar data 18-20min before substorm onset, with an increase in the anti-sunward component of the plasma velocity flowing across dawn sector of the polar cap and a peak in the dawn-to-dusk transpolar voltage. Nightside backscatter moved to lower latitudes as the growth phase progressed. At substorm onset a flow suppression region was observed on the nightside, with fast flows surrounding the suppressed flow region. The dawn-to-dusk transpolar voltage increased from ~40kV just before substorm onset to ~75kV 12min after onset. The low-latitude return flow started to increase at substorm onset and continued to increase until 8min after onset. The velocity flowing across the polar-cap peaked 12-14min after onset. This increase in the flux of the polar cap and the excitation of large-scale plasma flow occurred even though the IMF Bz component was increasing (becoming less negative during most of this time. This study is the first to statistically prove that nightside reconnection creates magnetic flux and excites high-latitude plasma flow in a similar way to dayside reconnection and that dayside and nightside reconnection, are two separate time-dependent processes.

  10. High frequency components of tracheal sound are emphasized during prolonged flow limitation

    International Nuclear Information System (INIS)

    Tenhunen, M; Huupponen, E; Saastamoinen, A; Kulkas, A; Himanen, S-L; Rauhala, E

    2009-01-01

    A nasal pressure transducer, which is used to study nocturnal airflow, also provides information about the inspiratory flow waveform. A round flow shape is presented during normal breathing. A flattened, non-round shape is found during hypopneas and it can also appear in prolonged episodes. The significance of this prolonged flow limitation is still not established. A tracheal sound spectrum has been analyzed further in order to achieve additional information about breathing during sleep. Increased sound frequencies over 500 Hz have been connected to obstruction of the upper airway. The aim of the present study was to examine the tracheal sound signal content of prolonged flow limitation and to find out whether prolonged flow limitation would consist of abundant high frequency activity. Sleep recordings of 36 consecutive patients were examined. The tracheal sound spectral analysis was performed on 10 min episodes of prolonged flow limitation, normal breathing and periodic apnea-hypopnea breathing. The highest total spectral amplitude, implicating loudest sounds, occurred during flow-limited breathing which also presented loudest sounds in all frequency bands above 100 Hz. In addition, the tracheal sound signal during flow-limited breathing constituted proportionally more high frequency activities compared to normal breathing and even periodic apnea-hypopnea breathing

  11. Condensation shocks in high momentum two-phase flows in condensing injectors

    International Nuclear Information System (INIS)

    Anand, G.; Christensen, R.N.

    1993-01-01

    This study presents a phenomenological and mathematical model of condensation shocks in high momentum two-phase flows in condensing injectors. The characteristics of the shock were related to the mode of vapor bubble collapse. Using cavitation terminology, the bubble collapse can be classified as inertially controlled or thermally controlled. Inertial bubble collapse occurs rapidly whereas, a thermally controlled collapse results in a significantly longer collapse time. The interdependence between the bubble collapse mode and the momentum and pressure of the flow, was analyzed in this study. For low-temperature-high-velocity flows a steep pressure rise with complete condensation was obtained. For a high-temperature-low velocity flow with noncondensables, low pressure recovery with incomplete condensation was observed. These trends are in agreement with previous experimental observations

  12. Mode decomposition methods for flows in high-contrast porous media. A global approach

    KAUST Repository

    Ghommem, Mehdi; Calo, Victor M.; Efendiev, Yalchin R.

    2014-01-01

    We apply dynamic mode decomposition (DMD) and proper orthogonal decomposition (POD) methods to flows in highly-heterogeneous porous media to extract the dominant coherent structures and derive reduced-order models via Galerkin projection. Permeability fields with high contrast are considered to investigate the capability of these techniques to capture the main flow features and forecast the flow evolution within a certain accuracy. A DMD-based approach shows a better predictive capability due to its ability to accurately extract the information relevant to long-time dynamics, in particular, the slowly-decaying eigenmodes corresponding to largest eigenvalues. Our study enables a better understanding of the strengths and weaknesses of the applicability of these techniques for flows in high-contrast porous media. Furthermore, we discuss the robustness of DMD- and POD-based reduced-order models with respect to variations in initial conditions, permeability fields, and forcing terms. © 2013 Elsevier Inc.

  13. Study on the flow nonuniformity in a high capacity Stirling pulse tube cryocooler

    Science.gov (United States)

    You, X.; Zhi, X.; Duan, C.; Jiang, X.; Qiu, L.; Li, J.

    2017-12-01

    High capacity Stirling-type pulse tube cryocoolers (SPTC) have promising applications in high temperature superconductive motor and gas liquefaction. However, with the increase of cooling capacity, its performance deviates from well-accepted one-dimensional model simulation, such as Sage and Regen, mainly due to the strong field nonuniformity. In this study, several flow straighteners placed at both ends of the pulse tube are investigated to improve the flow distribution. A two-dimensional model of the pulse tube based on the computational fluid dynamics (CFD) method has been built to study the flow distribution of the pulse tube with different flow straighteners including copper screens, copper slots, taper transition and taper stainless slot. A SPTC set-up which has more than one hundred Watts cooling power at 80 K has been built and tested. The flow straighteners mentioned above have been applied and tested. The results show that with the best flow straightener the cooling performance of the SPTC can be significantly improved. Both CFD simulation and experiment show that the straighteners have impacts on the flow distribution and the performance of the high capacity SPTC.

  14. High Mach flow associated with plasma detachment in JT-60U

    International Nuclear Information System (INIS)

    Hatayama, A.; Hoshino, K.; Miyamoto, K.

    2003-01-01

    Recent new results of the high Mach flows associated with plasma detachment are presented on the basis of numerical simulations by a 2-D edge simulation code (the B2-Eirene code) and their comparisons with experiments in JT-60U W-shaped divertor plasma. High Mach flows appear near the ionization front away from the target plate. The plasma static pressure rapidly drops, while the total pressure is kept almost constant near the ionization front, because the ionization front near the X-point is clearly separated from the momentum loss region near the target plate. Redistribution from static to dynamic pressure without a large momentum loss is confirmed to be a possible mechanism of the high Mach flows. It has been also shown that the radial structure of the high Mach flow near the X point away from the target plate has a strong correlation with the DOD (Degree of Detachment) at the target plate. Also, we have made systematic analyses on the high Mach flows for both the 'Open' geometry and the 'W-shaped' geometry of JT-60U in order to clarify the geometric effects on the flows. (author)

  15. High resolution X-ray tomography for stationary multiphase flows

    International Nuclear Information System (INIS)

    Schmitz, D.; Reinecke, N.; Petritsch, G.; Mewes, D.

    1998-01-01

    The high resolution which can be obtained by computer assisted tomography is used to investigate the liquid distribution and void fraction in random and structured packing. With a spatial resolution of 0.4x0.4mm 2 it is possible even to detect thin liquid films on structured packings. The experimental set-up consists of a custom-built second generation tomograph. The imaged object consists of a column filled with either a random ceramic packing of spheres or a structured metal packing. The liquid and void fraction distribution in random and structured packings with a quiescent gaseous phase is visualized. The water/air system is used. The liquid distributor consists of a perforated plate. The experimental hold-up values averaged over the column cross-section are in good agreement with empirical equations. (author)

  16. Advanced power flow technologies for high current ICF accelerators

    International Nuclear Information System (INIS)

    VanDevender, J.P.; McDaniel, D.H.

    1978-01-01

    Two new technologies for raising the power density in high current, inertial confinement fusion accelerators have been developed in the past two years. Magnetic flashover inhibition utilizes the self-magnetic fields around the vacuum insulator surface to inhibit surface flashover; average electric fields of 40 Mv/m at magnetic fields of 1.1 T have been achieved. Self-magnetic insulation of long, vacuum transmission lines has been used to transport power at 1.6 x 10 14 W/m 2 over six meters and up to 1.6 x 10 15 W/m 2 over short distances in a radial anode-cathode feed. The recent data relevant to these new technologies and their implications for ICF will be explored

  17. High-resolution flow imaging of the carotid arteries

    International Nuclear Information System (INIS)

    Masaryk, T.J.; Modic, M.T.; Haacke, E.M.; Lenz, G.W.; Ross, J.S.

    1986-01-01

    Recently, high-contrast vascular images have been demonstrated using short TEs, gating and subtraction. However, to obtain short TE values, large gradients are required. This potentially limits the field of view, signal-to-noise- ratio, and resolution. Furthermore, gating in different parts of the cardiac cycle can lead to pixel misregistration. In this study, additional refocusing gradients were applied so that no velocity-dependent dephasing occurs at the echo restoring signal from moving blood. Two cardiac-gated sequences using the same trigger delay and one acquisition were obtained. Preliminary results indicate that good quality vascular images of the carotid bifurcation can be obtained with modifications of the spin-echo technique of with short TEs utilizing a gradient echo technique

  18. Schlieren study of a sonic jet injected into a supersonic cross flow using high-current pulsed LEDs

    NARCIS (Netherlands)

    Giskes, Ella; Verschoof, Ruben A.; Segerink, Frans B.; Venner, Cornelis H.

    2017-01-01

    Benefiting from the development of increasingly advanced high speed cameras, flow visualization and analysis nowadays yield detailed data of the flow field in many applications. Notwithstanding this progress, for high speed and supersonic flows it is still not trivial to capture high quality images.

  19. Retrograde Transvenous Ethanol Embolization of High-flow Peripheral Arteriovenous Malformations

    International Nuclear Information System (INIS)

    Linden, Edwin van der; Baalen, Jary M. van; Pattynama, Peter M. T.

    2012-01-01

    Purpose: To report the clinical efficiency and complications in patients treated with retrograde transvenous ethanol embolization of high-flow peripheral arteriovenous malformations (AVMs). Retrograde transvenous ethanol embolization of high-flow AVMs is a technique that can be used to treat AVMs with a dominant outflow vein whenever conventional interventional procedures have proved insufficient. Methods: This is a retrospective study of the clinical effectiveness and complications of retrograde embolization in five patients who had previously undergone multiple arterial embolization procedures without clinical success. Results: Clinical outcomes were good in all patients but were achieved at the cost of serious, although transient, complications in three patients. Conclusion: Retrograde transvenous ethanol embolization is a highly effective therapy for high-flow AVMs. However, because of the high complication rate, it should be reserved as a last resort, to be used after conventional treatment options have failed.

  20. Cavitation performance improvement of high specific speed mixed-flow pump

    International Nuclear Information System (INIS)

    Chen, T; Sun, Y B; Wu, D Z; Wang, L Q

    2012-01-01

    Cavitation performance improvement of large hydraulic machinery such as pump and turbine has been a hot topic for decades. During the design process of the pumps, in order to minimize size, weight and cost centrifugal and mixed-flow pump impellers are required to operate at the highest possible rotational speed. The rotational speed is limited by the phenomenon of cavitation. The hydraulic model of high-speed mixed-flow pump with large flow rate and high pumping head, which was designed based on the traditional method, always involves poor cavitation performance. In this paper, on the basis of the same hydraulic design parameters, two hydraulic models of high-speed mixed-flow pump were designed by using different methods, in order to investigate the cavitation and hydraulic performance of the two models, the method of computational fluid dynamics (CFD) was adopted for internal flow simulation of the high specific speed mixed-flow pump. Based on the results of numerical simulation, the influences of impeller parameters and three-dimensional configuration on pressure distribution of the blades' suction surfaces were analyzed. The numerical simulation results shows a better pressure distribution and lower pressure drop around the leading edge of the improved model. The research results could provide references to the design and optimization of the anti-cavitation blade.

  1. Experimental evaluation of permanent magnet probe flowmeter measuring high temperature liquid sodium flow in the ITSL

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Uiju; Kim, Yun Ho [Nuclear engineering Department, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Kim, Jong-Man; Kim, Tae-Joon [Korea Atomic Energy Research Institute, 1045 Daedeok-daero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Kim, Sung Joong, E-mail: sungjkim@mit.edu [Nuclear engineering Department, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of)

    2013-12-15

    Highlights: • An Instrument Test Sodium Loop (ITSL) has been built and tested in various conditions at KAERI. • Free fall of liquid sodium was conducted experimentally and numerically. • A Permanent Magnet Probe Flowmeter (PMPF) was experimented in the ITSL. • Excellent linearity of the PMPF was achieved under high temperature condition. - Abstract: The Instrument Test Sodium Loop (ITSL) installed at Korea Atomic Energy Research Institute (KAERI) is a medium-size experimental facility dedicated to obtaining relevant experimental data of liquid sodium flow characteristics under various thermal hydraulic conditions and sodium purification. The ITSL has been utilized to perform thermal flow measurement of the liquid sodium and to calibrate a Permanent Magnet Probe Flowmeter (PMPF). The primary objective of this study is to obtain liquid sodium flow rate given a wide temperature range using the PMPF. Non-stationary method was adopted for the calibration of the probe given the liquid sodium temperature range of 150–415 °C. A relationship between the measured voltage signal and flow rate was obtained successfully. It is observed that the calibration experiments result in excellent linear relationships between measured voltage and volumetric flow rate at various temperature conditions. Also a computational analysis using FlowMaster, is employed to facilitate the calibration process by predicting the liquid sodium flow rate. Finally the effect of the fluid temperature on thermal flow measurements is discussed in light of the obtained experimental data.

  2. Regional Groundwater Flow Assessment in a Prospective High-Level Radioactive Waste Repository of China

    Directory of Open Access Journals (Sweden)

    Xiaoyuan Cao

    2017-07-01

    Full Text Available The production of nuclear energy will result in high-level radioactive waste (HLRW, which brings potential environmental dangers. Selecting a proper disposal repository is a crucial step in the development of nuclear energy. This paper introduces firstly the hydrogeological conditions of the Beishan area in China. Next, a regional groundwater model is constructed using a multiphase flow simulator to analyze the groundwater flow pattern in the Beishan area. Model calibration shows that the simulated and observed hydraulic heads match well, and the simulated regional groundwater flow pattern is similar to the surface flow pattern from the channel network, indicating that the groundwater flow is mainly dependent on the topography. In addition, the simulated groundwater storage over the period from 2003 to 2014 is similar to the trend derived from the Gravity Recovery and Climate Experiment satellite-derived results. Last, the established model is used to evaluate the influences of the extreme climate and regional faults on the groundwater flow pattern. It shows that they do not have a significant influence on the regional groundwater flow patterns. This study will provide a preliminary reference for the regional groundwater flow assessment in the site of the HLRW in China.

  3. Study on flow fields in high specific speed centrifugal compressor with unpinched vaneless diffuser

    International Nuclear Information System (INIS)

    Tamaki, Hideaki

    2013-01-01

    Performance of centrifugal compressors strongly depends on their internal flow fields. CFD has become indispensable tool for getting the information about flow fields in centrifugal compressors. CFD codes are usually validated by some representative data or compared with calculated results by other CFD codes, in order to ensure their accuracies. However, learning their accuracies for all types of centrifugal compressor's specifications requires continuous works that compare experimental data obtained in developmental processes of various types of centrifugal compressors with CFD results. A prediction of a performance and a flow field of a centrifugal compressor by CFD is relatively accurate when the impact of separation and secondary flow on that flow field is weak, i.e. near design condition. Centrifugal compressors are deemed to have a wide operating range alongside high efficiencies at design points. Hence the prediction accuracy of CFD at off design conditions, where the impacts of separation and secondary flow on the flow field are strong, is critical for the design of the centrifugal compressors. This study therefore investigated the prediction accuracy of CFD using a centrifugal compressor whose geometry was intentionally changed to have a distorted flow field over a whole operating range, i.e. from choke to surge.

  4. Study on flow fields in high specific speed centrifugal compressor with unpinched vaneless diffuser

    Energy Technology Data Exchange (ETDEWEB)

    Tamaki, Hideaki [IHI Corporation, Yokoham (Japan)

    2013-06-15

    Performance of centrifugal compressors strongly depends on their internal flow fields. CFD has become indispensable tool for getting the information about flow fields in centrifugal compressors. CFD codes are usually validated by some representative data or compared with calculated results by other CFD codes, in order to ensure their accuracies. However, learning their accuracies for all types of centrifugal compressor's specifications requires continuous works that compare experimental data obtained in developmental processes of various types of centrifugal compressors with CFD results. A prediction of a performance and a flow field of a centrifugal compressor by CFD is relatively accurate when the impact of separation and secondary flow on that flow field is weak, i.e. near design condition. Centrifugal compressors are deemed to have a wide operating range alongside high efficiencies at design points. Hence the prediction accuracy of CFD at off design conditions, where the impacts of separation and secondary flow on the flow field are strong, is critical for the design of the centrifugal compressors. This study therefore investigated the prediction accuracy of CFD using a centrifugal compressor whose geometry was intentionally changed to have a distorted flow field over a whole operating range, i.e. from choke to surge.

  5. Investigation on the Core Bypass Flow in a Very High Temperature Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, Yassin

    2013-10-22

    Uncertainties associated with the core bypass flow are some of the key issues that directly influence the coolant mass flow distribution and magnitude, and thus the operational core temperature profiles, in the very high-temperature reactor (VHTR). Designers will attempt to configure the core geometry so the core cooling flow rate magnitude and distribution conform to the design values. The objective of this project is to study the bypass flow both experimentally and computationally. Researchers will develop experimental data using state-of-the-art particle image velocimetry in a small test facility. The team will attempt to obtain full field temperature distribution using racks of thermocouples. The experimental data are intended to benchmark computational fluid dynamics (CFD) codes by providing detailed information. These experimental data are urgently needed for validation of the CFD codes. The following are the project tasks: • Construct a small-scale bench-top experiment to resemble the bypass flow between the graphite blocks, varying parameters to address their impact on bypass flow. Wall roughness of the graphite block walls, spacing between the blocks, and temperature of the blocks are some of the parameters to be tested. • Perform CFD to evaluate pre- and post-test calculations and turbulence models, including sensitivity studies to achieve high accuracy. • Develop the state-of-the art large eddy simulation (LES) using appropriate subgrid modeling. • Develop models to be used in systems thermal hydraulics codes to account and estimate the bypass flows. These computer programs include, among others, RELAP3D, MELCOR, GAMMA, and GAS-NET. Actual core bypass flow rate may vary considerably from the design value. Although the uncertainty of the bypass flow rate is not known, some sources have stated that the bypass flow rates in the Fort St. Vrain reactor were between 8 and 25 percent of the total reactor mass flow rate. If bypass flow rates are on the

  6. Characterising Dynamic Instability in High Water-Cut Oil-Water Flows Using High-Resolution Microwave Sensor Signals

    Science.gov (United States)

    Liu, Weixin; Jin, Ningde; Han, Yunfeng; Ma, Jing

    2018-06-01

    In the present study, multi-scale entropy algorithm was used to characterise the complex flow phenomena of turbulent droplets in high water-cut oil-water two-phase flow. First, we compared multi-scale weighted permutation entropy (MWPE), multi-scale approximate entropy (MAE), multi-scale sample entropy (MSE) and multi-scale complexity measure (MCM) for typical nonlinear systems. The results show that MWPE presents satisfied variability with scale and anti-noise ability. Accordingly, we conducted an experiment of vertical upward oil-water two-phase flow with high water-cut and collected the signals of a high-resolution microwave resonant sensor, based on which two indexes, the entropy rate and mean value of MWPE, were extracted. Besides, the effects of total flow rate and water-cut on these two indexes were analysed. Our researches show that MWPE is an effective method to uncover the dynamic instability of oil-water two-phase flow with high water-cut.

  7. Multichannel readout ASIC design flow for high energy physics and cosmic rays experiments

    International Nuclear Information System (INIS)

    Voronin, A; Malankin, E

    2016-01-01

    In the large-scale high energy physics and astrophysics experiments multi-channel readout application specific integrated circuits (ASICs) are widely used. The ASICs for such experiments are complicated systems, which usually include both analog and digital building blocks. The complexity and large number of channels in such ASICs require the proper methodological approach to their design. The paper represents the mixed-signal design flow of the ASICs for high energy physics and cosmic rays experiments. This flow was successfully embedded to the development of the read-out ASIC prototype for the muon chambers of the CBM experiment. The approach was approved in UMC CMOS MMRF 180 nm process. The design flow enable to analyse the mixed-signal system operation on the different levels: functional, behavioural, schematic and post layout including parasitic elements. The proposed design flow allows reducing the simulation period and eliminating the functionality mismatches on the very early stage of the design. (paper)

  8. A study on impulsive sound attenuation for a high-pressure blast flow field

    International Nuclear Information System (INIS)

    Kang, Kuk Jeong; Ko, Sung Ho; Lee, Dong Soo

    2008-01-01

    The present work addresses a numerical study on impulsive sound attenuation for a complex high-pressure blast flow field; these characteristics are generated by a supersonic propellant gas flow through a shock tube into an ambient environment. A numerical solver for analyzing the high pressure blast flow field is developed in this study. From numerical simulations, wave dynamic processes (which include a first precursor shock wave, a second main propellant shock wave, and interactions in the muzzle blasts) are simulated and discussed. The pressure variation of the blast flow field is analyzed to evaluate the effect of a silencer. A live firing test is also performed to evaluate four different silencers. The results of this study will be helpful in understanding blast wave and in designing silencers

  9. A study on impulsive sound attenuation for a high-pressure blast flow field

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Kuk Jeong [Agency for Defence Development, Daejeon (Korea, Republic of); Ko, Sung Ho; Lee, Dong Soo [Chungnam National University, Daejeon (Korea, Republic of)

    2008-01-15

    The present work addresses a numerical study on impulsive sound attenuation for a complex high-pressure blast flow field; these characteristics are generated by a supersonic propellant gas flow through a shock tube into an ambient environment. A numerical solver for analyzing the high pressure blast flow field is developed in this study. From numerical simulations, wave dynamic processes (which include a first precursor shock wave, a second main propellant shock wave, and interactions in the muzzle blasts) are simulated and discussed. The pressure variation of the blast flow field is analyzed to evaluate the effect of a silencer. A live firing test is also performed to evaluate four different silencers. The results of this study will be helpful in understanding blast wave and in designing silencers

  10. Effects of High-Intensity Blood Flow Restriction Exercise on Muscle Fatigue

    Directory of Open Access Journals (Sweden)

    Neto Gabriel R.

    2014-07-01

    Full Text Available Strength training combined with blood flow restriction (BFR have been used to improve the levels of muscle adaptation. The aim of this paper was to investigate the acute effect of high intensity squats with and without blood flow restriction on muscular fatigue levels. Twelve athletes (aged 25.95 ± 0.84 years were randomized into two groups: without Blood Flow Restriction (NFR, n = 6 and With Blood Flow Restriction (WFR, n = 6 that performed a series of free weight squats with 80% 1-RM until concentric failure. The strength of the quadriceps extensors was assessed in a maximum voluntary isometric contraction integrated to signals from the surface electromyogram. The average frequency showed significant reductions in the WFR group for the vastus lateralis and vastus medialis muscles, and intergroup only for the vastus medialis. In conclusion, a set of squats at high intensity with BFR could compromise muscle strength immediately after exercise, however, differences were not significant between groups.

  11. Relaxed impact craters on Ganymede: Regional variation and high heat flows

    Science.gov (United States)

    Singer, Kelsi N.; Bland, Michael T.; Schenk, Paul M.; McKinnon, William B.

    2018-05-01

    Viscously relaxed craters provide a window into the thermal history of Ganymede, a satellite with copious geologic signs of past high heat flows. Here we present measurements of relaxed craters in four regions for which suitable imaging exists: near Anshar Sulcus, Tiamat Sulcus, northern Marius Regio, and Ganymede's south pole. We describe a technique to measure apparent depth, or depth of the crater with respect to the surrounding terrain elevation. Measured relaxation states are compared with results from finite element modeling to constrain heat flow scenarios [see companion paper: Bland et al. (2017)]. The presence of numerous, substantially relaxed craters indicates high heat flows-in excess of 30-40 mW m-2 over 2 Gyr, with many small (heat flows. Crater relaxation states are bimodal for some equatorial regions but not in the region studied near the south pole, which suggests regional variations in Ganymede's thermal history.

  12. Highly selective deuteration of pharmaceutically relevant nitrogen-containing heterocycles: a flow chemistry approach.

    Science.gov (United States)

    Ötvös, Sándor B; Mándity, István M; Fülöp, Ferenc

    2011-08-01

    A simple and efficient flow-based technique is reported for the catalytic deuteration of several model nitrogen-containing heterocyclic compounds which are important building blocks of pharmacologically active materials. A continuous flow reactor was used in combination with on-demand pressure-controlled electrolytic D(2) production. The D(2) source was D(2)O, the consumption of which was very low. The experimental set-up allows the fine-tuning of pressure, temperature, and flow rate so as to determine the optimal conditions for the deuteration reactions. The described procedure lacks most of the drawbacks of the conventional batch deuteration techniques, and additionally is highly selective and reproducible.

  13. Nearly Interactive Parabolized Navier-Stokes Solver for High Speed Forebody and Inlet Flows

    Science.gov (United States)

    Benson, Thomas J.; Liou, May-Fun; Jones, William H.; Trefny, Charles J.

    2009-01-01

    A system of computer programs is being developed for the preliminary design of high speed inlets and forebodies. The system comprises four functions: geometry definition, flow grid generation, flow solver, and graphics post-processor. The system runs on a dedicated personal computer using the Windows operating system and is controlled by graphical user interfaces written in MATLAB (The Mathworks, Inc.). The flow solver uses the Parabolized Navier-Stokes equations to compute millions of mesh points in several minutes. Sample two-dimensional and three-dimensional calculations are demonstrated in the paper.

  14. Towards a comprehensive assessment and framework for low and high flow water risks

    Science.gov (United States)

    Motschmann, Alina; Huggel, Christian; Drenkhan, Fabian; León, Christian

    2017-04-01

    Driven by international organizations such as the Intergovernmental Panel on Climate Change (IPCC) the past years have seen a move from a vulnerability concept of climate change impacts towards a risk framework. Risk is now conceived at the intersection of climate-driven hazard and socioeconomic-driven vulnerability and exposure. The concept of risk so far has been mainly adopted for sudden-onset events. However, for slow-onset and cumulative climate change impacts such as changing water resources there is missing clarity and experience how to apply a risk framework. Research has hardly dealt with the challenge of how to integrate both low and high flow risks in a common framework. Comprehensive analyses of risks related to water resources considering climate change within multi-dimensional drivers across different scales are complex and often missing in climate-sensitive mountain regions where data scarcity and inconsistencies represent important limitations. Here we review existing vulnerability and risk assessments of low and high flow water conditions and identify critical conceptual and practical gaps. Based on this, we develop an integrated framework for low and high flow water risks which is applicable to both past and future conditions. The framework explicitly considers a water balance model simulating both water supply and demand on a daily basis. We test and apply this new framework in the highly glacierized Santa River catchment (SRC, Cordillera Blanca, Peru), representative for many developing mountain regions with both low and high flow water risks and poor data availability. In fact, in the SRC, both low and high flow hazards, such as droughts and floods, play a central role especially for agricultural, hydropower, domestic and mining use. During the dry season (austral winter) people are increasingly affected by water scarcity due to shrinking glaciers supplying melt water. On the other hand during the wet season (austral summer) high flow water

  15. Magnetic field and force analysis of high Tc superconductor with flux flow and creep

    International Nuclear Information System (INIS)

    Yoshida, Yoshikatsu; Uesaka, Mitsuru; Miya, Kenzo

    1994-01-01

    This paper describes a new method for the magnetic force analysis of high T c superconductor based on the flux flow and creep model. The introduction of the artificial conductivity, which is used in the conventional method, is not needed. The CPU time requirement of the calculations is considerably lower than that in the case of the conventional method. Thereby the vibration of a levitated permanent magnet was numerically analyzed by taking into account the flux flow and creep

  16. High-Order Multioperator Compact Schemes for Numerical Simulation of Unsteady Subsonic Airfoil Flow

    Science.gov (United States)

    Savel'ev, A. D.

    2018-02-01

    On the basis of high-order schemes, the viscous gas flow over the NACA2212 airfoil is numerically simulated at a free-stream Mach number of 0.3 and Reynolds numbers ranging from 103 to 107. Flow regimes sequentially varying due to variations in the free-stream viscosity are considered. Vortex structures developing on the airfoil surface are investigated, and a physical interpretation of this phenomenon is given.

  17. Application of PIV to the Measurement of High Speed Jet Flows

    Science.gov (United States)

    Lourenco, L.

    1999-01-01

    The Particle Image Velocimetry, PIV, has been implemented for the investigation of high-speed jet flows at the NASA Langley Research Center. In this approach the velocity (displacement) is found as the location of a peak in the correlation map of particle images acquired in quick succession. In the study, the technique for the correct seeding of the flow field were developed and implemented and the operational parameters influencing the accuracy of the measurement have been optimized.

  18. Unchanged cerebral blood flow and oxidative metabolism after acclimatization to high altitude

    DEFF Research Database (Denmark)

    Møller, Kirsten; Paulson, Olaf B; Hornbein, Thomas F.

    2002-01-01

    The authors investigated the effect of acclimatization to high altitude on cerebral blood flow and oxidative metabolism at rest and during exercise. Nine healthy, native sea-level residents were studied 3 weeks after arrival at Chacaltaya, Bolivia (5,260 m) and after reacclimatization to sea level....... At high altitude at rest, arterial carbon dioxide tension, oxygen saturation, and oxygen tension were significantly reduced, and arterial oxygen content was increased because of an increase in hemoglobin concentration. Global cerebral blood flow was similar in the four conditions. Cerebral oxygen delivery...... and cerebral metabolic rates of oxygen and glucose also remained unchanged, whereas cerebral metabolic rates of lactate increased slightly but nonsignificantly at high altitude during exercise compared with high altitude at rest. Reaction time was unchanged. The data indicate that cerebral blood flow...

  19. Influence of elbow curvature on flow structure at elbow outlet under high Reynolds number condition

    Energy Technology Data Exchange (ETDEWEB)

    Ono, A., E-mail: ono.ayako@jaea.go.jp [Oarai Research and Development Center, Japan Atomic Energy Agency, Narita 4002, Oarai, Ibaraki 311-1393 (Japan); Kimura, N.; Kamide, H.; Tobita, A. [Oarai Research and Development Center, Japan Atomic Energy Agency, Narita 4002, Oarai, Ibaraki 311-1393 (Japan)

    2011-11-15

    In the design of Japan Sodium-cooled Fast Reactor (JSFR), coolant velocity is beyond 9 m/s in the primary hot leg pipe of 1.27 m diameter. The Reynolds number in the piping reaches 4.2 Multiplication-Sign 10{sup 7}. Moreover, a short-elbow is adopted in the hot leg pipe in order to achieve compact plant layout and to reduce plant construction cost. Therefore, the flow-induced vibration (FIV) arising from the piping geometry may occur in the short-elbow pipe. The FIV is due to the excitation source which is caused by the pressure fluctuation in the pipe. The pressure fluctuation in the pipe is closely related with the velocity fluctuation. As the first step of clarification of the FIV mechanism, it is important to grasp the mechanism of flow fluctuation in the elbow. In this study, water experiments with two types of elbows with different curvature ratios were conducted in order to investigate the interaction between flow separation and the secondary flow due to the elbow curvature. The experiments were conducted with the short-elbow and the long-elbow under Re = 1.8 Multiplication-Sign 10{sup 5} and 5.4 Multiplication-Sign 10{sup 5} conditions. The velocity fields in the elbows were measured using a high-speed Particle Image Velocimetry (PIV). The time-series of axial velocity fields and the cross-section velocity fields obtained by the high-speed PIV measurements revealed the unsteady and complex flow structure in the elbow. The flow separation always occurred in the short-elbow while the flow separation occurred intermittently in the long-elbow case. The circumferential secondary flows in clockwise and counterclockwise directions flowed forward downstream of reattachment point alternately in both elbows.

  20. High frame rate synthetic aperture vector flow imaging for transthoracic echocardiography

    Science.gov (United States)

    Villagómez-Hoyos, Carlos A.; Stuart, Matthias B.; Bechsgaard, Thor; Nielsen, Michael Bachmann; Jensen, Jørgen Arendt

    2016-04-01

    This work presents the first in vivo results of 2-D high frame rate vector velocity imaging for transthoracic cardiac imaging. Measurements are made on a healthy volunteer using the SARUS experimental ultrasound scanner connected to an intercostal phased-array probe. Two parasternal long-axis view (PLAX) are obtained, one centred at the aortic valve and another centred at the left ventricle. The acquisition sequence was composed of 3 diverging waves for high frame rate synthetic aperture flow imaging. For verification a phantom measurement is performed on a transverse straight 5 mm diameter vessel at a depth of 100 mm in a tissue-mimicking phantom. A flow pump produced a 2 ml/s constant flow with a peak velocity of 0.2 m/s. The average estimated flow angle in the ROI was 86.22° +/- 6.66° with a true flow angle of 90°. A relative velocity bias of -39% with a standard deviation of 13% was found. In-vivo acquisitions show complex flow patterns in the heart. In the aortic valve view, blood is seen exiting the left ventricle cavity through the aortic valve into the aorta during the systolic phase of the cardiac cycle. In the left ventricle view, blood flow is seen entering the left ventricle cavity through the mitral valve and splitting in two ways when approximating the left ventricle wall. The work presents 2-D velocity estimates on the heart from a non-invasive transthoracic scan. The ability of the method detecting flow regardless of the beam angle could potentially reveal a more complete view of the flow patterns presented on the heart.

  1. Direct numerical simulation of reactor two-phase flows enabled by high-performance computing

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Jun; Cambareri, Joseph J.; Brown, Cameron S.; Feng, Jinyong; Gouws, Andre; Li, Mengnan; Bolotnov, Igor A.

    2018-04-01

    Nuclear reactor two-phase flows remain a great engineering challenge, where the high-resolution two-phase flow database which can inform practical model development is still sparse due to the extreme reactor operation conditions and measurement difficulties. Owing to the rapid growth of computing power, the direct numerical simulation (DNS) is enjoying a renewed interest in investigating the related flow problems. A combination between DNS and an interface tracking method can provide a unique opportunity to study two-phase flows based on first principles calculations. More importantly, state-of-the-art high-performance computing (HPC) facilities are helping unlock this great potential. This paper reviews the recent research progress of two-phase flow DNS related to reactor applications. The progress in large-scale bubbly flow DNS has been focused not only on the sheer size of those simulations in terms of resolved Reynolds number, but also on the associated advanced modeling and analysis techniques. Specifically, the current areas of active research include modeling of sub-cooled boiling, bubble coalescence, as well as the advanced post-processing toolkit for bubbly flow simulations in reactor geometries. A novel bubble tracking method has been developed to track the evolution of bubbles in two-phase bubbly flow. Also, spectral analysis of DNS database in different geometries has been performed to investigate the modulation of the energy spectrum slope due to bubble-induced turbulence. In addition, the single-and two-phase analysis results are presented for turbulent flows within the pressurized water reactor (PWR) core geometries. The related simulations are possible to carry out only with the world leading HPC platforms. These simulations are allowing more complex turbulence model development and validation for use in 3D multiphase computational fluid dynamics (M-CFD) codes.

  2. Piezoelectric microvalve for precise control of gas flow at high pressure

    NARCIS (Netherlands)

    Fazal, I.; Elwenspoek, Michael Curt

    2008-01-01

    We present a normally open piezoelectric actuated micro valve, based on the novel concept of micro and fine machining technology. This new design allows a wide controllable range for high flow at a high pressure difference between inlet and outlet. This promising combination of micro and fine

  3. Accurate Angle Estimator for High-Frame-rate 2-D Vector Flow Imaging

    DEFF Research Database (Denmark)

    Villagómez Hoyos, Carlos Armando; Stuart, Matthias Bo; Lindskov Hansen, Kristoffer

    2016-01-01

    This paper presents a novel approach for estimating 2-D flow angles using a high-frame-rate ultrasound method. The angle estimator features high accuracy and low standard deviation (SD) over the full 360° range. The method is validated on Field II simulations and phantom measurements using...

  4. High PRF ultrafast sliding compound doppler imaging: fully qualitative and quantitative analysis of blood flow.

    Science.gov (United States)

    Kang, Jinbum; Jang, Won Seuk; Yoo, Yangmo

    2018-02-09

    Ultrafast compound Doppler imaging based on plane-wave excitation (UCDI) can be used to evaluate cardiovascular diseases using high frame rates. In particular, it provides a fully quantifiable flow analysis over a large region of interest with high spatio-temporal resolution. However, the pulse-repetition frequency (PRF) in the UCDI method is limited for high-velocity flow imaging since it has a tradeoff between the number of plane-wave angles (N) and acquisition time. In this paper, we present high PRF ultrafast sliding compound Doppler imaging method (HUSDI) to improve quantitative flow analysis. With the HUSDI method, full scanline images (i.e. each tilted plane wave data) in a Doppler frame buffer are consecutively summed using a sliding window to create high-quality ensemble data so that there is no reduction in frame rate and flow sensitivity. In addition, by updating a new compounding set with a certain time difference (i.e. sliding window step size or L), the HUSDI method allows various Doppler PRFs with the same acquisition data to enable a fully qualitative, retrospective flow assessment. To evaluate the performance of the proposed HUSDI method, simulation, in vitro and in vivo studies were conducted under diverse flow circumstances. In the simulation and in vitro studies, the HUSDI method showed improved hemodynamic representations without reducing either temporal resolution or sensitivity compared to the UCDI method. For the quantitative analysis, the root mean squared velocity error (RMSVE) was measured using 9 angles (-12° to 12°) with L of 1-9, and the results were found to be comparable to those of the UCDI method (L  =  N  =  9), i.e.  ⩽0.24 cm s -1 , for all L values. For the in vivo study, the flow data acquired from a full cardiac cycle of the femoral vessels of a healthy volunteer were analyzed using a PW spectrogram, and arterial and venous flows were successfully assessed with high Doppler PRF (e.g. 5 kHz at L

  5. High PRF ultrafast sliding compound doppler imaging: fully qualitative and quantitative analysis of blood flow

    Science.gov (United States)

    Kang, Jinbum; Jang, Won Seuk; Yoo, Yangmo

    2018-02-01

    Ultrafast compound Doppler imaging based on plane-wave excitation (UCDI) can be used to evaluate cardiovascular diseases using high frame rates. In particular, it provides a fully quantifiable flow analysis over a large region of interest with high spatio-temporal resolution. However, the pulse-repetition frequency (PRF) in the UCDI method is limited for high-velocity flow imaging since it has a tradeoff between the number of plane-wave angles (N) and acquisition time. In this paper, we present high PRF ultrafast sliding compound Doppler imaging method (HUSDI) to improve quantitative flow analysis. With the HUSDI method, full scanline images (i.e. each tilted plane wave data) in a Doppler frame buffer are consecutively summed using a sliding window to create high-quality ensemble data so that there is no reduction in frame rate and flow sensitivity. In addition, by updating a new compounding set with a certain time difference (i.e. sliding window step size or L), the HUSDI method allows various Doppler PRFs with the same acquisition data to enable a fully qualitative, retrospective flow assessment. To evaluate the performance of the proposed HUSDI method, simulation, in vitro and in vivo studies were conducted under diverse flow circumstances. In the simulation and in vitro studies, the HUSDI method showed improved hemodynamic representations without reducing either temporal resolution or sensitivity compared to the UCDI method. For the quantitative analysis, the root mean squared velocity error (RMSVE) was measured using 9 angles (-12° to 12°) with L of 1-9, and the results were found to be comparable to those of the UCDI method (L  =  N  =  9), i.e.  ⩽0.24 cm s-1, for all L values. For the in vivo study, the flow data acquired from a full cardiac cycle of the femoral vessels of a healthy volunteer were analyzed using a PW spectrogram, and arterial and venous flows were successfully assessed with high Doppler PRF (e.g. 5 kHz at L

  6. A High Performance Pulsatile Pump for Aortic Flow Experiments in 3-Dimensional Models.

    Science.gov (United States)

    Chaudhury, Rafeed A; Atlasman, Victor; Pathangey, Girish; Pracht, Nicholas; Adrian, Ronald J; Frakes, David H

    2016-06-01

    Aortic pathologies such as coarctation, dissection, and aneurysm represent a particularly emergent class of cardiovascular diseases. Computational simulations of aortic flows are growing increasingly important as tools for gaining understanding of these pathologies, as well as for planning their surgical repair. In vitro experiments are required to validate the simulations against real world data, and the experiments require a pulsatile flow pump system that can provide physiologic flow conditions characteristic of the aorta. We designed a newly capable piston-based pulsatile flow pump system that can generate high volume flow rates (850 mL/s), replicate physiologic waveforms, and pump high viscosity fluids against large impedances. The system is also compatible with a broad range of fluid types, and is operable in magnetic resonance imaging environments. Performance of the system was validated using image processing-based analysis of piston motion as well as particle image velocimetry. The new system represents a more capable pumping solution for aortic flow experiments than other available designs, and can be manufactured at a relatively low cost.

  7. On the POD based reduced order modeling of high Reynolds flows

    Science.gov (United States)

    Behzad, Fariduddin; Helenbrook, Brian; Ahmadi, Goodarz

    2012-11-01

    Reduced-order modeling (ROM) of a high Reynolds fluid flow using the proper orthogonal decomposition (POD) was studied. Particular attention was given to incompressible, unsteady flow over a two-dimensional NACA0015 airfoil. The Reynolds number is 105 and the angle of attacked of the airfoil is 12°. For DNS solution, hp-finite element method is employed to drive flow samples from which the POD modes are extracted. Particular attention is paid on two issues. First, the stability of POD-ROM resimulation of the turbulent flow is studied. High Reynolds flow contains a lot of fluctuating modes. So, to reach a certain amount of error, more POD modes are needed and the effect of truncation of POD modes is more important. Second, the role of convergence rate on the results of POD. Due to complexity of the flow, convergence of the governing equations is more difficult and the influences of weak convergence appear in the results of POD-ROM. For each issue, the capability of the POD-ROM is assessed in terms of predictions quality of times upon which the POD model was derived. The results are compared with DNS solution and the accuracy and efficiency of different cases are evaluated.

  8. Evidence Support and Guidelines for Using Heated, Humidified, High-Flow Nasal Cannulae in Neonatology: Oxford Nasal High-Flow Therapy Meeting, 2015.

    Science.gov (United States)

    Roehr, Charles C; Yoder, Bradley A; Davis, Peter G; Ives, Kevin

    2016-12-01

    Nasal high-flow therapy (nHFT) has become a popular form of noninvasive respiratory support in neonatal intensive care units. A meeting held in Oxford, UK, in June 2015 examined the evidence base and proposed a consensus statement. In summary, nHFT is effective for support of preterm infants following extubation. There is growing evidence evaluating its use in the primary treatment of respiratory distress. Further study is needed to assess which clinical conditions are most amenable to nHFT support, the most effective flow rates, and escalation and weaning strategies. Its suitability as first-line treatment needs to be further evaluated. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Holography as a highly efficient renormalization group flow. I. Rephrasing gravity

    Science.gov (United States)

    Behr, Nicolas; Kuperstein, Stanislav; Mukhopadhyay, Ayan

    2016-07-01

    We investigate how the holographic correspondence can be reformulated as a generalization of Wilsonian renormalization group (RG) flow in a strongly interacting large-N quantum field theory. We first define a highly efficient RG flow as one in which the Ward identities related to local conservation of energy, momentum and charges preserve the same form at each scale. To achieve this, it is necessary to redefine the background metric and external sources at each scale as functionals of the effective single-trace operators. These redefinitions also absorb the contributions of the multitrace operators to these effective Ward identities. Thus, the background metric and external sources become effectively dynamical, reproducing the dual classical gravity equations in one higher dimension. Here, we focus on reconstructing the pure gravity sector as a highly efficient RG flow of the energy-momentum tensor operator, leaving the explicit constructive field theory approach for generating such RG flows to the second part of the work. We show that special symmetries of the highly efficient RG flows carry information through which we can decode the gauge fixing of bulk diffeomorphisms in the corresponding gravity equations. We also show that the highly efficient RG flow which reproduces a given classical gravity theory in a given gauge is unique provided the endpoint can be transformed to a nonrelativistic fixed point with a finite number of parameters under a universal rescaling. The results obtained here are used in the second part of this work, where we do an explicit field-theoretic construction of the RG flow and obtain the dual classical gravity theory.

  10. Development of high-frame rate neutron radiography and quantitative measurement method for multiphase flow research

    International Nuclear Information System (INIS)

    Mishima, K.; Hibiki, T.

    1998-01-01

    Neutron radiography (NR) is one of the radiographic techniques which makes use of the difference in attenuation characteristics of neutrons in materials. Fluid measurement using the NR technique is a non-intrusive method which enables visualization of dynamic images of multiphase flow of opaque fluids and/or in a metallic duct. To apply the NR technique to multiphase flow research, high frame-rate NR was developed by combining up-to-date technologies for neutron sources, scintillator, high-speed video and image intensifier. This imaging system has several advantages such as a long recording time (up to 21 minutes), high-frame-rate (up to 1000 frames/s) imaging and there is no need for a triggering signal. Visualization studies of air-water two-phase flow in a metallic duct and molten metal-water interaction were performed at recording speeds of 250, 500 and 1000 frames/s. The qualities of the consequent images were sufficient to observe the flow pattern and behavior. It was also demonstrated that some characteristics of two-phase flow could be measured from these images in collaboration with image processing techniques. By utilizing geometrical information extracted from NR images, data on flow regime, bubble rise velocity, and wave height and interfacial area in annular flow were obtained. By utilizing attenuation characteristics of neutrons in materials, measurements of void profile and average void fraction were performed. It was confirmed that this new technique may have significant advantages both in visualizing and measuring high-speed fluid phenomena when other methods, such as an optical method and X-ray radiography, cannot be applied. (author)

  11. The new high resolution method of Godunov`s type for 3D viscous flow calculations

    Energy Technology Data Exchange (ETDEWEB)

    Yershov, S.V.; Rusanov, A.V. [Ukranian National Academy of Sciences, Kahrkov (Ukraine)

    1996-12-31

    The numerical method is suggested for the calculations of the 3D viscous compressible flows described by the thin-layer Reynolds-averaged Navier-Stokes equations. The method is based on the Godunov`s finite-difference scheme and it uses the ENO reconstruction suggested by Harten to achieve the uniformly high-order accuracy. The computational efficiency is provided with the simplified multi grid approach and the implicit step written in {delta} -form. The turbulent effects are simulated with the Baldwin - Lomax turbulence model. The application package FlowER is developed to calculate the 3D turbulent flows within complex-shape channels. The numerical results for the 3D flow around a cylinder and through the complex-shaped channels show the accuracy and the reliability of the suggested method. (author)

  12. Study on transient hydrodynamic performance and cavitation characteristic of high-speed mixed-flow pump

    International Nuclear Information System (INIS)

    Chen, T; Liu, Y L; Sun, Y B; Wang, L Q; Wu, D Z

    2013-01-01

    In order to analyse the hydrodynamic performance and cavitation characteristic of a high-speed mixed-flow pump during transient operations, experimental studies were carried out. The transient hydrodynamic performance and cavitation characteristics of the mixed-flow pump with guide vane during start-up operation processes were tested on the pump performance test-bed. Performance tests of the pump were carried out under various inlet pressures and speed-changing operations. The real-time instantaneous external characteristics such as rotational speed, hydraulic head, flow rate, suction pressure and discharge pressure of the pump were measured. Based on the experimental results, the effect of fluid acceleration on the hydrodynamic performances and cavitation characteristics of the mixed-flow pump were analysed and evaluated

  13. The new high resolution method of Godunov`s type for 3D viscous flow calculations

    Energy Technology Data Exchange (ETDEWEB)

    Yershov, S V; Rusanov, A V [Ukranian National Academy of Sciences, Kahrkov (Ukraine)

    1997-12-31

    The numerical method is suggested for the calculations of the 3D viscous compressible flows described by the thin-layer Reynolds-averaged Navier-Stokes equations. The method is based on the Godunov`s finite-difference scheme and it uses the ENO reconstruction suggested by Harten to achieve the uniformly high-order accuracy. The computational efficiency is provided with the simplified multi grid approach and the implicit step written in {delta} -form. The turbulent effects are simulated with the Baldwin - Lomax turbulence model. The application package FlowER is developed to calculate the 3D turbulent flows within complex-shape channels. The numerical results for the 3D flow around a cylinder and through the complex-shaped channels show the accuracy and the reliability of the suggested method. (author)

  14. Variable High Order Multiblock Overlapping Grid Methods for Mixed Steady and Unsteady Multiscale Viscous Flows

    Science.gov (United States)

    Sjogreen, Bjoern; Yee, H. C.

    2007-01-01

    Flows containing steady or nearly steady strong shocks in parts of the flow field, and unsteady turbulence with shocklets on other parts of the flow field are difficult to capture accurately and efficiently employing the same numerical scheme even under the multiblock grid or adaptive grid refinement framework. On one hand, sixth-order or higher shock-capturing methods are appropriate for unsteady turbulence with shocklets. On the other hand, lower order shock-capturing methods are more effective for strong steady shocks in terms of convergence. In order to minimize the shortcomings of low order and high order shock-capturing schemes for the subject flows,a multi- block overlapping grid with different orders of accuracy on different blocks is proposed. Test cases to illustrate the performance of the new solver are included.

  15. Parametric Approach to Assessing Performance of High-Lift Device Active Flow Control Architectures

    Directory of Open Access Journals (Sweden)

    Yu Cai

    2017-02-01

    Full Text Available Active Flow Control is at present an area of considerable research, with multiple potential aircraft applications. While the majority of research has focused on the performance of the actuators themselves, a system-level perspective is necessary to assess the viability of proposed solutions. This paper demonstrates such an approach, in which major system components are sized based on system flow and redundancy considerations, with the impacts linked directly to the mission performance of the aircraft. Considering the case of a large twin-aisle aircraft, four distinct active flow control architectures that facilitate the simplification of the high-lift mechanism are investigated using the demonstrated approach. The analysis indicates a very strong influence of system total mass flow requirement on architecture performance, both for a typical mission and also over the entire payload-range envelope of the aircraft.

  16. High-energy redox-flow batteries with hybrid metal foam electrodes.

    Science.gov (United States)

    Park, Min-Sik; Lee, Nam-Jin; Lee, Seung-Wook; Kim, Ki Jae; Oh, Duk-Jin; Kim, Young-Jun

    2014-07-09

    A nonaqueous redox-flow battery employing [Co(bpy)3](+/2+) and [Fe(bpy)3](2+/3+) redox couples is proposed for use in large-scale energy-storage applications. We successfully demonstrate a redox-flow battery with a practical operating voltage of over 2.1 V and an energy efficiency of 85% through a rational cell design. By utilizing carbon-coated Ni-FeCrAl and Cu metal foam electrodes, the electrochemical reactivity and stability of the nonaqueous redox-flow battery can be considerably enhanced. Our approach intoduces a more efficient conversion of chemical energy into electrical energy and enhances long-term cell durability. The cell exhibits an outstanding cyclic performance of more than 300 cycles without any significant loss of energy efficiency. Considering the increasing demands for efficient energy storage, our achievement provides insight into a possible development pathway for nonaqueous redox-flow batteries with high energy densities.

  17. Effects of high frequency fluctuations on DNS of turbulent open-channel flow with high Pr passive scalar transport

    International Nuclear Information System (INIS)

    Yamamoto, Yoshinobu; Kunugi, Tomoaki; Serizawa, Akimi

    2002-01-01

    In this study, investigation on effects of high frequency fluctuations on DNS of turbulent open-channel flows with high Pr passive scalar transport was conducted. As the results, although significant differences of energy spectra behaviors in temperature fields, are caused at high wave number region where insignificant area for velocity components, large difference dose not caused in mean and statistic behaviors in temperature component. But, if the buoyancy were considered, this temperature high-frequency fluctuations would be greatly changed mean and statistics behaviors from the difference of the accuracy and resolution at high wave number region. (author)

  18. High-efficiency particulate air filter behavior at high-speed flows

    International Nuclear Information System (INIS)

    Tang, P.K.; Gregory, W.S.; Ricketts, C.I.; Smith, P.R.

    1984-04-01

    This paper presents a filter model based on the principle of fluid flow through porous media. The model includes both laminar and turbulent effects. The coefficients used in the model are determined empirically based on existing data. Deviation from the model is discussed

  19. Probability modeling of high flow extremes in Yingluoxia watershed, the upper reaches of Heihe River basin

    Science.gov (United States)

    Li, Zhanling; Li, Zhanjie; Li, Chengcheng

    2014-05-01

    Probability modeling of hydrological extremes is one of the major research areas in hydrological science. Most basins in humid and semi-humid south and east of China are concerned for probability modeling analysis of high flow extremes. While, for the inland river basin which occupies about 35% of the country area, there is a limited presence of such studies partly due to the limited data availability and a relatively low mean annual flow. The objective of this study is to carry out probability modeling of high flow extremes in the upper reach of Heihe River basin, the second largest inland river basin in China, by using the peak over threshold (POT) method and Generalized Pareto Distribution (GPD), in which the selection of threshold and inherent assumptions for POT series are elaborated in details. For comparison, other widely used probability distributions including generalized extreme value (GEV), Lognormal, Log-logistic and Gamma are employed as well. Maximum likelihood estimate is used for parameter estimations. Daily flow data at Yingluoxia station from 1978 to 2008 are used. Results show that, synthesizing the approaches of mean excess plot, stability features of model parameters, return level plot and the inherent independence assumption of POT series, an optimum threshold of 340m3/s is finally determined for high flow extremes in Yingluoxia watershed. The resulting POT series is proved to be stationary and independent based on Mann-Kendall test, Pettitt test and autocorrelation test. In terms of Kolmogorov-Smirnov test, Anderson-Darling test and several graphical diagnostics such as quantile and cumulative density function plots, GPD provides the best fit to high flow extremes in the study area. The estimated high flows for long return periods demonstrate that, as the return period increasing, the return level estimates are probably more uncertain. The frequency of high flow extremes exhibits a very slight but not significant decreasing trend from 1978 to

  20. High-speed cell recognition algorithm for ultrafast flow cytometer imaging system

    Science.gov (United States)

    Zhao, Wanyue; Wang, Chao; Chen, Hongwei; Chen, Minghua; Yang, Sigang

    2018-04-01

    An optical time-stretch flow imaging system enables high-throughput examination of cells/particles with unprecedented high speed and resolution. A significant amount of raw image data is produced. A high-speed cell recognition algorithm is, therefore, highly demanded to analyze large amounts of data efficiently. A high-speed cell recognition algorithm consisting of two-stage cascaded detection and Gaussian mixture model (GMM) classification is proposed. The first stage of detection extracts cell regions. The second stage integrates distance transform and the watershed algorithm to separate clustered cells. Finally, the cells detected are classified by GMM. We compared the performance of our algorithm with support vector machine. Results show that our algorithm increases the running speed by over 150% without sacrificing the recognition accuracy. This algorithm provides a promising solution for high-throughput and automated cell imaging and classification in the ultrafast flow cytometer imaging platform.

  1. Positivity-preserving space-time CE/SE scheme for high speed flows

    KAUST Repository

    Shen, Hua

    2017-03-02

    We develop a space-time conservation element and solution element (CE/SE) scheme using a simple slope limiter to preserve the positivity of the density and pressure in computations of inviscid and viscous high-speed flows. In general, the limiter works with all existing CE/SE schemes. Here, we test the limiter on a central Courant number insensitive (CNI) CE/SE scheme implemented on hybrid unstructured meshes. Numerical examples show that the proposed limiter preserves the positivity of the density and pressure without disrupting the conservation law; it also improves robustness without losing accuracy in solving high-speed flows.

  2. Microturbulence and Flow Shear in High-performance JET ITB Plasma; TOPICAL

    International Nuclear Information System (INIS)

    R.V. Budny; A. Andre; A. Bicoulet; C. Challis; G.D. Conway; W. Dorland; D.R. Ernst; T.S. Hahm; T.C. Hender; D. McCune; G. Rewoldt; S.E. Sharapov

    2001-01-01

    The transport, flow shear, and linear growth rates of microturbulence are studied for a Joint European Torus (JET) plasma with high central q in which an internal transport barrier (ITB) forms and grows to a large radius. The linear microturbulence growth rates of the fastest growing (most unstable) toroidal modes with high toroidal mode number are calculated using the GS2 and FULL gyrokinetic codes. These linear growth rates, gamma (subscript lin) are large, but the flow-shearing rates, gamma (subscript ExB) (dominated by the toroidal rotation contribution) are also comparably large when and where the ITB exists

  3. Positivity-preserving space-time CE/SE scheme for high speed flows

    KAUST Repository

    Shen, Hua; Parsani, Matteo

    2017-01-01

    We develop a space-time conservation element and solution element (CE/SE) scheme using a simple slope limiter to preserve the positivity of the density and pressure in computations of inviscid and viscous high-speed flows. In general, the limiter works with all existing CE/SE schemes. Here, we test the limiter on a central Courant number insensitive (CNI) CE/SE scheme implemented on hybrid unstructured meshes. Numerical examples show that the proposed limiter preserves the positivity of the density and pressure without disrupting the conservation law; it also improves robustness without losing accuracy in solving high-speed flows.

  4. Measurements of low density, high velocity flow by electron beam fluorescence technique

    International Nuclear Information System (INIS)

    Soga, Takeo; Takanishi, Masaya; Yasuhara, Michiru

    1981-01-01

    A low density chamber with an electron gun system was made for the measurements of low density, high velocity (high Mach number) flow. This apparatus is a continuous running facility. The number density and the rotational temperature in the underexpanding free jet of nitrogen were measured along the axis of the jet by the electron beam fluorescence technique. The measurements were carried out from the vicinity of the exit of the jet to far downstream of the first Mach disk. Rotational nonequilibrium phenomena were observed in the hypersonic flow field as well as in the shock wave (Mach disk). (author)

  5. Flow distribution of pebble bed high temperature gas cooled reactors using large eddy simulation

    International Nuclear Information System (INIS)

    Gokhan Yesilyurt; Hassan, Y.A.

    2003-01-01

    A High Temperature Gas-cooled Reactor (HTGR) is one of the renewed reactor designs to play a role in nuclear power generation. This reactor design concepts is currently under consideration and development worldwide. Since the HTGR concept offers inherent safety, has a very flexible fuel cycle with capability to achieve high burnup levels, and provides good thermal efficiency of power plant, it can be considered for further development and improvement as a reactor concept of generation IV. The combination of coated particle fuel, inert helium gas as coolant and graphite moderated reactor makes it possible to operate at high temperature yielding a high efficiency. In this study the simulation of turbulent transport for the gas through the gaps of the spherical fuel elements (fuel pebbles) will be performed. This will help in understanding the highly three-dimensional, complex flow phenomena in pebble bed caused by flow curvature. Under these conditions, heat transfer in both laminar and turbulent flows varies noticeably around curved surfaces. Curved flows would be present in the presence of contiguous curved surfaces. In the case of a laminar flow and of an appreciable effect of thermogravitional forces, the Nusselt (Nu) number depends significantly on the curvature shape of the surface. It changes with order of 10 times. The flow passages through the gap between the fuel balls have concave and convex configurations. Here the action of the centrifugal forces manifests itself differently on convex and concave parts of the flow path (suppression or stimulation of turbulence). The flow of this type has distinctive features. In such flow there is a pressure gradient, which strongly affects the boundary layer behavior. The transition from a laminar to turbulent flow around this curved flow occurs at deferent Reynolds (Re) numbers. Consequently, noncircular curved flows as in the pebble-bed situation, in detailed local sense, is interesting to be investigated. To the

  6. Application and evaluation of LS-PIV technique for the monitoring of river surface velocities in high flow conditions

    OpenAIRE

    Jodeau , M.; Hauet , A.; Paquier , A.; Le Coz , J.; Dramais , G.

    2008-01-01

    Large Scale Particle Image Velocimetry (LS-PIV) is used to measure the surface flow velocities in a mountain stream during high flow conditions due to a reservoir release. A complete installation including video acquisition from a mobile elevated viewpoint and artificial flow seeding has been developed and implemented. The LS-PIV method was adapted in order to take into account the specific constraints of these high flow conditions. Using a usual LS-PIV data processing, significant variations...

  7. Energy transformation, transfer, and release dynamics in high speed turbulent flows

    Science.gov (United States)

    2017-03-01

    Secondly, a new high -order (4 th -order) convective flux formulation was developed that uses the tabulated information, yet produces a fully consistent...Klippenstein 2012 Comprehensive H2/O2 Kinetic Model for High - Pressure Combustion. Int. J. Chem. Kinetics 44:444-474. Cabot, W.H., A.W. Cook, P.L. Miller, D.E...AFRL-AFOSR-VA-TR-2017-0054 Energy Transformation, Transfer, and Release Dynamics in High -Speed Turbulent Flows Paul Dimotakis CALIFORNIA INSTITUTE

  8. Cross-flow shearing effects on the trajectory of highly buoyant bent-over plumes

    Science.gov (United States)

    Tohidi, Ali; Kaye, Nigel Berkeley; Gollner, Michael J.

    2017-11-01

    The dynamics of highly buoyant plumes in cross-flow is ubiquitous throughout both industrial and environmental phenomena. The rise of smoke from a chimney, wastewater discharge into river currents, and dispersion of wildfire plumes are only a few instances. There have been many previous studies investigating the behavior of jets and highly buoyant plumes in cross-flow. So far, however, very little attention has been paid to the role of shearing effects in the boundary layer on the plume trajectory, particularly on the rise height. Numerical simulations and dimensional analysis are conducted to characterize the near- and far-field behavior of a highly buoyant plume in a boundary layer cross-flow. The results show that shear in the cross-flow leads to large differences in the rise height of the plume in relation to a uniform cross-flow, especially at far-field. This material is based upon work supported by the National Science Foundation under Grant No.1200560. Any opinions, findings, and conclusions or recommendations expressed in the material are of the authors and do not necessarily reflect the views of NSF.

  9. Abnormal high surface heat flow caused by the Emeishan mantle plume

    Science.gov (United States)

    Jiang, Qiang; Qiu, Nansheng; Zhu, Chuanqing

    2016-04-01

    It is commonly believed that increase of heat flow caused by a mantle plume is small and transient. Seafloor heat flow data near the Hawaiian hotspot and the Iceland are comparable to that for oceanic lithosphere elsewhere. Numerical modeling of the thermal effect of the Parana large igneous province shows that the added heat flow at the surface caused by the magmatic underplating is less than 5mW/m2. However, the thermal effect of Emeishan mantle plume (EMP) may cause the surface hear-flow abnormally high. The Middle-Late Emeishan mantle plume is located in the western Yangtze Craton. The Sichuan basin, to the northeast of the EMP, is a superimposed basin composed of Paleozoic marine carbonate rocks and Mesozoic-Cenozoic terrestrial clastic rocks. The vitrinite reflectance (Ro) data as a paleogeothermal indicator records an apparent change of thermal regime of the Sichuan basin. The Ro profiles from boreholes and outcrops which are close to the center of the basalt province exhibit a 'dog-leg' style at the unconformity between the Middle and Upper Permian, and they show significantly higher gradients in the lower subsection (pre-Middle Permian) than the Upper subsection (Upper Permian to Mesozoic). Thermal history inversion based on these Ro data shows that the lower subsection experienced a heat flow peak much higher than that of the upper subsection. The abnormal heat flow in the Sichuan basin is consistent with the EMP in temporal and spatial distribution. The high-temperature magmas from deep mantle brought heat to the base of the lithosphere, and then large amount of heat was conducted upwards, resulting in the abnormal high surface heat flow.

  10. Experiments on the flow field physics of confluent boundary layers for high-lift systems

    Science.gov (United States)

    Nelson, Robert C.; Thomas, F. O.; Chu, H. C.

    1994-01-01

    The use of sub-scale wind tunnel test data to predict the behavior of commercial transport high lift systems at in-flight Reynolds number is limited by the so-called 'inverse Reynolds number effect'. This involves an actual deterioration in the performance of a high lift device with increasing Reynolds number. A lack of understanding of the relevant flow field physics associated with numerous complicated viscous flow interactions that characterize flow over high-lift devices prohibits computational fluid dynamics from addressing Reynolds number effects. Clearly there is a need for research that has as its objective the clarification of the fundamental flow field physics associated with viscous effects in high lift systems. In this investigation, a detailed experimental investigation is being performed to study the interaction between the slat wake and the boundary layer on the primary airfoil which is known as a confluent boundary layer. This little-studied aspect of the multi-element airfoil problem deserves special attention due to its importance in the lift augmentation process. The goal of this research is is to provide an improved understanding of the flow physics associated with high lift generation. This process report will discuss the status of the research being conducted at the Hessert Center for Aerospace Research at the University of Notre Dame. The research is sponsored by NASA Ames Research Center under NASA grant NAG2-905. The report will include a discussion of the models that have been built or that are under construction, a description of the planned experiments, a description of a flow visualization apparatus that has been developed for generating colored smoke for confluent boundary layer studies and some preliminary measurements made using our new 3-component fiber optic LDV system.

  11. Development of Localized Arc Filament RF Plasma Actuators for High-Speed and High Reynolds Number Flow Control

    Science.gov (United States)

    2010-01-01

    high-speed flows is problematic due to their low forcing frequency (for mechanical actuators) and low forcing amplitude (for piezo actuators...very low fraction of DC power is coupled to the actuators (5-10%), with the rest of the power dissipated in massive ballast resistors acting as heat... resistors . The use of high-power resistors also significantly increases the weight and size of the plasma generator and makes scaling to a large number of

  12. Fundamental research of two-phase flows with high liquid/gas density ratios

    International Nuclear Information System (INIS)

    Mishima, Kaichiro; Hibiki, Takashi; Saito, Yasushi; Tobita, Yoshiharu; Konishi, Kensuke; Suzuki, Tohru

    2000-07-01

    In order to analyze the boiling of a fuel-steel mixture pool formed during the core disruptive accident in a fast breeder reactor, it is important to understand the flow characteristics of gas-liquid two-phase pools containing molten reactor materials. Since the liquid/gas density ratio is high, the characteristics of such two-phase flows may differ from those of ordinary flows such as water/air flow. In this study, as a fundamental research of two-phase flows with a high liquid/gas density ratio, the experiments were performed to visualize and measure molten metal (lead-bismuth)/nitrogen gas two-phase flows using a neutron radiography technique. From these experiments, fundamental data such as bubble shapes, void fractions and liquid velocity fields were obtained. In addition, the momentum exchange model of SIMMER-III, which has been developed by JNC, was assessed and improved using the experimental data. In the visualization by neutron radiography, it was found that deformed ellipsoidal bubbles could be seen with smaller gas flux or lower void fractions, and spherical cap bubbles could be seen with larger gas flux or higher void fractions. In addition, a correlation applicable to SIMMER-III was proposed through a comparison between the experimental data and traditional empirical correlations. Furthermore, a visualization experiment using gold-cadmium tracer particles showed that the image processing technique used in the quantification of void fractions is applicable to the measurement of the liquid velocity fields. On the other hand, in the analysis by SIMMER-III, it was confirmed that the original momentum exchange model was appropriate for ellipsoidal bobby flows and that the accuracy of SIMMER-III for cap bubbly flows was much improved with the proposed correlation. Moreover, a new procedure, in which the appropriate drag coefficient could be automatically selected according to bubble shape, was developed. The SIMMER-III code improved through this study can

  13. High Enthalpy Effects on Two Boundary Layer Disturbances in Supersonic and Hypersonic Flow

    Science.gov (United States)

    Wagnild, Ross Martin

    The fluid flow phenomenon of boundary layer transition is a complicated and difficult process to model and predict. The importance of the state of the boundary layer with regard to vehicle design cannot be understated. The high enthalpy environment in which high speed vehicles operate in further complicates the transition process by adding several more degrees of freedom. In this environment, the internal properties of the gas can stabilize or destabilize the boundary layer as well as modify the disturbances that cause transition. In the current work, the interaction of two types of disturbances with the high enthalpy flow environment are analyzed. The first is known as a second mode disturbance, which is acoustic in nature. The second type is known as a transient growth disturbance and is associated with flows behind roughness elements. Theoretical analyses, linear stability analyses, and computation fluid dynamics (CFD) are used to determine the ways in which these disturbances interact with the high enthalpy environment as well as the consequences of these interactions. First, acoustic wave are directly studied in order to gain a basic understanding of the response of second mode disturbances in the high enthalpy boundary layer. Next, this understanding is used in interpreting the results of several computations attempting to simulate the flow through a high enthalpy flow facility as well as experiments attempting to take advantage of the acoustic interaction with the high enthalpy environment. Because of the difficulty in modeling these experiments, direct simulations of acoustic waves in a hypersonic flow of a gas with molecular vibration are performed. Lastly, compressible transient growth disturbances are simulated using a linear optimal disturbance solver as well as a CFD solver. The effect of an internal molecular process on this type of disturbance is tested through the use of a vibrational mode. It is the goal of the current work to reinforce the

  14. Development of a micro flow-through cell for high field NMR spectroscopy.

    Energy Technology Data Exchange (ETDEWEB)

    Alam, Todd Michael; McIntyre, Sarah K.

    2011-05-01

    A highly transportable micro flow-through detection cell for nuclear magnetic resonance (NMR) spectroscopy has been designed, fabricated and tested. This flow-through cell allows for the direct coupling between liquid chromatography (LC) and gel permeation chromatography (GPC) resulting in the possibility of hyphenated LC-NMR and GPC-NMR. The advantage of the present flow cell design is that it is independent and unconnected to the detection probe electronics, is compatible with existing commercial high resolution NMR probes, and as such can be easily implemented at any NMR facility. Two different volumes were fabricated corresponding to between {approx}3.8 and 10 {micro}L detection volume. Examples of the performance of the cell on different NMR instruments, and using different NMR detection probes were demonstrated.

  15. Relaxed impact craters on Ganymede: Regional variation and high heat flows

    Science.gov (United States)

    Singer, Kelsi N.; Bland, Michael T.; Schenk, Paul M.; McKinnon, William B.

    2018-01-01

    Viscously relaxed craters provide a window into the thermal history of Ganymede, a satellite with copious geologic signs of past high heat flows. Here we present measurements of relaxed craters in four regions for which suitable imaging exists: near Anshar Sulcus, Tiamat Sulcus, northern Marius Regio, and Ganymede's south pole. We describe a technique to measure apparent depth, or depth of the crater with respect to the surrounding terrain elevation. Measured relaxation states are compared with results from finite element modeling to constrain heat flow scenarios [see companion paper: Bland et al. (2017)]. The presence of numerous, substantially relaxed craters indicates high heat flows—in excess of 30–40 mW m−2 over 2 Gyr, with many small (heat flows. Crater relaxation states are bimodal for some equatorial regions but not in the region studied near the south pole, which suggests regional variations in Ganymede's thermal history.

  16. Hydrogen/Oxygen Reactions at High Pressures and Intermediate Temperatures: Flow Reactor Experiments and Kinetic Modeling

    DEFF Research Database (Denmark)

    Hashemi, Hamid; Christensen, Jakob Munkholt; Glarborg, Peter

    A series of experimental and numerical investigations into hydrogen oxidation at high pressures and intermediate temperatures has been conducted. The experiments were carried out in a high pressure laminar flow reactor at 50 bar pressure and a temperature range of 600–900 K. The equivalence ratio......, the mechanism is used to simulate published data on ignition delay time and laminar burning velocity of hydrogen. The flow reactor results show that at reducing, stoichiometric, and oxidizing conditions, conversion starts at temperatures of 750–775 K, 800–825 K, and 800–825 K, respectively. In oxygen atmosphere......, ignition occurs at the temperature of 775–800 K. In general, the present model provides a good agreement with the measurements in the flow reactor and with recent data on laminar burning velocity and ignition delay time....

  17. Flow-Based Systems for Rapid and High-Precision Enzyme Kinetics Studies

    Directory of Open Access Journals (Sweden)

    Supaporn Kradtap Hartwell

    2012-01-01

    Full Text Available Enzyme kinetics studies normally focus on the initial rate of enzymatic reaction. However, the manual operation of steps of the conventional enzyme kinetics method has some drawbacks. Errors can result from the imprecise time control and time necessary for manual changing the reaction cuvettes into and out of the detector. By using the automatic flow-based analytical systems, enzyme kinetics studies can be carried out at real-time initial rate avoiding the potential errors inherent in manual operation. Flow-based systems have been developed to provide rapid, low-volume, and high-precision analyses that effectively replace the many tedious and high volume requirements of conventional wet chemistry analyses. This article presents various arrangements of flow-based techniques and their potential use in future enzyme kinetics applications.

  18. Rapid continuous flow synthesis of high-quality silver nanocubes and nanospheres

    KAUST Repository

    Mehenni, Hakim

    2013-01-01

    We report a biphasic-liquid segmented continuous flow method for the synthesis of high-quality plasmonic single crystal silver nanocubes and nanospheres. The nanocubes were synthesized with controllable edge lengths from 20 to 48 nm. Single crystal nanospheres with a mean size of 29 nm were obtained by in-line continuous-flow etching of as-produced 39 nm nanocubes with an aqueous solution of FeNO3. In comparison to batch synthesis, the demonstrated processes represent highly scalable reactions, in terms of both production rate and endurance. The reactions were conducted in a commercially available flow-reactor system that is easily adaptable to industrial-scale production, facilitating widespread utilization of the procedure and the resulting nanoparticles. This journal is © The Royal Society of Chemistry 2013.

  19. EFFECTS OF SLOTTED BLADING ON SECONDARY FLOW IN HIGHLY LOADED COMPRESSOR CASCADE

    Directory of Open Access Journals (Sweden)

    RAMZI MDOUKI

    2013-10-01

    Full Text Available With the aim to increase allowable blade loadings and enlarge stable operating range in highly loaded compressor, this work is carried out in order to explore the potential of passive control via slotted bladings in linear cascade configurations under both design and stall conditions. Through an extensive 2D-numerical study, the effects of location, width and slope of slots were analysed and the best configuration was identified. Based on the optimal slot, the 3D aerodynamic performances of cascade were studied and the influence of slotted blading to control endwall flow was investigated. Both 2D and 3D calculations are performed on steady RANS solver with standard k-epsilon turbulence model and low Mach number regime. The total loss coefficient, turning angle and flow visualizations on the blade and end-wall surfaces are adopted to describe the different configurations. The obtained results show, for 2D situation, that a maximum of 28.3% reduction in loss coefficient had been reached and the flow turning was increased with approximately 5°. Concerning 3D flow fields the slots marked their benefit at large incoming flow angles which delays the separation on both end wall and blade suction surface at mid span. However, at design conditions, the slotted blades are not able to control secondary flows near the wall and so, lose their potential.

  20. Finite volume simulation of 2-D steady square lid driven cavity flow at high reynolds numbers

    Directory of Open Access Journals (Sweden)

    K. Yapici

    2013-12-01

    Full Text Available In this work, computer simulation results of steady incompressible flow in a 2-D square lid-driven cavity up to Reynolds number (Re 65000 are presented and compared with those of earlier studies. The governing flow equations are solved by using the finite volume approach. Quadratic upstream interpolation for convective kinematics (QUICK is used for the approximation of the convective terms in the flow equations. In the implementation of QUICK, the deferred correction technique is adopted. A non-uniform staggered grid arrangement of 768x768 is employed to discretize the flow geometry. Algebraic forms of the coupled flow equations are then solved through the iterative SIMPLE (Semi-Implicit Method for Pressure-Linked Equation algorithm. The outlined computational methodology allows one to meet the main objective of this work, which is to address the computational convergence and wiggled flow problems encountered at high Reynolds and Peclet (Pe numbers. Furthermore, after Re > 25000 additional vortexes appear at the bottom left and right corners that have not been observed in earlier studies.

  1. Flow performance of highly loaded axial fan with bowed rotor blades

    International Nuclear Information System (INIS)

    Chen, L; Liu, X J; Yang, A L; Dai, R

    2013-01-01

    In this paper, a partial bowed rotor blade was proposed for a newly designed high loaded axial fan. The blade was positively bowed 30 degrees from hub to 30 percent spanwise position. Flows of radial blade and bowed blade fans were numerically compared for various operation conditions. Results show that the fan's performance is improved. At the designed condition with flow coefficient of 0.52, the efficiency of the bowed blade fan is increased 1.44% and the static pressure rise is increased 11%. Comparing the flow structures, it can be found that the separated flow in the bowed fan is reduced and confined within 20 percent span, which is less than the 35 percent in the radial fan. It means that the bowed blade generates negative blade force and counteracts partial centrifugal force. It is alleviates the radial movements of boundary layers in fan's hub region. Flow losses due to 3D mixing are reduced in the rotor. Inlet flow to downstream stator is also improved

  2. Flow performance of highly loaded axial fan with bowed rotor blades

    Science.gov (United States)

    Chen, L.; Liu, X. J.; Yang, A. L.; Dai, R.

    2013-12-01

    In this paper, a partial bowed rotor blade was proposed for a newly designed high loaded axial fan. The blade was positively bowed 30 degrees from hub to 30 percent spanwise position. Flows of radial blade and bowed blade fans were numerically compared for various operation conditions. Results show that the fan's performance is improved. At the designed condition with flow coefficient of 0.52, the efficiency of the bowed blade fan is increased 1.44% and the static pressure rise is increased 11%. Comparing the flow structures, it can be found that the separated flow in the bowed fan is reduced and confined within 20 percent span, which is less than the 35 percent in the radial fan. It means that the bowed blade generates negative blade force and counteracts partial centrifugal force. It is alleviates the radial movements of boundary layers in fan's hub region. Flow losses due to 3D mixing are reduced in the rotor. Inlet flow to downstream stator is also improved.

  3. Highly Stable Anion Exchange Membranes for High-Voltage Redox-Flow Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Yushan [Univ. of Delaware, Newark, DE (United States)

    2018-02-26

    membrane in the sulfuric acid system was also achieved due to the high acid doping ability of the polymer structure. The cationic 9MeOTTP+-F6PBI PTFE reinforced membrane shows a cerium (IV) permeability that is 27-fold lower than that of Nafion 212. Excellent voltage and energy efficiencies with a 9MeOTTP+-F6PBI PTFE reinforced membrane were demonstrated in an all-vanadium redox flow battery (VRFB).

  4. Evolution of star-bearing molecular clouds: the high-velocity HCO+ flow in NGC 2071

    International Nuclear Information System (INIS)

    Wootten, A.; Loren, R.B.; Sandqvist, A.; Friberg, P.; Hjalmarson, Aa.

    1984-01-01

    The J = 1-0 and J = 302 lines of HCO + and H 13 CO + have been observed in the molecular cloud NGC 2071, where they map the dense portions of a bidirectional molecular flow. The high resolution (42'') of our observations has enabled us to determine the distribution of mass, momentum , and energy in the flow as a function of projected distance from the cluster. Both momentum and energy diminish with distance from the central cluster of infrared sources. The highest velocities at a given intensity in this dense flow occur in a limited region coincident with an infrared cluster and the densest part of the molecular cloud. Higher resolution (33'') CO and 13 CO observations reveal that the extreme velocities in the flow occur in regions displaced on opposite sides of the cluster, suggesting that the flow only becomes visible in molecular line emission at distances approx.0.1 pc from its supposed source. Lower velocity material containing most of the mass of the flow is found over larger regions, as expected if the flow has decelerated as it has evolved. Assuming conservation of momentum, the historical rate of momentum injection is found to have been roughly constant over a period of 10 4 years, suggesting a constancy of the average luminosity of the central cluster over that time. The J = 3--2 HCO + profile does not show the absorption which is a prominent feature of the J = 1--0 profile, and the J = 3--2 line appears to be a useful probe of conditions specific to the dense cores of clouds. The high velocity HCO + emission correlates very well with spatial and velocity events of molecular hydrogen emission. The abundance of HCO + [X(HCO + )approx.10 -8 ], and by inference the electron density, is similar in material at all velocities

  5. Spatial connectivity in a highly heterogeneous aquifer: From cores to preferential flow paths

    Science.gov (United States)

    Bianchi, M.; Zheng, C.; Wilson, C.; Tick, G.R.; Liu, Gaisheng; Gorelick, S.M.

    2011-01-01

    This study investigates connectivity in a small portion of the extremely heterogeneous aquifer at the Macrodispersion Experiment (MADE) site in Columbus, Mississippi. A total of 19 fully penetrating soil cores were collected from a rectangular grid of 4 m by 4 m. Detailed grain size analysis was performed on 5 cm segments of each core, yielding 1740 hydraulic conductivity (K) estimates. Three different geostatistical simulation methods were used to generate 3-D conditional realizations of the K field for the sampled block. Particle tracking calculations showed that the fastest particles, as represented by the first 5% to arrive, converge along preferential flow paths and exit the model domain within preferred areas. These 5% fastest flow paths accounted for about 40% of the flow. The distribution of preferential flow paths and particle exit locations is clearly influenced by the occurrence of clusters formed by interconnected cells with K equal to or greater than the 0.9 decile of the data distribution (10% of the volume). The fraction of particle paths within the high-K clusters ranges from 43% to 69%. In variogram-based K fields, some of the fastest paths are through media with lower K values, suggesting that transport connectivity may not require fully connected zones of relatively homogenous K. The high degree of flow and transport connectivity was confirmed by the values of two groups of connectivity indicators. In particular, the ratio between effective and geometric mean K (on average, about 2) and the ratio between the average arrival time and the arrival time of the fastest particles (on average, about 9) are consistent with flow and advective transport behavior characterized by channeling along preferential flow paths. ?? 2011 by the American Geophysical Union.

  6. The time scale for the transition to turbulence in a high Reynolds number, accelerated flow

    International Nuclear Information System (INIS)

    Robey, H.F.; Zhou Ye; Buckingham, A.C.; Keiter, P.; Remington, B.A.; Drake, R.P.

    2003-01-01

    An experiment is described in which an interface between materials of different density is subjected to an acceleration history consisting of a strong shock followed by a period of deceleration. The resulting flow at this interface, initiated by the deposition of strong laser radiation into the initially well characterized solid materials, is unstable to both the Richtmyer-Meshkov (RM) and Rayleigh-Taylor (RT) instabilities. These experiments are of importance in their ability to access a difficult experimental regime characterized by very high energy density (high temperature and pressure) as well as large Reynolds number and Mach number. Such conditions are of interest, for example, in the study of the RM/RT induced mixing that occurs during the explosion of a core-collapse supernova. Under these experimental conditions, the flow is in the plasma state and given enough time will transition to turbulence. By analysis of the experimental data and a corresponding one-dimensional numerical simulation of the experiment, it is shown that the Reynolds number is sufficiently large (Re>10 5 ) to support a turbulent flow. An estimate of three key turbulence length scales (the Taylor and Kolmogorov microscales and a viscous diffusion scale), however, shows that the temporal duration of the present flow is insufficient to allow for the development of a turbulent inertial subrange. A methodology is described for estimating the time required under these conditions for the development of a fully turbulent flow

  7. Comparison of Themodynamic and Transport Property Models for Computing Equilibrium High Enthalpy Flows

    Science.gov (United States)

    Ramasahayam, Veda Krishna Vyas; Diwakar, Anant; Bodi, Kowsik

    2017-11-01

    To study the flow of high temperature air in vibrational and chemical equilibrium, accurate models for thermodynamic state and transport phenomena are required. In the present work, the performance of a state equation model and two mixing rules for determining equilibrium air thermodynamic and transport properties are compared with that of curve fits. The thermodynamic state model considers 11 species which computes flow chemistry by an iterative process and the mixing rules considered for viscosity are Wilke and Armaly-Sutton. The curve fits of Srinivasan, which are based on Grabau type transition functions, are chosen for comparison. A two-dimensional Navier-Stokes solver is developed to simulate high enthalpy flows with numerical fluxes computed by AUSM+-up. The accuracy of state equation model and curve fits for thermodynamic properties is determined using hypersonic inviscid flow over a circular cylinder. The performance of mixing rules and curve fits for viscosity are compared using hypersonic laminar boundary layer prediction on a flat plate. It is observed that steady state solutions from state equation model and curve fits match with each other. Though curve fits are significantly faster the state equation model is more general and can be adapted to any flow composition.

  8. Wall modeled large eddy simulations of complex high Reynolds number flows with synthetic inlet turbulence

    International Nuclear Information System (INIS)

    Patil, Sunil; Tafti, Danesh

    2012-01-01

    Highlights: ► Large eddy simulation. ► Wall layer modeling. ► Synthetic inlet turbulence. ► Swirl flows. - Abstract: Large eddy simulations of complex high Reynolds number flows are carried out with the near wall region being modeled with a zonal two layer model. A novel formulation for solving the turbulent boundary layer equation for the effective tangential velocity in a generalized co-ordinate system is presented and applied in the near wall zonal treatment. This formulation reduces the computational time in the inner layer significantly compared to the conventional two layer formulations present in the literature and is most suitable for complex geometries involving body fitted structured and unstructured meshes. The cost effectiveness and accuracy of the proposed wall model, used with the synthetic eddy method (SEM) to generate inlet turbulence, is investigated in turbulent channel flow, flow over a backward facing step, and confined swirling flows at moderately high Reynolds numbers. Predictions are compared with available DNS, experimental LDV data, as well as wall resolved LES. In all cases, there is at least an order of magnitude reduction in computational cost with no significant loss in prediction accuracy.

  9. Development of a Dual-PIV system for high-speed flow applications

    Science.gov (United States)

    Schreyer, Anne-Marie; Lasserre, Jean J.; Dupont, Pierre

    2015-10-01

    A new Dual-particle image velocimetry (Dual-PIV) system for application in supersonic flows was developed. The system was designed for shock wave/turbulent boundary layer interactions with separation. This type of flow places demanding requirements on the system, from the large range of characteristic frequencies O(100 Hz-100 kHz) to spatial and temporal resolutions necessary for the measurement of turbulent quantities (Dolling in AIAA J 39(8):1517-1531, 2001; Dupont et al. in J Fluid Mech 559:255-277, 2006; Smits and Dussauge in Turbulent shear layers in supersonic flow, 2nd edn. Springer, New York, 2006). While classic PIV systems using high-resolution CCD sensors allow high spatial resolution, these systems cannot provide the required temporal resolution. Existing high-speed PIV systems provide temporal and CMOS sensor resolutions, and even laser pulse energies, that are not adapted to our needs. The only obvious solution allowing sufficiently high spatial resolution, access to high frequencies, and a high laser pulse energy is a multi-frame system: a Dual-PIV system, consisting of two synchronized PIV systems observing the same field of view, will give access to temporal characteristics of the flow. The key technology of our system is frequency-based image separation: two lasers of different wavelengths illuminate the field of view. The cross-pollution with laser light from the respective other branches was quantified during system validation. The overall system noise was quantified, and the prevailing error of only 2 % reflects the good spatial and temporal alignment. The quality of the measurement system is demonstrated with some results on a subsonic jet flow including the spatio-temporal inter-correlation functions between the systems. First measurements in a turbulent flat-plate boundary layer at Mach 2 show the same satisfactory data quality and are also presented and discussed.

  10. Estimating annual high-flow statistics and monthly and seasonal low-flow statistics for ungaged sites on streams in Alaska and conterminous basins in Canada

    Science.gov (United States)

    Wiley, Jeffrey B.; Curran, Janet H.

    2003-01-01

    Methods for estimating daily mean flow-duration statistics for seven regions in Alaska and low-flow frequencies for one region, southeastern Alaska, were developed from daily mean discharges for streamflow-gaging stations in Alaska and conterminous basins in Canada. The 15-, 10-, 9-, 8-, 7-, 6-, 5-, 4-, 3-, 2-, and 1-percent duration flows were computed for the October-through-September water year for 222 stations in Alaska and conterminous basins in Canada. The 98-, 95-, 90-, 85-, 80-, 70-, 60-, and 50-percent duration flows were computed for the individual months of July, August, and September for 226 stations in Alaska and conterminous basins in Canada. The 98-, 95-, 90-, 85-, 80-, 70-, 60-, and 50-percent duration flows were computed for the season July-through-September for 65 stations in southeastern Alaska. The 7-day, 10-year and 7-day, 2-year low-flow frequencies for the season July-through-September were computed for 65 stations for most of southeastern Alaska. Low-flow analyses were limited to particular months or seasons in order to omit winter low flows, when ice effects reduce the quality of the records and validity of statistical assumptions. Regression equations for estimating the selected high-flow and low-flow statistics for the selected months and seasons for ungaged sites were developed from an ordinary-least-squares regression model using basin characteristics as independent variables. Drainage area and precipitation were significant explanatory variables for high flows, and drainage area, precipitation, mean basin elevation, and area of glaciers were significant explanatory variables for low flows. The estimating equations can be used at ungaged sites in Alaska and conterminous basins in Canada where streamflow regulation, streamflow diversion, urbanization, and natural damming and releasing of water do not affect the streamflow data for the given month or season. Standard errors of estimate ranged from 15 to 56 percent for high-duration flow

  11. Flow Field Measurements of Methane-Oxygen Turbulent Nonpremixed Flames at High Pressure

    Science.gov (United States)

    Iino, Kimio; Kikkawa, Hoshitaka; Akamatsu, Fumiteru; Katsuki, Masashi

    We carried out the flow field measurement of methane-oxygen turbulent nonpremixed flame in non-combusting and combusting situations at high pressures using LDV. The main objectives are to study the influences of combustion on the turbulence structure at high pressures and to provide detailed data on which numerical predictions on such flows can rely. Direct observation and CH* chemiluminescence detection are conducted at high pressures up to 1.0MPa. It was found that the flame length at elevated pressures became constant. From flow field measurements, the following features of flames at elevated pressure were found: (1) the existence of flame suppressed turbulence in the upstream region of the jet and enhanced it in the downstream region with increasing pressure; (2) Turbulence in the flame was more anisotropic than in the corresponding cold jet in all regions of the flow with increasing pressure; (3) Reynolds shear stresses did not change at elevated pressure; (4) Combustion processes had a marked influence on the turbulence macroscale under high pressures, however, the turbulence macroscale was not changed even with the increase in pressure.

  12. Modeling and experiments on differential pumping in linear plasma generators operating at high gas flows

    NARCIS (Netherlands)

    Eck, van H.J.N.; Koppers, W.R.; Rooij, van G.J.; Goedheer, W.J.; Engeln, R.A.H.; Schram, D.C.; Lopes Cardozo, N.J.; Kleyn, A.W.

    2009-01-01

    The direct simulation Monte Carlo (DSMC) method was used to investigate the efficiency of differential pumping in linear plasma generators operating at high gas flows. Skimmers are used to separate the neutrals from the plasma beam, which is guided from the source to the target by a strong axial

  13. High resolution FISH on super-stretched flow-sorted plant chromosomes.

    NARCIS (Netherlands)

    Valárik, M.; Bartos, J.; Kovarova, P.; Kubalakova, M.; Jong, de J.H.S.G.M.; Dolezel, J.

    2004-01-01

    A novel high-resolution fluorescence in situ hybridisation (FISH) strategy, using super-stretched flow-sorted plant chromosomes as targets, is described. The technique that allows longitudinal extension of chromosomes of more than 100 times their original metaphase size is especially attractive for

  14. Nasal high flow therapy: a novel treatment rather than a more expensive oxygen device

    Directory of Open Access Journals (Sweden)

    Eleni Ischaki

    2017-09-01

    Full Text Available Nasal high flow is a promising novel oxygen delivery device, whose mechanisms of action offer some beneficial effects over conventional oxygen systems. The administration of a high flow of heated and humidified gas mixture promotes higher and more stable inspiratory oxygen fraction values, decreases anatomical dead space and generates a positive airway pressure that can reduce the work of breathing and enhance patient comfort and tolerance. Nasal high flow has been used as a prophylactic tool or as a treatment device mostly in patients with acute hypoxaemic respiratory failure, with the majority of studies showing positive results. Recently, its clinical indications have been expanded to post-extubated patients in intensive care or following surgery, for pre- and peri-oxygenation during intubation, during bronchoscopy, in immunocompromised patients and in patients with “do not intubate” status. In the present review, we differentiate studies that suggest an advantage (benefit from other studies that do not suggest an advantage (no benefit compared to conventional oxygen devices or noninvasive ventilation, and propose an algorithm in cases of nasal high flow application in patients with acute hypoxaemic respiratory failure of almost any cause.

  15. Characterization of Diamond Nanoparticles by High-Speed Micro-Thermal Field-Flow Fractionation

    Czech Academy of Sciences Publication Activity Database

    Janča, Josef

    2015-01-01

    Roč. 20, č. 8 (2015), s. 671-680 ISSN 1023-666X R&D Projects: GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 Keywords : diamond nanoparticles * high-speed microfluidic separation * micro-thermal field-flow fractionation, * article size distribution Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.515, year: 2015

  16. Electrical activity of the diaphragm during nCPAP and high flow nasal cannula

    NARCIS (Netherlands)

    de Waal, C. G.; Hutten, G. J.; Kraaijenga, J. V.; de Jongh, F. H.; van Kaam, A. H.

    2017-01-01

    Objective To determine if the electrical activity of the diaphragm, as measure of neural respiratory drive and breathing effort, changes over time in preterm infants transitioned from nasal continuous positive airway pressure (nCPAP) to high flow nasal cannula (HFNC). Design Prospective

  17. Long term high flow heated oxygen treatment in COPD – lung function and physical ability

    DEFF Research Database (Denmark)

    Weinreich, Ulla; Storgaard, Line; Hockey, Hans

    2017-01-01

    Introduction: Long term oxygen therapy (LTOT) improves survival in patients with COPD with resting hypoxemia. Despite this, a progressive loss of lung function and physical ability is expected in COPD. The AIRVO device delivers nasal high flow (NHF) warmed and humidified oxygen-enriched air, 20...

  18. Comparison of high order algorithms in Aerosol and Aghora for compressible flows

    Directory of Open Access Journals (Sweden)

    Mbengoue D. A.

    2013-12-01

    Full Text Available This article summarizes the work done within the Colargol project during CEMRACS 2012. The aim of this project is to compare the implementations of high order finite element methods for compressible flows that have been developed at ONERA and at INRIA for about one year, within the Aghora and Aerosol libraries.

  19. Optimizing transformations for automated, high throughput analysis of flow cytometry data.

    Science.gov (United States)

    Finak, Greg; Perez, Juan-Manuel; Weng, Andrew; Gottardo, Raphael

    2010-11-04

    In a high throughput setting, effective flow cytometry data analysis depends heavily on proper data preprocessing. While usual preprocessing steps of quality assessment, outlier removal, normalization, and gating have received considerable scrutiny from the community, the influence of data transformation on the output of high throughput analysis has been largely overlooked. Flow cytometry measurements can vary over several orders of magnitude, cell populations can have variances that depend on their mean fluorescence intensities, and may exhibit heavily-skewed distributions. Consequently, the choice of data transformation can influence the output of automated gating. An appropriate data transformation aids in data visualization and gating of cell populations across the range of data. Experience shows that the choice of transformation is data specific. Our goal here is to compare the performance of different transformations applied to flow cytometry data in the context of automated gating in a high throughput, fully automated setting. We examine the most common transformations used in flow cytometry, including the generalized hyperbolic arcsine, biexponential, linlog, and generalized Box-Cox, all within the BioConductor flowCore framework that is widely used in high throughput, automated flow cytometry data analysis. All of these transformations have adjustable parameters whose effects upon the data are non-intuitive for most users. By making some modelling assumptions about the transformed data, we develop maximum likelihood criteria to optimize parameter choice for these different transformations. We compare the performance of parameter-optimized and default-parameter (in flowCore) data transformations on real and simulated data by measuring the variation in the locations of cell populations across samples, discovered via automated gating in both the scatter and fluorescence channels. We find that parameter-optimized transformations improve visualization, reduce

  20. Optimizing transformations for automated, high throughput analysis of flow cytometry data

    Directory of Open Access Journals (Sweden)

    Weng Andrew

    2010-11-01

    Full Text Available Abstract Background In a high throughput setting, effective flow cytometry data analysis depends heavily on proper data preprocessing. While usual preprocessing steps of quality assessment, outlier removal, normalization, and gating have received considerable scrutiny from the community, the influence of data transformation on the output of high throughput analysis has been largely overlooked. Flow cytometry measurements can vary over several orders of magnitude, cell populations can have variances that depend on their mean fluorescence intensities, and may exhibit heavily-skewed distributions. Consequently, the choice of data transformation can influence the output of automated gating. An appropriate data transformation aids in data visualization and gating of cell populations across the range of data. Experience shows that the choice of transformation is data specific. Our goal here is to compare the performance of different transformations applied to flow cytometry data in the context of automated gating in a high throughput, fully automated setting. We examine the most common transformations used in flow cytometry, including the generalized hyperbolic arcsine, biexponential, linlog, and generalized Box-Cox, all within the BioConductor flowCore framework that is widely used in high throughput, automated flow cytometry data analysis. All of these transformations have adjustable parameters whose effects upon the data are non-intuitive for most users. By making some modelling assumptions about the transformed data, we develop maximum likelihood criteria to optimize parameter choice for these different transformations. Results We compare the performance of parameter-optimized and default-parameter (in flowCore data transformations on real and simulated data by measuring the variation in the locations of cell populations across samples, discovered via automated gating in both the scatter and fluorescence channels. We find that parameter

  1. Integrated flow reactor that combines high-shear mixing and microwave irradiation for biodiesel production

    International Nuclear Information System (INIS)

    Choedkiatsakul, I.; Ngaosuwan, K.; Assabumrungrat, S.; Tabasso, S.; Cravotto, G.

    2015-01-01

    A new simple flow system which is made up of a multi-rotor high-shear mixer connected to a multimode microwave reactor has been assembled. This simple loop reactor has been successfully used in the NaOH-catalyzed transesterification of refined palm oil in methanol. Thanks to optimal mass/heat transfer, full conversion was achieved within 5 min (biodiesel yield of 99.80%). High-quality biodiesel was obtained that is in accordance with international specifications and analytical ASTM standards. The procedure's high efficiency and low energy consumption should pave the way for process scale up. - Highlights: • The combination of HSM-MW flow system for biodiesel production has been proposed. • Highly efficient mass and heat transfer in transesterification reaction. • The hybrid reactor enables a complete conversion in 5 min reaction time. • The new system halved the energy consumption of conventional processes

  2. Dense granular Flows: a conceptual design of high-power neutron source

    Directory of Open Access Journals (Sweden)

    Yang Lei

    2017-01-01

    Full Text Available A high-power neutron source system is very useful for multifunctional applications, such as material facilities for advanced nuclear power, space radiation studies, radiography and tomography. Here the idea of inclined dense granular flow is utilized and developed in a new conceptual design of a compact high-power target to produce a high-energy and high-flux neutron irradiation (the flux is up to 1015 n/cm2/s or even 1016. Comparing to the traditional solid and liquid heavy metal targets, this design has advantages in material choice, fluid stability, heat removal, etc. In this paper the natures of the granular flows in an inclined chute are investigated and preliminary experimental and numerical results are reported. Then the feasibility of this design is discussed.

  3. Thermoconvective flow velocity in a high-speed magnetofluid seal after it has stopped

    OpenAIRE

    Krakov, M. S.; Nikiforov, I. V.

    2012-01-01

    Convective flow is investigated in the high-speed (linear velocity of the shaft seal is more than 1 m/s) magnetofluid shaft seal after it has been stopped. Magnetic fluid is preliminarily heated due to viscous friction in the moving seal. After the shaft has been stopped, nonuniform heated fluid remains under the action of a high-gradient magnetic field. Numerical analysis has revealed that in this situation, intense thermomagnetic convection is initiated. The velocity of magnetic fluid depen...

  4. High speed photography for investigating kiloampere discharges in supersonic air flows

    International Nuclear Information System (INIS)

    Jones, G.R.; Strachan, D.

    1975-01-01

    Examples of the use of conventional high speed photographic techniques are given for obtaining information about the behaviour of high current arc discharges in different gas flow fields. The photographic records yield information about the extent of both the luminous arc core and the surrounding heated volume of gas. A knowledge of these parameters leads to a better understanding of arc discharges which occur in gas blast circuit breakers. (author)

  5. Longitudinal Plasmoid in High-Speed Vortex Gas Flow Created by Capacity HF Discharge

    Science.gov (United States)

    2010-10-28

    interferometer with high space resolution, PIV method, FTIR spectrometer, optical spectrometer, pressure sensors with high time resolution, IR pyrometer and...of strong LP-vortex interaction. Intensive acoustic waves are created by CHFD in swirl flow in this regime. 38. Study of control of a longitudinal...quartz tube, 4- HF ball electrode, 5- Tesla’s transformer, 6- microwave interferometer, 7- video camera, 8-optical pyrometer , 9-pressure sensor, 10

  6. Triton-3He relative and differential flows and the high density behavior of nuclear symmetry

    International Nuclear Information System (INIS)

    Yong, Gaochan; Li, Baoan; Chen, Liewen

    2010-01-01

    Using a transport model coupled with a phase-space coalescence after-burner we study the triton- 3 He relative and differential transverse flows in semi-central 132 Sn + 124 Sn reactions at a beam energy of 400 MeV/nucleon. We find that the triton- 3 He pairs carry interesting information about the density dependence of the nuclear symmetry energy. The t- 3 He relative flow can be used as a particularly powerful probe of the high-density behavior of the nuclear symmetry energy. (author)

  7. Flow conditioning for improved optical propagation of beams through regions bounded by surfaces of high solidity

    International Nuclear Information System (INIS)

    Robey, H.F.; Albrecht, G.F.; Freitas, B.L.

    1991-01-01

    A flow conditioning system has been designed to maximize the thermal homogeneity in an enclosed region through which a laser beam must propagate. In the present application, such an enclosed region exists between the Nd:glass disks of a high average power solid-state laser amplifier. Experiments have been conducted on a test facility to quantify the magnitude of the beam losses due to thermal scattering. It is shown that the intensity of the incoherent light which is thermally scattered from this region can be reduced to less than 0.1% of the incident-beam intensity under apropriate flow and cooling conditions

  8. TF.Learn: TensorFlow's High-level Module for Distributed Machine Learning

    OpenAIRE

    Tang, Yuan

    2016-01-01

    TF.Learn is a high-level Python module for distributed machine learning inside TensorFlow. It provides an easy-to-use Scikit-learn style interface to simplify the process of creating, configuring, training, evaluating, and experimenting a machine learning model. TF.Learn integrates a wide range of state-of-art machine learning algorithms built on top of TensorFlow's low level APIs for small to large-scale supervised and unsupervised problems. This module focuses on bringing machine learning t...

  9. Experimental studies on particle deposition by thermophoresis and inertial impaction from particulate high temperature gas flow

    International Nuclear Information System (INIS)

    Kim, S.S.; Kim, Y.J.

    1987-01-01

    In view of fouling and erosion of gas turbine blade, heat exchanger and pipelines, increasing attention has been paid to particle deposition (transport) in high temperature flow systems. This is also necessary to develop a cleaning or filtration devices. Using 'real time' laser-light reflectivity and scanning electron microscope technique, we quantitatively treat particle size effect and the interaction between Brownian diffusion, thermoporesis (particle drift down a temperature gradient), and inertial impaction of particles (0.2 to 30 μm in diameter) in laminar hot combustion gas-particles flow (ca. 1565 K)

  10. Active Control of Flow Separation on a High-Lift System with Slotted Flap at High Reynolds Number

    Science.gov (United States)

    Khodadoust, Abdollah; Washburn, Anthony

    2007-01-01

    The NASA Energy Efficient Transport (EET) airfoil was tested at NASA Langley's Low- Turbulence Pressure Tunnel (LTPT) to assess the effectiveness of distributed Active Flow Control (AFC) concepts on a high-lift system at flight scale Reynolds numbers for a medium-sized transport. The test results indicate presence of strong Reynolds number effects on the high-lift system with the AFC operational, implying the importance of flight-scale testing for implementation of such systems during design of future flight vehicles with AFC. This paper describes the wind tunnel test results obtained at the LTPT for the EET high-lift system for various AFC concepts examined on this airfoil.

  11. Spread of a new parasitic B chromosome variant is facilitated by high gene flow.

    Directory of Open Access Journals (Sweden)

    María Inmaculada Manrique-Poyato

    Full Text Available The B24 chromosome variant emerged several decades ago in a Spanish population of the grasshopper Eyprepocnemis plorans and is currently reaching adjacent populations. Here we report, for the first time, how a parasitic B chromosome (a strictly vertically transmitted parasite expands its geographical range aided by high gene flow in the host species. For six years we analyzed B frequency in several populations to the east and west of the original population and found extensive spatial variation, but only a slight temporal trend. The highest B24 frequency was found in its original population (Torrox and it decreased closer to both the eastern and the western populations. The analysis of Inter Simple Sequence Repeat (ISSR markers showed the existence of a low but significant degree of population subdivision, as well as significant isolation by distance (IBD. Pairwise Nem estimates suggested the existence of high gene flow between the four populations located in the Torrox area, with higher values towards the east. No significant barriers to gene flow were found among these four populations, and we conclude that high gene flow is facilitating B24 diffusion both eastward and westward, with minor role for B24 drive due to the arrival of drive suppressor genes which are also frequent in the donor population.

  12. Further experiments for mean velocity profile of pipe flow at high Reynolds number

    Science.gov (United States)

    Furuichi, N.; Terao, Y.; Wada, Y.; Tsuji, Y.

    2018-05-01

    This paper reports further experimental results obtained in high Reynolds number actual flow facility in Japan. The experiments were performed in a pipe flow with water, and the friction Reynolds number was varied up to Reτ = 5.3 × 104. This high Reynolds number was achieved by using water as the working fluid and adopting a large-diameter pipe (387 mm) while controlling the flow rate and temperature with high accuracy and precision. The streamwise velocity was measured by laser Doppler velocimetry close to the wall, and the mean velocity profile, called log-law profile U+ = (1/κ) ln(y+) + B, is especially focused. After careful verification of the mean velocity profiles in terms of the flow rate accuracy and an evaluation of the consistency of the present results with those from previously measurements in a smaller pipe (100 mm), it was found that the value of κ asymptotically approaches a constant value of κ = 0.384.

  13. Wall modeling for the simulation of highly non-isothermal unsteady flows

    International Nuclear Information System (INIS)

    Devesa, A.

    2006-12-01

    Nuclear industry flows are most of the time characterized by their high Reynolds number, density variations (at low Mach numbers) and a highly unsteady behaviour (low to moderate frequencies). High Reynolds numbers are un-affordable by direct simulation (DNS), and simulations must either be performed by solving averaged equations (RANS), or by solving only the large eddies (LES), both using a wall model. A first investigation of this thesis dealt with the derivation and test of two variable density wall models: an algebraic law (CWM) and a zonal approach dedicated to LES (TBLE-ρ). These models were validated in quasi-isothermal cases, before being used in academic and industrial non-isothermal flows with satisfactory results. Then, a numerical experiment of pulsed passive scalars was performed by DNS, were two forcing conditions were considered: oscillations are imposed in the outer flow; oscillations come from the wall. Several frequencies and amplitudes of oscillations were taken into account in order to gain insights in unsteady effects in the boundary layer, and to create a database for validating wall models in such context. The temporal behaviour of two wall models (algebraic and zonal wall models) were studied and showed that a zonal model produced better results when used in the simulation of unsteady flows. (author)

  14. Ambipolar zinc-polyiodide electrolyte for a high-energy density aqueous redox flow battery.

    Science.gov (United States)

    Li, Bin; Nie, Zimin; Vijayakumar, M; Li, Guosheng; Liu, Jun; Sprenkle, Vincent; Wang, Wei

    2015-02-24

    Redox flow batteries are receiving wide attention for electrochemical energy storage due to their unique architecture and advantages, but progress has so far been limited by their low energy density (~25 Wh l(-1)). Here we report a high-energy density aqueous zinc-polyiodide flow battery. Using the highly soluble iodide/triiodide redox couple, a discharge energy density of 167 Wh l(-1) is demonstrated with a near-neutral 5.0 M ZnI2 electrolyte. Nuclear magnetic resonance study and density functional theory-based simulation along with flow test data indicate that the addition of an alcohol (ethanol) induces ligand formation between oxygen on the hydroxyl group and the zinc ions, which expands the stable electrolyte temperature window to from -20 to 50 °C, while ameliorating the zinc dendrite. With the high-energy density and its benign nature free from strong acids and corrosive components, zinc-polyiodide flow battery is a promising candidate for various energy storage applications.

  15. High-speed flow visualization in a pump-turbine under off-design operating conditions

    International Nuclear Information System (INIS)

    Hasmatuchi, V; Roth, S; Botero, F; Avellan, F; Farhat, M

    2010-01-01

    The flow hydrodynamics in a low specific speed radial pump-turbine reduced scale model is experimentally investigated under off-design operating conditions in generating mode. Wall pressure measurements, in the stator, synchronized with high-speed flow visualizations in the vaneless space between the impeller and the guide vanes using air bubbles injection are performed. When starting from the best efficiency point and increasing the runner speed, a significant increase of the pressure fluctuations is observed mainly in channels between wicket gates. The spectral analysis shows a rise of one stall cell, rotating with about 70% of the impeller frequency, at runaway, which further increases as the zero discharge condition is approached. Then a specific image processing technique is detailed and applied to create a synthetic instantaneous view of the flow pattern on the entire guide vanes circumference for an operating point in turbine-brake mode, where backflow and vortices accompany the stall passage.

  16. Pulsed operation of high-power light emitting diodes for imaging flow velocimetry

    International Nuclear Information System (INIS)

    Willert, C; Klinner, J; Moessner, S; Stasicki, B

    2010-01-01

    High-powered light emitting diodes (LED) are investigated for possible uses as light sources in flow diagnostics, in particular, as an alternative to laser-based illumination in particle imaging flow velocimetry in side-scatter imaging arrangements. Recent developments in solid state illumination resulted in mass-produced LEDs that provide average radiant power in excess of 10 W. By operating these LEDs with short duration, pulsed currents that are considerably beyond their continuous current damage threshold, light pulses can be generated that are sufficient to illuminate and image micron-sized particles in flow velocimetry. Time-resolved PIV measurements in water at a framing rate of 2kHz are presented. The feasibility of LED-based PIV measurements in air is also demonstrated

  17. Performance Limiting Flow Processes in High-State Loading High-Mach Number Compressors

    National Research Council Canada - National Science Library

    Tan, Choon S

    2008-01-01

    In high-stage loading high-Mach number (HLM) compressors, counter-rotating pairs of discrete vortices are shed at the trailing edge of the upstream blade row at a frequency corresponding to the downstream rotor blade passing frequency...

  18. Hydrodechlorination of TCE in a circulated electrolytic column at high flow rate.

    Science.gov (United States)

    Fallahpour, Noushin; Yuan, Songhu; Rajic, Ljiljana; Alshawabkeh, Akram N

    2016-02-01

    Palladium-catalytic hydrodechlorination of trichloroethylene (TCE) by cathodic H2 produced from water electrolysis has been tested. For a field in-well application, the flow rate is generally high. In this study, the performance of Pd-catalytic hydrodechlorination of TCE using cathodic H2 is evaluated under high flow rate (1 L min(-1)) in a circulated column system, as expected to occur in practice. An iron anode supports reduction conditions and it is used to enhance TCE hydrodechlorination. However, the precipitation occurs and high flow rate was evaluated to minimize its adverse effects on the process (electrode coverage, clogging, etc.). Under the conditions of 1 L min(-1) flow, 500 mA current, and 5 mg L(-1) initial TCE concentration, removal efficacy using iron anodes (96%) is significantly higher than by mixed metal oxide (MMO) anodes (66%). Two types of cathodes (MMO and copper foam) in the presence of Pd/Al2O3 catalyst under various currents (250, 125, and 62 mA) were used to evaluate the effect of cathode materials on TCE removal efficacy. The similar removal efficiencies were achieved for both cathodes, but more precipitation generated with copper foam cathode (based on the experiments done by authors). In addition to the well-known parameters such as current density, electrode materials, and initial TCE concentration, the high velocities of groundwater flow can have important implications, practically in relation to the flush out of precipitates. For potential field application, a cost-effective and sustainable in situ electrochemical process using a solar panel as power supply is being evaluated. Published by Elsevier Ltd.

  19. Secondary flows in the cooling channels of the high-performance light-water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Laurien, E.; Wintterle, Th. [Stuttgart Univ., Institute for Nuclear Technolgy and Energy Systems (IKE) (Germany)

    2007-07-01

    The new design of a High-Performance Light-Water Reactor (HPLWR) involves a three-pass core with an evaporator region, where the compressed water is heated above the pseudo-critical temperature, and two superheater regions. Due to the strong dependency of the supercritical water density on the temperature significant mass transfer between neighboring cooling channels is expected if the temperature is unevenly distributed across the fuel element. An inter-channel flow is then superimposed to the secondary flow vortices induced by the non-isotropy of turbulence. In order to gain insight into the resulting flow patterns as well as into temperature and density distributions within the various subchannels of the fuel element CFD (Computational Fluid Dynamics) calculations for the 1/8 fuel element are performed. For simplicity adiabatic boundary conditions at the moderator box and the fuel element box are assumed. Our investigation confirms earlier results obtained by subchannel analysis that the axial mass flux is significantly reduced in the corner subchannel of this fuel element resulting in a net mass flux towards the neighboring subchannels. Our results provide a first estimation of the magnitude of the secondary flows in the pseudo-critical region of a supercritical light-water reactor. Furthermore, it is demonstrated that CFD is an efficient tool for investigations of flow patterns within nuclear reactor fuel elements. (authors)

  20. How do rigid-lid assumption affect LES simulation results at high Reynolds flows?

    Science.gov (United States)

    Khosronejad, Ali; Farhadzadeh, Ali; SBU Collaboration

    2017-11-01

    This research is motivated by the work of Kara et al., JHE, 2015. They employed LES to model flow around a model of abutment at a Re number of 27,000. They showed that first-order turbulence characteristics obtained by rigid-lid (RL) assumption compares fairly well with those of level-set (LS) method. Concerning the second-order statistics, however, their simulation results showed a significant dependence on the method used to describe the free surface. This finding can have important implications for open channel flow modeling. The Reynolds number for typical open channel flows, however, could be much larger than that of Kara et al.'s test case. Herein, we replicate the reported study by augmenting the geometric and hydraulic scales to reach a Re number of one order of magnitude larger ( 200,000). The Virtual Flow Simulator (VFS-Geophysics) model in its LES mode is used to simulate the test case using both RL and LS methods. The computational results are validated using measured flow and free-surface data from our laboratory experiments. Our goal is to investigate the effects of RL assumption on both first-order and second order statistics at high Reynolds numbers that occur in natural waterways. Acknowledgment: Computational resources are provided by the Center of Excellence in Wireless & Information Technology (CEWIT) of Stony Brook University.

  1. Electroosmotic flow of Phan-Thien-Tanner fluids at high zeta potentials: An exact analytical solution

    Science.gov (United States)

    Sarma, Rajkumar; Deka, Nabajit; Sarma, Kuldeep; Mondal, Pranab Kumar

    2018-06-01

    We present a mathematical model to study the electroosmotic flow of a viscoelastic fluid in a parallel plate microchannel with a high zeta potential, taking hydrodynamic slippage at the walls into account in the underlying analysis. We use the simplified Phan-Thien-Tanner (s-PTT) constitutive relationships to describe the rheological behavior of the viscoelastic fluid, while Navier's slip law is employed to model the interfacial hydrodynamic slip. Here, we derive analytical solutions for the potential distribution, flow velocity, and volumetric flow rate based on the complete Poisson-Boltzmann equation (without considering the frequently used Debye-Hückel linear approximation). For the underlying electrokinetic transport, this investigation primarily reveals the influence of fluid rheology, wall zeta potential as modulated by the interfacial electrochemistry and interfacial slip on the velocity distribution, volumetric flow rate, and fluid stress, as well as the apparent viscosity. We show that combined with the viscoelasticity of the fluid, a higher wall zeta potential and slip coefficient lead to a phenomenal enhancement in the volumetric flow rate. We believe that this analysis, besides providing a deep theoretical insight to interpret the transport process, will also serve as a fundamental design tool for microfluidic devices/systems under electrokinetic influence.

  2. Recognition and measurement gas-liquid two-phase flow in a vertical concentric annulus at high pressures

    Science.gov (United States)

    Li, Hao; Sun, Baojiang; Guo, Yanli; Gao, Yonghai; Zhao, Xinxin

    2018-02-01

    The air-water flow characteristics under pressure in the range of 1-6 MPa in a vertical annulus were evaluated in this report. Time-resolved bubble rising velocity and void fraction were also measured using an electrical void fraction meter. The results showed that the pressure has remarkable effect on the density, bubble size and rise velocity of the gas. Four flow patterns (bubble, cap-bubble, cap-slug, and churn) were also observed instead of Taylor bubble at high pressure. Additionally, the transition process from bubble to cap-bubble was investigated at atmospheric and high pressures, respectively. The results revealed that the flow regime transition criteria for atmospheric pressure do not work at high pressure, hence a new flow regime transition model for annular flow channel geometry was developed to predict the flow regime transition, which thereafter exhibited high accuracy at high pressure condition.

  3. ULTRA-SHARP nonoscillatory convection schemes for high-speed steady multidimensional flow

    Science.gov (United States)

    Leonard, B. P.; Mokhtari, Simin

    1990-01-01

    For convection-dominated flows, classical second-order methods are notoriously oscillatory and often unstable. For this reason, many computational fluid dynamicists have adopted various forms of (inherently stable) first-order upwinding over the past few decades. Although it is now well known that first-order convection schemes suffer from serious inaccuracies attributable to artificial viscosity or numerical diffusion under high convection conditions, these methods continue to enjoy widespread popularity for numerical heat transfer calculations, apparently due to a perceived lack of viable high accuracy alternatives. But alternatives are available. For example, nonoscillatory methods used in gasdynamics, including currently popular TVD schemes, can be easily adapted to multidimensional incompressible flow and convective transport. This, in itself, would be a major advance for numerical convective heat transfer, for example. But, as is shown, second-order TVD schemes form only a small, overly restrictive, subclass of a much more universal, and extremely simple, nonoscillatory flux-limiting strategy which can be applied to convection schemes of arbitrarily high order accuracy, while requiring only a simple tridiagonal ADI line-solver, as used in the majority of general purpose iterative codes for incompressible flow and numerical heat transfer. The new universal limiter and associated solution procedures form the so-called ULTRA-SHARP alternative for high resolution nonoscillatory multidimensional steady state high speed convective modelling.

  4. A highly permeable and enhanced surface area carbon-cloth electrode for vanadium redox flow batteries

    Science.gov (United States)

    Zhou, X. L.; Zhao, T. S.; Zeng, Y. K.; An, L.; Wei, L.

    2016-10-01

    In this work, a high-performance porous electrode, made of KOH-activated carbon-cloth, is developed for vanadium redox flow batteries (VRFBs). The macro-scale porous structure in the carbon cloth formed by weaving the carbon fibers in an ordered manner offers a low tortuosity (∼1.1) and a broad pore distribution from 5 μm to 100 μm, rendering the electrode a high hydraulic permeability and high effective ionic conductivity, which are beneficial for the electrolyte flow and ion transport through the porous electrode. The use of KOH activation method to create nano-scale pores on the carbon-fiber surfaces leads to a significant increase in the surface area for redox reactions from 2.39 m2 g-1 to 15.4 m2 g-1. The battery assembled with the present electrode delivers an energy efficiency of 80.1% and an electrolyte utilization of 74.6% at a current density of 400 mA cm-2, as opposed to an electrolyte utilization of 61.1% achieved by using a conventional carbon-paper electrode. Such a high performance is mainly attributed to the combination of the excellent mass/ion transport properties and the high surface area rendered by the present electrode. It is suggested that the KOH-activated carbon-cloth electrode is a promising candidate in redox flow batteries.

  5. A highly energy-efficient flow-through electro-Fenton process for organic pollutants degradation

    International Nuclear Information System (INIS)

    Ma, Liang; Zhou, Minghua; Ren, Gengbo; Yang, Weilu; Liang, Liang

    2016-01-01

    Highlights: • A highly energy-efficient flow-through electro-Fenton reactor was designed. • It had high H 2 O 2 yield and low energy consumption for organic pollutants degradation. • The effect of operational parameters was optimized and possible process mechanism was studied. • The novel system performed wide practicability and potential for organic pollutants degradation. - Abstract: A highly energy-efficient flow-through Electro-Fenton (E-Fenton) reactor for oxidation of methylene blue (MB) from aqueous solution was designed using a perforated DSA as anode and the graphite felt modified by carbon black and polytetrafluoroethylene (PTFE) as cathode for the in situ generation of H 2 O 2 . The modified cathode had a high H 2 O 2 production with low energy consumption, which was characterized by scanning electron microscopy (SEM), nitrogen adsorption-desorption study and contact angle. The flow-through E-Fenton system was compared to the flow-by and regular one, and confirmed to be best on MB removal and TOC degradation. The operational parameters such as current density, pH, Fe 2+ concentration and flow rate were optimized. The MB and TOC removal efficiency of the effluents could keep above 90% and 50%, respectively, and the energy consumption was 23.0 kWh/kgTOC at the current density of 50 mA, pH 3, 0.3 mM Fe 2+ , and the flow rate of 7 mL/min. ·OH was proved to be the main oxidizing species in this system. After 5 times operation, the system, especially cathode, still showed good stability. Five more organic pollutants including orange II (OG), tartrazine, acetylsalicylic acid (ASA), tetracycline (TC) and 2,4-dichlorophen (2,4-DCP) were investigated and the electric energy consumption (EEC) was compared with literatures. All results demonstrated that this flow-through E-Fenton system was energy-efficient and potential for degradation of organic pollutants.

  6. Evolution of a polydispersed spray in heated and in highly turbulent flow

    Science.gov (United States)

    Moreau, Florian; Bazile, Rudy

    2009-11-01

    This work aims to study experimentally the dispersion and the evaporation of a polydispersed and bi-component spray in highly turbulent and heated flow. A chamber is designed to generate a heated turbulent flow in which two-component droplets are injected. The two components are octane (85%) and 3-pentanone (15%) and are chosen such that the 3-pentanone vapour concentration can be characterized by laser techniques. The experimental setup consists of a vertical channel with optical access. Before the heated air is injected in the channel, it passes through a turbulence generator. The carrier flow is characterized using Laser Doppler Anemometry. The turbulence is shown to have isotropic properties after a distance equal to four times the width of the channel and to have high levels up to 30%. The liquid phase is characterized with Phase Doppler Anemometry which allows to measure the diameter, the longitudinal and the radial velocity of the droplets. The spatial evolution of the diameter probability density function (PDF) and of the rms and mean velocities are obtained. Droplets mass fluxes are also calculated. In the mixture, 3-pentanone is the only component that fluoresces. So the vapour concentration of 3-pentanone in the carrier flow is determined using Laser Induced Fluorescence.

  7. Cerebral pressure-flow relationship in lowlanders and natives at high altitude.

    Science.gov (United States)

    Smirl, Jonathan D; Lucas, Samuel J E; Lewis, Nia C S; duManoir, Gregory R; Dumanior, Gregory R; Smith, Kurt J; Bakker, Akke; Basnyat, Aperna S; Ainslie, Philip N

    2014-02-01

    We investigated if dynamic cerebral pressure-flow relationships in lowlanders are altered at high altitude (HA), differ in HA natives and after return to sea level (SL). Lowlanders were tested at SL (n=16), arrival to 5,050 m, after 2-week acclimatization (with and without end-tidal PO2 normalization), and upon SL return. High-altitude natives (n=16) were tested at 5,050 m. Testing sessions involved resting spontaneous and driven (squat-stand maneuvers at very low (VLF, 0.05 Hz) and low (LF, 0.10 Hz) frequencies) measures to maximize blood pressure (BP) variability and improve assessment of the pressure-flow relationship using transfer function analysis (TFA). Blood flow velocity was assessed in the middle (MCAv) and posterior (PCAv) cerebral arteries. Spontaneous VLF and LF phases were reduced and coherence was elevated with acclimatization to HA (Pflow coupling. However, when BP was driven, both the frequency- and time-domain metrics were unaltered and comparable with HA natives. Acute mountain sickness was unrelated to TFA metrics. In conclusion, the driven cerebral pressure-flow relationship (in both frequency and time domains) is unaltered at 5,050 m in lowlanders and HA natives. Our findings indicate that spontaneous changes in TFA metrics do not necessarily reflect physiologically important alterations in the capacity of the brain to regulate BP.

  8. Bonneville Second Powerhouse Tailrace and High Flow Outfall: ADCP and drogue release field study; FINAL

    International Nuclear Information System (INIS)

    Cook, Chris B; Richmond, Marshall C; Guensch, Greg

    2001-01-01

    The Bonneville Project is one of four US Army Corps of Engineers operated dams along the Lower Columbia River. Each year thousands of smelt pass through this Project on their way to the Pacific Ocean. High flow outfalls, if specifically designed for fish passage, are thought to have as good or better smelt survival rates as spillways. To better understand the hydrodynamic flow field around an operating outfall, the Corps of Engineers commissioned measurement of water velocities in the tailrace of the Second Powerhouse. These data also are necessary for proper calibration and verification of three-dimensional numerical models currently under development at PNNL. Hydrodynamic characterization of the tailrace with and without the outfall operating was accomplished through use of a surface drogue and acoustic Doppler current profiler (ADCP). Both the ADCP and drogue were linked to a GPS (global positioning system); locating the data in both space and time. Measurements focused on the area nearest to the high flow outfall, however several ADCP transects and drogue releases were performed away from the outfall to document ambient flow field conditions when the outfall was not operating

  9. Interbasin flow revisited: The contribution of local recharge to high-discharge springs, Death Valley, CA

    Science.gov (United States)

    Anderson, Katherine; Nelson, Stephen; Mayo, Alan; Tingey, David

    2006-05-01

    Springs in the Furnace Creek area (Texas, Travertine, and Nevares Springs) of Death Valley National Park exhibit high discharge rates and depleted δ18O VSMOW (˜-13‰) and δD VSMOW (˜-102‰) values. Isotopic depletion of this magnitude and large spring fluxes (˜10,000 L/min) suggests that modern local recharge in the arid Furnace Creek drainage cannot be responsible for spring fluxes. An alternate explanation, interbasin flow, is difficult to envisage due to the stratigraphic and structural relationships of bedrock in intervening ranges, although it is the most common conceptual model for Furnace Creek spring flows. High-flux springs at Furnace Creek nonetheless respond modestly to modern climate in terms of discharge rate and isotopic composition. Hydrographs show a climate response and variations in time-series stable isotope data of widely spaced springs track one another. Small, but measurable quantities of tritium (water for these springs may be, there appears to be a subtle, but recent climatic influence. Estimates of flow at nearby mountain springs produce discharge rates per square kilometer of catchment that, by analogy, could support from 20 to 300% of the flow at large Death Valley springs under the current climate. Yet, 14C model ages suggest valley-bottom springs at Furnace Creek (5500-14,500 yr) contain a large component of older water, suggesting that much of the water was recharged during a pluvial period (Younger Dryas?) when net infiltration would have been much higher and isotopically depleted. 14C model ages are also of similar age, or younger, than many 'up gradient' waters, rather than being older as would be expected for interbasin flow. Chemical evolution models of solutes are consistent with both local recharge and interbasin transfer from Ash Meadows. However, when considered with isotopic constraints, interbasin flow becomes obviously untenable. Estimates of the thickness of alluvium and semi-consolidated Tertiary units in the

  10. Computational thermal-fluid dynamics analysis of the laminar flow regime in the meander flow geometry characterizing the heat exchanger used in high temperature superconducting current leads

    International Nuclear Information System (INIS)

    Rizzo, Enrico; Heller, Reinhard; Richard, Laura Savoldi; Zanino, Roberto

    2013-01-01

    Highlights: • The laminar regime in the meander flow geometry has been analysed with a previously validated computational strategy. • Several meander flow geometries as well as flow conditions have been analysed. • A range for the Reynolds number has been defined in which the flow can be considered laminar. • Correlations for the pressure drop and the heat transfer coefficients in the laminar regime have been derived. • A comparison between the computed the experimental pressure drop of the W7-X HTS current lead prototype is presented. -- Abstract: The Karlsruhe Institute of Technology and the Politecnico di Torino have developed and validated a computational thermal-fluid dynamics (CtFD) strategy for the systematic analysis of the thermal-hydraulics inside the meander flow heat exchanger used in high-temperature superconducting current leads for fusion applications. In the recent past, the application of this CtFD technique has shown that some operating conditions occurring in these devices may not reach the turbulent regime region. With that motivation, the CtFD analysis of the helium thermal-fluid dynamics inside different meander flow geometries is extended here to the laminar flow regime. Our first aim is to clarify under which operative conditions the flow regime can be considered laminar and how the pressure drop as well as the heat transfer are related to the geometrical parameters and to the flow conditions. From the results of this analysis, correlations for the pressure drop and for the heat transfer coefficient in the meander flow geometry have been derived, which are applicable with good accuracy to the design of meander flow heat exchangers over a broad range of geometrical parameters

  11. Computational thermal-fluid dynamics analysis of the laminar flow regime in the meander flow geometry characterizing the heat exchanger used in high temperature superconducting current leads

    Energy Technology Data Exchange (ETDEWEB)

    Rizzo, Enrico, E-mail: enrico.rizzo@kit.edu [Institute for Technical Physics, Karlsruhe Institute of Technology, 76021 Karlsruhe (Germany); Heller, Reinhard [Institute for Technical Physics, Karlsruhe Institute of Technology, 76021 Karlsruhe (Germany); Richard, Laura Savoldi; Zanino, Roberto [Dipartimento Energia, Politecnico di Torino, 10129 Torino (Italy)

    2013-11-15

    Highlights: • The laminar regime in the meander flow geometry has been analysed with a previously validated computational strategy. • Several meander flow geometries as well as flow conditions have been analysed. • A range for the Reynolds number has been defined in which the flow can be considered laminar. • Correlations for the pressure drop and the heat transfer coefficients in the laminar regime have been derived. • A comparison between the computed the experimental pressure drop of the W7-X HTS current lead prototype is presented. -- Abstract: The Karlsruhe Institute of Technology and the Politecnico di Torino have developed and validated a computational thermal-fluid dynamics (CtFD) strategy for the systematic analysis of the thermal-hydraulics inside the meander flow heat exchanger used in high-temperature superconducting current leads for fusion applications. In the recent past, the application of this CtFD technique has shown that some operating conditions occurring in these devices may not reach the turbulent regime region. With that motivation, the CtFD analysis of the helium thermal-fluid dynamics inside different meander flow geometries is extended here to the laminar flow regime. Our first aim is to clarify under which operative conditions the flow regime can be considered laminar and how the pressure drop as well as the heat transfer are related to the geometrical parameters and to the flow conditions. From the results of this analysis, correlations for the pressure drop and for the heat transfer coefficient in the meander flow geometry have been derived, which are applicable with good accuracy to the design of meander flow heat exchangers over a broad range of geometrical parameters.

  12. An experimental investigation of the flow physics of high-lift systems

    Science.gov (United States)

    Thomas, Flint O.; Nelson, R. C.

    1995-01-01

    This progress report is a series of overviews outlining experiments on the flow physics of confluent boundary layers for high-lift systems. The research objectives include establishing the role of confluent boundary layer flow physics in high-lift production; contrasting confluent boundary layer structures for optimum and non-optimum C(sub L) cases; forming a high quality, detailed archival data base for CFD/modelling; and examining the role of relaminarization and streamline curvature. Goals of this research include completing LDV study of an optimum C(sub L) case; performing detailed LDV confluent boundary layer surveys for multiple non-optimum C(sub L) cases; obtaining skin friction distributions for both optimum and non-optimum C(sub L) cases for scaling purposes; data analysis and inner and outer variable scaling; setting-up and performing relaminarization experiments; and a final report establishing the role of leading edge confluent boundary layer flow physics on high-lift performance.

  13. Study of flow fractionation characteristics of magnetic chromatography utilizing high-temperature superconducting bulk magnet

    Directory of Open Access Journals (Sweden)

    Satoshi Fukui, Yoshihiro Shoji, Jun Ogawa, Tetsuo Oka, Mitsugi Yamaguchi, Takao Sato, Manabu Ooizumi, Hiroshi Imaizumi and Takeshi Ohara

    2009-01-01

    Full Text Available We present numerical simulation of separating magnetic particles with different magnetic susceptibilities by magnetic chromatography using a high-temperature superconducting bulk magnet. The transient transport is numerically simulated for two kinds of particles having different magnetic susceptibilities. The time evolutions were calculated for the particle concentration in the narrow channel of the spiral arrangement placed in the magnetic field. The field is produced by the highly magnetized high-temperature superconducting bulk magnet. The numerical results show the flow velocity difference of the particle transport corresponding to the difference in the magnetic susceptibility, as well as the possible separation of paramagnetic particles of 20 nm diameter.

  14. Study of flow fractionation characteristics of magnetic chromatography utilizing high-temperature superconducting bulk magnet.

    Science.gov (United States)

    Fukui, Satoshi; Shoji, Yoshihiro; Ogawa, Jun; Oka, Tetsuo; Yamaguchi, Mitsugi; Sato, Takao; Ooizumi, Manabu; Imaizumi, Hiroshi; Ohara, Takeshi

    2009-02-01

    We present numerical simulation of separating magnetic particles with different magnetic susceptibilities by magnetic chromatography using a high-temperature superconducting bulk magnet. The transient transport is numerically simulated for two kinds of particles having different magnetic susceptibilities. The time evolutions were calculated for the particle concentration in the narrow channel of the spiral arrangement placed in the magnetic field. The field is produced by the highly magnetized high-temperature superconducting bulk magnet. The numerical results show the flow velocity difference of the particle transport corresponding to the difference in the magnetic susceptibility, as well as the possible separation of paramagnetic particles of 20 nm diameter.

  15. Subaqueous ice-contact fans: Depositional systems characterised by highly aggradational supercritical flow conditions

    Science.gov (United States)

    Lang, Joerg; Winsemann, Jutta

    2015-04-01

    Subaqueous ice-contact fans are deposited by high-energy plane-wall jets from subglacial conduits into standing water bodies. Highly aggradational conditions during flow expansion and deceleration allow for the preservation of bedforms related to supercritical flows, which are commonly considered rare in the depositional record. We present field examples from gravelly and sandy subaqueous ice-contact fan successions, which indicate that deposition by supercritical flows might be considered as a characteristic feature of these depositional systems. The studied successions were deposited in deep ice-dammed lakes, which formed along the margins of the Middle Pleistocene Scandinavian ice sheets across Northern Germany. The gravel-rich subaqueous fan deposits are dominated by large scour-fills (up to 25 m wide and 3 m) deep and deposits of turbulent hyperconcentrated flows, which are partly attributed to supercritical flow conditions (Winsemann et al., 2009). Scours (up to 4.5 m wide and 0.9 m deep) infilled by gravelly backsets are observed above laterally extensive erosional surfaces and are interpreted as deposits of cyclic steps. Laterally discontinuous beds of low-angle cross-stratified gravel are interpreted as antidune deposits. Downflow and up-section the gravel-rich deposits pass into sand-rich successions, which include deposits of chutes-and-pools, breaking antidunes, stationary antidunes and humpback dunes (Lang and Winsemann, 2013). Deposits of chutes-and-pools and breaking antidunes are characterised by scour-fills (up to 4 m wide and 1.2 m deep) comprising backsets or gently dipping sigmoidal foresets. Stationary antidune deposits consist of laterally extensive sinusoidal waveforms with long wavelengths (1-12 m) and low amplitudes (0.1-0.5 m), which formed under quasi-steady flows at the lower limit of the supercritical flow stage and high rates of sedimentation. Humpback dunes are characterised by divergent sigmoidal foresets and are interpreted as

  16. On the application of the method of turbulent flow to transient and quasi-stationary flow calculations in high temperature reactors with spherical fuel elements

    International Nuclear Information System (INIS)

    Hoefer, I.

    1980-12-01

    For the calculation of flows in high-temperature reactors and of their temperature behavior the equations of the method of turbulent flow in the primitive form are derived for inhomogeneous regions. This system of equations is appropriate for the investigation of transient and quasi-stationary phenomena in pebble beds. By modification of the flow function in parallel arranged reflector channels a parallel flow can be simulated. For simplification the flow in region with a smaller pressure loss is assumed to be a potential flow. For the numerical solution of the time-dependent convective parts of the system of equations a number of explicit and implicit difference methods are compared. If the method using UP-WIND differences is taken to be an interpolation method the introduction of an extension becomes possible, which together with preliminary integration of the fictional terms allows to apply larger time steps. The algebraic system of equations for numerical calculation of a steady flow field also is established by formation of UP-WIND differences for the convective terms. By mathematical verification of some examples the applicability of the mathematical model for flow problems in pebble beds with forced or natural convection is shown. (orig.) [de

  17. Validation and application of an high-order spectral difference method for flow induced noise simulation

    KAUST Repository

    Parsani, Matteo

    2011-09-01

    The main goal of this paper is to develop an efficient numerical algorithm to compute the radiated far field noise provided by an unsteady flow field from bodies in arbitrary motion. The method computes a turbulent flow field in the near fields using a high-order spectral difference method coupled with large-eddy simulation approach. The unsteady equations are solved by advancing in time using a second-order backward difference formulae scheme. The nonlinear algebraic system arising from the time discretization is solved with the nonlinear lowerupper symmetric GaussSeidel algorithm. In the second step, the method calculates the far field sound pressure based on the acoustic source information provided by the first step simulation. The method is based on the Ffowcs WilliamsHawkings approach, which provides noise contributions for monopole, dipole and quadrupole acoustic sources. This paper will focus on the validation and assessment of this hybrid approach using different test cases. The test cases used are: a laminar flow over a two-dimensional (2D) open cavity at Re = 1.5 × 10 3 and M = 0.15 and a laminar flow past a 2D square cylinder at Re = 200 and M = 0.5. In order to show the application of the numerical method in industrial cases and to assess its capability for sound field simulation, a three-dimensional turbulent flow in a muffler at Re = 4.665 × 10 4 and M = 0.05 has been chosen as a third test case. The flow results show good agreement with numerical and experimental reference solutions. Comparison of the computed noise results with those of reference solutions also shows that the numerical approach predicts noise accurately. © 2011 IMACS.

  18. Noise levels of neonatal high-flow nasal cannula devices--an in-vitro study.

    Science.gov (United States)

    König, Kai; Stock, Ellen L; Jarvis, Melanie

    2013-01-01

    Excessive ambient noise levels have been identified as a potential risk factor for adverse outcome in very preterm infants. Noise level measurements for continuous positive airway pressure (CPAP) devices demonstrated that these constantly exceed current recommendations. The use of high-flow nasal cannula (HFNC) as an alternative non-invasive ventilation modality has become more popular in recent years in neonatal care. To study noise levels of two HFNC devices commonly used in newborns. As a comparison, noise levels of a continuous flow CPAP device were also studied. In-vitro study. The noise levels of two contemporary HFNC devices (Fisher & Paykel NHF™ and Vapotherm Precision Flow®) and one CPAP device (Dräger Babylog® 8000 plus) were measured in the oral cavity of a newborn manikin in an incubator in a quiet environment. HFNC flows of 4-8 l/min and CPAP pressures of 4-8 cm H2O were applied. The CPAP flow was set at 8 l/min as per unit practice. Vapotherm HFNC generated the highest noise levels, measuring 81.2-91.4 dB(A) with increasing flow. Fisher & Paykel HFNC noise levels were between 78.8 and 81.2 dB(A). The CPAP device generated the lowest noise levels between 73.9 and 77.4 dB(A). Both HFNC devices generated higher noise levels than the CPAP device. All noise levels were far above current recommendations of the American Academy of Pediatrics. In light of the long duration of non-invasive respiratory support of very preterm infants, less noisy devices are required to prevent the potentially adverse effects of continuing excessive noise exposure in the neonatal intensive care unit. Copyright © 2013 S. Karger AG, Basel.

  19. Are high flow nasal cannulae noisier than bubble CPAP for preterm infants?

    Science.gov (United States)

    Roberts, C T; Dawson, J A; Alquoka, E; Carew, P J; Donath, S M; Davis, P G; Manley, B J

    2014-07-01

    Noise exposure in the neonatal intensive care unit is believed to be a risk factor for hearing loss in preterm neonates. Continuous positive airway pressure (CPAP) devices exceed recommended noise levels. High flow nasal cannulae (HFNC) are an increasingly popular alternative to CPAP for treating preterm infants, but there are no in vivo studies assessing noise production by HFNC. To study whether HFNC are noisier than bubble CPAP (BCPAP) for preterm infants. An observational study of preterm infants receiving HFNC or BCPAP. Noise levels within the external auditory meatus (EAM) were measured using a microphone probe tube connected to a calibrated digital dosimeter. Noise was measured across a range of frequencies and reported as decibels A-weighted (dBA). A total of 21 HFNC and 13 BCPAP noise measurements were performed in 21 infants. HFNC gas flows were 2-5 L/min, and BCPAP gas flows were 6-10 L/min with set pressures of 5-7 cm of water. There was no evidence of a difference in average noise levels measured at the EAM: mean difference (95% CI) of -1.6 (-4.0 to 0.9) dBA for HFNC compared to BCPAP. At low frequency (500 Hz), HFNC was mean (95% CI) 3.0 (0.3 to 5.7) dBA quieter than BCPAP. Noise increased with increasing BCPAP gas flow (p=0.007), but not with increasing set pressure. There was a trend to noise increasing with increasing HFNC gas flows. At the gas flows studied, HFNC are not noisier than BCPAP for preterm infants.

  20. Drag reduction using wrinkled surfaces in high Reynolds number laminar boundary layer flows

    Science.gov (United States)

    Raayai-Ardakani, Shabnam; McKinley, Gareth H.

    2017-09-01

    Inspired by the design of the ribbed structure of shark skin, passive drag reduction methods using stream-wise riblet surfaces have previously been developed and tested over a wide range of flow conditions. Such textures aligned in the flow direction have been shown to be able to reduce skin friction drag by 4%-8%. Here, we explore the effects of periodic sinusoidal riblet surfaces aligned in the flow direction (also known as a "wrinkled" texture) on the evolution of a laminar boundary layer flow. Using numerical analysis with the open source Computational Fluid Dynamics solver OpenFOAM, boundary layer flow over sinusoidal wrinkled plates with a range of wavelength to plate length ratios ( λ / L ), aspect ratios ( 2 A / λ ), and inlet velocities are examined. It is shown that in the laminar boundary layer regime, the riblets are able to retard the viscous flow inside the grooves creating a cushion of stagnant fluid that the high-speed fluid above can partially slide over, thus reducing the shear stress inside the grooves and the total integrated viscous drag force on the plate. Additionally, we explore how the boundary layer thickness, local average shear stress distribution, and total drag force on the wrinkled plate vary with the aspect ratio of the riblets as well as the length of the plate. We show that riblets with an aspect ratio of close to unity lead to the highest reduction in the total drag, and that because of the interplay between the local stress distribution on the plate and stream-wise evolution of the boundary layer the plate has to exceed a critical length to give a net decrease in the total drag force.

  1. High-pressure plastic scintillation detector for measuring radiogenic gases in flow systems

    CERN Document Server

    Schell, W R; Yoon, S R; Tobin, M J

    1999-01-01

    Radioactive gases are emitted into the atmosphere from nuclear electric power and nuclear fuel reprocessing plants, from hospitals discarding xenon used in diagnostic medicine, as well as from nuclear weapons tests. A high-pressure plastic scintillation detector was constructed to measure atmospheric levels of such radioactive gases by detecting the beta and internal conversion (IC) electron decays. Operational tests and calibrations were made that permit integration of the flow detectors into a portable Gas Analysis, Separation and Purification system (GASP). The equipment developed can be used for measuring fission gases released from nuclear reactor sources and/or as part of monitoring equipment for enforcing the Comprehensive Test Ban Treaty. The detector is being used routinely for in-line gas separation efficiency measurements, at the elevated operational pressures used for the high-pressure swing analysis system (2070 kPa) and at flow rates of 5-15 l/min . This paper presents the design features, opera...

  2. Advanced lattice Boltzmann scheme for high-Reynolds-number magneto-hydrodynamic flows

    Science.gov (United States)

    De Rosis, Alessandro; Lévêque, Emmanuel; Chahine, Robert

    2018-06-01

    Is the lattice Boltzmann method suitable to investigate numerically high-Reynolds-number magneto-hydrodynamic (MHD) flows? It is shown that a standard approach based on the Bhatnagar-Gross-Krook (BGK) collision operator rapidly yields unstable simulations as the Reynolds number increases. In order to circumvent this limitation, it is here suggested to address the collision procedure in the space of central moments for the fluid dynamics. Therefore, an hybrid lattice Boltzmann scheme is introduced, which couples a central-moment scheme for the velocity with a BGK scheme for the space-and-time evolution of the magnetic field. This method outperforms the standard approach in terms of stability, allowing us to simulate high-Reynolds-number MHD flows with non-unitary Prandtl number while maintaining accuracy and physical consistency.

  3. High-velocity two-phase flow two-dimensional modeling

    International Nuclear Information System (INIS)

    Mathes, R.; Alemany, A.; Thilbault, J.P.

    1995-01-01

    The two-phase flow in the nozzle of a LMMHD (liquid metal magnetohydrodynamic) converter has been studied numerically and experimentally. A two-dimensional model for two-phase flow has been developed including the viscous terms (dragging and turbulence) and the interfacial mass, momentum and energy transfer between the phases. The numerical results were obtained by a finite volume method based on the SIMPLE algorithm. They have been verified by an experimental facility using air-water as a simulation pair and a phase Doppler particle analyzer for velocity and droplet size measurement. The numerical simulation of a lithium-cesium high-temperature pair showed that a nearly homogeneous and isothermal expansion of the two phases is possible with small pressure losses and high kinetic efficiencies. In the throat region a careful profiling is necessary to reduce the inertial effects on the liquid velocity field

  4. Thermoconvective flow velocity in a high-speed magnetofluid seal after it has stopped

    Science.gov (United States)

    Krakov, M. S.; Nikiforov, I. V.

    2012-09-01

    Convective flow is investigated in the high-speed (linear velocity of the shaft seal is more than 1 m/s) magnetofluid shaft seal after it has been stopped. Magnetic fluid is preliminarily heated due to viscous friction in the moving seal. After the shaft has been stopped, nonuniform heated fluid remains under the action of a high-gradient magnetic field. Numerical analysis has revealed that in this situation, intense thermomagnetic convection is initiated. The velocity of magnetic fluid depends on its viscosity. For the fluid with viscosity of 2 × 10-4 m2/s the maximum flow velocity within the volume of magnetic fluid with a characteristic size of 1 mm can attain a value of 10 m/s.

  5. Plasma flow reactor for steady state monitoring of physical and chemical processes at high temperatures.

    Science.gov (United States)

    Koroglu, Batikan; Mehl, Marco; Armstrong, Michael R; Crowhurst, Jonathan C; Weisz, David G; Zaug, Joseph M; Dai, Zurong; Radousky, Harry B; Chernov, Alex; Ramon, Erick; Stavrou, Elissaios; Knight, Kim; Fabris, Andrea L; Cappelli, Mark A; Rose, Timothy P

    2017-09-01

    We present the development of a steady state plasma flow reactor to investigate gas phase physical and chemical processes that occur at high temperature (1000 flow injector). We have modeled the system using computational fluid dynamics simulations that are bounded by measured temperatures. In situ line-of-sight optical emission and absorption spectroscopy have been used to determine the structures and concentrations of molecules formed during rapid cooling of reactants after they pass through the plasma. Emission spectroscopy also enables us to determine the temperatures at which these dynamic processes occur. A sample collection probe inserted from the open end of the reactor is used to collect condensed materials and analyze them ex situ using electron microscopy. The preliminary results of two separate investigations involving the condensation of metal oxides and chemical kinetics of high-temperature gas reactions are discussed.

  6. Measurement of flow field in the pebble bed type high temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    Lee, Sa Ya; Lee, Jae Young

    2008-01-01

    In this study, flow field measurement of the Pebble Bed Reactor(PBR) for the High Temperature Gascooled Reactor(HTGR) was performed. Large number of pebbles in the core of PBR provides complicated flow channel. Due to the complicated geometries, numerical analysis has been intensively made rather than experimental observation. However, the justification of computational simulation by the experimental study is crucial to develop solid analysis of design method. In the present study, a wind tunnel installed with pebbles stacked was constructed and equipped with the Particle Image Velocimetry(PIV). We designed the system scaled up to realize the room temperature condition according to the similarity. The PIV observation gave us stagnation points, low speed region so that the suspected high temperature region can be identified. With the further supplementary experimental works, the present system may produce valuable data to justify the Computational Fluid Dynamics(CFD) simulation method

  7. High-throughput tri-colour flow cytometry technique to assess Plasmodium falciparum parasitaemia in bioassays

    DEFF Research Database (Denmark)

    Tiendrebeogo, Regis W; Adu, Bright; Singh, Susheel K

    2014-01-01

    BACKGROUND: Unbiased flow cytometry-based methods have become the technique of choice in many laboratories for high-throughput, accurate assessments of malaria parasites in bioassays. A method to quantify live parasites based on mitotracker red CMXRos was recently described but consistent...... distinction of early ring stages of Plasmodium falciparum from uninfected red blood cells (uRBC) remains a challenge. METHODS: Here, a high-throughput, three-parameter (tri-colour) flow cytometry technique based on mitotracker red dye, the nucleic acid dye coriphosphine O (CPO) and the leucocyte marker CD45...... for enumerating live parasites in bioassays was developed. The technique was applied to estimate the specific growth inhibition index (SGI) in the antibody-dependent cellular inhibition (ADCI) assay and compared to parasite quantification by microscopy and mitotracker red staining. The Bland-Altman analysis...

  8. High performance parallel computing of flows in complex geometries: II. Applications

    International Nuclear Information System (INIS)

    Gourdain, N; Gicquel, L; Staffelbach, G; Vermorel, O; Duchaine, F; Boussuge, J-F; Poinsot, T

    2009-01-01

    Present regulations in terms of pollutant emissions, noise and economical constraints, require new approaches and designs in the fields of energy supply and transportation. It is now well established that the next breakthrough will come from a better understanding of unsteady flow effects and by considering the entire system and not only isolated components. However, these aspects are still not well taken into account by the numerical approaches or understood whatever the design stage considered. The main challenge is essentially due to the computational requirements inferred by such complex systems if it is to be simulated by use of supercomputers. This paper shows how new challenges can be addressed by using parallel computing platforms for distinct elements of a more complex systems as encountered in aeronautical applications. Based on numerical simulations performed with modern aerodynamic and reactive flow solvers, this work underlines the interest of high-performance computing for solving flow in complex industrial configurations such as aircrafts, combustion chambers and turbomachines. Performance indicators related to parallel computing efficiency are presented, showing that establishing fair criterions is a difficult task for complex industrial applications. Examples of numerical simulations performed in industrial systems are also described with a particular interest for the computational time and the potential design improvements obtained with high-fidelity and multi-physics computing methods. These simulations use either unsteady Reynolds-averaged Navier-Stokes methods or large eddy simulation and deal with turbulent unsteady flows, such as coupled flow phenomena (thermo-acoustic instabilities, buffet, etc). Some examples of the difficulties with grid generation and data analysis are also presented when dealing with these complex industrial applications.

  9. Titer plate formatted continuous flow thermal reactors for high throughput applications: fabrication and testing

    International Nuclear Information System (INIS)

    Park, Daniel Sang-Won; Chen, Pin-Chuan; You, Byoung Hee; Kim, Namwon; Park, Taehyun; Lee, Tae Yoon; Soper, Steven A; Nikitopoulos, Dimitris E; Murphy, Michael C; Datta, Proyag; Desta, Yohannes

    2010-01-01

    A high throughput, multi-well (96) polymerase chain reaction (PCR) platform, based on a continuous flow (CF) mode of operation, was developed. Each CFPCR device was confined to a footprint of 8 × 8 mm 2 , matching the footprint of a well on a standard micro-titer plate. While several CFPCR devices have been demonstrated, this is the first example of a high-throughput multi-well continuous flow thermal reactor configuration. Verification of the feasibility of the multi-well CFPCR device was carried out at each stage of development from manufacturing to demonstrating sample amplification. The multi-well CFPCR devices were fabricated by micro-replication in polymers, polycarbonate to accommodate the peak temperatures during thermal cycling in this case, using double-sided hot embossing. One side of the substrate contained the thermal reactors and the opposite side was patterned with structures to enhance thermal isolation of the closely packed constant temperature zones. A 99 bp target from a λ-DNA template was successfully amplified in a prototype multi-well CFPCR device with a total reaction time as low as ∼5 min at a flow velocity of 3 mm s −1 (15.3 s cycle −1 ) and a relatively low amplification efficiency compared to a bench-top thermal cycler for a 20-cycle device; reducing the flow velocity to 1 mm s −1 (46.2 s cycle −1 ) gave a seven-fold improvement in amplification efficiency. Amplification efficiencies increased at all flow velocities for 25-cycle devices with the same configuration.

  10. The Role of Heated Humidified High-flow Nasal Cannula as Noninvasive Respiratory Support in Neonates

    Directory of Open Access Journals (Sweden)

    Ke-Yun Chao

    2017-08-01

    Full Text Available Recently, heated humidified high-flow nasal cannula (HHHFNC has been introduced and applied as a noninvasive respiratory support in neonates. Although HHHFNC is widely used in neonates presenting with respiratory distress, the efficiency and safety when compared with nasal continuous positive airway pressure or noninvasive positive pressure ventilation are still controversial. This review aims to evaluate the performance and applications of HHHFNC in neonates.

  11. Microbial activities in a vertical-flow wetland system treating sewage sludge with high organic loads

    Energy Technology Data Exchange (ETDEWEB)

    Wang, R. Y.; Perissol, C.; Baldy, V.; Bonin, G.; Korboulewsky, N.

    2009-07-01

    The rhizosphere is the most active zone in treatment wetlands where take place physicochemical and biological processes between the substrate, plants, microorganisms, and contaminants. Microorganisms play the key role in the mineralisation of organic matter. substrate respiration and phosphatase activities (acid and alkaline) were chosen as indicators of microbial activities, and studied in a vertical-flow wetland system receiving sewage sludge with high organic loads under the Mediterranean climate. (Author)

  12. The decomposition of methyltrichlorosilane: Studies in a high-temperature flow reactor

    Energy Technology Data Exchange (ETDEWEB)

    Allendorf, M.D.; Osterheld, T.H.; Melius, C.F.

    1994-01-01

    Experimental measurements of the decomposition of methyltrichlorosilane (MTS), a common silicon carbide precursor, in a high-temperature flow reactor are presented. The results indicate that methane and hydrogen chloride are major products of the decomposition. No chlorinated silane products were observed. Hydrogen carrier gas was found to increase the rate of MTS decomposition. The observations suggest a radical-chain mechanism for the decomposition. The implications for silicon carbide chemical vapor deposition are discussed.

  13. Simulation of electron and ion bipolar flow in high current diode with magnetic insulation

    International Nuclear Information System (INIS)

    Vrba, P.; Engelko, V.I.

    1990-08-01

    Numerical simulation of the formation of the collector ion flow in a magnetically insulated ion diode (MID) with a hollow cylindrical and cone-shaped cathode was studied. Such cathodes are often used for the production of tubular high current microsecond electron beams. The ions, emitted by the collector and born as a result of ionization of the residual gas by the electron beam, are focused into the cathode plasma region. This effect can adversely influence the diode operation

  14. Flow simulations past helicopters at different flight conditions using low and high order CFD methods

    International Nuclear Information System (INIS)

    Mamou, M.; Xu, H.; Khalid, M.

    2004-01-01

    The present paper contains a comprehensive literature survey on helicopter flow analyses and describes some true unsteady flows past helicopter rotors obtained using low and high order CFD models. The low order model is based on a panel method coupled with a viscous boundary layer approach and a compressibility correction. The USAERO software is used for the computations. The high order model is based on Euler and Navier-Stokes equations. For the high order models, a true unsteady scheme, as implemented in the CFD-FASTRAN code using the Euler equations, is considered for flows past hovering rotor. On the other hand, a quasi-steady approach, using the WIND code with the Navier-Stokes equations and the SST turbulence model, is used to assess the validity of the approach for the simulation of flows past a helicopter in forward flight conditions. When using the high order models, a Chimera grid technique is used to describe the blade motions within the parent stationary grid. Comparisons with experimental data are performed and the true unsteady simulations provide a reasonable agreement with the available experimental data. The panel method and the quasisteady approach are found to overestimate the loads on the helicopter rotors. The USAERO panel code is found to produce more thrust owing to some error sources in the computations when a wake-surface collision occurs, as the blades interact with their own wakes. The automatic cutting of the wake sheets, as they approach the model surface, is not working properly at every time step. (author)

  15. Flow simulations past helicopters at different flight conditions using low and high order CFD methods

    Energy Technology Data Exchange (ETDEWEB)

    Mamou, M.; Xu, H.; Khalid, M. [National Research Council of Canada, Inst. for Aerospace Research, Ottawa, Ontario (Canada)]. E-mail: Mahmoud.Mamou@nrc-cnrc.gc.ca

    2004-07-01

    The present paper contains a comprehensive literature survey on helicopter flow analyses and describes some true unsteady flows past helicopter rotors obtained using low and high order CFD models. The low order model is based on a panel method coupled with a viscous boundary layer approach and a compressibility correction. The USAERO software is used for the computations. The high order model is based on Euler and Navier-Stokes equations. For the high order models, a true unsteady scheme, as implemented in the CFD-FASTRAN code using the Euler equations, is considered for flows past hovering rotor. On the other hand, a quasi-steady approach, using the WIND code with the Navier-Stokes equations and the SST turbulence model, is used to assess the validity of the approach for the simulation of flows past a helicopter in forward flight conditions. When using the high order models, a Chimera grid technique is used to describe the blade motions within the parent stationary grid. Comparisons with experimental data are performed and the true unsteady simulations provide a reasonable agreement with the available experimental data. The panel method and the quasisteady approach are found to overestimate the loads on the helicopter rotors. The USAERO panel code is found to produce more thrust owing to some error sources in the computations when a wake-surface collision occurs, as the blades interact with their own wakes. The automatic cutting of the wake sheets, as they approach the model surface, is not working properly at every time step. (author)

  16. High Pressure Combustion Experimental Facility(HPCEF) for Studies on Combustion in Reactive Flows

    Science.gov (United States)

    2017-12-13

    SECURITY CLASSIFICATION OF: 1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND SUBTITLE 13. SUPPLEMENTARY NOTES 12. DISTRIBUTION AVAILIBILITY STATEMENT 6...Report: High Pressure Combustion Experimental Facility (HPCEF) for Studies on Combustion in Reactive Flows The views, opinions and/or findings... contained in this report are those of the author(s) and should not contrued as an official Department of the Army position, policy or decision, unless so

  17. Ordinary High Flows and the Stage-Discharge Relationship in the Arid West Region

    Science.gov (United States)

    2011-07-01

    other authorized documents. DESTROY THIS REPORT WHEN NO LONGER NEEDED. DO NOT RETURN IT TO THE ORIGINATOR . ERDC/CRREL TR-11-12 iii Table of...occurring physical features such as bedrock banks for higher flows. A more complete description of the types of controls and their significance for...Most precipitation falls as snow Sagebrush; Xerophytic shrub vegetation Aridisols low in humus and high in calcium carbonate Most of the

  18. Application of a Full Reynolds Stress Model to High Lift Flows

    Science.gov (United States)

    Lee-Rausch, E. M.; Rumsey, C. L.; Eisfeld, B.

    2016-01-01

    A recently developed second-moment Reynolds stress model was applied to two challenging high-lift flows: (1) transonic flow over the ONERA M6 wing, and (2) subsonic flow over the DLR-F11 wing-body configuration from the second AIAA High Lift Prediction Workshop. In this study, the Reynolds stress model results were contrasted with those obtained from one- and two{equation turbulence models, and were found to be competitive in terms of the prediction of shock location and separation. For an ONERA M6 case, results from multiple codes, grids, and models were compared, with the Reynolds stress model tending to yield a slightly smaller shock-induced separation bubble near the wing tip than the simpler models, but all models were fairly close to the limited experimental surface pressure data. For a series of high-lift DLR{F11 cases, the range of results was more limited, but there was indication that the Reynolds stress model yielded less-separated results than the one-equation model near maximum lift. These less-separated results were similar to results from the one-equation model with a quadratic constitutive relation. Additional computations need to be performed before a more definitive assessment of the Reynolds stress model can be made.

  19. Mode decomposition methods for flows in high-contrast porous media. Global-local approach

    KAUST Repository

    Ghommem, Mehdi; Presho, Michael; Calo, Victor M.; Efendiev, Yalchin R.

    2013-01-01

    In this paper, we combine concepts of the generalized multiscale finite element method (GMsFEM) and mode decomposition methods to construct a robust global-local approach for model reduction of flows in high-contrast porous media. This is achieved by implementing Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD) techniques on a coarse grid computed using GMsFEM. The resulting reduced-order approach enables a significant reduction in the flow problem size while accurately capturing the behavior of fully-resolved solutions. We consider a variety of high-contrast coefficients and present the corresponding numerical results to illustrate the effectiveness of the proposed technique. This paper is a continuation of our work presented in Ghommem et al. (2013) [1] where we examine the applicability of POD and DMD to derive simplified and reliable representations of flows in high-contrast porous media on fully resolved models. In the current paper, we discuss how these global model reduction approaches can be combined with local techniques to speed-up the simulations. The speed-up is due to inexpensive, while sufficiently accurate, computations of global snapshots. © 2013 Elsevier Inc.

  20. Simulation of flow around a slender body at high angles of attack

    Directory of Open Access Journals (Sweden)

    Obeid Osama

    2017-01-01

    Full Text Available LES of the flow around an ogive-cylinder body at high angles of attack were carried out to investigate the possibility of the development of asymmetric wake-vortex without the introduction of artificial perturbations. The study investigated the effect of grid resolution and scheme bias on the solution. The numerical solution was found to be sensitive to the bias in the numerical scheme. The simulation was carried for angles of attack α = 30°, 40°, 50°, 55°, and 60°. The simulation at α = 30° − 40° produced symmetric wake-vortex. At α = 50°, the wake-vortex is also symmetric but with vortex separation. At α = 60°, the wake-vortex becomes asymmetric. At 60°, the wake-vortex is highly asymmetric with vortex separation and breakdown. It was concluded that asymmetric flow around slender bodies at high angles of attack can be simulated in the absence geometrical or flow perturbations.

  1. Mode decomposition methods for flows in high-contrast porous media. Global-local approach

    KAUST Repository

    Ghommem, Mehdi

    2013-11-01

    In this paper, we combine concepts of the generalized multiscale finite element method (GMsFEM) and mode decomposition methods to construct a robust global-local approach for model reduction of flows in high-contrast porous media. This is achieved by implementing Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD) techniques on a coarse grid computed using GMsFEM. The resulting reduced-order approach enables a significant reduction in the flow problem size while accurately capturing the behavior of fully-resolved solutions. We consider a variety of high-contrast coefficients and present the corresponding numerical results to illustrate the effectiveness of the proposed technique. This paper is a continuation of our work presented in Ghommem et al. (2013) [1] where we examine the applicability of POD and DMD to derive simplified and reliable representations of flows in high-contrast porous media on fully resolved models. In the current paper, we discuss how these global model reduction approaches can be combined with local techniques to speed-up the simulations. The speed-up is due to inexpensive, while sufficiently accurate, computations of global snapshots. © 2013 Elsevier Inc.

  2. Numerical study on increasing mass flow ratio by energy deposition of high frequency pulsed laser

    International Nuclear Information System (INIS)

    Wang Diankai; Hong Yanji; Li Qian

    2013-01-01

    The mass flow ratio (MFR) of air breathing ramjet inlet would be decreased, when the Mach number is lower than the designed value. High frequency pulsed laser energy was deposited upstream of the cowl lip to reflect the stream so as to increase the MFR. When the Mach number of the flow was 5.0, and the static pressure and temperature of the flow were 2 551.6 Pa and 116.7 K, respectively, two-dimensional non-stationary compressible RANS equations were solved with upwind format to study the mechanisms of increasing MFR by high frequency pulsed laser energy deposition. The laser deposition frequency was 100 kHz and the average power was 500 W. The crossing point of the first forebody oblique shock and extension line of cowl lip was selected as the expected point. Then the deposition position was optimized by searching near the expected point. The results indicate that with the optimization of laser energy deposition position, the MFR would be increased from 63% to 97%. The potential value of increasing MFR by high frequency pulsed laser energy deposition was proved. The method for selection of the energy deposition position was also presented. (authors)

  3. A high-pressure plug flow reactor for combustion chemistry investigations

    International Nuclear Information System (INIS)

    Lu, Zhewen; Cochet, Julien; Leplat, Nicolas; Yang, Yi; Brear, Michael J

    2017-01-01

    A plug flow reactor (PFR) is built for investigating the oxidation chemistry of fuels at up to 50 bar and 1000 K. These conditions include those corresponding to the low temperature combustion (i.e. the autoignition) that commonly occurs in internal combustion engines. Turbulent flow that approximates ideal, plug flow conditions is established in a quartz tube reactor. The reacting mixture is highly diluted by excess air to reduce the reaction rates for kinetic investigations. A novel mixer design is used to achieve fast mixing of the preheated air and fuel vapour at the reactor entrance, reducing the issue of reaction initialization in kinetic modelling. A water-cooled probe moves along the reactor extracting gases for further analysis. Measurement of the sampled gas temperature uses an extended form of a three-thermocouple method that corrects for radiative heat losses from the thermocouples to the enclosed PFR environment. Investigation of the PFR’s operation is first conducted using non-reacting flows, and then with isooctane oxidation at 900 K and 10 bar. Mixing of the non-reacting temperature and species fields is shown to be rapid. The measured fuel consumption and CO formation are then closely reproduced by kinetic modelling using an extensively validated iso-octane mechanism from the literature and the corrected gas temperature. Together, these results demonstrate the PFR’s utility for chemical kinetic investigations. (paper)

  4. Design of a high-lift experiment in water including active flow control

    International Nuclear Information System (INIS)

    Beutel, T; Schwerter, M; Büttgenbach, S; Leester-Schädel, M; Sattler, S; El Sayed, Y; Radespiel, R; Zander, M; Sinapius, M; Wierach, P

    2014-01-01

    This paper describes the structural design of an active flow-control experiment. The aim of the experiment is to investigate the increase in efficiency of an internally blown Coanda flap using unsteady blowing. The system uses tailor-made microelectromechanical (MEMS) pressure sensors to determine the state of the oncoming flow and an actuated lip to regulate the mass flow and velocity of a stream near a wall over the internally blown flap. Sensors and actuators are integrated into a highly loaded system that is extremely compact. The sensors are connected to a bus system that feeds the data into a real-time control system. The piezoelectric actuators using the d 33 effect at a comparable low voltage of 120 V are integrated into a lip that controls the blowout slot height. The system is designed for closed-loop control that efficiently avoids flow separation on the Coanda flap. The setup is designed for water-tunnel experiments in order to reduce the free-stream velocity and the system’s control frequency by a factor of 10 compared with that in air. This paper outlines the function and verification of the system’s main components and their development. (technical note)

  5. Thermal Flow and Structure Stability Analyses of High Power Waterload for 2450 MHz microwave applications

    International Nuclear Information System (INIS)

    Seon, S. W.; Kim, H. J.; Wang, S. J.; Kim, J. N.

    2016-01-01

    This study is focused on analyzing the internal flow dynamics in the waterload by changing the inlet and outlet locations and adding guide pipeline to the inlet. The internal flow field simulation is done with CFX tool to compare the water flow velocity and temperature distributions in the waterload. The waterload absorbs RF power, converts it to thermal power, and increases the water temperature so that heat could be quickly removed by the water injection. And it is installed on the end of transmission line and is used to absorb reflected RF power. High power waterload with cone-shaped quartz is designed for 10-30 kW power handling at 2450 MHz microwave system. The thermal flow and structural stability analysis for the 2450 MHz waterload is done using ANSYS and the results are presented in this work. Relocation of the inlet and addition of the guide pipeline in the simulation shows a decrease in the localized maximum water temperature and increased water velocity around the heat source. It is also shown that the modified waterload is structurally more stable

  6. Region-scale groundwater flow modelling of generic high level waste disposal sites

    International Nuclear Information System (INIS)

    Metcalfe, D.

    1996-02-01

    Regional-scale groundwater flow modelling analyses are performed on generic high level waste (HLW) disposal sites to assess the extent to which a large crystalline rock mass such as a pluton or batholith can be expected to contain and isolate HLW in terms of hydraulic considerations, for a variety of geologic and hydrogeologic conditions. The two-dimensional cross-sectional conceptual models of generic HLW disposal sites are evaluated using SWIFT III, which is a finite-difference flow and transport code. All steps leading to the final results and conclusions are incorporated in this report. The available data and information on geological and hydrogeologic conditions in plutons and batholiths are summarized. The generic conceptual models developed from this information are defined in terms of the finite difference grid, the geologic and hydrogeologic properties and the hydrologic boundary conditions used. The modelled results are described with contour maps showing the modelled head fields, groundwater flow paths and travel times and groundwater flux rates within the modelled systems. The results of the modelling analyses are used to develop general conclusions on the scales and patterns of groundwater flow in granitic plutons and batholiths. The conclusions focus on geologic and hydrogeologic characteristics that can result in favourable conditions, in terms of hydraulic considerations, for a HLW repository. (author) 43 refs., 9 tabs., 40 figs

  7. Flow characteristics of a pilot-scale high temperature, short time pasteurizer.

    Science.gov (United States)

    Tomasula, P M; Kozempel, M F

    2004-09-01

    In this study, we present a method for determining the fastest moving particle (FMP) and residence time distribution (RTD) in a pilot-scale high temperature, short time (HTST) pasteurizer to ensure that laboratory or pilot-scale HTST apparatus meets the Pasteurized Milk Ordinance standards for pasteurization of milk and can be used for obtaining thermal inactivation data. The overall dimensions of the plate in the pasteurizer were 75 x 115 mm, with a thickness of 0.5 mm and effective diameter of 3.0 mm. The pasteurizer was equipped with nominal 21.5- and 52.2-s hold tubes, and flow capacity was variable from 0 to 20 L/h. Tracer studies were used to determine FMP times and RTD data to establish flow characteristics. Using brine milk as tracer, the FMP time for the short holding section was 18.6 s and for the long holding section was 36 s at 72 degrees C, compared with the nominal times of 21.5 and 52.2 s, respectively. The RTD study indicates that the short hold section was 45% back mixed and 55% plug flow for whole milk at 72 degrees C. The long hold section was 91% plug and 9% back mixed for whole milk at 72 degrees C. This study demonstrates that continuous laboratory and pilot-scale pasteurizers may be used to study inactivation of microorganisms only if the flow conditions in the holding tube are established for comparison with commercial HTST systems.

  8. High Performance Hydrogen/Bromine Redox Flow Battery for Grid-Scale Energy Storage

    Energy Technology Data Exchange (ETDEWEB)

    Cho, KT; Ridgway, P; Weber, AZ; Haussener, S; Battaglia, V; Srinivasan, V

    2012-01-01

    The electrochemical behavior of a promising hydrogen/bromine redox flow battery is investigated for grid-scale energy-storage application with some of the best redox-flow-battery performance results to date, including a peak power of 1.4 W/cm(2) and a 91% voltaic efficiency at 0.4 W/cm(2) constant-power operation. The kinetics of bromine on various materials is discussed, with both rotating-disk-electrode and cell studies demonstrating that a carbon porous electrode for the bromine reaction can conduct platinum-comparable performance as long as sufficient surface area is realized. The effect of flow-cell designs and operating temperature is examined, and ohmic and mass-transfer losses are decreased by utilizing a flow-through electrode design and increasing cell temperature. Charge/discharge and discharge-rate tests also reveal that this system has highly reversible behavior and good rate capability. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.018211jes] All rights reserved.

  9. A high-pressure plug flow reactor for combustion chemistry investigations

    Science.gov (United States)

    Lu, Zhewen; Cochet, Julien; Leplat, Nicolas; Yang, Yi; Brear, Michael J.

    2017-10-01

    A plug flow reactor (PFR) is built for investigating the oxidation chemistry of fuels at up to 50 bar and 1000 K. These conditions include those corresponding to the low temperature combustion (i.e. the autoignition) that commonly occurs in internal combustion engines. Turbulent flow that approximates ideal, plug flow conditions is established in a quartz tube reactor. The reacting mixture is highly diluted by excess air to reduce the reaction rates for kinetic investigations. A novel mixer design is used to achieve fast mixing of the preheated air and fuel vapour at the reactor entrance, reducing the issue of reaction initialization in kinetic modelling. A water-cooled probe moves along the reactor extracting gases for further analysis. Measurement of the sampled gas temperature uses an extended form of a three-thermocouple method that corrects for radiative heat losses from the thermocouples to the enclosed PFR environment. Investigation of the PFR’s operation is first conducted using non-reacting flows, and then with isooctane oxidation at 900 K and 10 bar. Mixing of the non-reacting temperature and species fields is shown to be rapid. The measured fuel consumption and CO formation are then closely reproduced by kinetic modelling using an extensively validated iso-octane mechanism from the literature and the corrected gas temperature. Together, these results demonstrate the PFR’s utility for chemical kinetic investigations.

  10. Numerical simulation of nonequilibrium flow in high-enthalpy shock tunnel

    Energy Technology Data Exchange (ETDEWEB)

    Kaneko, M.; Men' shov, I.; Nakamura, Y

    2005-03-01

    The flow field of a nozzle starting process with thermal and chemical nonequilibrium has been simulated. This flow is produced in high enthalpy impulse facilities such as the free piston shock tunnel. The governing equations are the axisymmetric, compressible Navier-Stokes equations. In this study, Park's two-temperature model, where air consists of five species, is used for defining the thermodynamic properties of air as a driven gas. The numerical scheme employed here is the hybrid scheme of the explicit and implicit methods, which was developed in our laboratory, along with AUSM{sup +} to evaluate inviscid fluxes. In the present simulation, the Mach number of an incident shock wave is set at M{sub s}=10.0. It corresponds to a specific enthalpy, h{sub 0}, of 12 MJ/kg. The results clearly show the complicated thermal and chemical nonequilibrium flow field around the end of the shock tube section and at the nozzle inlet during the initial stage of the nozzle starting process. They also suggest that the phenomenon of nozzle melting might be associated with a flow separation at the nozzle inlet.

  11. Contribution to the multidimensional modelling of convective high pressure boiling flows for pressurised water reactors

    International Nuclear Information System (INIS)

    Gueguen, J.

    2013-01-01

    This study is a contribution to the modelling of multidimensional high pressure boiling flows relative to PWR. Numerical simulation of such two-phase flows is considered to be an interesting way for the DNB understanding. The first part of this study exposes a two-dimensional steady state two-phase flows model able to predict velocity and temperature profiles in tube. The mixture balanced equations are used with the eddy diffusivity concept to close the turbulent transport terms. The second part is devoted to the development of the model in the general two dimensional case. Contrary to the steady state model, this model is independent of experimental data and implies the use of an original local homogeneous relaxation model (HRM). The results obtained from the comparison with the data bank DEBORA reveals that in a mixture approach two sub models are sufficient to obtain a physical good description of turbulent boiling flows. Some limitations appear at conditions close to DNB conditions. The turbulent closures and the relaxation time in the HRM model have been clearly identified as the most important and sensitive parameters in the model. (author) [fr

  12. Development of a Three-Dimensional Unstructured Euler Solver for High-Speed Flows

    Directory of Open Access Journals (Sweden)

    Tudorel Petronel AFILIPOAE

    2015-12-01

    Full Text Available This paper addresses the solution of the compressible Euler equations on hexahedral meshes for supersonic and hypersonic flows. Spatial discretization is accomplished by a cell-centered finite-volume formulation which employs two different upwind schemes for the computation of convective fluxes. Second-order solutions are attained through a linear state reconstruction technique that yields highly resolved flows in smooth regions while providing a sharp and clean resolution of shocks. The solution gradients required for the higher-order spatial discretization are estimated by a least-square method while Venkatakrishnan limiter is employed to preserve monotonicity and avoid oscillations in the presence of shocks. Furthermore, solutions are advanced in time by an explicit third-order Runge-Kutta scheme and convergence to steady state is accelerated using implicit residual smoothing. Flow around a circular arc in a channel and flow past a circular cylinder are studied and results are presented for various Mach numbers together with comparisons to theoretical and experimental data where possible.

  13. A high-performance carbon nanoparticle-decorated graphite felt electrode for vanadium redox flow batteries

    International Nuclear Information System (INIS)

    Wei, L.; Zhao, T.S.; Zhao, G.; An, L.; Zeng, L.

    2016-01-01

    Highlights: • Propose a carbon nanoparticle-decorated graphite felt electrode for VRFBs. • The energy efficiency is up to 84.8% at 100 mA cm"−"2. • The new electrode allows the peak power density to reach 508 mW cm"−"2. - Abstract: Increasing the performance of vanadium redox flow batteries (VRFBs), especially the energy efficiency and power density, is critically important to reduce the system cost to a level for widespread commercialization. Unlike conventional VRFBs with flow-through structure, in this work we create a VRFB featuring a flow-field structure with a carbon nanoparticle-decorated graphite felt electrode for the battery. This novel structure, exhibiting a significantly reduced ohmic loss through reducing electrode thickness, an increased surface area and improved electrocatalytic activity by coating carbon nanoparticles, allows the energy efficiency up to 84.8% at a current density of as high as 100 mA cm"−"2 and the peak power density to reach a value of 508 mW cm"−"2. In addition, it is demonstrated that the battery with this proposed structure exhibits a substantially improved rate capability and capacity retention as opposed to conventional flow-through structured battery with thick graphite felt electrodes.

  14. Thermal Flow and Structure Stability Analyses of High Power Waterload for 2450 MHz microwave applications

    Energy Technology Data Exchange (ETDEWEB)

    Seon, S. W.; Kim, H. J.; Wang, S. J. [National Fusion Research Institute, Daejeon (Korea, Republic of); Kim, J. N. [KRF, Anyang (Korea, Republic of)

    2016-05-15

    This study is focused on analyzing the internal flow dynamics in the waterload by changing the inlet and outlet locations and adding guide pipeline to the inlet. The internal flow field simulation is done with CFX tool to compare the water flow velocity and temperature distributions in the waterload. The waterload absorbs RF power, converts it to thermal power, and increases the water temperature so that heat could be quickly removed by the water injection. And it is installed on the end of transmission line and is used to absorb reflected RF power. High power waterload with cone-shaped quartz is designed for 10-30 kW power handling at 2450 MHz microwave system. The thermal flow and structural stability analysis for the 2450 MHz waterload is done using ANSYS and the results are presented in this work. Relocation of the inlet and addition of the guide pipeline in the simulation shows a decrease in the localized maximum water temperature and increased water velocity around the heat source. It is also shown that the modified waterload is structurally more stable.

  15. Cadence® High High-Speed PCB Design Flow Workshop

    CERN Document Server

    2006-01-01

    Last release of Cadence High-Speed PCB Design methodology (PE142) based on Concept-HDL schematic editor, Constraint Manager, SPECCTRAQuest signal integrity analysis tool and ALLEGRO layout associated with SPECCTRA auto router tools, is now enough developed and stable to be taken into account for high-speed board designs at CERN. The implementation of this methodology, build around the new Constraint Manager program, is essential when you have to develop a board having a lot of high-speed design rules such as terminated lines, large bus structures, maximum length, timing, crosstalk etc.. that could not be under control by traditional method. On more conventional designs, formal aspect of the methodology could avoid misunderstanding between hardware and ALLEGRO layout designers, minimizing prototype iteration, development time and price. The capability to keep trace of the original digital designer intents in schematic or board layout, loading formal constraints in EDMS, could also be considered for LHC electro...

  16. Model Reduction of Computational Aerothermodynamics for Multi-Discipline Analysis in High Speed Flows

    Science.gov (United States)

    Crowell, Andrew Rippetoe

    This dissertation describes model reduction techniques for the computation of aerodynamic heat flux and pressure loads for multi-disciplinary analysis of hypersonic vehicles. NASA and the Department of Defense have expressed renewed interest in the development of responsive, reusable hypersonic cruise vehicles capable of sustained high-speed flight and access to space. However, an extensive set of technical challenges have obstructed the development of such vehicles. These technical challenges are partially due to both the inability to accurately test scaled vehicles in wind tunnels and to the time intensive nature of high-fidelity computational modeling, particularly for the fluid using Computational Fluid Dynamics (CFD). The aim of this dissertation is to develop efficient and accurate models for the aerodynamic heat flux and pressure loads to replace the need for computationally expensive, high-fidelity CFD during coupled analysis. Furthermore, aerodynamic heating and pressure loads are systematically evaluated for a number of different operating conditions, including: simple two-dimensional flow over flat surfaces up to three-dimensional flows over deformed surfaces with shock-shock interaction and shock-boundary layer interaction. An additional focus of this dissertation is on the implementation and computation of results using the developed aerodynamic heating and pressure models in complex fluid-thermal-structural simulations. Model reduction is achieved using a two-pronged approach. One prong focuses on developing analytical corrections to isothermal, steady-state CFD flow solutions in order to capture flow effects associated with transient spatially-varying surface temperatures and surface pressures (e.g., surface deformation, surface vibration, shock impingements, etc.). The second prong is focused on minimizing the computational expense of computing the steady-state CFD solutions by developing an efficient surrogate CFD model. The developed two

  17. Investigation on asymmetric flow over a blunt-nose slender body at high angle of attack

    Science.gov (United States)

    Zhongyang, Qi; Yankui, Wang; Lei, Wang; Qian, Li

    2017-12-01

    The asymmetric vortices over a blunt-nose slender body are investigated experimentally and numerically at a high angle of attack (AoA, α = 50°) and a Reynolds number of Re D = 1.54 × 105 on the basis of an incoming free-stream velocity and diameter (D) of the model. A micro-perturbation in the form of a hemispherical protrusion with a radius of r = 0.012D is introduced and attached on the nose of the slender body to control the behavior of the asymmetric vortices. Given the predominant role of micro perturbation in the asymmetric vortex pattern, a square wave, which is singly periodic, is observed for side-force variation by setting the circumferential angle (θ) of the micro perturbation from 0° to 360°. The asymmetric vortex pattern and the corresponding side force are manageable and highly dependent on the location of perturbation. The flow structure over the blunt-nose slender body is clarified by building a physical model of asymmetric vortex flow structure in a regular state at a high AoA (α = 50°). This model is divided into several regions by flow structure development along the model body-axis, i.e., inception region at x/D ≤ 3.0, triple-vortex region at 3.0 ≤ x/D ≤ 6.0, four-vortex region at 6.0 ≤ x/D ≤ 8.5, and five-vortex region at 8.5 ≤ x/D ≤ 12. The model reveals a complicated multi-vortex system. The associated pressure distributions and flow characteristics are discussed in detail.

  18. High rates of gene flow by pollen and seed in oak populations across Europe.

    Directory of Open Access Journals (Sweden)

    Sophie Gerber

    Full Text Available Gene flow is a key factor in the evolution of species, influencing effective population size, hybridisation and local adaptation. We analysed local gene flow in eight stands of white oak (mostly Quercus petraea and Q. robur, but also Q. pubescens and Q. faginea distributed across Europe. Adult trees within a given area in each stand were exhaustively sampled (range [239, 754], mean 423, mapped, and acorns were collected ([17,147], 51 from several mother trees ([3], [47], 23. Seedlings ([65,387], 178 were harvested and geo-referenced in six of the eight stands. Genetic information was obtained from screening distinct molecular markers spread across the genome, genotyping each tree, acorn or seedling. All samples were thus genotyped at 5-8 nuclear microsatellite loci. Fathers/parents were assigned to acorns and seedlings using likelihood methods. Mating success of male and female parents, pollen and seed dispersal curves, and also hybridisation rates were estimated in each stand and compared on a continental scale. On average, the percentage of the wind-borne pollen from outside the stand was 60%, with large variation among stands (21-88%. Mean seed immigration into the stand was 40%, a high value for oaks that are generally considered to have limited seed dispersal. However, this estimate varied greatly among stands (20-66%. Gene flow was mostly intraspecific, with large variation, as some trees and stands showed particularly high rates of hybridisation. Our results show that mating success was unevenly distributed among trees. The high levels of gene flow suggest that geographically remote oak stands are unlikely to be genetically isolated, questioning the static definition of gene reserves and seed stands.

  19. Changes to subaqueous delta bathymetry following a high river flow event, Wax Lake Delta, LA, USA

    Science.gov (United States)

    Whaling, A. R.; Shaw, J.

    2017-12-01

    Sediment transport capacity is increased during high river flow (flood) events which are characterized by discharges that exceed the 15 year median daily statistic. The Wax Lake Delta (WLD) in coastal Louisiana has experienced 19 of these high flow events in the past 20 years, yet the depositional patterns of single floods are rarely measured in a field-scale deltaic setting. We characterize flood deposition and erosion patterns on the subaqueous portion of the WLD by differencing two Digital Elevation Models (DEMs) constructed from bathymetric surveys before and after the third largest flood in the WLD's recorded history. The total suspended sediment discharge for the 496 day inter-survey period was 2.14x107 cubic meters measured 21 km upstream of the delta apex. The difference map showed 1.06x107 cubic meters of sediment was deposited and 8.2x106 cubic meters was eroded, yielding 2.40x106 cubic meters of net deposition in the survey area ( 79.7 km2 ). Therefore the average deposition rate was 0.061 mm/day. Channel planform remained relatively unchanged for five out of six distributary passes however Gadwall Pass experienced a maximum channel displacement of 166 m ( 1 channel width) measured from the thalweg centerline. Channel tip extension was negligible. In addition, channel displacement was not concentrated at any portion along the channel centerline. Maximum erosion occurred within channel margins and increased upstream whereas maximum deposition occurred immediately outside the channel margins. Sediment eroded from the survey area was either subsequently re-deposited or transported out of the system. Our results show that up to 77.4% of deposition in the survey area originated from sediment eroded during the flood. Surprisingly, only 11.2% of the total suspended sediment discharge was retained in the subaqueous portion of the delta after the flood. We conclude that a high flow event does not produce channel progradation. Rather, high flow causes delta

  20. Optimization of High-Resolution Continuous Flow Analysis for Transient Climate Signals in Ice Cores

    DEFF Research Database (Denmark)

    Bigler, Matthias; Svensson, Anders; Kettner, Ernesto

    2011-01-01

    Over the past two decades, continuous flow analysis (CFA) systems have been refined and widely used to measure aerosol constituents in polar and alpine ice cores in very high-depth resolution. Here we present a newly designed system consisting of sodium, ammonium, dust particles, and electrolytic...... meltwater conductivity detection modules. The system is optimized for high- resolution determination of transient signals in thin layers of deep polar ice cores. Based on standard measurements and by comparing sections of early Holocene and glacial ice from Greenland, we find that the new system features...

  1. A high-energy-density redox flow battery based on zinc/polyhalide chemistry.

    Science.gov (United States)

    Zhang, Liqun; Lai, Qinzhi; Zhang, Jianlu; Zhang, Huamin

    2012-05-01

    Zn and the Art of Battery Development: A zinc/polyhalide redox flow battery employs Br(-) /ClBr(2-) and Zn/Zn(2+) redox couples in its positive and negative half-cells, respectively. The performance of the battery is evaluated by charge-discharge cycling tests and reveals a high energy efficiency of 81%, based on a Coulombic efficiency of 96% and voltage efficiency of 84%. The new battery technology can provide high performance and energy density at an acceptable cost. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Cool C-shocks and high-velocity flows in molecular clouds

    International Nuclear Information System (INIS)

    Smith, M.D.; Brand, P.W.J.L.

    1990-01-01

    C-shocks can be driven through dense clouds when the neutrals and magnetic field interact weakly due to a paucity of ions. We develop a method for calculating C-shock properties with the aim of interpreting the observed high-velocity molecular hydrogen. A high Mach number approximation, corresponding to low temperatures, is employed. Under strong cooling conditions the flow is continuous even though a subsonic region may be present downstream. Analytic expressions for the maximum temperature, dissociation fraction, self-ionization level and J-shock transition are derived. (author)

  3. Optical Flow-Field Techniques Used for Measurements in High-Speed Centrifugal Compressors

    Science.gov (United States)

    Skoch, Gary J.

    1999-01-01

    The overall performance of a centrifugal compressor depends on the performance of the impeller and diffuser as well as on the interactions occurring between these components. Accurate measurements of the flow fields in each component are needed to develop computational models that can be used in compressor design codes. These measurements must be made simultaneously over an area that covers both components so that researchers can understand the interactions occurring between the two components. Optical measurement techniques are being used at the NASA Lewis Research Center to measure the velocity fields present in both the impeller and diffuser of a 4:1 pressure ratio centrifugal compressor operating at several conditions ranging from design flow to surge. Laser Doppler Velocimetry (LDV) was used to measure the intrablade flows present in the impeller, and the results were compared with analyses obtained from two three-dimensional viscous codes. The development of a region of low throughflow velocity fluid within this high-speed impeller was examined and compared with a similar region first observed in a large low-speed centrifugal impeller at Lewis. Particle Image Velocimetry (PIV) is a relatively new technique that has been applied to measuring the diffuser flow fields. PIV can collect data rapidly in the diffuser while avoiding the light-reflection problems that are often encountered when LDV is used. The Particle Image Velocimeter employs a sheet of pulsed laser light that is introduced into the diffuser in a quasi-radial direction through an optical probe inserted near the diffuser discharge. The light sheet is positioned such that its centerline is parallel to the hub and shroud surfaces and such that it is parallel to the diffuser vane, thereby avoiding reflections from the solid surfaces. Seed particles small enough to follow the diffuser flow are introduced into the compressor at an upstream location. A high-speed charge-coupled discharge (CCD) camera is

  4. A new phase coding method using a slice selection gradient for high speed flow velocity meaurements in NMR tomography

    International Nuclear Information System (INIS)

    Oh, C.H.; Cho, Z.H.; California Univ., Irvine

    1986-01-01

    A new phase coding method using a selection gradient for high speed NMR flow velocity measurements is introduced and discussed. To establish a phase-velocity relationship of flow under the slice selection gradient and spin-echo RF pulse, the Bloch equation was numerically solved under the assumption that only one directional flow exists, i.e. in the direction of slice selection. Details of the numerical solution of the Bloch equation and techniques related to the numerical computations are also given. Finally, using the numerical calculation, high speed flow velocity measurement was attempted and found to be in good agreement with other complementary controlled measurements. (author)

  5. Numerical analysis of high-speed liquid lithium free-surface flow

    International Nuclear Information System (INIS)

    Gordeev, Sergej; Heinzel, Volker; Stieglitz, Robert

    2012-01-01

    Highlights: ► The free surface behavior of a high speed lithium jet is investigated by means of a CFD LES analysis. ► The study is aiming to validate adequate LES technique. ► The Osaka University experiments with liquid lithium jet have been simulated. ► Four cases with jet flow velocities of 4, 9, 13 and 15 m/s are analyzed. ► Calculation results show a good qualitative and a quantitative agreement with the experimental data. - Abstract: The free-surface stability of the target of the International Fusion Material Irradiation Facility (IFMIF) is one of the crucial issues, since the spatio-temporal behavior of the free-surface determines the neutron flux to be generated. This article investigates the relation between the evolution of a wall boundary layer in a convergent nozzle and the free surface shape of a high speed lithium jet by means of a CFD LES analysis using the Osaka University experiments. The study is aiming to validate adequate LES technique to analyze the individual flow phenomena observed. Four cases with jet flow velocities of 4, 9, 13 and 15 m/s are analyzed. First analyses of calculation results show that the simulation exhibits a good qualitative and a quantitative agreement with the experimental data, which allows in the future a more realistic prediction of the IFMIF target behavior.

  6. Experimental and Computational Study of Trapped Vortex Combustor Sector Rig with High-Speed Diffuser Flow

    Directory of Open Access Journals (Sweden)

    R. C. Hendricks

    2001-01-01

    Full Text Available The Trapped Vortex Combustor (TVC potentially offers numerous operational advantages over current production gas turbine engine combustors. These include lower weight, lower pollutant emissions, effective flame stabilization, high combustion efficiency, excellent high altitude relight capability, and operation in the lean burn or RQL modes of combustion. The present work describes the operational principles of the TVC, and extends diffuser velocities toward choked flow and provides system performance data. Performance data include EINOx results for various fuel-air ratios and combustor residence times, combustion efficiency as a function of combustor residence time, and combustor lean blow-out (LBO performance. Computational fluid dynamics (CFD simulations using liquid spray droplet evaporation and combustion modeling are performed and related to flow structures observed in photographs of the combustor. The CFD results are used to understand the aerodynamics and combustion features under different fueling conditions. Performance data acquired to date are favorable compared to conventional gas turbine combustors. Further testing over a wider range of fuel-air ratios, fuel flow splits, and pressure ratios is in progress to explore the TVC performance. In addition, alternate configurations for the upstream pressure feed, including bi-pass diffusion schemes, as well as variations on the fuel injection patterns, are currently in test and evaluation phases.

  7. Characteristics of high-latitude precursor flows ahead of dipolarization fronts

    Science.gov (United States)

    Li, Jia-Zheng; Zhou, Xu-Zhi; Runov, Andrei; Angelopoulos, Vassilis; Liu, Jiang; Pan, Dong-Xiao; Zong, Qiu-Gang

    2017-05-01

    Dipolarization fronts (DFs), earthward propagating structures in the magnetotail current sheet characterized by sharp enhancements of northward magnetic field, are capable of converting electromagnetic energy into particle kinetic energy. The ions previously accelerated and reflected at the DFs can contribute to plasma flows ahead of the fronts, which have been identified as DF precursor flows in both the near-equatorial plasma sheet and far from it, near the plasma sheet boundary. Using observations from the THEMIS (Time History of Events and Macroscale Interactions during Substorms) spacecraft, we show that the earthward particle and energy flux enhancements ahead of DFs are statistically larger farther away from the neutral sheet (at high latitudes) than in the near-equatorial region. High-latitude particle and energy fluxes on the DF dawnside are found to be significantly greater than those on the duskside, which is opposite to the dawn-dusk asymmetries previously found near the equatorial region. Using forward and backward tracing test-particle simulations, we then explain and reproduce the observed latitude-dependent characteristics of DF precursor flows, providing a better understanding of ion dynamics associated with dipolarization fronts.

  8. Multi-resolution Delta-plus-SPH with tensile instability control: Towards high Reynolds number flows

    Science.gov (United States)

    Sun, P. N.; Colagrossi, A.; Marrone, S.; Antuono, M.; Zhang, A. M.

    2018-03-01

    It is well known that the use of SPH models in simulating flow at high Reynolds numbers is limited because of the tensile instability inception in the fluid region characterized by high vorticity and negative pressure. In order to overcome this issue, the δ+-SPH scheme is modified by implementing a Tensile Instability Control (TIC). The latter consists of switching the momentum equation to a non-conservative formulation in the unstable flow regions. The loss of conservation properties is shown to induce small errors, provided that the particle distribution is regular. The latter condition can be ensured thanks to the implementation of a Particle Shifting Technique (PST). The novel variant of the δ+-SPH is proved to be effective in preventing the onset of tensile instability. Several challenging benchmark tests involving flows past bodies at large Reynolds numbers have been used. Within this a simulation characterized by a deforming foil that resembles a fish-like swimming body is used as a practical application of the δ+-SPH model in biological fluid mechanics.

  9. Supercavitating flow around high-speed underwater projectile near free surface induced by air entrainment

    Directory of Open Access Journals (Sweden)

    Chang Xu

    2018-03-01

    Full Text Available Cavitating flow near free surface is a complicated issue and may provide new inspiration on high-speed surface cruising. This study observes stable supercavitating flow as a new phenomenon in a launch experiment of axisymmetric projectile when the upper side of the projectile coincides with the free surface. A numerical approach is established using large eddy-simulation and volume-of-fluid methods, and good agreements are achieved between numerical and experimental results. Supercavity formation mechanism is revealed by analyzing the experiment photographs and the iso-surface of 90% water volume fraction in numerical results. The entrainment of a large amount of air into the cavity can cause the pressure inside the cavity to similarly increase with the pressure outside the cavity, which makes the actual cavitation number close to zero and is similar to supercavitation. Cases with various headforms of the projectile and cavitation numbers on the cavitating flow, as well as the drag reduction effects are further examined. Results indicate that the present strategy near the free surface could possibly be a new effective approach for high-speed cruising after vigorous design optimization in the future.

  10. Void Fraction Measurement in Subcooled-Boiling Flow Using High-Frame-Rate Neutron Radiography

    International Nuclear Information System (INIS)

    Kureta, Masatoshi; Akimoto, Hajime; Hibiki, Takashi; Mishima, Kaichiro

    2001-01-01

    A high-frame-rate neutron radiography (NR) technique was applied to measure the void fraction distribution in forced-convective subcooled-boiling flow. The focus was experimental technique and error estimation of the high-frame-rate NR. The results of void fraction measurement in the boiling flow were described. Measurement errors on instantaneous and time-averaged void fractions were evaluated experimentally and analytically. Measurement errors were within 18 and 2% for instantaneous void fraction (measurement time is 0.89 ms), and time-averaged void fraction, respectively. The void fraction distribution of subcooled boiling was measured using atmospheric-pressure water in rectangular channels with channel width 30 mm, heated length 100 mm, channel gap 3 and 5 mm, inlet water subcooling from 10 to 30 K, and mass velocity ranging from 240 to 2000 kg/(m 2 .s). One side of the channel was heated homogeneously. Instantaneous void fraction and time-averaged void fraction distribution were measured parametrically. The effects of flow parameters on void fraction were investigated

  11. Domain Decomposition Preconditioners for Multiscale Flows in High-Contrast Media

    KAUST Repository

    Galvis, Juan; Efendiev, Yalchin

    2010-01-01

    In this paper, we study domain decomposition preconditioners for multiscale flows in high-contrast media. We consider flow equations governed by elliptic equations in heterogeneous media with a large contrast in the coefficients. Our main goal is to develop domain decomposition preconditioners with the condition number that is independent of the contrast when there are variations within coarse regions. This is accomplished by designing coarse-scale spaces and interpolators that represent important features of the solution within each coarse region. The important features are characterized by the connectivities of high-conductivity regions. To detect these connectivities, we introduce an eigenvalue problem that automatically detects high-conductivity regions via a large gap in the spectrum. A main observation is that this eigenvalue problem has a few small, asymptotically vanishing eigenvalues. The number of these small eigenvalues is the same as the number of connected high-conductivity regions. The coarse spaces are constructed such that they span eigenfunctions corresponding to these small eigenvalues. These spaces are used within two-level additive Schwarz preconditioners as well as overlapping methods for the Schur complement to design preconditioners. We show that the condition number of the preconditioned systems is independent of the contrast. More detailed studies are performed for the case when the high-conductivity region is connected within coarse block neighborhoods. Our numerical experiments confirm the theoretical results presented in this paper. © 2010 Society for Industrial and Applied Mathematics.

  12. Development of localized arc filament RF plasma actuators for high-speed and high Reynolds number flow control

    International Nuclear Information System (INIS)

    Kim, J.-H.; Nishihara, M.; Adamovich, I.V.; Samimy, M.; Gorbatov, S.V.; Pliavaka, F.V.

    2010-01-01

    Recently developed localized arc filament plasma actuators (LAFPAs) have shown tremendous control authority in high-speed and high Reynolds number flow for mixing enhancement and noise mitigation. Previously, these actuators were powered by a high-voltage pulsed DC plasma generator with low energy coupling efficiency of 5-10%. In the present work, a new custom-designed 8-channel pulsed radio frequency (RF) plasma generator has been developed to power up to 8 plasma actuators operated over a wide range of forcing frequencies (up to 50 kHz) and duty cycles (1-50%), and at high energy coupling efficiency (up to 80-85%). This reduces input electrical power requirements by approximately an order of magnitude, down to 12 W per actuator operating at 10% duty cycle. The new pulsed RF plasma generator is scalable to a system with a large number of channels. Performance of pulsed RF plasma actuators used for flow control was studied in a Mach 0.9 circular jet with a Reynolds number of about 623,000 and compared with that of pulsed DC actuators. Eight actuators were distributed uniformly on the perimeter of a 2.54-cm diameter circular nozzle extension. Both types of actuators coupled approximately the same amount of power to the flow, but with drastically different electrical inputs to the power supplies. Particle image velocimetry measurements showed that jet centerline Mach number decay produced by DC and RF actuators operating at the same forcing frequencies and duty cycles is very similar. At a forcing Strouhal number near 0.3, close to the jet column instability frequency, well-organized periodic structures, with similar patterns and dimensions, were generated in the jets forced by both DC and RF actuators. Far-field acoustic measurements demonstrated similar trends in the overall sound pressure level (OASPL) change produced by both types of actuators, resulting in OASPL reduction up to 1.2-1.5 dB in both cases. We conclude that pulsed RF actuators demonstrate flow

  13. Motion of water droplets in the counter flow of high-temperature combustion products

    Science.gov (United States)

    Volkov, R. S.; Strizhak, P. A.

    2018-01-01

    This paper presents the experimental studies of the deceleration, reversal, and entrainment of water droplets sprayed in counter current flow to a rising stream of high-temperature (1100 K) combustion gases. The initial droplets velocities 0.5-2.5 m/s, radii 10-230 μm, relative volume concentrations 0.2·10-4-1.8·10-4 (m3 of water)/(m3 of gas) vary in the ranges corresponding to promising high-temperature (over 1000 K) gas-vapor-droplet applications (for example, polydisperse fire extinguishing using water mist, fog, or appropriate water vapor-droplet veils, thermal or flame treatment of liquids in the flow of combustion products or high-temperature air; creating coolants based on flue gas, vapor and water droplets; unfreezing of granular media and processing of the drossed surfaces of thermal-power equipment; ignition of liquid and slurry fuel droplets). A hardware-software cross-correlation complex, high-speed (up to 105 fps) video recording tools, panoramic optical techniques (Particle Image Velocimetry, Particle Tracking Velocimetry, Interferometric Particle Imagine, Shadow Photography), and the Tema Automotive software with the function of continuous monitoring have been applied to examine the characteristics of the processes under study. The scale of the influence of initial droplets concentration in the gas flow on the conditions and features of their entrainment by high-temperature gases has been specified. The dependencies Red = f(Reg) and Red' = f(Reg) have been obtained to predict the characteristics of the deceleration of droplets by gases at different droplets concentrations.

  14. Dynamic behaviour of high-pressure natural-gas flow in pipelines

    International Nuclear Information System (INIS)

    Gato, L.M.C.; Henriques, J.C.C.

    2005-01-01

    The aim of the present study is the numerical modelling of the dynamic behaviour of high-pressure natural-gas flow in pipelines. The numerical simulation was performed by solving the conservation equations, for one-dimensional compressible flow, using the Runge-Kutta discontinuous Galerkin method, with third-order approximation in space and time. The boundary conditions were imposed using a new weak formulation based on the characteristic variables. The occurrence of pressure oscillations in natural-gas pipelines was studied as a result of the compression wave originated by the rapid closure of downstream shut-off valves. The effect of the partial reflection of pressure waves was also analyzed in the transition between pipes of different cross-sectional areas

  15. Parameterised Model of 2D Combustor Exit Flow Conditions for High-Pressure Turbine Simulations

    Directory of Open Access Journals (Sweden)

    Marius Schneider

    2017-12-01

    Full Text Available An algorithm is presented generating a complete set of inlet boundary conditions for Reynolds-averaged Navier–Stokes computational fluid dynamics (RANS CFD of high-pressure turbines to investigate their interaction with lean and rich burn combustors. The method shall contribute to understanding the sensitivities of turbine aerothermal performance in a systematic approach. The boundary conditions are based on a set of input parameters controlling velocity, temperature, and turbulence fields. All other quantities are derived from operating conditions and additional modelling assumptions. The algorithm is coupled with a CFD solver by applying the generated profiles as inlet boundary conditions. The successive steps to derive consistent flow profiles are described and results are validated against flow fields extracted from combustor CFD.

  16. Multiscale Lattice Boltzmann method for flow simulations in highly heterogenous porous media

    KAUST Repository

    Li, Jun

    2013-01-01

    A lattice Boltzmann method (LBM) for flow simulations in highly heterogeneous porous media at both pore and Darcy scales is proposed in the paper. In the pore scale simulations, flow of two phases (e.g., oil and gas) or two immiscible fluids (e.g., water and oil) are modeled using cohesive or repulsive forces, respectively. The relative permeability can be computed using pore-scale simulations and seamlessly applied for intermediate and Darcy-scale simulations. A multiscale LBM that can reduce the computational complexity of existing LBM and transfer the information between different scales is implemented. The results of coarse-grid, reduced-order, simulations agree very well with the averaged results obtained using fine grid.

  17. Unsaturated flow and transport through fractured rock related to high-level waste repositories

    International Nuclear Information System (INIS)

    Evans, D.D.; Rasmussen, T.C.

    1991-01-01

    Research results are summarized for a US Nuclear Regulatory Commission contract with the University of Arizona focusing on field and laboratory methods for characterizing unsaturated fluid flow and solute transport related to high-level radioactive waste repositories. Characterization activities are presented for the Apache Leap Tuff field site. The field site is located in unsaturated, fractured tuff in central Arizona. Hydraulic, pneumatic, and thermal characteristics of the tuff are summarized, along with methodologies employed to monitor and sample hydrologic and geochemical processes at the field site. Thermohydrologic experiments are reported which provide laboratory and field data related to the effects conditions and flow and transport in unsaturated, fractured rock. 29 refs., 17 figs., 21 tabs

  18. Dynamic behaviour of high-pressure natural-gas flow in pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Gato, L.M.C. [Department of Mechanical Engineering, Instituto Superior Tecnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon (Portugal)]. E-mail: lgato@mail.ist.utl.pt; Henriques, J.C.C. [Department of Mechanical Engineering, Instituto Superior Tecnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon (Portugal)]. E-mail: jcch@mail.ist.utl.pt

    2005-10-01

    The aim of the present study is the numerical modelling of the dynamic behaviour of high-pressure natural-gas flow in pipelines. The numerical simulation was performed by solving the conservation equations, for one-dimensional compressible flow, using the Runge-Kutta discontinuous Galerkin method, with third-order approximation in space and time. The boundary conditions were imposed using a new weak formulation based on the characteristic variables. The occurrence of pressure oscillations in natural-gas pipelines was studied as a result of the compression wave originated by the rapid closure of downstream shut-off valves. The effect of the partial reflection of pressure waves was also analyzed in the transition between pipes of different cross-sectional areas.

  19. Effect of coupling behavior on groundwater flow for geological disposal of radioactive high level waste

    International Nuclear Information System (INIS)

    Kurikami, Hiroshi; Kobayashi, Akira; Ohnishi, Yuzo; Chijimatsu, Masakazu

    2003-01-01

    In order to estimate the effects of coupled thermal-hydraulic-mechanical phenomena in near-field for geological disposal of high-level radioactive waste on a vast groundwater flow system, a far-field analysis was simulated based on the results of the simulation of coupled phenomena in near-field using averaged tensor and heat flux. From the results of the coupled analyses of near-field and far-field it was clarified that groundwater flow system was influenced by coupled phenomena in near-field. Moreover, it can be said that groundwater flux into a disposal tunnel is regarded as a complement to safety assessment of a disposal because it strongly correlates with traveling time of groundwater. (author)

  20. Intriguingly high convective heat transfer enhancement of nanofluid coolants in laminar flows

    Science.gov (United States)

    Xie, Huaqing; Li, Yang; Yu, Wei

    2010-05-01

    We reported on investigation of the convective heat transfer enhancement of nanofluids as coolants in laminar flows inside a circular copper tube with constant wall temperature. Nanofluids containing Al 2O 3, ZnO, TiO 2, and MgO nanoparticles were prepared with a mixture of 55 vol.% distilled water and 45 vol.% ethylene glycol as base fluid. It was found that the heat transfer behaviors of the nanofluids were highly depended on the volume fraction, average size, species of the suspended nanoparticles and the flow conditions. MgO, Al 2O 3, and ZnO nanofluids exhibited superior enhancements of heat transfer coefficient, with the highest enhancement up to 252% at a Reynolds number of 1000 for MgO nanofluid. Our results demonstrated that these oxide nanofluids might be promising alternatives for conventional coolants.

  1. Intriguingly high convective heat transfer enhancement of nanofluid coolants in laminar flows

    International Nuclear Information System (INIS)

    Xie Huaqing; Li Yang; Yu Wei

    2010-01-01

    We reported on investigation of the convective heat transfer enhancement of nanofluids as coolants in laminar flows inside a circular copper tube with constant wall temperature. Nanofluids containing Al 2 O 3 , ZnO, TiO 2 , and MgO nanoparticles were prepared with a mixture of 55 vol.% distilled water and 45 vol.% ethylene glycol as base fluid. It was found that the heat transfer behaviors of the nanofluids were highly depended on the volume fraction, average size, species of the suspended nanoparticles and the flow conditions. MgO, Al 2 O 3 , and ZnO nanofluids exhibited superior enhancements of heat transfer coefficient, with the highest enhancement up to 252% at a Reynolds number of 1000 for MgO nanofluid. Our results demonstrated that these oxide nanofluids might be promising alternatives for conventional coolants.

  2. Intriguingly high convective heat transfer enhancement of nanofluid coolants in laminar flows

    Energy Technology Data Exchange (ETDEWEB)

    Xie Huaqing, E-mail: hqxie@eed.sspu.c [School of Urban Development and Environmental Engineering, Shanghai Second Polytechnic University, Shanghai 201209 (China); Li Yang; Yu Wei [School of Urban Development and Environmental Engineering, Shanghai Second Polytechnic University, Shanghai 201209 (China)

    2010-05-31

    We reported on investigation of the convective heat transfer enhancement of nanofluids as coolants in laminar flows inside a circular copper tube with constant wall temperature. Nanofluids containing Al{sub 2}O{sub 3}, ZnO, TiO{sub 2}, and MgO nanoparticles were prepared with a mixture of 55 vol.% distilled water and 45 vol.% ethylene glycol as base fluid. It was found that the heat transfer behaviors of the nanofluids were highly depended on the volume fraction, average size, species of the suspended nanoparticles and the flow conditions. MgO, Al{sub 2}O{sub 3}, and ZnO nanofluids exhibited superior enhancements of heat transfer coefficient, with the highest enhancement up to 252% at a Reynolds number of 1000 for MgO nanofluid. Our results demonstrated that these oxide nanofluids might be promising alternatives for conventional coolants.

  3. Ventilation of high-speed flows, an alternating methodology for the ventilator design

    International Nuclear Information System (INIS)

    Saldarriaga V, Juan G.; Navarrete, J.; Galeano B, Luis A.

    1996-01-01

    This article is about a research developed at Universidad de los Andes on the ventilation of high velocity flows as prevention against cavitations erosion. The research was a consequence of the results found in the physical model of the Guavio River Hydroelectric Project near Bogota and was based in a general model study of a spillway with ventilation system, which did not represent a particular prototype. In the Guavio study one conclusion was obtained:in every ventilation system there are three unknowns which are the air discharge injected to the water flow (design object variable), the sub pressure under the water jet and the jump length of that jet. In the research those three variables were studied using dimensional analysis and multivariable regressions in order to find a set of three equations that allow the design of this type of structures. The new equations are more general than those reported in technical literature

  4. A magnetically actuated, high momentum rate MEMS pulsed microjet for active flow control

    International Nuclear Information System (INIS)

    Ducloux, O; Viard, R; Talbi, A; Pernod, P; Preobrazhensky, V; Gimeno, L; Merlen, A; Deblock, Y

    2009-01-01

    A small-sized, high momentum rate (>10 −2 N), dynamically actuated microvalve fulfilling the functional specifications for active aerodynamic flow control was designed, fabricated and characterized. The prototype consists of a microfabricated silicon channel pinched by an actuated poly(dimethyl siloxane) (PDMS) polymer membrane. Actuation is provided by coupling an inductive driving coil and a NdFeB permanent magnet fixed on the PDMS elastomeric membrane. The development of a specific microfabrication process, and a complete characterization of the fabricated prototypes are presented in this paper. The yield air microjet performances reach 150 m s −1 for an actuation frequency situated in the range [0 Hz–400 Hz] and an outlet area of about 1 mm 2 . Experimental results also show that the use of a vectoring plate placed at the outlet of the microvalve provided not only easier integration of the microsystem, but also improved the penetration of the microjet into the main flow

  5. High-flow nasal cannula: transient fashion or new method of non-invasive ventilatory assistance?

    Science.gov (United States)

    Mosca, F; Colnaghi, M; Agosti, M; Fumagalli, M

    2012-10-01

    Respiratory failure in the premature infants remains a difficult challenge. An alternative to the use of nasal continuous positive airway pressure (NCPAP) as a non-invasive modality to support respiratory distress in premature infants has been the recent introduction of high flow nasal cannula (HFNC) devices in many neonatal units. There has been increased use of HFNC presumably because of anecdotal reports and experience that it is easy to use, and well tolerated by the infants, while experiencing decreased nasal septumerosion. The paucity of evidence regarding its efficacy and safety, would support a caution approach to the use of HFNC. Particular concern has focused on the imprecise regulation and generation of pressure that may occur at higher flows especially in the smallest of infants.

  6. A high-performance dual-scale porous electrode for vanadium redox flow batteries

    Science.gov (United States)

    Zhou, X. L.; Zeng, Y. K.; Zhu, X. B.; Wei, L.; Zhao, T. S.

    2016-09-01

    In this work, we present a simple and cost-effective method to form a dual-scale porous electrode by KOH activation of the fibers of carbon papers. The large pores (∼10 μm), formed between carbon fibers, serve as the macroscopic pathways for high electrolyte flow rates, while the small pores (∼5 nm), formed on carbon fiber surfaces, act as active sites for rapid electrochemical reactions. It is shown that the Brunauer-Emmett-Teller specific surface area of the carbon paper is increased by a factor of 16 while maintaining the same hydraulic permeability as that of the original carbon paper electrode. We then apply the dual-scale electrode to a vanadium redox flow battery (VRFB) and demonstrate an energy efficiency ranging from 82% to 88% at current densities of 200-400 mA cm-2, which is record breaking as the highest performance of VRFB in the open literature.

  7. Using NIF to Test Theories of High-Pressure, High-Rate Plastic Flow in Metals

    Science.gov (United States)

    Rudd, Robert E.; Arsenlis, A.; Cavallo, R. M.; Huntington, C. M.; McNaney, J. M.; Park, H. S.; Powell, P.; Prisbrey, S. T.; Remington, B. A.; Swift, D.; Wehrenberg, C. E.; Yang, L.

    2017-10-01

    Precisely controlled plasmas are playing key roles both as pump and probe in experiments to understand the strength of solid metals at high energy density (HED) conditions. In concert with theoretical advances, these experiments have enabled a predictive capability to model material strength at Mbar pressures and high strain rates. Here we describe multiscale strength models developed for tantalum starting with atomic bonding and extending up through the mobility of individual dislocations, the evolution of dislocation networks and so on until the ultimate material response at the scale of an experiment. Experiments at the National Ignition Facility (NIF) probe strength in metals ramp compressed to 1-8 Mbar. The model is able to predict 1 Mbar experiments without adjustable parameters. The combination of experiment and theory has shown that solid metals can behave significantly differently at HED conditions. We also describe recent studies of lead compressed to 3-5 Mbar. Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA273.

  8. Analysis of high-speed rotating flow inside gas centrifuge casing

    Science.gov (United States)

    Pradhan, Sahadev

    2017-11-01

    The generalized analytical model for the radial boundary layer inside the gas centrifuge casing in which the inner cylinder is rotating at a constant angular velocity Ωi while the outer one is stationary, is formulated for studying the secondary gas flow field due to wall thermal forcing, inflow/outflow of light gas along the boundaries, as well as due to the combination of the above two external forcing. The analytical model includes the sixth order differential equation for the radial boundary layer at the cylindrical curved surface in terms of master potential (χ) , which is derived from the equations of motion in an axisymmetric (r - z) plane. The linearization approximation is used, where the equations of motion are truncated at linear order in the velocity and pressure disturbances to the base flow, which is a solid-body rotation. Additional approximations in the analytical model include constant temperature in the base state (isothermal compressible Couette flow), high aspect ratio (length is large compared to the annular gap), high Reynolds number, but there is no limitation on the Mach number. The discrete eigenvalues and eigenfunctions of the linear operators (sixth-order in the radial direction for the generalized analytical equation) are obtained. The solutions for the secondary flow is determined in terms of these eigenvalues and eigenfunctions. These solutions are compared with direct simulation Monte Carlo (DSMC) simulations and found excellent agreement (with a difference of less than 15%) between the predictions of the analytical model and the DSMC simulations, provided the boundary conditions in the analytical model are accurately specified.

  9. Use of flow cytometry for high-throughput cell population estimates in fixed brain tissue

    Directory of Open Access Journals (Sweden)

    Nicole A Young

    2012-07-01

    Full Text Available The numbers and types of cells in an area of cortex define its function. Therefore it is essential to characterize the numbers and distributions of total cells in areas of the cortex, as well as to identify numbers of subclasses of neurons and glial cells. To date, the large size of the primate brain and the lack of innovation in cell counting methods have been a roadblock to obtaining high-resolution maps of cell and neuron density across the cortex in humans and non-human primates. Stereological counting methods and the isotropic fractionator are valuable tools for estimating cell numbers, but are better suited to smaller, well-defined brain structures or to cortex as a whole. In the present study, we have extended our flow-cytometry based counting method, the flow fractionator (Collins et al., 2010a, to include high-throughput total cell population estimates in homogenized cortical samples. We demonstrate that our method produces consistent, accurate and repeatable cell estimates quickly. The estimates we report are in excellent agreement with estimates for the same samples obtained using a Neubauer chamber and a fluorescence microscope. We show that our flow cytometry-based method for total cell estimation in homogenized brain tissue is more efficient and more precise than manual counting methods. The addition of automated nuclei counting to our flow fractionator method allows for a fully automated, rapid characterization of total cells and neuronal and non-neuronal populations in human and non-human primate brains, providing valuable data to further our understanding of the functional organization of normal, aging and diseased brains.

  10. High performance parallel computing of flows in complex geometries: I. Methods

    International Nuclear Information System (INIS)

    Gourdain, N; Gicquel, L; Montagnac, M; Vermorel, O; Staffelbach, G; Garcia, M; Boussuge, J-F; Gazaix, M; Poinsot, T

    2009-01-01

    Efficient numerical tools coupled with high-performance computers, have become a key element of the design process in the fields of energy supply and transportation. However flow phenomena that occur in complex systems such as gas turbines and aircrafts are still not understood mainly because of the models that are needed. In fact, most computational fluid dynamics (CFD) predictions as found today in industry focus on a reduced or simplified version of the real system (such as a periodic sector) and are usually solved with a steady-state assumption. This paper shows how to overcome such barriers and how such a new challenge can be addressed by developing flow solvers running on high-end computing platforms, using thousands of computing cores. Parallel strategies used by modern flow solvers are discussed with particular emphases on mesh-partitioning, load balancing and communication. Two examples are used to illustrate these concepts: a multi-block structured code and an unstructured code. Parallel computing strategies used with both flow solvers are detailed and compared. This comparison indicates that mesh-partitioning and load balancing are more straightforward with unstructured grids than with multi-block structured meshes. However, the mesh-partitioning stage can be challenging for unstructured grids, mainly due to memory limitations of the newly developed massively parallel architectures. Finally, detailed investigations show that the impact of mesh-partitioning on the numerical CFD solutions, due to rounding errors and block splitting, may be of importance and should be accurately addressed before qualifying massively parallel CFD tools for a routine industrial use.

  11. Arrayed architectures for multi-stage Si-micromachined high-flow Knudsen pumps

    International Nuclear Information System (INIS)

    Qin, Yutao; An, Seungdo; Gianchandani, Yogesh B

    2015-01-01

    This paper reports an evaluation and a comparison of two architectures for implementing Si-micromachined high-flow Knudsen pumps. Knudsen pumps, which operate on the principle of thermal transpiration, have been shown to have great promise for micro-scale gas phase fluidic systems such as micro gas chromatographs. Simultaneously achieving both a high flow rate and adequate blocking pressure has been a persistent challenge, which is addressed in this work by combining multiple pumps in series and addressing the resulting challenges in thermal management. The basic building block is a Si-micromachined pump with  ≈100 000 parallel channels in a 4 mm  ×  6 mm footprint. In the primary approach, multiple pump stages are stacked vertically with interleaved Si-micromachined spacers. A stacked 4-stage Knudsen pump has a form factor of 10 mm  ×  8 mm  ×  6 mm. In an alternate approach, multiple stages are arranged in a planar array. The experimental results demonstrate multiplication of the output pressure head with the number of stages, while the flow rate is maintained. For example, a stacked 4-stage Knudsen pump with 8 W power operated at atmospheric pressure provided a blocking pressure of 0.255 kPa, which was 3.6  ×  of that provided by a single-stage pump with 2 W power; while both provided a  ≈  30 sccm maximum flow rate. The performance can be customized for practical applications such as micro gas chromatography. (paper)

  12. High-Flow Nasal Interface Improves Oxygenation in Patients Undergoing Bronchoscopy

    Directory of Open Access Journals (Sweden)

    Umberto Lucangelo

    2012-01-01

    Full Text Available During bronchoscopy hypoxemia is commonly found and oxygen supply can be delivered by interfaces fed with high gas flows. Recently, the high-flow nasal cannula (HFNC has been introduced for oxygen therapy in adults, but they have not been used so far during bronchoscopy in adults. Forty-five patients were randomly assigned to 3 groups receiving oxygen: 40 L/min through a Venturi mask (V40, N=15, nasal cannula (N40, N=15, and 60 L/min through a nasal cannula (N60, N=15 during bronchoscopy. Gas exchange and circulatory variables were sampled before (FiO2 = 0.21, at the end of bronchoscopy (FiO2 = 0.5, and thereafter (V40, FiO2 = 0.35. In 8 healthy volunteers oxygen was randomly delivered according to V40, N40, and N60 settings, and airway pressure was measured. At the end of bronchoscopy, N60 presented higher PaO2, PaO2/FiO2, and SpO2 than V40 and N40 that did not differ between them. In the volunteers (N60 median airway pressure amounted to 3.6 cmH2O. Under a flow rate of 40 L/min both the Venturi mask and HFNC behaved similarly, but nasal cannula associated with a 60 L/min flow produced the better results, thus indicating its use in mild respiratory dysfunctions.

  13. An exact and consistent adjoint method for high-fidelity discretization of the compressible flow equations

    Science.gov (United States)

    Subramanian, Ramanathan Vishnampet Ganapathi

    Methods and computing hardware advances have enabled accurate predictions of complex compressible turbulence phenomena, such as the generation of jet noise that motivates the present effort. However, limited understanding of underlying physical mechanisms restricts the utility of such predictions since they do not, by themselves, indicate a route to design improvement. Gradient-based optimization using adjoints can circumvent the flow complexity to guide designs. Such methods have enabled sensitivity analysis and active control of turbulence at engineering flow conditions by providing gradient information at computational cost comparable to that of simulating the flow. They accelerate convergence of numerical design optimization algorithms, though this is predicated on the availability of an accurate gradient of the discretized flow equations. This is challenging to obtain, since both the chaotic character of the turbulence and the typical use of discretizations near their resolution limits in order to efficiently represent its smaller scales will amplify any approximation errors made in the adjoint formulation. Formulating a practical exact adjoint that avoids such errors is especially challenging if it is to be compatible with state-of-the-art simulation methods used for the turbulent flow itself. Automatic differentiation (AD) can provide code to calculate a nominally exact adjoint, but existing general-purpose AD codes are inefficient to the point of being prohibitive for large-scale turbulence simulations. We analyze the compressible flow equations as discretized using the same high-order workhorse methods used for many high-fidelity compressible turbulence simulations, and formulate a practical space--time discrete-adjoint method without changing the basic discretization. A key step is the definition of a particular discrete analog of the continuous norm that defines our cost functional; our selection leads directly to an efficient Runge--Kutta-like scheme

  14. Development of Advanced High Lift Leading Edge Technology for Laminar Flow Wings

    Science.gov (United States)

    Bright, Michelle M.; Korntheuer, Andrea; Komadina, Steve; Lin, John C.

    2013-01-01

    This paper describes the Advanced High Lift Leading Edge (AHLLE) task performed by Northrop Grumman Systems Corporation, Aerospace Systems (NGAS) for the NASA Subsonic Fixed Wing project in an effort to develop enabling high-lift technology for laminar flow wings. Based on a known laminar cruise airfoil that incorporated an NGAS-developed integrated slot design, this effort involved using Computational Fluid Dynamics (CFD) analysis and quality function deployment (QFD) analysis on several leading edge concepts, and subsequently down-selected to two blown leading-edge concepts for testing. A 7-foot-span AHLLE airfoil model was designed and fabricated at NGAS and then tested at the NGAS 7 x 10 Low Speed Wind Tunnel in Hawthorne, CA. The model configurations tested included: baseline, deflected trailing edge, blown deflected trailing edge, blown leading edge, morphed leading edge, and blown/morphed leading edge. A successful demonstration of high lift leading edge technology was achieved, and the target goals for improved lift were exceeded by 30% with a maximum section lift coefficient (Cl) of 5.2. Maximum incremental section lift coefficients ( Cl) of 3.5 and 3.1 were achieved for a blown drooped (morphed) leading edge concept and a non-drooped leading edge blowing concept, respectively. The most effective AHLLE design yielded an estimated 94% lift improvement over the conventional high lift Krueger flap configurations while providing laminar flow capability on the cruise configuration.

  15. LES of High-Reynolds-Number Coanda Flow Separating from a Rounded Trailing Edge of a Circulation Control Airfoil

    Science.gov (United States)

    Nichino, Takafumi; Hahn, Seonghyeon; Shariff, Karim

    2010-01-01

    This slide presentation reviews the Large Eddy Simulation of a high reynolds number Coanda flow that is separated from a round trailing edge of a ciruclation control airfoil. The objectives of the study are: (1) To investigate detailed physics (flow structures and statistics) of the fully turbulent Coanda jet applied to a CC airfoil, by using LES (2) To compare LES and RANS results to figure out how to improve the performance of existing RANS models for this type of flow.

  16. High-temperature plastic flow of a precipitation-hardened FeCoNiCr high entropy alloy

    Energy Technology Data Exchange (ETDEWEB)

    He, J.Y.; Wang, H.; Wu, Y.; Liu, X.J. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Nieh, T.G. [Department of Materials Science and Engineering, the University of Tennessee, Knoxville, TN 37996 (United States); Lu, Z.P., E-mail: luzhaoping@163.com [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China)

    2017-02-16

    In this work, we systematically investigated flow behavior of a high entropy alloy (HEA) strengthened by coherent γ′ precipitates in the temperature range of 1023–1173 K. In contrast to the single-phase FeCoNiCrMn HEA, this precipitate-hardened alloy, i.e., (FeCoNiCr){sub 94}Ti{sub 2}Al{sub 4}, exhibited large reduction of the steady-state strain rate (by ~2 orders of magnitude) or drastic enhancement in flow stress, indicating significant improvement in high-temperature properties. Our results showed that the deformation could be divided into two regimes. At temperatures below 1123 K, coherent γ′ precipitates effectively blocked the dislocation motion, thus resulted in a threshold stress effect. Above 1123 K, however, γ′ particles dissolved and the deformation was controlled by the ordinary dislocation climb mechanism. In addition, we conducted transmission electron microscopy to characterize dislocation-precipitate interaction to provide microstructural evidences to support our conclusion of the specific deformation mechanisms in the two temperature regimes.

  17. Metal-Organic Frameworks as Highly Active Electrocatalysts for High-Energy Density, Aqueous Zinc-Polyiodide Redox Flow Batteries.

    Science.gov (United States)

    Li, Bin; Liu, Jian; Nie, Zimin; Wang, Wei; Reed, David; Liu, Jun; McGrail, Pete; Sprenkle, Vincent

    2016-07-13

    The new aqueous zinc-polyiodide redox flow battery (RFB) system with highly soluble active materials as well as ambipolar and bifunctional designs demonstrated significantly enhanced energy density, which shows great potential to reduce RFB cost. However, the poor kinetic reversibility and electrochemical activity of the redox reaction of I3(-)/I(-) couples on graphite felts (GFs) electrode can result in low energy efficiency. Two nanoporous metal-organic frameworks (MOFs), MIL-125-NH2 and UiO-66-CH3, that have high surface areas when introduced to GF surfaces accelerated the I3(-)/I(-) redox reaction. The flow cell with MOF-modified GFs serving as a positive electrode showed higher energy efficiency than the pristine GFs; increases of about 6.4% and 2.7% occurred at the current density of 30 mA/cm(2) for MIL-125-NH2 and UiO-66-CH3, respectively. Moreover, UiO-66-CH3 is more promising due to its excellent chemical stability in the weakly acidic electrolyte. This letter highlights a way for MOFs to be used in the field of RFBs.

  18. Boiling transition and the possibility of spontaneous nucleation under high subcooling and high mass flux density flow in a tube

    International Nuclear Information System (INIS)

    Fukuyama, Y.; Kuriyama, T.; Hirata, M.

    1986-01-01

    Boiling transition and inverted annular heat transfer for R-113 have been investigated experimentally in a horizontal tube of 1.2 X 10/sup -3/ meter inner diameter with heating length over inner diameter ratio of 50. Experiments cover a high mass flux density range, a high local subcooling range and a wide local pressure range. Heat transfer characteristics were obtained by using heat flux control steady-state apparatus. Film boiling treated here is limited to the case of inverted annular heat transfer with very thin vapor film, on the order of 10/sup -6/ meter. Moreover, film boiling region is always limited to a certain downstream part, since the system has a pressure gradient along the flow direction. Discussions are presented on the parametric trends of boiling heat transfer characteristic curves and characteristic points. The possible existence is suggested of a spontaneous nucleation control surface boiling phenomena. And boiling transition heat flux and inverted annular heat transfer were correlated

  19. Linear drag law for high-Reynolds-number flow past an oscillating body

    Science.gov (United States)

    Agre, Natalie; Childress, Stephen; Zhang, Jun; Ristroph, Leif

    2016-07-01

    An object immersed in a fast flow typically experiences fluid forces that increase with the square of speed. Here we explore how this high-Reynolds-number force-speed relationship is affected by unsteady motions of a body. Experiments on disks that are driven to oscillate while progressing through air reveal two distinct regimes: a conventional quadratic relationship for slow oscillations and an anomalous scaling for fast flapping in which the time-averaged drag increases linearly with flow speed. In the linear regime, flow visualization shows that a pair of counterrotating vortices is shed with each oscillation and a model that views a train of such dipoles as a momentum jet reproduces the linearity. We also show that appropriate scaling variables collapse the experimental data from both regimes and for different oscillatory motions into a single drag-speed relationship. These results could provide insight into the aerodynamic resistance incurred by oscillating wings in flight and they suggest that vibrations can be an effective means to actively control the drag on an object.

  20. Numerical Investigation of Double-Cone Flows with High Enthalpy Effects

    Science.gov (United States)

    Nompelis, I.; Candler, G. V.

    2009-01-01

    A numerical study of shock/shock and shock/boundary layer interactions generated by a double-cone model that is placed in a hypersonic free-stream is presented. Computational results are compared with the experimental measurements made at the CUBRC LENS facility for nitrogen flows at high enthalpy conditions. The CFD predictions agree well with surface pressure and heat-flux measurements for all but one of the double-cone cases that have been studied by the authors. Unsteadiness is observed in computations of one of the LENS cases, however for this case the experimental measurements show that the flowfield is steady. To understand this discrepancy, several double-cone experiments performed in two different facilities with both air and nitrogen as the working gas are examined in the present study. Computational results agree well with measurements made in both the AEDC tunnel 9 and the CUBRC LENS facility for double-cone flows at low free-stream Reynolds numbers where the flow is steady. It is shown that at higher free- stream pressures the double-cone simulations develop instabilities that result in an unsteady separation.

  1. Velocity profile measurement of lead-lithium flows by high-temperature ultrasonic doppler velocimetry

    International Nuclear Information System (INIS)

    Ueki, Y.; Kunugi, T.; Hirabayashi, Masaru; Nagai, Keiichi; Saito, Junichi; Ara, Kuniaki; Morley, N.B.

    2014-01-01

    This paper describes a high-temperature ultrasonic Doppler Velocimetry (HT-UDV) technique that has been successfully applied to measure velocity profiles of the lead-lithium eutectic alloy (PbLi) flows. The impact of tracer particles is investigated to determine requirements for HT-UDV measurement of PbLi flows. The HT-UDV system is tested on a PbLi flow driven by a rotating-disk in an inert atmosphere. We find that a sufficient amount of particles contained in the molten PbLi are required to successfully measure PbLi velocity profiles by HT-UDV. An X-ray diffraction analysis is performed to identify those particles in PbLi, and indicates that those particles were made of the lead mono-oxide (PbO). Since the specific densities of PbLi and PbO are close to each other, the PbO particles are expected to be well-dispersed in the bulk of molten PbLi. We conclude that the excellent dispersion of PbO particles enables in HT-UDV to obtain reliable velocity profiles for operation times of around 12 hours. (author)

  2. Dip Phenomenon in High-Curved Turbulent Flows and Application of Entropy Theory

    Directory of Open Access Journals (Sweden)

    Donatella Termini

    2018-03-01

    Full Text Available The estimation of velocity profile in turbulent open channels is a difficult task due to the significant effects of the secondary flow. The present paper investigates the mechanism of the velocity-dip phenomenon, whereby the location of the maximum velocity appears to be below the free surface. Previous studies conducted in straight channels relate the mechanism of the velocity-dip phenomenon to secondary flow induced by anisotropy of turbulence. This work focuses on high-curved channels where the secondary motion, which is also induced by the channel’s curvature, evolves along the bend. The width-to-depth ratio, B/h, is one of the most important parameters that are affecting the secondary motion entity. In particular, the present study aims to investigate the evolution of the velocity-dip along the bend for two values of the width-to-depth ratio and the applicability of the entropic model for the dip-phenomenon estimation. The results show that the velocity-dip is more accentuated for low values of the width-to-depth ratio, where the secondary motion plays a fundamental role in the distribution of the downstream flow velocity, although the velocity-dip is also present when the aspect ratio is higher than 10. Furthermore, the velocity profiles that were estimated by applying the entropic model are in good agreement with the measured ones, especially for B/h < 10.

  3. A multiscale method for modeling high-aspect-ratio micro/nano flows

    Science.gov (United States)

    Lockerby, Duncan; Borg, Matthew; Reese, Jason

    2012-11-01

    In this paper we present a new multiscale scheme for simulating micro/nano flows of high aspect ratio in the flow direction, e.g. within long ducts, tubes, or channels, of varying section. The scheme consists of applying a simple hydrodynamic description over the entire domain, and allocating micro sub-domains in very small ``slices'' of the channel. Every micro element is a molecular dynamics simulation (or other appropriate model, e.g., a direct simulation Monte Carlo method for micro-channel gas flows) over the local height of the channel/tube. The number of micro elements as well as their streamwise position is chosen to resolve the geometrical features of the macro channel. While there is no direct communication between individual micro elements, coupling occurs via an iterative imposition of mass and momentum-flux conservation on the macro scale. The greater the streamwise scale of the geometry, the more significant is the computational speed-up when compared to a full MD simulation. We test our new multiscale method on the case of a converging/diverging nanochannel conveying a simple Lennard-Jones liquid. We validate the results from our simulations by comparing them to a full MD simulation of the same test case. Supported by EPSRC Programme Grant, EP/I011927/1.

  4. Low flow water quality in rivers; septic tank systems and high-resolution phosphorus signals

    International Nuclear Information System (INIS)

    Macintosh, K.A.; Jordan, P.; Cassidy, R.; Arnscheidt, J.; Ward, C.

    2011-01-01

    Rural point sources of phosphorus (P), including septic tank systems, provide a small part of the overall phosphorus budget to surface waters in agricultural catchments but can have a disproportionate impact on the low flow P concentration of receiving rivers. This has particular importance as the discharges are approximately constant into receiving waters and these have restricted dilution capacity during ecologically sensitive summer periods. In this study, a number of identified high impact septic systems were replaced with modern sequential batch reactors in three rural catchments during a monitoring period of 4 years. Sub-hourly P monitoring was conducted using bankside-analysers. Results show that strategic replacement of defective septic tank systems with modern systems and polishing filters decreased the low flow P concentration of one catchment stream by 0.032 mg TP L −1 (0.018 mg TRP L −1 ) over the 4 years. However two of the catchment mitigation efforts were offset by continued new-builds that increased the density of septic systems from 3.4 km −2 to 4.6 km −2 and 13.8 km −2 to 17.2 km −2 and subsequently increased low flow P concentrations. Future considerations for septic system mitigation should include catchment carrying capacity as well as technology changes.

  5. A Photographic study of subcooled flow boiling burnout at high heat flux and velocity

    Energy Technology Data Exchange (ETDEWEB)

    Celata, G.P.; Mariani, A.; Zummo, G. [ENEA, National Institute of Thermal-Fluid Dynamics, Rome (Italy); Cumo, M. [University of Rome (Italy); Gallo, D. [University of Palermo (Italy). Department of Nuclear Engineering

    2007-01-15

    The present paper reports the results of a visualization study of the burnout in subcooled flow boiling of water, with square cross section annular geometry (formed by a central heater rod contained in a duct characterized by a square cross section). The coolant velocity is in the range 3-10m/s. High speed movies of flow pattern in subcooled flow boiling of water from the onset of nucleate boiling up to physical burnout of the heater are recorded. From video images (single frames taken with a stroboscope light and an exposure time of 1{mu}s), the following general behaviour of vapour bubbles was observed: when the rate of bubble generation is increasing, with bubbles growing in the superheated layer close to the heating wall, their coalescence produces a type of elongated bubble called vapour blanket. One of the main features of the vapour blanket is that it is rooted to the nucleation site on the heated surface. Bubble dimensions are given as a function of thermal-hydraulic tested conditions for the whole range of velocity until the burnout region. A qualitative analysis of the behaviour of four stainless steel heater wires with different macroscopic surface finishes is also presented, showing the importance of this parameter on the dynamics of the bubbles and on the critical heat flux. (author)

  6. Development and application of a particle image velocimeter for high-speed flows

    Science.gov (United States)

    Molezzi, M. J.; Dutton, J. C.

    1992-01-01

    A particle image velocimetry (PIV) system has been developed for use in high-speed separated air flows. The image acquisition system uses two 550 mJ/pulse Nd:YAG lasers and is fully controlled by a host Macintosh computer. The interrogation system is also Macintosh-based and performs interrogations at approximately 2.3 sec/spot and 4.0 sec/spot when using the Young's fringe and autocorrelation methods, respectively. The system has been proven in preliminary experiments using known-displacement simulated PIV photographs and a simple axisymmetric jet flow. Further results have been obtained in a transonic wind tunnel operating at Mach 0.4 to 0.5 (135 m/s to 170 m/s). PIV experiments were done with an empty test section to provide uniform flow data for comparison with pressure and LDV data, then with a two-dimensional base model, revealing features of the von Karman vortex street wake and underlying small scale turbulence.

  7. A Low-Cost, High-Performance System for Fluorescence Lateral Flow Assays

    Directory of Open Access Journals (Sweden)

    Linda G. Lee

    2013-10-01

    Full Text Available We demonstrate a fluorescence lateral flow system that has excellent sensitivity and wide dynamic range. The illumination system utilizes an LED, plastic lenses and plastic and colored glass filters for the excitation and emission light. Images are collected on an iPhone 4. Several fluorescent dyes with long Stokes shifts were evaluated for their signal and nonspecific binding in lateral flow. A wide range of values for the ratio of signal to nonspecific binding was found, from 50 for R-phycoerythrin (R-PE to 0.15 for Brilliant Violet 605. The long Stokes shift of R-PE allowed the use of inexpensive plastic filters rather than costly interference filters to block the LED light. Fluorescence detection with R-PE and absorbance detection with colloidal gold were directly compared in lateral flow using biotinylated bovine serum albumen (BSA as the analyte. Fluorescence provided linear data over a range of 0.4–4,000 ng/mL with a 1,000-fold signal change while colloidal gold provided non-linear data over a range of 16–4,000 ng/mL with a 10-fold signal change. A comparison using human chorionic gonadotropin (hCG as the analyte showed a similar advantage in the fluorescent system. We believe our inexpensive yet high-performance platform will be useful for providing quantitative and sensitive detection in a point-of-care setting.

  8. Molecular Materials for Nonaqueous Flow Batteries with a High Coulombic Efficiency and Stable Cycling.

    Science.gov (United States)

    Milton, Margarita; Cheng, Qian; Yang, Yuan; Nuckolls, Colin; Hernández Sánchez, Raúl; Sisto, Thomas J

    2017-12-13

    This manuscript presents a working redox battery in organic media that possesses remarkable cycling stability. The redox molecules have a solubility over 1 mol electrons/liter, and a cell with 0.4 M electron concentration is demonstrated with steady performance >450 cycles (>74 days). Such a concentration is among the highest values reported in redox flow batteries with organic electrolytes. The average Coulombic efficiency of this cell during cycling is 99.868%. The stability of the cell approaches the level necessary for a long lifetime nonaqueous redox flow battery. For the membrane, we employ a low cost size exclusion cellulose membrane. With this membrane, we couple the preparation of nanoscale macromolecular electrolytes to successfully avoid active material crossover. We show that this cellulose-based membrane can support high voltages in excess of 3 V and extreme temperatures (-20 to 110 °C). These extremes in temperature and voltage are not possible with aqueous systems. Most importantly, the nanoscale macromolecular platforms we present here for our electrolytes can be readily tuned through derivatization to realize the promise of organic redox flow batteries.

  9. Giant High-Flow Type Pulmonary Arteriovenous Malformation: Coil Embolization with Flow Control by Balloon Occlusion and an Anchored Detachable Coil

    International Nuclear Information System (INIS)

    Kanematsu, Masayuki; Kondo, Hiroshi; Goshima, Satoshi; Tsuge, Yusuke; Watanabe, Haruo; Moriyama, Noriyuki

    2012-01-01

    Pulmonary arteriovenous malformations (PAVMs) are often treated by pushable fibered or non-fibered microcoils, using an anchor or scaffold technique or with an Amplatzer plug through a guiding sheath. When performing percutaneous transcatheter microcoil embolization, there is a risk of coil migration, particularly with high-flow type PAVMs. The authors report on a unique treatment in a patient with a giant high-flow PAVM whose nidus had a maximum diameter of 6 cm. A detachable coil, not detached from a delivery wire (an anchored detachable coil), was first placed in the feeding artery under flow control by balloon occlusion, and then multiple microcoils were packed proximally to the anchored detachable coil. After confirming the stability of the microcoils during a gradual deflation of the balloon, we finally released the first detachable coil. The nidus was reduced in size to 15 mm at one year postoperatively.

  10. Stability Improvement of High-Pressure-Ratio Turbocharger Centrifugal Compressor by Asymmetric Flow Control-Part I: Non-Axisymmetrical Flow in Centrifugal Compressor.

    Science.gov (United States)

    Yang, Mingyang; Zheng, Xinqian; Zhang, Yangjun; Bamba, Takahiro; Tamaki, Hideaki; Huenteler, Joern; Li, Zhigang

    2013-03-01

    This is Part I of a two-part paper documenting the development of a novel asymmetric flow control method to improve the stability of a high-pressure-ratio turbocharger centrifugal compressor. Part I focuses on the nonaxisymmetrical flow in a centrifugal compressor induced by the nonaxisymmetrical geometry of the volute while Part II describes the development of an asymmetric flow control method to avoid the stall on the basis of the characteristic of nonaxisymmetrical flow. To understand the asymmetries, experimental measurements and corresponding numerical simulation were carried out. The static pressure was measured by probes at different circumferential and stream-wise positions to gain insights about the asymmetries. The experimental results show that there is an evident nonaxisymmetrical flow pattern throughout the compressor due to the asymmetric geometry of the overhung volute. The static pressure field in the diffuser is distorted at approximately 90 deg in the rotational direction of the volute tongue throughout the diffuser. The magnitude of this distortion slightly varies with the rotational speed. The magnitude of the static pressure distortion in the impeller is a function of the rotational speed. There is a significant phase shift between the static pressure distributions at the leading edge of the splitter blades and the impeller outlet. The numerical steady state simulation neglects the aforementioned unsteady effects found in the experiments and cannot predict the phase shift, however, a detailed asymmetric flow field structure is obviously obtained.

  11. Development of Modal Analysis for the Study of Global Modes in High Speed Boundary Layer Flows

    Science.gov (United States)

    Brock, Joseph Michael

    Boundary layer transition for compressible flows remains a challenging and unsolved problem. In the context of high-speed compressible flow, transitional and turbulent boundary-layers produce significantly higher surface heating caused by an increase in skin-friction. The higher heating associated with transitional and turbulent boundary layers drives thermal protection systems (TPS) and mission trajectory bounds. Proper understanding of the mechanisms that drive transition is crucial to the successful design and operation of the next generation spacecraft. Currently, prediction of boundary-layer transition is based on experimental efforts and computational stability analysis. Computational analysis, anchored by experimental correlations, offers an avenue to assess/predict stability at a reduced cost. Classical methods of Linearized Stability Theory (LST) and Parabolized Stability Equations (PSE) have proven to be very useful for simple geometries/base flows. Under certain conditions the assumptions that are inherent to classical methods become invalid and the use of LST/PSE is inaccurate. In these situations, a global approach must be considered. A TriGlobal stability analysis code, Global Mode Analysis in US3D (GMAUS3D), has been developed and implemented into the unstructured solver US3D. A discussion of the methodology and implementation will be presented. Two flow configurations are presented in an effort to validate/verify the approach. First, stability analysis for a subsonic cylinder wake is performed and results compared to literature. Second, a supersonic blunt cone is considered to directly compare LST/PSE analysis and results generated by GMAUS3D.

  12. Coupling amplified DNA from flow-sorted chromosomes to high-density SNP mapping in barley

    Directory of Open Access Journals (Sweden)

    Bartoš Jan

    2008-06-01

    Full Text Available Abstract Background Flow cytometry facilitates sorting of single chromosomes and chromosome arms which can be used for targeted genome analysis. However, the recovery of microgram amounts of DNA needed for some assays requires sorting of millions of chromosomes which is laborious and time consuming. Yet, many genomic applications such as development of genetic maps or physical mapping do not require large DNA fragments. In such cases time-consuming de novo sorting can be minimized by utilizing whole-genome amplification. Results Here we report a protocol optimized in barley including amplification of DNA from only ten thousand chromosomes, which can be isolated in less than one hour. Flow-sorted chromosomes were treated with proteinase K and amplified using Phi29 multiple displacement amplification (MDA. Overnight amplification in a 20-microlitre reaction produced 3.7 – 5.7 micrograms DNA with a majority of products between 5 and 30 kb. To determine the purity of sorted fractions and potential amplification bias we used quantitative PCR for specific genes on each chromosome. To extend the analysis to a whole genome level we performed an oligonucleotide pool assay (OPA for interrogation of 1524 loci, of which 1153 loci had known genetic map positions. Analysis of unamplified genomic DNA of barley cv. Akcent using this OPA resulted in 1426 markers with present calls. Comparison with three replicates of amplified genomic DNA revealed >99% concordance. DNA samples from amplified chromosome 1H and a fraction containing chromosomes 2H – 7H were examined. In addition to loci with known map positions, 349 loci with unknown map positions were included. Based on this analysis 40 new loci were mapped to 1H. Conclusion The results indicate a significant potential of using this approach for physical mapping. Moreover, the study showed that multiple displacement amplification of flow-sorted chromosomes is highly efficient and representative which

  13. Improved Diffuse Fluorescence Flow Cytometer Prototype for High Sensitivity Detection of Rare Circulating Cells In Vivo

    Science.gov (United States)

    Pestana, Noah Benjamin

    Accurate quantification of circulating cell populations is important in many areas of pre-clinical and clinical biomedical research, for example, in the study of cancer metastasis or the immune response following tissue and organ transplants. Normally this is done "ex-vivo" by drawing and purifying a small volume of blood and then analyzing it with flow cytometry, hemocytometry or microfludic devices, but the sensitivity of these techniques are poor and the process of handling samples has been shown to affect cell viability and behavior. More recently "in vivo flow cytometry" (IVFC) techniques have been developed where fluorescently-labeled cells flowing in a small blood vessel in the ear or retina are analyzed, but the sensitivity is generally poor due to the small sampling volume. To address this, our group recently developed a method known as "Diffuse Fluorescence Flow Cytometry" (DFFC) that allows detection and counting of rare circulating cells with diffuse photons, offering extremely high single cell counting sensitivity. In this thesis, an improved DFFC prototype was designed and validated. The chief improvements were three-fold, i) improved optical collection efficiency, ii) improved detection electronics, and iii) development of a method to mitigate motion artifacts during in vivo measurements. In combination, these improvements yielded an overall instrument detection sensitivity better than 1 cell/mL in vivo, which is the most sensitive IVFC system reported to date. Second, development and validation of a low-cost microfluidic device reader for analysis of ocular fluids is described. We demonstrate that this device has equivalent or better sensitivity and accuracy compared a fluorescence microscope, but at an order-of-magnitude reduced cost with simplified operation. Future improvements to both instruments are also discussed.

  14. Large-eddy simulation/Reynolds-averaged Navier-Stokes hybrid schemes for high speed flows

    Science.gov (United States)

    Xiao, Xudong

    Three LES/RANS hybrid schemes have been proposed for the prediction of high speed separated flows. Each method couples the k-zeta (Enstrophy) BANS model with an LES subgrid scale one-equation model by using a blending function that is coordinate system independent. Two of these functions are based on turbulence dissipation length scale and grid size, while the third one has no explicit dependence on the grid. To implement the LES/RANS hybrid schemes, a new rescaling-reintroducing method is used to generate time-dependent turbulent inflow conditions. The hybrid schemes have been tested on a Mach 2.88 flow over 25 degree compression-expansion ramp and a Mach 2.79 flow over 20 degree compression ramp. A special computation procedure has been designed to prevent the separation zone from expanding upstream to the recycle-plane. The code is parallelized using Message Passing Interface (MPI) and is optimized for running on IBM-SP3 parallel machine. The scheme was validated first for a flat plate. It was shown that the blending function has to be monotonic to prevent the RANS region from appearing in the LES region. In the 25 deg ramp case, the hybrid schemes provided better agreement with experiment in the recovery region. Grid refinement studies demonstrated the importance of using a grid independent blend function and further improvement with experiment in the recovery region. In the 20 deg ramp case, with a relatively finer grid, the hybrid scheme characterized by grid independent blending function well predicted the flow field in both the separation region and the recovery region. Therefore, with "appropriately" fine grid, current hybrid schemes are promising for the simulation of shock wave/boundary layer interaction problems.

  15. High-flow, low-head pumps provide safe passage for Pacific salmon

    International Nuclear Information System (INIS)

    Anon

    2004-01-01

    The installation of 29 ultra-low head, high capacity submersible pump and auxiliary equipment at the Rocky Reach Dam in Washington State to allow juvenile salmon safe passage on their journey down the Columbia River to the Pacific Ocean is described. The reputed cost of the project is US$160 million; its purpose is to get juvenile salmon safely around the Rocky Reach Dam without interfering with the dam's original mission of generating electric power. The project is the most expensive fish bypass on any Columbia River dam. Getting the salmon safely around the dam is intended to reduce the impact of hydroelectric power projects on the basin's salmon stocks which are now estimated at less than 10 per cent of their historic size, despite major hatchery programs. The Columbia River has the second largest volume flow of any river in the United States, and millions of people depend on it for employment in water-related industries, and for transportation. The new horizontally installed propeller pump was developed by ITT Flygt; it utilizes planetary gear reduced to match the motor speed with the propeller rpm. Each 90 kW propeller pump has a flow rate of seven cubic meters per second at a head of 0.55 metres. The auxiliary equipment includes 10 racks of flap gates to prevent reverse flow, electric controls, remote supervision, testing, installation and maintenance facilities. It is anticipated that the new bypass will allow the Chelan County Public Utility Department, owners of the facility, to phase out all current spills, except for a 16 per cent spill for 40 days each spring for Sockeye salmon which tend to travel too deep to use the bypass. Prior to installation of this new facility, 60 to 70 per cent of average daily flow in the spring and summer had to be sacrificed to accommodate all species of salmon and steelhead, with corresponding losses of power generating capacity

  16. Humidification performance of two high-flow nasal cannula devices: a bench study.

    Science.gov (United States)

    Chikata, Yusuke; Izawa, Masayo; Okuda, Nao; Itagaki, Taiga; Nakataki, Emiko; Onodera, Mutsuo; Imanaka, Hideaki; Nishimura, Masaji

    2014-08-01

    Delivering heated and humidified medical gas at 20-60 L/min, high-flow nasal cannula (HFNC) creates low levels of PEEP and ameliorates respiratory mechanics. It has become a common therapy for patients with respiratory failure. However, independent measurement of heat and humidity during HFNC and comparison of HFNC devices are lacking. We evaluated 2 HFNC (Airvo 2 and Optiflow system) devices. Each HFNC was connected to simulated external nares using the manufacturer's standard circuit. The Airvo 2 outlet-chamber temperature was set at 37°C. The Optiflow system incorporated an O2/air blender and a heated humidifier, which was set at 40°C/3. For both systems, HFNC flow was tested at 20, 40, and 50 L/min. Simulating spontaneous breathing using a mechanical ventilator and TTL test lung, we tested tidal volumes (VT) of 300, 500, and 700 mL, and breathing frequencies of 10 and 20 breaths/min. The TTL was connected to the simulated external nares with a standard ventilator circuit. To prevent condensation, the circuit was placed in an incubator maintained at 37°C. Small, medium, and large nasal prongs were tested. Absolute humidity (AH) of inspired gas was measured at the simulated external nares. At 20, 40, and 50 L/min of flow, respective AH values for the Airvo 2 were 35.3 ± 2.0, 37.1 ± 2.2, and 37.6 ± 2.1 mg/L, and for the Optiflow system, 33.1 ± 1.5, 35.9 ± 1.7, and 36.2 ± 1.8 mg/L. AH was lower at 20 L/min of HFNC flow than at 40 and 50 L/min (P 30 mg/L.

  17. High Resolution DNS of Turbulent Flows using an Adaptive, Finite Volume Method

    Science.gov (United States)

    Trebotich, David

    2014-11-01

    We present a new computational capability for high resolution simulation of incompressible viscous flows. Our approach is based on cut cell methods where an irregular geometry such as a bluff body is intersected with a rectangular Cartesian grid resulting in cut cells near the boundary. In the cut cells we use a conservative discretization based on a discrete form of the divergence theorem to approximate fluxes for elliptic and hyperbolic terms in the Navier-Stokes equations. Away from the boundary the method reduces to a finite difference method. The algorithm is implemented in the Chombo software framework which supports adaptive mesh refinement and massively parallel computations. The code is scalable to 200,000 + processor cores on DOE supercomputers, resulting in DNS studies at unprecedented scale and resolution. For flow past a cylinder in transition (Re = 300) we observe a number of secondary structures in the far wake in 2D where the wake is over 120 cylinder diameters in length. These are compared with the more regularized wake structures in 3D at the same scale. For flow past a sphere (Re = 600) we resolve an arrowhead structure in the velocity in the near wake. The effectiveness of AMR is further highlighted in a simulation of turbulent flow (Re = 6000) in the contraction of an oil well blowout preventer. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Advanced Scientific Computing Research, Applied Mathematics program under Contract Number DE-AC02-05-CH11231.

  18. Investigation of a zirconia co-fired ceramic calorimetric microsensor for high-temperature flow measurements

    International Nuclear Information System (INIS)

    Lekholm, Ville; Persson, Anders; Klintberg, Lena; Thornell, Greger

    2015-01-01

    This paper describes the design, fabrication and characterization of a flow sensor for high-temperature, or otherwise aggressive, environments, like, e.g. the propulsion system of a small spacecraft. The sensor was fabricated using 8 mol% yttria stabilized zirconia (YSZ8) high-temperature co-fired ceramic (HTCC) tape and screen printed platinum paste. A calorimetric flow sensor design was used, with five 80 µm wide conductors, separated by 160 µm, in a 0.4 mm wide, 0.1 mm deep and 12.5 mm long flow channel. The central conductor was used as a heater for the sensor, and the two adjacent conductors were used to resistively measure the heat transferred from the heater by forced convection. The two outermost conductors were used to study the influence of an auxiliary heat source on the sensor. The resistances of the sensor conductors were measured using four-point connections, as the gas flow rate was slowly increased from 0 to 40 sccm, with different power supplied through the central heater, as well as with an upstream or downstream heater powered. In this study, the thermal and electrical integrability of microcomponents on the YSZ8 substrate was of particular interest and, hence, the influence of thermal and ionic conduction in the substrate was studied in detail. The effect of the ion conductivity of YSZ8 was studied by measuring the resistance of a platinum conductor and the resistance between two adjacent conductors on YSZ8, in a furnace at temperatures from 20 to 930 °C and by measuring the resistance with increasing current through a conductor. With this design, the influence of ion conductivity through the substrate became apparent above 700 °C. The sensitivity of the sensor was up to 1 mΩ sccm −1 in a range of 0–10 sccm. The results show that the signal from the sensor is influenced by the integrated auxiliary heating conductors and that these auxiliary heaters provide a way to balance disturbing heat sources, e.g. thrusters or other

  19. A Novel Tool for High-Throughput Screening of Granulocyte-Specific Antibodies Using the Automated Flow Cytometric Granulocyte Immunofluorescence Test (Flow-GIFT

    Directory of Open Access Journals (Sweden)

    Xuan Duc Nguyen

    2011-01-01

    Full Text Available Transfusion-related acute lung injury (TRALI is a severe complication related with blood transfusion. TRALI has usually been associated with antibodies against leukocytes. The flow cytometric granulocyte immunofluorescence test (Flow-GIFT has been introduced for routine use when investigating patients and healthy blood donors. Here we describe a novel tool in the automation of the Flow-GIFT that enables a rapid screening of blood donations. We analyzed 440 sera from healthy female blood donors for the presence of granulocyte antibodies. As positive controls, 12 sera with known antibodies against anti-HNA-1a, -b, -2a; and -3a were additionally investigated. Whole-blood samples from HNA-typed donors were collected and the test cells isolated using cell sedimentation in a Ficoll density gradient. Subsequently, leukocytes were incubated with the respective serum and binding of antibodies was detected using FITC-conjugated antihuman antibody. 7-AAD was used to exclude dead cells. Pipetting steps were automated using the Biomek NXp Multichannel Automation Workstation. All samples were prepared in the 96-deep well plates and analyzed by flow cytometry. The standard granulocyte immunofluorescence test (GIFT and granulocyte agglutination test (GAT were also performed as reference methods. Sixteen sera were positive in the automated Flow-GIFT, while five of these sera were negative in the standard GIFT (anti—HNA 3a, n = 3; anti—HNA-1b, n = 1 and GAT (anti—HNA-2a, n = 1. The automated Flow-GIFT was able to detect all granulocyte antibodies, which could be only detected in GIFT in combination with GAT. In serial dilution tests, the automated Flow-GIFT detected the antibodies at higher dilutions than the reference methods GIFT and GAT. The Flow-GIFT proved to be feasible for automation. This novel high-throughput system allows an effective antigranulocyte antibody detection in a large donor population in order to prevent TRALI due to transfusion of

  20. A novel tool for high-throughput screening of granulocyte-specific antibodies using the automated flow cytometric granulocyte immunofluorescence test (Flow-GIFT).

    Science.gov (United States)

    Nguyen, Xuan Duc; Dengler, Thomas; Schulz-Linkholt, Monika; Klüter, Harald

    2011-02-03

    Transfusion-related acute lung injury (TRALI) is a severe complication related with blood transfusion. TRALI has usually been associated with antibodies against leukocytes. The flow cytometric granulocyte immunofluorescence test (Flow-GIFT) has been introduced for routine use when investigating patients and healthy blood donors. Here we describe a novel tool in the automation of the Flow-GIFT that enables a rapid screening of blood donations. We analyzed 440 sera from healthy female blood donors for the presence of granulocyte antibodies. As positive controls, 12 sera with known antibodies against anti-HNA-1a, -b, -2a; and -3a were additionally investigated. Whole-blood samples from HNA-typed donors were collected and the test cells isolated using cell sedimentation in a Ficoll density gradient. Subsequently, leukocytes were incubated with the respective serum and binding of antibodies was detected using FITC-conjugated antihuman antibody. 7-AAD was used to exclude dead cells. Pipetting steps were automated using the Biomek NXp Multichannel Automation Workstation. All samples were prepared in the 96-deep well plates and analyzed by flow cytometry. The standard granulocyte immunofluorescence test (GIFT) and granulocyte agglutination test (GAT) were also performed as reference methods. Sixteen sera were positive in the automated Flow-GIFT, while five of these sera were negative in the standard GIFT (anti-HNA 3a, n = 3; anti-HNA-1b, n = 1) and GAT (anti-HNA-2a, n = 1). The automated Flow-GIFT was able to detect all granulocyte antibodies, which could be only detected in GIFT in combination with GAT. In serial dilution tests, the automated Flow-GIFT detected the antibodies at higher dilutions than the reference methods GIFT and GAT. The Flow-GIFT proved to be feasible for automation. This novel high-throughput system allows an effective antigranulocyte antibody detection in a large donor population in order to prevent TRALI due to transfusion of blood products.

  1. High Accuracy Acoustic Relative Humidity Measurement inDuct Flow with Air

    Directory of Open Access Journals (Sweden)

    Cees van der Geld

    2010-08-01

    Full Text Available An acoustic relative humidity sensor for air-steam mixtures in duct flow is designed and tested. Theory, construction, calibration, considerations on dynamic response and results are presented. The measurement device is capable of measuring line averaged values of gas velocity, temperature and relative humidity (RH instantaneously, by applying two ultrasonic transducers and an array of four temperature sensors. Measurement ranges are: gas velocity of 0–12 m/s with an error of ±0.13 m/s, temperature 0–100 °C with an error of ±0.07 °C and relative humidity 0–100% with accuracy better than 2 % RH above 50 °C. Main advantage over conventional humidity sensors is the high sensitivity at high RH at temperatures exceeding 50 °C, with accuracy increasing with increasing temperature. The sensors are non-intrusive and resist highly humid environments.

  2. High accuracy acoustic relative humidity measurement in duct flow with air.

    Science.gov (United States)

    van Schaik, Wilhelm; Grooten, Mart; Wernaart, Twan; van der Geld, Cees

    2010-01-01

    An acoustic relative humidity sensor for air-steam mixtures in duct flow is designed and tested. Theory, construction, calibration, considerations on dynamic response and results are presented. The measurement device is capable of measuring line averaged values of gas velocity, temperature and relative humidity (RH) instantaneously, by applying two ultrasonic transducers and an array of four temperature sensors. Measurement ranges are: gas velocity of 0-12 m/s with an error of ± 0.13 m/s, temperature 0-100 °C with an error of ± 0.07 °C and relative humidity 0-100% with accuracy better than 2 % RH above 50 °C. Main advantage over conventional humidity sensors is the high sensitivity at high RH at temperatures exceeding 50 °C, with accuracy increasing with increasing temperature. The sensors are non-intrusive and resist highly humid environments.

  3. Diffuse interfacelets in transcritical flows of propellants into high-pressure combustors

    Science.gov (United States)

    Urzay, Javier; Jofre, Lluis

    2017-11-01

    Rocket engines and new generations of high-power jet engines and diesel engines oftentimes involve the injection of one or more reactants at subcritical temperatures into combustor environments at high pressures, and more particularly, at pressures higher than those corresponding to the critical points of the individual components of the mixture, which typically range from 13 to 50 bars for most propellants. This class of trajectories in the thermodynamic space has been traditionally referred to as transcritical. Under particular conditions often found in hydrocarbon-fueled chemical propulsion systems, and despite the prevailing high pressures, the flow in the combustor may contain regions close to the injector where a diffuse interface is formed in between the fuel and oxidizer streams that is sustained by surface-tension forces as a result of the elevation of the critical pressure of the mixture. This talk describes progress towards modeling these effects in the conservation equations. Funded by the US Department of Energy.

  4. Implicit high-order discontinuous Galerkin method with HWENO type limiters for steady viscous flow simulations

    Science.gov (United States)

    Jiang, Zhen-Hua; Yan, Chao; Yu, Jian

    2013-08-01

    Two types of implicit algorithms have been improved for high order discontinuous Galerkin (DG) method to solve compressible Navier-Stokes (NS) equations on triangular grids. A block lower-upper symmetric Gauss-Seidel (BLU-SGS) approach is implemented as a nonlinear iterative scheme. And a modified LU-SGS (LLU-SGS) approach is suggested to reduce the memory requirements while retain the good convergence performance of the original LU-SGS approach. Both implicit schemes have the significant advantage that only the diagonal block matrix is stored. The resulting implicit high-order DG methods are applied, in combination with Hermite weighted essentially non-oscillatory (HWENO) limiters, to solve viscous flow problems. Numerical results demonstrate that the present implicit methods are able to achieve significant efficiency improvements over explicit counterparts and for viscous flows with shocks, and the HWENO limiters can be used to achieve the desired essentially non-oscillatory shock transition and the designed high-order accuracy simultaneously.

  5. Numerical simulations of helium flow through prismatic fuel elements of very high temperature reactors

    International Nuclear Information System (INIS)

    Ribeiro, Felipe Lopes; Pinto, Joao Pedro C.T.A.

    2013-01-01

    The 4 th generation Very High Temperature Reactor (VHTR) most popular concept uses a graphite-moderated and helium cooled core with an outlet gas temperature of approximately 1000 deg C. The high output temperature allows the use of the process heat and the production of hydrogen through the thermochemical iodine-sulfur process as well as highly efficient electricity generation. There are two concepts of VHTR core: the prismatic block and the pebble bed core. The prismatic block core has two popular concepts for the fuel element: multihole and annular. In the multi-hole fuel element, prismatic graphite blocks contain cylindrical flow channels where the helium coolant flows removing heat from cylindrical fuel rods positioned in the graphite. In the other hand, the annular type fuel element has annular channels around the fuel. This paper shows the numerical evaluations of prismatic multi-hole and annular VHTR fuel elements and does a comparison between the results of these assembly reactors. In this study the analysis were performed using the CFD code ANSYS CFX 14.0. The simulations were made in 1/12 fuel element models. A numerical validation was performed through the energy balance, where the theoretical and the numerical generated heat were compared for each model. (author)

  6. Flow boiling heat transfer on nanowire-coated surfaces with highly wetting liquid

    International Nuclear Information System (INIS)

    Shin, Sangwoo; Choi, Geehong; Kim, Beom Seok; Cho, Hyung Hee

    2014-01-01

    Owing to the recent advances in nanotechnology, one significant progress in energy technology is increased cooling ability. It has recently been shown that nanowires can improve pool boiling heat transfer due to the unique features such as enhanced wetting and enlarged nucleation sites. Applying such nanowires on a flow boiling, which is another major class of boiling phenomenon that is associated with forced convection, is yet immature and scarce despite its importance in various applications such as liquid cooling of energy, electronics and refrigeration systems. Here, we investigate flow boiling heat transfer on surfaces that are coated with SiNWs (silicon nanowires). Also, we use highly-wetting dielectric liquid, FC-72, as a working fluid. An interesting wetting behavior is observed where the presence of SiNWs reduces wetting and wicking that in turn leads to significant decrease of CHF (critical heat flux) compared to the plain surface, which opposes the current consensus. Also, the effects of nanowire length and Reynolds number on the boiling heat transfer are shown to be highly nonmonotonic. We attempt to explain such an unusual behavior on the basis of wetting, nucleation and forced convection, and we show that such factors are highly coupled in a way that lead to unusual behavior. - Highlights: • Observation of suppressed wettability in the presence of surface roughness (nanowires). • Significant reduction of critical heat flux in the presence of nanowires. • Nonmonotonic behavior of heat transfer coefficient vs. nanowire length and Reynolds number

  7. Genetic search for an optimal power flow solution from a high density cluster

    Energy Technology Data Exchange (ETDEWEB)

    Amarnath, R.V. [Hi-Tech College of Engineering and Technology, Hyderabad (India); Ramana, N.V. [JNTU College of Engineering, Jagityala (India)

    2008-07-01

    This paper proposed a novel method to solve optimal power flow (OPF) problems. The method is based on a genetic algorithm (GA) search from a High Density Cluster (GAHDC). The algorithm of the proposed method includes 3 stages, notably (1) a suboptimal solution is obtained via a conventional analytical method, (2) a high density cluster, which consists of other suboptimal data points from the first stage, is formed using a density-based cluster algorithm, and (3) a genetic algorithm based search is carried out for the exact optimal solution from a low population sized, high density cluster. The final optimal solution thoroughly satisfies the well defined fitness function. A standard IEEE 30-bus test system was considered for the simulation study. Numerical results were presented and compared with the results of other approaches. It was concluded that although there is not much difference in numerical values, the proposed method has the advantage of minimal computational effort and reduced CPU time. As such, the method would be suitable for online applications such as the present Optimal Power Flow problem. 24 refs., 2 tabs., 4 figs.

  8. Enabling high-rate electrochemical flow capacitors based on mesoporous carbon microspheres suspension electrodes

    Science.gov (United States)

    Tian, Meng; Sun, Yueqing; Zhang, Chuanfang (John); Wang, Jitong; Qiao, Wenming; Ling, Licheng; Long, Donghui

    2017-10-01

    Electrochemical flow capacitor (EFC) is a promising technology for grid energy storage, which combines the fast charging/discharging capability of supercapacitors with the scalable energy capacity of flow batteries. In this study, we report a high-power-density EFC using mesoporous carbon microspheres (MCMs) as suspension electrodes. By using a simple yet effective spray-drying technique, monodispersed MCMs with average particle size of 5 μm, high BET surface area of 1150-1267 m2 g-1, large pore volume of 2-4 cm3 g-1 and controllable mesopore size of 7-30 nm have been successfully prepared. The resultant MCMs suspension electrode shows excellent stability and considerable high capacitance of 100 F g-1 and good cycling ability (86% of initial capacitance after 10000 cycles). Specially, the suspension electrode exhibits excellent rate performance with 75% capacitance retention from 2 to 100 mV s-1, significantly higher than that of microporous carbon electrodes (20∼30%), due to the developed mesoporous channels facilitating for rapid ion diffusion. In addition, the electrochemical responses on both negative and positive suspension electrodes are studied, based on which an optimal capacitance matching between them is suggested for large-scale EFC unit.

  9. A Case of Pneumothorax due to High-Flow Nasal Cannula Oxygen Therapy

    Directory of Open Access Journals (Sweden)

    Çapan Konca

    2017-08-01

    Full Text Available Invasive and noninvasive mechanical ventilation (MV applications are used for patients with respiratory insufficiency. Noninvasive MV has been increasingly used in pediatric intensive care units in recent years. For this purpose, high-flow nasal cannula (HFNC oxygen therapy is a treatment method that has been increasingly used. Despite the numerous studies reporting the advantages of this method, there are also a few studies reporting that undesirable conditions can be observed. In this paper, in order to contribute to the literature, we present a 3-month-old baby who developed pneumothorax during HFNC implementation.

  10. A high-order solver for aerodynamic flow simulations and comparison of different numerical schemes

    Science.gov (United States)

    Mikhaylov, Sergey; Morozov, Alexander; Podaruev, Vladimir; Troshin, Alexey

    2017-11-01

    An implementation of high order of accuracy Discontinuous Galerkin method is presented. Reconstruction is done for the conservative variables. Gradients are calculated using the BR2 method. Coordinate transformations are done by serendipity elements. In computations with schemes of order higher than 2, curvature of the mesh lines is taken into account. A comparison with finite volume methods is performed, including WENO method with linear weights and single quadrature point on a cell side. The results of the following classical tests are presented: subsonic flow around a circular cylinder in an ideal gas, convection of two-dimensional isentropic vortex, and decay of the Taylor-Green vortex.

  11. Versatile, High Quality and Scalable Continuous Flow Production of Metal-Organic Frameworks

    Science.gov (United States)

    Rubio-Martinez, Marta; Batten, Michael P.; Polyzos, Anastasios; Carey, Keri-Constanti; Mardel, James I.; Lim, Kok-Seng; Hill, Matthew R.

    2014-01-01

    Further deployment of Metal-Organic Frameworks in applied settings requires their ready preparation at scale. Expansion of typical batch processes can lead to unsuccessful or low quality synthesis for some systems. Here we report how continuous flow chemistry can be adapted as a versatile route to a range of MOFs, by emulating conditions of lab-scale batch synthesis. This delivers ready synthesis of three different MOFs, with surface areas that closely match theoretical maxima, with production rates of 60 g/h at extremely high space-time yields. PMID:24962145

  12. Interactive Data Exploration for High-Performance Fluid Flow Computations through Porous Media

    KAUST Repository

    Perovic, Nevena

    2014-09-01

    © 2014 IEEE. Huge data advent in high-performance computing (HPC) applications such as fluid flow simulations usually hinders the interactive processing and exploration of simulation results. Such an interactive data exploration not only allows scientiest to \\'play\\' with their data but also to visualise huge (distributed) data sets in both an efficient and easy way. Therefore, we propose an HPC data exploration service based on a sliding window concept, that enables researches to access remote data (available on a supercomputer or cluster) during simulation runtime without exceeding any bandwidth limitations between the HPC back-end and the user front-end.

  13. Liquid Hydrogen Regulated Low Pressure High Flow Pneumatic Panel AFT Arrow Analysis

    Science.gov (United States)

    Jones, Kelley, M.

    2013-01-01

    Project Definition: Design a high flow pneumatic regulation panel to be used with helium and hydrogen. The panel will have two circuits, one for gaseous helium (GHe) supplied from the GHe Movable Storage Units (MSUs) and one for gaseous hydrogen (GH2) supplied from an existing GH2 Fill Panel. The helium will supply three legs; to existing panels and on the higher pressure leg and Simulated Flight Tanks (SFTs) for the lower pressure legs. The hydrogen line will pressurize a 33,000 gallon vacuum jacketed vessel.

  14. Effects of Injection Timing on Fluid Flow Characteristics of Partially Premixed Combustion Based on High-Speed Particle Image Velocimetry

    KAUST Repository

    Izadi Najafabadi, Mohammad; Tanov, Slavey; Wang, Hua; Somers, Bart; Johansson, Bengt; Dam, Nico

    2017-01-01

    behavior. The scope of the present study is to investigate the fluid flow characteristics of PPC at different injection timings. To this end, high-speed Particle Image Velocimetry (PIV) is implemented in a light-duty optical engine to measure fluid flow

  15. High-Flow Vascular Malformation in the Sigmoid Mesentery Successfully Treated with a Combination of Transarterial and Transvenous Embolization

    Energy Technology Data Exchange (ETDEWEB)

    Kamo, Minobu, E-mail: kamomino@luke.ac.jp; Yagihashi, Kunihiro [St. Luke’s International Hospital, Department of Radiology (Japan); Okamoto, Takeshi; Nakamura, Kenji; Fujita, Yoshiyuki [St. Luke’s International Hospital, Department of Gastroenterology (Japan); Kurihara, Yasuyuki [St. Luke’s International Hospital, Department of Radiology (Japan)

    2016-12-15

    Mesenteric high-flow vascular malformation can cause various clinical symptoms and demand specific therapeutic interventions owing to its peculiar hemodynamics. We report a case of high-flow vascular malformation in the sigmoid mesentery which presented with ischemic colitis. The main trunk of the inferior mesenteric vein was occluded. After partially effective transarterial embolization, transvenous embolization was performed using a microballoon catheter advanced to the venous component of the lesion via the marginal vein. Complete occlusion of the lesion was achieved. Combination of transarterial and transvenous embolization may allow us to apply endovascular treatment to a wider variety of high-flow lesions in the area and possibly avoid the bowel resection.

  16. Impact of climate change on the stream flow of the lower Brahmaputra: trends in high and low flows based on discharge-weighted ensemble modelling

    Directory of Open Access Journals (Sweden)

    A. K. Gain

    2011-05-01

    Full Text Available Climate change is likely to have significant effects on the hydrology. The Ganges-Brahmaputra river basin is one of the most vulnerable areas in the world as it is subject to the combined effects of glacier melt, extreme monsoon rainfall and sea level rise. To what extent climate change will impact river flow in the Brahmaputra basin is yet unclear, as climate model studies show ambiguous results. In this study we investigate the effect of climate change on both low and high flows of the lower Brahmaputra. We apply a novel method of discharge-weighted ensemble modeling using model outputs from a global hydrological models forced with 12 different global climate models (GCMs. Our analysis shows that only a limited number of GCMs are required to reconstruct observed discharge. Based on the GCM outputs and long-term records of observed flow at Bahadurabad station, our method results in a multi-model weighted ensemble of transient stream flow for the period 1961–2100. Using the constructed transients, we subsequently project future trends in low and high river flow. The analysis shows that extreme low flow conditions are likely to occur less frequent in the future. However a very strong increase in peak flows is projected, which may, in combination with projected sea level change, have devastating effects for Bangladesh. The methods presented in this study are more widely applicable, in that existing multi-model streamflow simulations from global hydrological models can be weighted against observed streamflow data to assess at first order the effects of climate change for specific river basins.

  17. Construction of Low Dissipative High Order Well-Balanced Filter Schemes for Non-Equilibrium Flows

    Science.gov (United States)

    Wang, Wei; Yee, H. C.; Sjogreen, Bjorn; Magin, Thierry; Shu, Chi-Wang

    2009-01-01

    The goal of this paper is to generalize the well-balanced approach for non-equilibrium flow studied by Wang et al. [26] to a class of low dissipative high order shock-capturing filter schemes and to explore more advantages of well-balanced schemes in reacting flows. The class of filter schemes developed by Yee et al. [30], Sjoegreen & Yee [24] and Yee & Sjoegreen [35] consist of two steps, a full time step of spatially high order non-dissipative base scheme and an adaptive nonlinear filter containing shock-capturing dissipation. A good property of the filter scheme is that the base scheme and the filter are stand alone modules in designing. Therefore, the idea of designing a well-balanced filter scheme is straightforward, i.e., choosing a well-balanced base scheme with a well-balanced filter (both with high order). A typical class of these schemes shown in this paper is the high order central difference schemes/predictor-corrector (PC) schemes with a high order well-balanced WENO filter. The new filter scheme with the well-balanced property will gather the features of both filter methods and well-balanced properties: it can preserve certain steady state solutions exactly; it is able to capture small perturbations, e.g., turbulence fluctuations; it adaptively controls numerical dissipation. Thus it shows high accuracy, efficiency and stability in shock/turbulence interactions. Numerical examples containing 1D and 2D smooth problems, 1D stationary contact discontinuity problem and 1D turbulence/shock interactions are included to verify the improved accuracy, in addition to the well-balanced behavior.

  18. Resistance calculation of un-fully developed two-phase flow through high differential pressure regulating valves

    International Nuclear Information System (INIS)

    Xu Mingyang; Wang Wenran; Wang Jiaying

    1999-01-01

    To reduce the flow velocity in the high differential pressure regulating valve with labyrinth. A type of complicated valve core structure were designed with tortuous flow path made from reversal double elbows. It is very difficult to calculate the pressure-drop of the un-fully developed two-phase flow under high temperature and pressure which flow through the valve core. A calculation method called 'constant (varing) pressure-drop progressing step by step design method' was developed. The complicated flow path was disintegrated into a series of independent resistance units and with the valve stem end progressing step by step the dimensions of the flow path were designed in accordance with the principle that in every position the total pressure-drop of the valve should amount to that required by the design goal curve. In the course of calculating the total pressure-drop, the valve flow path was also divided into a series of independent resistance units. The experiment results show that design flow characteristics are approximately consistent with the flow characteristics measured in the test

  19. Intermittent aerosol delivery to the lungs during high-flow nasal cannula therapy.

    Science.gov (United States)

    Golshahi, Laleh; Longest, P Worth; Azimi, Mandana; Syed, Aamer; Hindle, Michael

    2014-10-01

    Use of submicrometer particles combined with condensational growth techniques has been proposed to reduce drug losses within components of high-flow nasal cannula therapy systems and to enhance the dose reaching the lower respiratory tract. These methods have been evaluated using continuous inhalation flow rather than realistic inhalation/exhalation breathing cycles. The goal of this study was to evaluate in vitro aerosol drug delivery using condensational growth techniques during high-flow nasal cannula therapy using realistic breathing profiles and incorporating intermittent aerosol delivery techniques. A mixer-heater combined with a vibrating mesh nebulizer was used to generate a submicrometer aerosol using a formulation of 0.2% albuterol sulfate and 0.2% sodium chloride in water. Delivery efficiency of the aerosol for 1 min through a nasal cannula was considered using an intermittent delivery regime with aerosol being emitted for either the entire inhalation time (2 s) or half of the inhalation period (1 s) and compared with continuous delivery. The deposition of the aerosol was evaluated in the nasal delivery components (ventilator tubing and cannula) and an in vitro adult nose-mouth-throat (NMT) model using 3 realistic breathing profiles. Significant improvements in dose delivered to the exit of the NMT model (ex-NMT) were observed for both condensational growth methods using intermittent aerosol delivery compared with continuous delivery, and increasing the tidal volume was found useful. The combination of the largest tidal volume with the shortest intermittent delivery time resulted in the lowest respiration losses and the highest ex-NMT delivered dose. Intermittent aerosol delivery using realistic breathing profiles of submicrometer condensational growth aerosols was found to be efficient in delivering nasally administered drugs in an in vitro airway model. Copyright © 2014 by Daedalus Enterprises.

  20. Embolization techniques for high-flow arteriovenous malformations with a dominant outflow vein.

    Science.gov (United States)

    Conway, Allan M; Qato, Khalil; Drury, Jennifer; Rosen, Robert J

    2015-04-01

    The aim of this study was to assess the management and outcomes of arteriovenous malformations (AVMs) with a dominant outflow vein (DOV) treated with retrograde venous embolization. A retrospective review was performed from November 2010 to May 2014 on all patients with a high-flow AVM and associated DOV who underwent transvenous embolization of the DOV. Indications, techniques, complications, and outcomes were reviewed. Fourteen patients (five male; 36%) underwent transvenous embolization of high-flow AVMs with a DOV. Median age was 41.6 years (15.7-65.8 years). The AVM was located on an extremity in eight patients (57%) and in the pelvis in six patients (43%). The indication for the procedure was pain in 11 patients (79%), swelling in 3 patients (21%), a nonhealing wound in 1 patient (7%), and impotence in 1 patient (7%). The median number of prior procedures to treat the AVM was 2.5 (0-13). Transvenous embolization with coils was performed in 13 patients (93%). The Amplatzer vascular plug and Amplatzer septal occluder (St. Jude Medical, St. Paul, Minn) were used in four patients (29%). Concurrent percutaneous puncture embolization of the AVM nidus was used in seven patients (50%) and transcatheter arterial embolization in eight patients (57%). Technical angiographic success was seen in all patients. Five patients (36%) experienced a complete response to treatment, whereas eight (57%) experienced a partial response. Seven patients (50%) required further procedures for residual symptoms. AVMs with a DOV can be successfully treated by a transvenous approach. Percutaneous puncture embolization of the nidus or draining vein and transcatheter arterial embolization may assist in reducing flow. Copyright © 2015 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

  1. Experimental heat transfer to supercritical carbon dioxide flowing upward vertical tube with highly conducting surroundings

    International Nuclear Information System (INIS)

    Son, Hyung M.; Suh, Kune Y.

    2012-01-01

    Highlights: ► Performed experiment for the upward SCO 2 flow surrounded by highly conducting metal. ► Selected dimensionless groups representing the property variations and buoyancy. ► Developed the heat transfer correlation for the mixed thermal boundary condition. ► Wrote a finite element heat transfer code to find the appropriate correlation. ► Coupled the 1D convection and 2D heat conduction via heat transfer coefficient. - Abstract: This paper presents heat transfer characteristics of supercritical carbon dioxide flow inside vertical circular pipe surrounded by highly conducting material, and develops an adequate tool to test the performance of available heat transfer correlations with. The possible situations are illustrated for the nuclear power plant to which the above-mentioned geometric configuration might be applicable. An experimental loop with vertical circular geometry is designed and constructed to test the upward flow in supercritical state when the axial heat transfer is enhanced by the surrounding metals, resulting in a wall boundary condition between the constant heat flux and temperature. The set of correlations and important findings are critically reviewed from extensive literature survey. Incorporating nondimensional groups resorting to past insights from the available literature, a convective heat transfer correlation is proposed. The optimization procedure is described which utilizes a random walk method along with the in-house finite element heat transfer code to determine the coefficients of the proposed heat transfer correlation. The proposed methodology can be applied to evaluation of heat transfer when the heat transfer coefficient data cannot directly be determined from the experiment.

  2. Real-Time, Non-Intrusive Detection of Liquid Nitrogen in Liquid Oxygen at High Pressure and High Flow

    Science.gov (United States)

    Singh, Jagdish P.; Yueh, Fang-Yu; Kalluru, Rajamohan R.; Harrison, Louie

    2012-01-01

    An integrated fiber-optic Raman sensor has been designed for real-time, nonintrusive detection of liquid nitrogen in liquid oxygen (LOX) at high pressures and high flow rates in order to monitor the quality of LOX used during rocket engine ground testing. The integrated sensor employs a high-power (3-W) Melles Griot diode-pumped, solid-state (DPSS), frequency-doubled Nd:YAG 532- nm laser; a modified Raman probe that has built-in Raman signal filter optics; two high-resolution spectrometers; and photomultiplier tubes (PMTs) with selected bandpass filters to collect both N2 and O2 Raman signals. The PMT detection units are interfaced with National Instruments Lab- VIEW for fast data acquisition. Studies of sensor performance with different detection systems (i.e., spectrometer and PMT) were carried out. The concentration ratio of N2 and O2 can be inferred by comparing the intensities of the N2 and O2 Raman signals. The final system was fabricated to measure N2 and O2 gas mixtures as well as mixtures of liquid N2 and LOX

  3. Microbiological contamination in high and low flow oxygen humidifiers: A systematic review.

    Science.gov (United States)

    de la Fuente-Sancho, I; Romeu-Bordas, Ó; Fernández-Aedo, I; Vallejo De la Hoz, G; Ballesteros-Peña, S

    2017-12-16

    To determine the risk of microbiological contamination with hospital use high- and low-flow bubbling humidifiers. A systematic literature review was carried out in 6 databases. Observational or experimental studies published between 1990 and 2016 were selected, written in English or Spanish, and in which microbiological contamination with hospital use high- and low-flow bubbling humidifiers was investigated. A total of 12 articles were included: 4 analyzed the water from reusable humidifiers, 4 analyzed the water from prefilled system humidifiers, and the rest compared samples from both models. Microbial contamination was observed in all studies in which reusable humidifiers were evaluated, usually involving common bacteria from the skin flora, while potential pathogenic species were notified in 2 studies. No microbial contamination was isolated from reusable humidifiers, regardless of whether they had been consecutively used over time by a single patient or by several patients. On one hand, there seems to be a low risk of contamination during the first weeks of use of prefilled humidifiers, which allows multiple use in different patients, without a risk of cross-contamination. On the other hand, it should be underscored that handling reusable humidifiers without correct aseptic measures can increase the risk of contamination; replacing reusable humidifiers with prefilled models therefore could be the safest option. Copyright © 2017. Publicado por Elsevier España, S.L.U.

  4. High-pressure plastic scintillation detector for measuring radiogenic gases in flow systems

    International Nuclear Information System (INIS)

    Schell, W.R.; Tobin, M.J.; Vives-Batlle, J.; Yoon, S.R.

    1999-01-01

    Radioactive gases are emitted into the atmosphere from nuclear electric power and nuclear fuel reprocessing plants, from hospitals discarding xenon used in diagnostic medicine, as well as from nuclear weapons tests. A high-pressure plastic scintillation detector was constructed to measure atmospheric levels of such radioactive gases by detecting the beta and internal conversion (IC) electron decays. Operational tests and calibrations were made that permit integration of the flow detectors into a portable Gas Analysis, Separation and Purification system (GASP). The equipment developed can be used for measuring fission gases released from nuclear reactor sources and/or as part of monitoring equipment for enforcing the Comprehensive Test Ban Treaty. The detector is being used routinely for in-line gas separation efficiency measurements, at the elevated operational pressures used for the high-pressure swing analysis system (2070 kPa) and at flow rates of 5-15 l/min. This paper presents the design features, operational methods, calibration, and detector applications. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  5. High-pressure plastic scintillation detector for measuring radiogenic gases in flow systems

    Science.gov (United States)

    Schell, W. R.; Vives-Batlle, J.; Yoon, S. R.; Tobin, M. J.

    1999-02-01

    Radioactive gases are emitted into the atmosphere from nuclear electric power and nuclear fuel reprocessing plants, from hospitals discarding xenon used in diagnostic medicine, as well as from nuclear weapons tests. A high-pressure plastic scintillation detector was constructed to measure atmospheric levels of such radioactive gases by detecting the beta and internal conversion (IC) electron decays. Operational tests and calibrations were made that permit integration of the flow detectors into a portable Gas Analysis, Separation and Purification system (GASP). The equipment developed can be used for measuring fission gases released from nuclear reactor sources and/or as part of monitoring equipment for enforcing the Comprehensive Test Ban Treaty. The detector is being used routinely for in-line gas separation efficiency measurements, at the elevated operational pressures used for the high-pressure swing analysis system (2070 kPa) and at flow rates of 5-15 l/min [1, 2]. This paper presents the design features, operational methods, calibration, and detector applications.

  6. High-pressure plastic scintillation detector for measuring radiogenic gases in flow systems

    International Nuclear Information System (INIS)

    Schell, W.R.; Vives-Batlle, J.; Yoon, S.R; Tobin, M.J.

    1999-01-01

    Radioactive gases are emitted into the atmosphere from nuclear electric power and nuclear fuel reprocessing plants, from hospitals discarding xenon used in diagnostic medicine, as well as from nuclear weapons tests. A high-pressure plastic scintillation detector was constructed to measure atmospheric levels of such radioactive gases by detecting the beta and internal conversion (IC) electron decays. Operational tests and calibrations were made that permit integration of the flow detectors into a portable Gas Analysis, Separation and Purification system (GASP). The equipment developed can be used for measuring fission gases released from nuclear reactor sources and/or as part of monitoring equipment for enforcing the Comprehensive Test Ban Treaty. The detector is being used routinely for in-line gas separation efficiency measurements, at the elevated operational pressures used for the high-pressure swing analysis system (2070 kPa) and at flow rates of 5-15 l/min . This paper presents the design features, operational methods, calibration, and detector applications

  7. Significant Improvements in Pyranometer Nighttime Offsets Using High-Flow DC Ventilation

    Energy Technology Data Exchange (ETDEWEB)

    Kutchenreiter, Mark; Michalski, J.J.; Long, C.N.; Habte, Aron

    2017-05-22

    Accurate solar radiation measurements using pyranometers are required to understand radiative impacts on the Earth's energy budget, solar energy production, and to validate radiative transfer models. Ventilators of pyranometers, which are used to keep the domes clean and dry, also affect instrument thermal offset accuracy. This poster presents a high-level overview of the ventilators for single-black-detector pyranometers and black-and-white pyranometers. For single-black-detector pyranometers with ventilators, high-flow-rate (50-CFM and higher), 12-V DC fans lower the offsets, lower the scatter, and improve the predictability of nighttime offsets compared to lower-flow-rate (35-CFM), 120-V AC fans operated in the same type of environmental setup. Black-and-white pyranometers, which are used to measure diffuse horizontal irradiance, sometimes show minor improvement with DC fan ventilation, but their offsets are always small, usually no more than 1 W/m2, whether AC- or DC-ventilated.

  8. Effects of variable specific heat on energy transfer in a high-temperature supersonic channel flow

    Science.gov (United States)

    Chen, Xiaoping; Li, Xiaopeng; Dou, Hua-Shu; Zhu, Zuchao

    2018-05-01

    An energy transfer mechanism in high-temperature supersonic turbulent flow for variable specific heat (VSH) condition through turbulent kinetic energy (TKE), mean kinetic energy (MKE), turbulent internal energy (TIE) and mean internal energy (MIE) is proposed. The similarities of energy budgets between VSH and constant specific heat (CSH) conditions are investigated by introducing a vibrational energy excited degree and considering the effects of fluctuating specific heat. Direct numerical simulation (DNS) of temporally evolving high-temperature supersonic turbulent channel flow is conducted at Mach number 3.0 and Reynolds number 4800 combined with a constant dimensional wall temperature 1192.60 K for VSH and CSH conditions to validate the proposed energy transfer mechanism. The differences between the terms in the two kinetic energy budgets for VSH and CSH conditions are small; however, the magnitude of molecular diffusion term for VSH condition is significantly smaller than that for CSH condition. The non-negligible energy transfer is obtained after neglecting several small terms of diffusion, dissipation and compressibility related. The non-negligible energy transfer involving TIE includes three processes, in which energy can be gained from TKE and MIE and lost to MIE. The same non-negligible energy transfer through TKE, MKE and MIE is observed for both the conditions.

  9. Transcatheter embolization for high blood flow vascular malformations of oral maxillofacial region

    International Nuclear Information System (INIS)

    Sun Zengtao; Liu Zuoqin; Li Jijun; Tang Jun; Shang Jianqiang; Chen Jie

    2007-01-01

    Objective: To explore the treatment and efficiency of high blood flow vascular malformations of oral maxillofacial region with super-selective arterial embolization. Methods: 18 cases underwent angiography of the head and neck before treatment and then followed by super-selective catheterization with microcatheter to embolize the feeding vessels of the vascular malformations with PVA. 8 cases underwent surgical excision within 72 hours after the embolization and the other 10 cases passed through the arterial radical emboliztion treatment. Results: Technical success ratio reached 100% with no complications causing skin necrosis or incorrect arterial embolization else where in the skull. All 8 cases undergone preoperative embolization showed obviously less bleeding, easier removal of the mass and reduction of operation time. 10 cases with radical arterial embolization manifested reduction of swelling and improvement of organ function within 1 to 24 months after the procedure. 5 patients were cured with only once operation, 4 cases with twice operation and 1 with the thrice. Conclusions: Aterial embolization is a safe and effective method in the treatment of high blood flow vascular malformations of oral maxillofacial region. (authors)

  10. A Fully Automated High-Throughput Flow Cytometry Screening System Enabling Phenotypic Drug Discovery.

    Science.gov (United States)

    Joslin, John; Gilligan, James; Anderson, Paul; Garcia, Catherine; Sharif, Orzala; Hampton, Janice; Cohen, Steven; King, Miranda; Zhou, Bin; Jiang, Shumei; Trussell, Christopher; Dunn, Robert; Fathman, John W; Snead, Jennifer L; Boitano, Anthony E; Nguyen, Tommy; Conner, Michael; Cooke, Mike; Harris, Jennifer; Ainscow, Ed; Zhou, Yingyao; Shaw, Chris; Sipes, Dan; Mainquist, James; Lesley, Scott

    2018-05-01

    The goal of high-throughput screening is to enable screening of compound libraries in an automated manner to identify quality starting points for optimization. This often involves screening a large diversity of compounds in an assay that preserves a connection to the disease pathology. Phenotypic screening is a powerful tool for drug identification, in that assays can be run without prior understanding of the target and with primary cells that closely mimic the therapeutic setting. Advanced automation and high-content imaging have enabled many complex assays, but these are still relatively slow and low throughput. To address this limitation, we have developed an automated workflow that is dedicated to processing complex phenotypic assays for flow cytometry. The system can achieve a throughput of 50,000 wells per day, resulting in a fully automated platform that enables robust phenotypic drug discovery. Over the past 5 years, this screening system has been used for a variety of drug discovery programs, across many disease areas, with many molecules advancing quickly into preclinical development and into the clinic. This report will highlight a diversity of approaches that automated flow cytometry has enabled for phenotypic drug discovery.

  11. State of the Art High-Throughput Approaches to Genotoxicity: Flow Micronucleus, Ames II, GreenScreen and Comet

    Science.gov (United States)

    State of the Art High-Throughput Approaches to Genotoxicity: Flow Micronucleus, Ames II, GreenScreen and Comet (Presented by Dr. Marilyn J. Aardema, Chief Scientific Advisor, Toxicology, Dr. Leon Stankowski, et. al. (6/28/2012)

  12. Clinical studies with high flow nasal cannula oxygen delivery in 2015

    Directory of Open Access Journals (Sweden)

    David Sotello

    2016-04-01

    Full Text Available HFNC devices can provide humidified oxygen at high flow rates with high FiO2s.  This method of oxygen delivery appears to be more comfortable than using noninvasive ventilation, and it does improve oxygenation, reduce respiratory rates, and reduce the sense of dyspnea.  This modality has been studied most in patients with acute hypoxemic respiratory failure. The study reported by Frat et al provides good evidence that patients with moderate to severe respiratory failure (PaO2/FiO2 < 200 may benefit the most. The more complex the patient’s underlying medical problems are the more likely HFNC therapy to fail

  13. Investigation of bubble flow regimes in nucleate boiling of highly-wetting liquids

    International Nuclear Information System (INIS)

    Tong, W.; Bar-Cohen, A.; Simon, T.W.

    1991-01-01

    This paper describes an investigation of the bubble flow regimes in nucleate boiling of FC-72, a highly-wetting liquid. Theoretically analysis of vapor bubble generation and departure from the heated surface reveals that the heat fluxes required for the merging of consecutive bubbles, for highly-wetting liquids, lie in the upper range of the nucleate boiling heat flux. A visual and photographic study of nucleate boiling from sputtered platinum surfaces has supported the theoretical results and shown that the isolated bubble behavior extends to at least 50-80% of the critical heat flux, considerably higher than observed by others with water. Lateral coalescence of adjacent bubbles has been found to be a more likely cause of the termination of the isolated bubble regime. These findings suggest that thermal transport models which are based on isolated bubble behavior may be applicable to nearly the entire range of nucleate boiling of electronic cooling fluids

  14. New method for eliminating the statistical bias in highly turbulent flow measurements

    International Nuclear Information System (INIS)

    Nakao, S.I.; Terao, Y.; Hirata, K.I.; Kitakyushu Industrial Research Institute, Fukuoka, Japan)

    1987-01-01

    A simple method was developed for eliminating statistical bias which can be applied to highly turbulent flows with the sparse and nonuniform seeding conditions. Unlike the method proposed so far, a weighting function was determined based on the idea that the statistical bias could be eliminated if the asymmetric form of the probability density function of the velocity data were corrected. Moreover, the data more than three standard deviations away from the mean were discarded to remove the apparent turbulent intensity resulting from noise. The present method was applied to data obtained in the wake of a block, which provided local turbulent intensities up to about 120 percent, it was found to eliminate the statistical bias with high accuracy. 9 references

  15. Toward high-efficiency and detailed Monte Carlo simulation study of the granular flow spallation target

    Science.gov (United States)

    Cai, Han-Jie; Zhang, Zhi-Lei; Fu, Fen; Li, Jian-Yang; Zhang, Xun-Chao; Zhang, Ya-Ling; Yan, Xue-Song; Lin, Ping; Xv, Jian-Ya; Yang, Lei

    2018-02-01

    The dense granular flow spallation target is a new target concept chosen for the Accelerator-Driven Subcritical (ADS) project in China. For the R&D of this kind of target concept, a dedicated Monte Carlo (MC) program named GMT was developed to perform the simulation study of the beam-target interaction. Owing to the complexities of the target geometry, the computational cost of the MC simulation of particle tracks is highly expensive. Thus, improvement of computational efficiency will be essential for the detailed MC simulation studies of the dense granular target. Here we present the special design of the GMT program and its high efficiency performance. In addition, the speedup potential of the GPU-accelerated spallation models is discussed.

  16. A compatible high-order meshless method for the Stokes equations with applications to suspension flows

    Science.gov (United States)

    Trask, Nathaniel; Maxey, Martin; Hu, Xiaozhe

    2018-02-01

    A stable numerical solution of the steady Stokes problem requires compatibility between the choice of velocity and pressure approximation that has traditionally proven problematic for meshless methods. In this work, we present a discretization that couples a staggered scheme for pressure approximation with a divergence-free velocity reconstruction to obtain an adaptive, high-order, finite difference-like discretization that can be efficiently solved with conventional algebraic multigrid techniques. We use analytic benchmarks to demonstrate equal-order convergence for both velocity and pressure when solving problems with curvilinear geometries. In order to study problems in dense suspensions, we couple the solution for the flow to the equations of motion for freely suspended particles in an implicit monolithic scheme. The combination of high-order accuracy with fully-implicit schemes allows the accurate resolution of stiff lubrication forces directly from the solution of the Stokes problem without the need to introduce sub-grid lubrication models.

  17. The use of high-flow nasal oxygen in COPD patients

    Directory of Open Access Journals (Sweden)

    Silva Santos P

    2016-09-01

    Full Text Available Pedro Silva Santos,1 Antonio M Esquinas21Pulmonology Unit, Centro Hospitalar e Universitário de Coimbra – Hospitais da Universidade de Coimbra, Coimbra, Portugal; 2Internsive Care Unit, Hospital Morales Meseguer, Múrcia, SpainHigh-flow nasal cannula (HFNC oxygen therapy is an innovative and useful mode for the treatment of patients with respiratory failure.1–3 It delivers heated and humidified air providing higher and more expected gas flow rates and fraction inspired oxygen (FiO2 than traditional oxygen therapy.2     We read the article by Bräunlich et al1 carefully and congratulate the authors on their study about the use of nasal high-flow therapy in COPD patients. There are, however, some limitations to the study that need to be considered.    First, this study has a small number of patients, particularly in groups A and B, which in our opinion will affect the comparison of data with the group C that contains a greater variety of patients with more severe outcomes, including forced expiratory volume in 1 second and forced vital capacity. Second, as a study on mean airway pressure, it would be interesting to evaluate partial pressure of CO2 with higher flows.    Third, one of the aims of this study was to characterize changes in hypercapnia, so it is not correct to include nonhypercapnic patients. Fourth, it would be interesting to know the FiO2 that was given and whether the patients had domiciliary oxygen or noninvasive ventilation, as most of them are hypercapnic patients. Finally, regarding comfort and dyspnea scale, HFNC showed better results, which may increase its use when intolerant to noninvasive ventilation.    In short, HFNC is an interesting mode for the future treatment of COPD patients with respiratory failure, which may lead to larger and randomized trials to confirm this indication.View original paper by Bräunlich et al.

  18. Tribological properties of high-speed steel treated by compression plasma flow

    International Nuclear Information System (INIS)

    Cherenda, K.K.; Uglov, V.V.; Anishchik, V.M.; Stalmashonak, A.K.; Astashinski, V.M.

    2004-01-01

    Full text: The investigation of tribological properties of two high-speed steels AISI M2 and AISI Tl treated by the nitrogen compression plasma flow was the main aim of this work. Two types of samples were investigated before and after quenching. The plasma flow was received in a magneto-plasma compressor. The impulse duration was ∼100 μs, the number of impulses varied in the range of 1-5, the nitrogen pressure in the chamber was 400-4000 Pa, the energy absorbed by the sample was 2-10 J/cm 2 per impulse. Tribological properties were examined by means of a tribometer TAYl under conditions of dry friction. The Vickers's microhardness was measured by a hard meter PMT3. X-ray diffraction analysis, Auger electron spectroscopy, scanning electron microscopy and energy dispersion microanalysis were used for samples characterization. The earlier conducted investigations showed that the compression plasma flow suited well for the improvement of tribological properties of iron and low-alloyed steels due to the formation of hardening nitrides in the near surface layer. It was found that in the case of high-speed steels only not quenched samples had increased hardness after treatment. The latter can be explained by the formation of hardening nitrides though the phase analysis did not clearly reveal their presence. The element composition confirmed the presence of nitrogen in the surface layer with the concentration up to 30 at. %. The treatment of quenched samples almost always resulted in the hardness decrease due to the dissolution or partial dissolution of alloying elements carbides: M 6 C, MC, M 23 C 6 . The rate of carbides dissolution increased with the growth of the energy absorbed by the sample. The treated samples showed a lower value of the friction coefficient than the untreated one. It could be explained by the formation of nitrogenous austenite which was found out by the phase analysis. At the same time the compression plasma flow strongly influenced surface

  19. Flow-Field Characteristics of High-Temperature Annular Buoyant Jets and Their Development Laws Influenced by Ventilation System

    OpenAIRE

    Wang, Yi; Huang, Yanqiu; Liu, Jiaping; Wang, Hai; Liu, Qiuhan

    2013-01-01

    The flow-field characteristics of high-temperature annular buoyant jets as well as the development laws influenced by ventilation system were studied using numerical methods to eliminate the pollutants effectively in this paper. The development laws of high-temperature annular buoyant jets were analyzed and compared with previous studies, including radial velocity distribution, axial velocity and temperature decay, reattachment position, cross-section diameter, volumetric flow rate, and veloc...

  20. Spectral characteristics of aurorae connected with high-velocity flows of the solar wind from coronal holes

    International Nuclear Information System (INIS)

    Khviyuzova, T.A.; Leont'ev, S.V.

    1997-01-01

    Bright electron aurorae almost always followed by red lower edge occur when the Earth is being passed by high-velocity flows from coronal holes within the auroral range at the night meridian. In contrast to other types of the solar wind the high-velocity flows from coronal holes do not cause the occurrence of A type red polar aurorae, that is, the spectrum of electrons pouring into the Earth atmosphere in these cases is shifted towards higher energies