Staab, Katie Lynn; Holzman, Roi; Hernandez, L Patricia; Wainwright, Peter C
2012-05-01
A protrusible upper jaw has independently evolved multiple times within teleosts and has been implicated in the success of two groups in particular: Acanthomorpha and Cypriniformes. We use digital particle image velocimetry (DPIV) to compare suction feeding flow dynamics in a representative of each of these clades: goldfish and bluegill. Using DPIV, we contrast the spatial pattern of flow, the temporal relationship between flow and head kinematics, and the contribution of jaw protrusion to the forces exerted on prey. As expected, the spatial patterns of flow were similar in the two species. However, goldfish were slower to reach maximal kinematic excursions, and were more flexible in the relative timing of jaw protrusion, other jaw movements and suction flows. Goldfish were also able to sustain flow speeds for a prolonged period of time as compared with bluegill, in part because goldfish generate lower peak flow speeds. In both species, jaw protrusion increased the force exerted on the prey. However, slower jaw protrusion in goldfish resulted in less augmentation of suction forces. This difference in force exerted on prey corresponds with differences in trophic niches and feeding behavior of the two species. The bluegill uses powerful suction to capture insect larvae whereas the goldfish uses winnowing to sort through detritus and sediment. The kinethmoid of goldfish may permit jaw protrusion that is independent of lower jaw movement, which could explain the ability of goldfish to decouple suction flows (due to buccal expansion) from upper jaw protrusion. Nevertheless, our results show that jaw protrusion allows both species to augment the force exerted on prey, suggesting that this is a fundamental benefit of jaw protrusion to suction feeders.
Heat transfer enhancement of free surface MHD-flow by a protrusion wall
International Nuclear Information System (INIS)
Hulin Huang; Bo Li
2010-01-01
Due to the magnetohydrodynamic (MHD) effect on the flow, which degrades heat transfer coefficients by pulsation suppression of external magnetic field on the flow, a hemispherical protrusion wall is applied to free surface MHD-flow system as a heat transfer enhancement, because the hemispherical protrusion wall has some excellent characteristics including high heat transfer coefficients, low friction factors and high overall thermal performances. So, the characteristics of the fluid flow and heat transfer of the free surface MHD-flow with hemispherical protrusion wall are simulated numerically and the influence of some parameters, such as protrusion height δ/D, and Hartmann number, are also discussed in this paper. It is found that, in the range of Hartmann number 30 ≤ Ha ≤ 70, the protrusion wall assemblies can achieve heat transfer enhancements (Nu/Nu 0 ) of about 1.3-2.3 relative to the smooth channel, while the friction loss (f/f 0 ) increases by about 1.34-1.45. Thus, the high Nusselt number can be obtained when the protrusion wall with a radically lower friction loss increase, which may help get much higher overall thermal performances.
CHF Enhancement by Surface Patterning based on Hydrodynamic Instability Model
Energy Technology Data Exchange (ETDEWEB)
Seo, Han; Bang, In Cheol [UNIST, Ulsan (Korea, Republic of)
2015-05-15
If the power density of a device exceeds the CHF point, bubbles and vapor films will be covered on the whole heater surface. Because vapor films have much lower heat transfer capabilities compared to the liquid layer, the temperature of the heater surface will increase rapidly, and the device could be damaged due to the heater burnout. Therefore, the prediction and the enhancement of the CHF are essential to maximizing the efficient heat removal region. Numerous studies have been conducted to describe the CHF phenomenon, such as hydrodynamic instability theory, macrolayer dryout theory, hot/dry spot theory, and bubble interaction theory. The hydrodynamic instability model, proposed by Zuber, is the predominant CHF model that Helmholtz instability attributed to the CHF. Zuber assumed that the Rayleigh-Taylor (RT) instability wavelength is related to the Helmholtz wavelength. Lienhard and Dhir proposed a CHF model that Helmholtz instability wavelength is equal to the most dangerous RT wavelength. In addition, they showed the heater size effect using various heater surfaces. Lu et al. proposed a modified hydrodynamic theory that the Helmholtz instability was assumed to be the heater size and the area of the vapor column was used as a fitting factor. The modified hydrodynamic theories were based on the change of Helmholtz wavelength related to the RT instability wavelength. In the present study, the change of the RT instability wavelength, based on the heater surface modification, was conducted to show the CHF enhancement based on the heater surface patterning in a plate pool boiling. Sapphire glass was used as a base heater substrate, and the Pt film was used as a heating source. The patterning surface was based on the change of RT instability wavelength. In the present work the study of the CHF was conducted using bare Pt and patterned heating surfaces.
Device for cutting protrusions
Bzorgi, Fariborz M [Knoxville, TN
2011-07-05
An apparatus for clipping a protrusion of material is provided. The protrusion may, for example, be a bolt head, a nut, a rivet, a weld bead, or a temporary assembly alignment tab protruding from a substrate surface of assembled components. The apparatus typically includes a cleaver having a cleaving edge and a cutting blade having a cutting edge. Generally, a mounting structure configured to confine the cleaver and the cutting blade and permit a range of relative movement between the cleaving edge and the cutting edge is provided. Also typically included is a power device coupled to the cutting blade. The power device is configured to move the cutting edge toward the cleaving edge. In some embodiments the power device is activated by a momentary switch. A retraction device is also generally provided, where the retraction device is configured to move the cutting edge away from the cleaving edge.
Sobhani, M.; Behzadmehr, A.
2018-05-01
This study is a numerical investigation of the effect of improving heat transfer namely, modified rough (dimples and protrusions) surfaces on the mixed convective heat transfer of a turbulent flow in a horizontal tube. The effects of different dimples-protrusions arrangements on the improving the thermal performance of a rough tube are investigated at various Richardson numbers. Three dimensional governing equations are discretized by the finite-volume technique. Based on the obtained results the dimples-protrusions arrangements are modified to find a suitable configuration for which heat transfer coefficient and pressure drop to be balanced. Modified dimples-protrusions arrangements that shows higher performance is presented. Its average thermal performance 18% and 11% is higher than the other arrangements. In addition, the results show that roughening a smooth tube is more effective at the higher Richardson number.
New Star-Like Surfacetexture for Enhanced Hydrodynamic Lubrication Performance
Directory of Open Access Journals (Sweden)
Uddin M.S.
2017-09-01
Full Text Available This paper presents a numerical modelling and optimization of a new ‘star-like’ geometric texture shape with an aim to improve tribological performance. Initial studies showed that the triangle effect is the most dominant in reducing the friction. Motivated with this, a ‘star-like’ texture shape consisting of a series of triangular spikes around the centre of the texture is proposed. It is hypothesised that by increasing the triangular effect on a texture shape, the converging micro-wedge effect is expected to increase, hence increasing the film pressure and reducing the friction. Using the well-known Reynolds boundary conditions, numerical modelling of surface texturing is implemented via finite difference method. Simulation results showed that the number of apex points of the new ‘star-like’ texture has a significant effect on the film pressure and the friction coefficient. A 6-pointed texture at a texture density of 0.4 is shown to be the optimum shape. The new optimum star-like texture reduces the friction coefficient by 80%, 64.39%, 19.32% and 16.14%, as compared to ellipse, chevron, triangle and circle, respectively. This indicates the potential benefit of the proposed new shape in further enhancing the hydrodynamic lubrication performance of slider bearing contacts.
CFD simulations to study the effects of wall protrusions on microfluidic mixing
Sarkar, Sourav; Singh, K. K.; Shankar, V.; Shenoy, K. T.
2015-08-01
In this study the effects of different types of wall protrusions on microfluidic mixing are studied using computational fluid dynamics (CFD) simulations. Two new protrusions, single first bracket protrusions and double opposite first bracket protrusions (DOFBPs), are conceptualized, evaluated through CFD simulations and compared to protrusions having standard geometrical shapes, e.g. rectangular protrusions, triangular protrusions and semicircular protrusions. In the range of Reynolds numbers covered in this study, the microchannel having an opposed T-junction and DOFBPs is found to provide good mixing. A hybrid approach relying on the modification of microfluidic junctions as well as wall protrusions for enhancing microfluidic mixing is also evaluated. The microchannel based on the hybrid approach of an OA 10°-20°-165° WY-junction and DOFBPs is also found to provide very good mixing for a wide range of Reynolds numbers.
Li, Pan; Song, Yuan; Wang, Shuai; Tao, Zheng; Yu, Shuili; Liu, Yanan
2015-01-01
The rate of reduction reactions of zero-valent metal nanoparticles is restricted by their agglomeration. Hydrodynamic cavitation was used to overcome the disadvantage in this study. Experiments for decolorization of methyl orange azo dye by zero-valent copper nanoparticles were carried out in aqueous solution with and without hydrodynamic cavitation. The results showed that hydrodynamic cavitation greatly accelerated the decolorization rate of methyl orange. The size of nanoparticles was decreased after hydrodynamic cavitation treatment. The effects of important operating parameters such as discharge pressure, initial solution pH, and copper nanoparticle concentration on the degradation rates were studied. It was observed that there was an optimum discharge pressure to get best decolorization performance. Lower solution pH were favorable for the decolorization. The pseudo-first-order kinetic constant for the degradation of methyl orange increased linearly with the copper dose. UV-vis spectroscopic and Fourier transform infrared (FT-IR) analyses confirmed that many degradation intermediates were formed. The results indicated hydroxyl radicals played a key role in the decolorization process. Therefore, the enhancement of decolorization by hydrodynamic cavitation could due to the deagglomeration of nanoparticles as well as the oxidation by the in situ generated hydroxyl radicals. These findings greatly increase the potential of the Cu(0)/hydrodynamic cavitation technique for use in the field of treatment of wastewater containing hazardous materials. Copyright © 2014 Elsevier B.V. All rights reserved.
Enhancement of thermal photon production in event-by-event hydrodynamics
International Nuclear Information System (INIS)
Chatterjee, Rupa; Holopainen, Hannu; Renk, Thorsten; Eskola, Kari J.
2011-01-01
Thermal photon emission is widely believed to reflect properties of the earliest, hottest evolution stage of the medium created in ultrarelativistic heavy-ion collisions. Previous computations of photon emission have been carried out using a hydrodynamical medium description with smooth, averaged initial conditions. Recently, more sophisticated hydrodynamical models that calculate observables by averaging over many evolutions with event-by-event fluctuating initial conditions (ICs) have been developed. Given their direct connection to the early time dynamics, thermal photon emission appears to be an ideal observable to probe fluctuations in the medium initial state. In this work, we demonstrate that including fluctuations in the ICs may lead to an enhancement of the thermal photon yield of about a factor of 2 in the region 2 T <4 GeV/c (where thermal photon production dominates the direct photon yield) compared to a scenario using smooth, averaged ICs. Consequently, a much better agreement with PHENIX data is found. This can be understood in terms of the strong temperature dependence of thermal photon production, translating into a sensitivity to the presence of hotspots in an event and thus establishing thermal photons as a suitable probe to characterize IC fluctuations.
Analysis of skin permeation-enhancing mechanism of iontophoresis using hydrodynamic pore theory.
Manabe, E; Numajiri, S; Sugibayashi, K; Morimoto, Y
2000-05-15
The effects of constant DC iontophoresis (0-1.5 mA/0.966 cm(2)) on the permeation of three hydrophilic compounds, antipyrine (ANP, M.W. 188.23), sucrose (SR, M.W. 342.30) and 1-kestose (KT, M.W. 506.73), through excised hairless rat skin were evaluated using hydrodynamic pore theory. The electro-osmotic flow caused by iontophoresis was measured using deuterium oxide (D(2)O). The penetration-enhancing mechanism of iontophoresis was found to increase solvent flow through electro-osmosis and pore enlargement and/or new pore production in the skin barrier, together with enhancement of electrochemical potential difference across the skin. These effects were closely related to the strength of the current applied. The electro-osmotic flow of D(2)O (J(D(2)O)) greatly enhanced the skin permeation clearance of all hydrophilic penetrants (CL(drug)). Pore production was classified into reversible and irreversible processes, which resulted from lower (0-0.5 mA/0.966 cm(2)) and higher (0.5-1. 5 mA/0.966 cm(2)) currents, respectively. Thus, the enhancing effects of iontophoresis on skin permeation of nonionic hydrophilic compounds can be explained by increase in pore size and higher solvent flow.
Hydrodynamic modelling of a tidal delta wetland using an enhanced quasi-2D model
Wester, Sjoerd J.; Grimson, Rafael; Minotti, Priscilla G.; Booija, Martijn J.; Brugnach, Marcela
2018-04-01
Knowledge about the hydrological regime of wetlands is key to understand their physical and biological properties. Modelling hydrological and hydrodynamic processes within a wetland is therefore becoming increasingly important. 3D models have successfully modelled wetland dynamics but depend on very detailed bathymetry and land topography. Many 1D and 2D models of river deltas highly simplify the interaction between the river and wetland area or simply neglect the wetland area. This study proposes an enhanced quasi-2D modelling strategy that captures the interaction between river discharge and moon tides and the resulting hydrodynamics, while using the scarce data available. The water flow equations are discretised with an interconnected irregular cell scheme, in which a simplification of the 1D Saint-Venant equations is used to define the water flow between cells. The spatial structure of wetlands is based on the ecogeomorphology in complex estuarine deltas. The islands within the delta are modelled with levee cells, creek cells and an interior cell representing a shallow marsh wetland. The model is calibrated for an average year and the model performance is evaluated for another average year and additionally an extreme dry three-month period and an extreme wet three-month period. The calibration and evaluation are done based on two water level measurement stations and two discharge measurement stations, all located in the main rivers. Additional calibration is carried out with field water level measurements in a wetland area. Accurate simulations are obtained for both calibration and evaluation with high correlations between observed and simulated water levels and simulated discharges in the same order of magnitude as observed discharges. Calibration against field measurements showed that the model can successfully simulate the overflow mechanism in wetland areas. A sensitivity analysis for several wetland parameters showed that these parameters are all
Terán Hilares, Ruly; Ramos, Lucas; da Silva, Silvio Silvério; Dragone, Giuliano; Mussatto, Solange I; Santos, Júlio César Dos
2018-06-01
Hydrodynamic cavitation (HC) is a process technology with potential for application in different areas including environmental, food processing, and biofuels production. Although HC is an undesirable phenomenon for hydraulic equipment, the net energy released during this process is enough to accelerate certain chemical reactions. The application of cavitation energy to enhance the efficiency of lignocellulosic biomass pretreatment is an interesting strategy proposed for integration in biorefineries for the production of bio-based products. Moreover, the use of an HC-assisted process was demonstrated as an attractive alternative when compared to other conventional pretreatment technologies. This is not only due to high pretreatment efficiency resulting in high enzymatic digestibility of carbohydrate fraction, but also, by its high energy efficiency, simple configuration, and construction of systems, besides the possibility of using on the large scale. This paper gives an overview regarding HC technology and its potential for application on the pretreatment of lignocellulosic biomass. The parameters affecting this process and the perspectives for future developments in this area are also presented and discussed.
Toytman, I; Silbergleit, A; Simanovski, D; Palanker, D
2010-10-01
Transparent biological tissues can be precisely dissected with ultrafast lasers using optical breakdown in the tight focal zone. Typically, tissues are cut by sequential application of pulses, each of which produces a single cavitation bubble. We investigate the hydrodynamic interactions between simultaneous cavitation bubbles originating from multiple laser foci. Simultaneous expansion and collapse of cavitation bubbles can enhance the cutting efficiency, by increasing the resulting deformations in tissue, and the associated rupture zone. An analytical model of the flow induced by the bubbles is presented and experimentally verified. The threshold strain of the material rupture is measured in a model tissue. Using the computational model and the experimental value of the threshold strain one can compute the shape of the rupture zone in tissue resulting from application of multiple bubbles. With the threshold strain of 0.7 two simultaneous bubbles produce a continuous cut when applied at the distance 1.35 times greater than that required in sequential approach. Simultaneous focusing of the laser in multiple spots along the line of intended cut can extend this ratio to 1.7. Counterpropagating jets forming during collapse of two bubbles in materials with low viscosity can further extend the cutting zone-up to approximately a factor of 1.5.
Cai, Meiqiang; Hu, Jianqiang; Lian, Guanghu; Xiao, Ruiyang; Song, Zhijun; Jin, Micong; Dong, Chunying; Wang, Quanyuan; Luo, Dewen; Wei, Zongsu
2018-04-01
The dewatering of waste activated sludge by integrated hydrodynamic cavitation (HC) and Fenton reaction was explored in this study. We first investigated the effects of initial pH, sludge concentration, flow rate, and H 2 O 2 concentration on the sludge dewaterability represented by water content, capillary suction time and specific resistance to filtration. The results of dewatering tests showed that acidic pH and low sludge concentration were favorable to improve dewatering performance in the HC/Fenton system, whereas optimal flow rate and H 2 O 2 concentration applied depended on the system operation. To reveal the synergism of HC/Fenton treatment, a suite of analysis were implemented: three-dimensional excitation emission matrix (3-DEEM) spectra of extracellular polymeric substances (EPS) such as proteins and polysaccharides, zeta potential and particle size of sludge flocs, and SEM/TEM imaging of sludge morphology. The characterization results indicate a three-step mechanism, namely HC fracture of different EPS in sludge flocs, Fenton oxidation of the released EPS, and Fe(III) re-flocculation, that is responsible for the synergistically enhanced sludge dewatering. Results of current study provide a basis to improve our understanding on the sludge dewatering performance by HC/Fenton treatment and possible scale-up of the technology for use in wastewater treatment plants. Copyright © 2017 Elsevier B.V. All rights reserved.
Konakhina, I. A.; Khusnutdinova, E. M.; Khamidullina, G. R.; Khamidullina, A. F.
2016-06-01
This paper describes a mathematical model of flow-related hydrodynamic processes for rheologically complex high-viscosity bitumen oil and oil-water suspensions and presents methods to improve the design and performance of oil pipelines.
2010-01-01
... Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS... orientation of the hinge axis shall be horizontal. A plane surface shall be applied to any protrusion from the... direction along the axis of the nipple. The normal of the plane surface shall be maintained parallel to the...
Transanal protrusion of intussusceptions in children
Directory of Open Access Journals (Sweden)
Ezomike Uchechukwu Obiora
2014-01-01
Full Text Available Background: The aim of the following study is to report our management experience and outcome of transanal protrusion of intussusceptions. Patients and Methods: Retrospective analysis of all cases of intussusceptions protruding through the anal opening from January 2008 to June 2013. Results: Of 62 cases of intussusceptions, transanal protrusion occurred in 10 patients (16% anal protrusion rate with a male:female ratio of 2:3. They were aged 4-96 months (mean 22.6 ± 30.7, median 7.5 months. Six were infants while four were above 1 year. Duration of symptoms ranged from 2 to 14 days (mean 5.9 days ± 3.4 with only two patients presenting within 48 h. Clinical features included vomiting (100%, abdominal pains (100%, bloody mucoid stool (100%, abdominal distension (90%, and palpable left iliac fossa mass (70%. Three patients had preceding diarrhoea (30% and two had preceding upper respiratory tract infection (20%. Duration of hospital stay ranged from 5 to 23 days (mean 12 days ± 5.6. Findings at surgery included seven ileocolic and two colocolic intussusceptions (one patient died before surgery. Operative procedures were right hemicolectomy (5, operative manual reduction (3, left hemicolectomy (1 giving a 67% bowel resection rate. One patient died giving a 10% mortality rate. Conclusion: Transanal protrusion occurred more in females and is associated with late presentation, older age, high bowel resection rate, and high mortality.
Energy Technology Data Exchange (ETDEWEB)
Singh, A.K., E-mail: anilks@barc.gov.in [Laser & Plasma Technology Division, BARC, Mumbai, 400085 (India); Suryawanshi, Sachin R.; More, M.A. [Department of Physics, Savitribai Phule Pune University, Pune, 411007 (India); Basu, S. [Solid State Physics Division, BARC, Mumbai, 40085 (India); Sinha, Sucharita [Laser & Plasma Technology Division, BARC, Mumbai, 400085 (India)
2017-02-28
Highlights: • Array of self assembled micro-protrusions have been generated on stainless steel surfaces by femtosecond pulsed laser irradiation. • Density of the formed micro-protrusions is ∼5.6 × 105 protrusions/cm{sup 2}. • Laser treated surface is mainly composed of iron oxide and cementite phases. • Micro-structured sample has shown good field emission properties – low turn on field, high field enhancement factor and stable emission current. - Abstract: This paper reports our results on femtosecond (fs) pulsed laser induced surface micro/nano structuring of stainless steel 304 (SS 304) samples and their characterization in terms of surface morphology, formed material phases on laser irradiation and field emission studies. Our investigations reveal that nearly uniform and dense array of hierarchical micro-protrusions (density: ∼5.6 × 10{sup 5} protrusions/cm{sup 2}) is formed upon laser treatment. Typical tip diameters of the generated protrusions are in the range of 2–5 μm and these protrusions are covered with submicron sized features. Grazing incidence X-ray diffraction (GIXRD) analysis of the laser irradiated sample surface has shown formation mainly of iron oxides and cementite (Fe{sub 3}C) phases in the treated region. These laser micro-structured samples have shown good field emission properties such as low turn on field (∼4.1 V/μm), high macroscopic field enhancement factor (1830) and stable field emission current under ultra high vacuum conditions.
Sahu, M. K.; Pandey, K. M.; Chatterjee, S.
2018-05-01
In this two dimensional numerical investigation, small rectangular channel with right angled triangular protrusions in the bottom wall of test section is considered. A slot nozzle is placed at the middle of top wall of channel which impinges air normal to the protruded surface. A duct flow and nozzle flow combined to form cross flow which is investigated for heat transfer enhancement of protruded channel. The governing equations for continuity, momentum, energy along with SST k-ω turbulence model are solved with finite volume based Computational fluid dynamics code ANSYS FLUENT 14.0. The range of duct Reynolds number considered for this analysis is 8357 to 51760. The ratios of pitch of protrusion to height of duct considered are 0.5, 0.64 and 0.82. The ratios of height of protrusion to height of duct considered are 0.14, 0.23 and 0.29. The effect of duct Reynolds number, pitch and height of protrusion on thermal-hydraulic performance is studied under cross flow condition. It is found that heat transfer rate is more at relatively larger pitch and small pressure drop is found in case of low height of protrusion.
Infantile Perineal Protrusion in Two Monochorionic Twins
Directory of Open Access Journals (Sweden)
Paola Cavicchioli
2014-11-01
Full Text Available Case Report - Two female monochorionic-monoamniotic twins showed the same kind of infantile perineal protrusion (IPP at birth. Lesions in both twins progressively healed until resolution in 6 weeks' time; none of the twins have manifested, till date, alvus disturbances. Discussion and Literature Review - A literature review numbers approximately 100 reports of IPP. This condition has been classically classified into three categories: congenital/familiar (i.e., female sex, positive parental history of IPP, acquired (mainly due to constipation, and associated with lichen sclerosus et atrophicus. Conclusions and Final Remarks - This case report describes, for the first time, the presence of IPP in monochorionic-monoamniotic twins, supporting the existence of hereditary/genetic factors in the developing of this condition.
Directory of Open Access Journals (Sweden)
N. A. Kiselev
2017-01-01
Full Text Available The paper analyses a technique to calculate the Leontiev tube and shows that there are several ways to increase operating efficiency of this device of gas-dynamic energy separation. Application of regular relief (dimples and protrusions on the wall between supersonic and subsonic channels is one of them.Analyses the results available in publications of experimentally numerically investigated influence of semi-spherical protrusions in the slot channels on the enhancement of heat transfer and drag coefficients at various Reynolds numbers.Shows that at the laminar flow owing to semi-spherical protrusions in the slot channel a heat transfer coefficient can be 1.1‑2.6 times increased with simultaneous 1.7‑4.8 times growth of drag coefficient (as compared to the smooth channel.At transition and turbulent flows the heat transfer enhancement, because of shallow dimples (depth-to-print diameter ratio is from 0.1 to 0.25, can reach 1.1‑2.4 times, with simultaneous 1.2‑7.9 times growth of the drag coefficient (as compared to smooth channel.Using the higher protrusions can provide up to 3.0‑3.5 times heat transfer intensification, but in this case there is an outrunning growth of the drag coefficient.It is shown that the staggered array of the shallow spherical protrusions is advisable to use for heat transfer enhancement in the subsonic channel of the Leontiev tube. The shallow spherical dimples correspond to them and operate as heat transfer intensifiers in the supersonic channel.The paper proposes a mechanism that enables taking into consideration an impact of the protrusions in the slot channel on the intensification of the heat transfer and momentum processes when calculating the gas-dynamic energy separation device (Leontiev tube using the known (earlier published technique.The study has been implemented under supporting Grant no. 15-08-08428 of the Russian Foundation for Basic Research.
DEFF Research Database (Denmark)
Terán Hilares, Ruly; Ramos, Lucas; da Silva, Silvio Silvério
2018-01-01
to accelerate certain chemical reactions. The application of cavitation energy to enhance the efficiency of lignocellulosic biomass pretreatment is an interesting strategy proposed for integration in biorefineries for the production of bio-based products. Moreover, the use of an HC-assisted process...... was demonstrated as an attractive alternative when compared to other conventional pretreatment technologies. This is not only due to high pretreatment efficiency resulting in high enzymatic digestibility of carbohydrate fraction, but also, by its high energy efficiency, simple configuration, and construction...... of systems, besides the possibility of using on the large scale. This paper gives an overview regarding HC technology and its potential for application on the pretreatment of lignocellulosic biomass. The parameters affecting this process and the perspectives for future developments in this area are also...
Membrane Protrusion Coarsening and Nanotubulation within Giant Unilamellar Vesicles
Węgrzyn, Ilona; Jeffries, Gavin D. M.; Nagel, Birgit; Katterle, Martin; Gerrard, Simon R.; Brown, Tom; Orwar, Owe; Jesorka, Aldo
2011-01-01
implementation of an IR laser via an optical fiber, enabling localized directed heating. Polymer-membrane interactions were monitored using confocal imaging techniques as subsequent membrane protrusions occurred and lipid nanotubes formed in response
International Nuclear Information System (INIS)
Preibisch, S; Dietzel, D; Buschmann, M H; Friebe, C
2011-01-01
This study is motivated by the observation that recent investigations of dimpled surfaces employed for enhancing heat transfer rarely go beyond general parameters like pressure losses and heat transfer performance. Here, we explore a real world dimpled cross-flow heat exchanger. In particular, we are interested in the global parameters, but also in the local flow situation around a single dimplelike protrusion. Detailed PIV-experiments and simulations of the local flow around single protrusions and groups of them reveal the flow structures essential for heat transfer. These local results are brought in conjunction with the general performance of the heat exchanger. Based on local results, simulations of the complete heat exchanger are carried out which are found to be in reasonable agreement with the global parameters found experimentally.
Influence of bimaxillary protrusion on the perception of smile esthetics.
Almutairi, Terki K; Albarakati, Sahar F; Aldrees, Abdullah M
2015-01-01
To evaluate the impact of bimaxillary protrusion on smile esthetics as perceived by dental professionals and laypersons. One hundred and fifty evaluators, equally distributed into their respective panels (orthodontists, general dentists, and laypersons), participated in this cross-sectional study conducted in April to December 2012 in Riyadh, Saudi Arabia. The patient sample consisted of 14 female patients divided equally into 2 groups: bimaxillary protrusion patients, and patients who have had 4-premolar extraction treatment. Two standardized photographs (frontal and three-quarter close-up smile views), and a lateral cephalogram were taken for each patient. The evaluators were asked to rate the attractiveness of each photo according to a 100-mm visual analog scale. These esthetic ratings were correlated with the patients' cephalometric measurements. The bimaxillary protrusion group was rated significantly as less attractive than the treatment group by each evaluator panel. Panel comparison showed that laypeople were less receptive of bimaxillary protrusion than dental professionals. Frontal and three-quarter views of the same smiles were not similarly rated for esthetic perceptions. Correlational analysis revealed that the dentoalveolar measurement with the highest significant negative correlation to the smile esthetics was the upper incisors to palatal plane (U1-PP) angle. Patients with bimaxillary protrusion were found to be less attractive than patients who were treated for the condition. This was especially evident among the laypersons. An increase in the upper incisor inclination, as well as a decrease in the interincisal angle compounds the bimaxillary effect.
Retinal Nerve Fiber Layer Protrusion Associated with Tilted Optic Discs.
Chiang, Jaclyn; Yapp, Michael; Ly, Angelica; Hennessy, Michael P; Kalloniatis, Michael; Zangerl, Barbara
2018-03-01
This study resulted in the identification of an optic nerve head (ONH) feature associated with tilted optic discs, which might potentially contribute to ONH pathologies. Knowledge of such findings will enhance clinical insights and drive future opportunities to understand disease processes related to tilted optic discs. The aim of this study was to identify novel retinal nerve fiber layer (RNFL) anomalies by evaluating tilted optic discs using optical coherence tomography. An observed retinal nerve fiber protrusion was further investigated for association with other morphological or functional parameters. A retrospective review of 400 randomly selected adult patients with ONH examinations was conducted in a referral-only, diagnostic imaging center. After excluding other ONH pathologies, 215 patients were enrolled and evaluated for optic disc tilt and/or torsion. Gross anatomical ONH features, including size and rim or parapapillary region elevation, were assessed with stereoscopic fundus photography. Optical coherence tomography provided detailed morphological information of individual retinal layers. Statistical analysis was applied to identify significant changes between individual patient cohorts. A dome-shaped hyperreflective RNFL bulge, protruding into the neurosensory retina at the optic disc margins, was identified in 17 eyes with tilted optic discs. Available follow-up data were inconclusive regarding natural changes with this ONH feature. This RNFL herniation was significantly correlated with smaller than average optic disc size (P = .005), congenital disc tilt (P optic discs, which has not previously been assessed as an independent ONH structure. The feature is predominantly related to congenital crowded, small optic discs and variable between patients. This study is an important first step to elucidate diagnostic capabilities of tilted disc morphological changes and understanding associated functional deficits.
Luciano, Rezzolla
2013-01-01
Relativistic hydrodynamics is a very successful theoretical framework to describe the dynamics of matter from scales as small as those of colliding elementary particles, up to the largest scales in the universe. This book provides an up-to-date, lively, and approachable introduction to the mathematical formalism, numerical techniques, and applications of relativistic hydrodynamics. The topic is typically covered either by very formal or by very phenomenological books, but is instead presented here in a form that will be appreciated both by students and researchers in the field. The topics covered in the book are the results of work carried out over the last 40 years, which can be found in rather technical research articles with dissimilar notations and styles. The book is not just a collection of scattered information, but a well-organized description of relativistic hydrodynamics, from the basic principles of statistical kinetic theory, down to the technical aspects of numerical methods devised for the solut...
Bonneau, Dominique; Souchet, Dominique
2014-01-01
This Series provides the necessary elements to the development and validation of numerical prediction models for hydrodynamic bearings. This book describes the rheological models and the equations of lubrication. It also presents the numerical approaches used to solve the above equations by finite differences, finite volumes and finite elements methods.
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 1; Issue 9. Hydrodynamic Lubrication Experiment with 'Floating' Drops. Jaywant H Arakeri K R Sreenivas. General Article Volume 1 Issue 9 September 1996 pp 51-58. Fulltext. Click here to view fulltext PDF. Permanent link:
Milne-Thomson, L M
2011-01-01
This classic exposition of the mathematical theory of fluid motion is applicable to both hydrodynamics and aerodynamics. Based on vector methods and notation with their natural consequence in two dimensions - the complex variable - it offers more than 600 exercises and nearly 400 diagrams. Prerequisites include a knowledge of elementary calculus. 1968 edition.
Energy Technology Data Exchange (ETDEWEB)
Bulatov, A.I.; Chernov, V.S.; Prokopov, L.I.; Proselkov, Yu.M.; Tikhonov, Yu.P.
1980-01-15
A hydrodynamic disperser is suggested which contains a housing, slit nozzles installed on a circular base arranged opposite from each other, resonators secured opposite the nozzle and outlet sleeve. In order to improve the effectiveness of dispersion by throttling the flow, each resonator is made in the form of a crimped plate with crimpings that decrease in height in a direction towards the nozzle.
Lower bounds for protrusion replacement by counting equivalence classes
Jansen, B.M.P.; Wulms, J.J.H.M.; Guo, J.; Hermelin, D.
2017-01-01
Garnero et al. [SIAM J. Discrete Math. 2015, 29(4):1864-1894] recently introduced a framework based on dynamic programming to make applications of the protrusion replacement technique constructive and to obtain explicit upper bounds on the involved constants. They show that for several graph
Lower bounds for protrusion replacement by counting equivalence classes
Jansen, B.M.P.; Wulms, J.J.H.M.
2016-01-01
Garnero et al. [SIAM J. Discrete Math. 2015, 29(4):1864--1894] recently introduced a framework based on dynamic programming to make applications of the protrusion replacement technique constructive and to obtain explicit upper bounds on the involved constants. They show that for several graph
Čehovin, Matej; Medic, Alojz; Kompare, Boris; Žgajnar Gotvajn, Andreja
2016-12-01
Drinking water contains organic matter that occasionally needs to be treated to assure its sufficient quality and safety for the consumers. H2O2 and UV advanced oxidation processes (H2O2/UV AOPs) were combined with hydrodynamic cavitation (HC) to assess the effects on the removal of selected organic pollutants. Water samples containing humic acid, methylene blue dye and micropollutants (metaldehyde, diatrizoic acid, iohexol) were treated first by H2O2 (dosages from 1 to 12 mg L-1) and UV (dosages from 300 to 2800 mJ cm-2) AOPs alone and later in combination with HC, generated by nozzles and orifice plates (4, 8, 18 orifices). Using HC, the removal of humic acid was enhanced by 5-15%, methylene blue by 5-20% and metaldehyde by approx. 10%. Under favouring conditions, i.e. high UV absorbance of the matrix (more than 0.050 cm-1 at a wavelength of 254 nm) and a high pollutant to oxidants ratio, HC was found to improve the hydrodynamic conditions in the photolytic reactor, to improve the subjection of the H2O2 to the UV fluence rate distribution and to enhance the removal of the tested organic pollutants, thus showing promising potential of further research in this field.
Signaling by Cellular Protrusions: Keeping the Conversation Private.
Buszczak, Michael; Inaba, Mayu; Yamashita, Yukiko M
2016-07-01
Information exchange between different cells makes multicellular life possible. Signaling between cells can occur over long distances, as in the case of hormone signaling, or it can take place over short distances between immediately juxtaposed neighbors, as in the case of stem cell-niche signaling. The ability of signal-sending and -receiving cells to communicate with one another in a specific manner is of paramount importance in the proper development and function of tissues. Growing evidence indicates that different cellular protrusions help to achieve specificity in signaling that occurs between distinct cell types. Here, we focus on new roles for cellular protrusions in cell-to-cell communication, drawing special attention to how stem cells use specialized extensions to promote reception of self-renewing signals emanating from the niche. Copyright © 2016 Elsevier Ltd. All rights reserved.
Coordination of membrane and actin cytoskeleton dynamics during filopodia protrusion.
Directory of Open Access Journals (Sweden)
Changsong Yang
2009-05-01
Full Text Available Leading edge protrusion of migrating cells involves tightly coordinated changes in the plasma membrane and actin cytoskeleton. It remains unclear whether polymerizing actin filaments push and deform the membrane, or membrane deformation occurs independently and is subsequently stabilized by actin filaments. To address this question, we employed an ability of the membrane-binding I-BAR domain of IRSp53 to uncouple the membrane and actin dynamics and to induce filopodia in expressing cells. Using time-lapse imaging and electron microscopy of IRSp53-I-BAR-expressing B16F1 melanoma cells, we demonstrate that cells are not able to protrude or maintain durable long extensions without actin filaments in their interior, but I-BAR-dependent membrane deformation can create a small and transient space at filopodial tips that is subsequently filled with actin filaments. Moreover, the expressed I-BAR domain forms a submembranous coat that may structurally support these transient actin-free protrusions until they are further stabilized by the actin cytoskeleton. Actin filaments in the I-BAR-induced filopodia, in contrast to normal filopodia, do not have a uniform length, are less abundant, poorly bundled, and display erratic dynamics. Such unconventional structural organization and dynamics of actin in I-BAR-induced filopodia suggests that a typical bundle of parallel actin filaments is not necessary for generation and mechanical support of the highly asymmetric filopodial geometry. Together, our data suggest that actin filaments may not directly drive the protrusion, but only stabilize the space generated by the membrane deformation; yet, such stabilization is necessary for efficient protrusion.
Primary extra-skeletal Ewing's sarcoma mimicking a disc protrusion.
Ruelle, A; Boccardo, M
1987-07-01
One of the rarest cases of primary epidural neoplasm is a soft tissue sarcoma histologically similar to Ewing's sarcoma of the bone. In the literature only eleven cases of such an extra-skeletal Ewing's sarcoma have been described. The authors report an additional case presenting as a disc protrusion in a young male. The authors include some diagnostic, prognostic and nosologic remarks about this condition.
Carotid artery protrusion and dehiscence in patients with acromegaly.
Sasagawa, Yasuo; Tachibana, Osamu; Doai, Mariko; Hayashi, Yasuhiko; Tonami, Hisao; Iizuka, Hideaki; Nakada, Mitsutoshi
2016-10-01
Acromegaly is a systemic disease which causes multiple bony alterations. Some authors reported that acromegalic patients have risk factors for an intraoperative vascular injury due to the specific anatomical features of their sphenoid sinus. The objective of our study was to analyze the anatomic characteristics of sphenoid sinus in acromegalic patients compared with controls, by evaluation of computed tomography (CT) findings. We examined 45 acromegalic (acromegaly group) and 45 non-acromegalic patients (control group) with pituitary adenomas who were matched for sex, age, height, tumor size, and cavernous sinus invasion (Knosp grade). Preoperative CT of the pituitary region including the sphenoid sinus was used to evaluate the following anatomic characteristics: type of sphenoid sinus (sellar or pre-sellar/conchal); intrasphenoid septa (non/single or multiple); carotid artery protrusion; carotid artery dehiscence; intercarotid distance. Sixteen acromegalic patients (35.5 %) and 6 controls (13.3 %) had carotid artery protrusion. Additionally, 10 acromegalic patients (22.2 %) and 3 controls (6.6 %) had carotid artery dehiscence. Carotid artery protrusion and dehiscence were more frequent in the acromegaly group than in control group (p = 0.013 and 0.035, respectively). Other anatomic characteristics (type of sphenoid sinus, intrasphenoid septa, and intracarotid distance) showed no significant differences between acromegaly and control groups. Our study suggests that carotid artery protrusion and dehiscence occur more frequently among acromegalic patients, compared with non-acromegalic patients. It is important for surgeons to be aware of these anatomic variations to avoid vital complications, such as carotid injuries, during surgery.
Mechanisms of leading edge protrusion in interstitial migration
Wilson, Kerry; Lewalle, Alexandre; Fritzsche, Marco; Thorogate, Richard; Duke, Tom; Charras, Guillaume
2013-01-01
While the molecular and biophysical mechanisms underlying cell protrusion on two-dimensional substrates are well understood, our knowledge of the actin structures driving protrusion in three-dimensional environments is poor, despite relevance to inflammation, development and cancer. Here we report that, during chemotactic migration through microchannels with 5 μm × 5 μm cross-sections, HL60 neutrophil-like cells assemble an actin-rich slab filling the whole channel cross-section at their front. This leading edge comprises two distinct F-actin networks: an adherent network that polymerizes perpendicular to cell-wall interfaces and a ‘free’ network that grows from the free membrane at the cell front. Each network is polymerized by a distinct nucleator and, due to their geometrical arrangement, the networks interact mechanically. On the basis of our experimental data, we propose that, during interstitial migration, medial growth of the adherent network compresses the free network preventing its retrograde movement and enabling new polymerization to be converted into forward protrusion. PMID:24305616
Lee, Ilgyu; Han, Jong-In
2015-06-01
Simultaneous treatment (combining with cell disruption and lipid extraction) using hydrodynamic cavitation (HC) was applied to Nannochloropsis salina to demonstrate a simple and integrated way to produce oil from wet microalgae. A high lipid yield from the HC (25.9-99.0%) was observed compared with autoclave (16.2-66.5%) and ultrasonication (5.4-26.9%) in terms of the specific energy input (500-10,000 kJ/kg). The optimal conditions for the simultaneous treatment were established using a statistical approach. The efficiency of the simultaneous method was also demonstrated by comparing each separate treatment. The maximum lipid yield (predicted: 45.9% and experimental: 45.5%) was obtained using 0.89% sulfuric acid with a cavitation number of 1.17 for a reaction time of 25.05 min via response surface methodology. Considering its comparable extractability, energy-efficiency, and potential for scale-up, HC may be a promising method to achieve industrial-scale microalgae operation. Copyright © 2015 Elsevier Ltd. All rights reserved.
International Nuclear Information System (INIS)
Colgate, S.A.
1981-01-01
The explosion of a star supernova occurs at the end of its evolution when the nuclear fuel in its core is almost, or completely, consumed. The star may explode due to a small residual thermonuclear detonation, type I SN or it may collapse, type I and type II SN leaving a neutron star remnant. The type I progenitor should be thought to be an old accreting white dwarf, 1.4 M/sub theta/, with a close companion star. A type II SN is thought to be a massive young star 6 to 10 M/sub theta/. The mechanism of explosion is still a challenge to our ability to model the most extreme conditions of matter and hydrodynamics that occur presently and excessively in the universe. 39 references
Renilson, Martin
2015-01-01
This book adopts a practical approach and presents recent research together with applications in real submarine design and operation. Topics covered include hydrostatics, manoeuvring, resistance and propulsion of submarines. The author briefly reviews basic concepts in ship hydrodynamics and goes on to show how they are applied to submarines, including a look at the use of physical model experiments. The issues associated with manoeuvring in both the horizontal and vertical planes are explained, and readers will discover suggested criteria for stability, along with rudder and hydroplane effectiveness. The book includes a section on appendage design which includes information on sail design, different arrangements of bow planes and alternative stern configurations. Other themes explored in this book include hydro-acoustic performance, the components of resistance and the effect of hull shape. Readers will value the author’s applied experience as well as the empirical expressions that are presented for use a...
Guyon, Etienne; Petit, Luc; Mitescu, Catalin D
2015-01-01
This new edition is an enriched version of the textbook of fluid dynamics published more than 10 years ago. It retains the same physically oriented pedagogical perspective. This book emphasizes, as in the first edition, experimental inductive approaches and relies on the study of the mechanisms at play and on dimensional analysis rather than more formal approaches found in many classical textbooks in the field. The need for a completely new version also originated from the increase, over the last few decades, of the cross-overs between the mechanical and physical approaches, as is visible in international meetings and joint projects. Hydrodynamics is more widely linked today to other fields of experimental sciences: materials, environment, life sciences and earth sciences, as well as engineering sciences.
International Nuclear Information System (INIS)
Wilkins, M.L.
1979-01-01
Various aspects of hydrodynamics and elastic--plastic flow are introduced for the purpose of defining hydrodynamic terms and explaining what some of the important hydrodynamic concepts are. The first part covers hydrodynamic theory; and discussed fundamental hydrodynamic equations, discontinuities, and shock, detonation, and elastic--plastic waves. The second part deals with applications of hydrodynamic theory to material equations of state, spall, Taylor instabilities, and detonation pressure measurements
Thermo-hydrodynamic lubrication in hydrodynamic bearings
Bonneau, Dominique; Souchet, Dominique
2014-01-01
This Series provides the necessary elements to the development and validation of numerical prediction models for hydrodynamic bearings. This book describes the thermo-hydrodynamic and the thermo-elasto-hydrodynamic lubrication. The algorithms are methodically detailed and each section is thoroughly illustrated.
International Nuclear Information System (INIS)
Pryce, M.H.L.
1985-01-01
A dominant mechanism contributing to hydrodynamic dispersion in fluid flow through rocks is variation of travel speeds within the channels carrying the fluid, whether these be interstices between grains, in granular rocks, or cracks in fractured crystalline rocks. The complex interconnections of the channels ensure a mixing of those parts of the fluid which travel more slowly and those which travel faster. On a macroscopic scale this can be treated statistically in terms of the distribution of times taken by a particle of fluid to move from one surface of constant hydraulic potential to another, lower, potential. The distributions in the individual channels are such that very long travel times make a very important contribution. Indeed, while the mean travel time is related to distance by a well-defined transport speed, the mean square is effectively infinite. This results in an asymmetrical plume which differs markedly from a gaussian shape. The distribution of microscopic travel times is related to the distribution of apertures in the interstices, or in the microcracks, which in turn are affected in a complex way by the stresses acting on the rock matrix
Bruinsma, Robijn; Grosberg, Alexander Y.; Rabin, Yitzhak; Zidovska, Alexandra
2014-01-01
Following recent observations of large scale correlated motion of chromatin inside the nuclei of live differentiated cells, we present a hydrodynamic theory—the two-fluid model—in which the content of a nucleus is described as a chromatin solution with the nucleoplasm playing the role of the solvent and the chromatin fiber that of a solute. This system is subject to both passive thermal fluctuations and active scalar and vector events that are associated with free energy consumption, such as ATP hydrolysis. Scalar events drive the longitudinal viscoelastic modes (where the chromatin fiber moves relative to the solvent) while vector events generate the transverse modes (where the chromatin fiber moves together with the solvent). Using linear response methods, we derive explicit expressions for the response functions that connect the chromatin density and velocity correlation functions to the corresponding correlation functions of the active sources and the complex viscoelastic moduli of the chromatin solution. We then derive general expressions for the flow spectral density of the chromatin velocity field. We use the theory to analyze experimental results recently obtained by one of the present authors and her co-workers. We find that the time dependence of the experimental data for both native and ATP-depleted chromatin can be well-fitted using a simple model—the Maxwell fluid—for the complex modulus, although there is some discrepancy in terms of the wavevector dependence. Thermal fluctuations of ATP-depleted cells are predominantly longitudinal. ATP-active cells exhibit intense transverse long wavelength velocity fluctuations driven by force dipoles. Fluctuations with wavenumbers larger than a few inverse microns are dominated by concentration fluctuations with the same spectrum as thermal fluctuations but with increased intensity. PMID:24806919
Membrane Protrusion Coarsening and Nanotubulation within Giant Unilamellar Vesicles
Węgrzyn, Ilona
2011-11-16
Hydrophobic side groups on a stimuli-responsive polymer, encapsulated within a single giant unilamellar vesicle, enable membrane attachment during compartment formation at elevated temperatures. We thermally modulated the vesicle through implementation of an IR laser via an optical fiber, enabling localized directed heating. Polymer-membrane interactions were monitored using confocal imaging techniques as subsequent membrane protrusions occurred and lipid nanotubes formed in response to the polymer hydrogel contraction. These nanotubes, bridging the vesicle membrane to the contracting hydrogel, were retained on the surface of the polymer compartment, where they were transformed into smaller vesicles in a process reminiscent of cellular endocytosis. This development of a synthetic vesicle system containing a stimuli-responsive polymer could lead to a new platform for studying inter/intramembrane transport through lipid nanotubes. © 2011 American Chemical Society.
Cellular blebs: pressure-driven, axisymmetric, membrane protrusions
Woolley, Thomas E.
2013-07-16
Blebs are cellular protrusions that are used by cells for multiple purposes including locomotion. A mechanical model for the problem of pressure-driven blebs based on force and moment balances of an axisymmetric shell model is proposed. The formation of a bleb is initiated by weakening the shell over a small region, and the deformation of the cellular membrane from the cortex is obtained during inflation. However, simply weakening the shell leads to an area increase of more than 4 %, which is physically unrealistic. Thus, the model is extended to include a reconfiguration process that allows large blebs to form with small increases in area. It is observed that both geometric and biomechanical constraints are important in this process. In particular, it is shown that although blebs are driven by a pressure difference across the cellular membrane, it is not the limiting factor in determining bleb size. © 2013 Springer-Verlag Berlin Heidelberg.
Hydrodynamic characteristics of sailfish and swordfish
Sagong, Woong; Jeon, Woo-Pyung; Choi, Haecheon
2009-11-01
The sailfish and swordfish are known as fastest sea animals, reaching their maximum speeds of more than 100km/h. Recently, Sagong et al. (2008, Phys. Fluids) investigated the role of V- shaped protrusions existing on the sailfish skin in the skin-friction reduction but those protrusions did not make a direct role in reducing drag. On the other hand, the long bill has been regarded as a device of reducing drag by separation delay through turbulence generation. In the present study, we investigate the hydrodynamic characteristics of sailfish and swordfish by installing the stuffed ones in a wind tunnel and measuring the drag on their bodies and boundary-layer velocities above the body surfaces. The drag coefficients of sailfish and swordfish are 0.0075 and 0.009 based on the free-stream velocity and wetted area, respectively. They are comparable to or smaller than those of other kinds of fish such as the dogfish, tuna and trout. Next, the role of bill on the drag is studied. The drag without bill or with an artificial short bill is lower than that with the original long bill, indicating that the bill does not reduce the drag at all. From the velocity measurement near the body surfaces, we found that flow separation does not occur even without bill, and thus the conjecture that the flow separation is delayed through turbulence generation by the bill is not valid.
Measurements of the Curvature of Protrusions/Retrusions on Migrating Recrystallization Boundaries
DEFF Research Database (Denmark)
Zhang, Yubin; Godfrey, A.; Juul Jensen, Dorte
2009-01-01
Two methods to quantify protrusions/retrusions and to estimate local boundary curvature from sample plane sections are proposed. The methods are used to evaluate the driving force due to curvature of the protrusions/retrusions for partially recrystallized pure nickel cold rolled to 96% reduction...
Carbon protrusions on PTFE surface prepared by ion irradiation and chemical defluorination
Kobayashi, T.; Iwaki, M.
2006-01-01
A surface of PTFE was covered with small protrusions by ion-beam irradiation. In this study, we converted PTFE protrusions into carbon protrusions by a defluorination (carbonization) process using sodium vapor. The morphology, composition and structure were analyzed by SEM-EDX, Raman spectroscopy and TEM. The irradiated PTFE sheets were packed in evacuated glass tubes with a sodium block and kept at 473 K for 2-48 h. The samples were then rinsed in HCl and distilled water to remove NaF precipitates. The EDX measurement showed that the NaF precipitates were completely removed by washing, and the percentage of carbon atoms was controlled from 60% to 99% by the treatment. Raman spectra showed that graphite structures grow during the defluorination process. TEM micrographs showed that the protrusions have a bubble structure and are covered with a thin wall. The carbonized protrusions were conductive and grew perpendicular to the substrate.
Modified protrusion arch for anterior crossbite correction - a case report.
Roy, Abhishek Singha; Singh, Gulshan Kr; Tandon, Pradeep; Chaudhary, Ramsukh
2013-01-01
Borderline and mild skeletal Class III relationships in adult patients are usually treated by orthodontic camouflage. Reasonably rood results have been achieved with nonsurgical teatment of anterior crossbite. Class III malocclusion may be associated with mandibular prognathism, maxillary retrognathism, or both. Class III maxillary retrognathism generally involves anterior crossbite, which must be opened if upper labial brackets are to be bonded. If multiple teeth are in crossbite, after opening the bite usual step is to ligate forward or advancement arch made of 0.018" or 0.020" stainless steel or NiTi wire main arch that must be kept separated 2 mm from the slot ofupper incisor braces. Two stops or omegas are made 1 mm mesial to the tubes of the molar bands that will impede main arch from slipping,and in this manner the arch will push the anterior teeth forward Here we have fabricated a modified multiple loop protrusion arch to correct an anterior crossbite with severe crowding that was not amenable to correct by advancement arches.
AFM tip-sample convolution effects for cylinder protrusions
Shen, Jian; Zhang, Dan; Zhang, Fei-Hu; Gan, Yang
2017-11-01
A thorough understanding about the AFM tip geometry dependent artifacts and tip-sample convolution effect is essential for reliable AFM topographic characterization and dimensional metrology. Using rigid sapphire cylinder protrusions (diameter: 2.25 μm, height: 575 nm) as the model system, a systematic and quantitative study about the imaging artifacts of four types of tips-two different pyramidal tips, one tetrahedral tip and one super sharp whisker tip-is carried out through comparing tip geometry dependent variations in AFM topography of cylinders and constructing the rigid tip-cylinder convolution models. We found that the imaging artifacts and the tip-sample convolution effect are critically related to the actual inclination of the working cantilever, the tip geometry, and the obstructive contacts between the working tip's planes/edges and the cylinder. Artifact-free images can only be obtained provided that all planes and edges of the working tip are steeper than the cylinder sidewalls. The findings reported here will contribute to reliable AFM characterization of surface features of micron or hundreds of nanometers in height that are frequently met in semiconductor, biology and materials fields.
Morphological change of self-organized protrusions of fluoropolymer surface by ion beam irradiation
International Nuclear Information System (INIS)
Kitamura, Akane; Kobayashi, Tomohiro; Satoh, Takahiro; Koka, Masashi; Kamiya, Tomihiro; Suzuki, Akihiro; Terai, Takayuki
2013-01-01
Polytetrafluoroethylene (PTFE) and fluorinated ethylene propylene (FEP) are typical fluoropolymers displaying several desirable technological properties such as electrical insulation and high chemical resistance. When their surfaces are irradiated with ion beams, dense micro-protrusions formed after the emergence and spread of micropores across the entire irradiated area, allowing culture cells to spread on the top of the protrusions. In this study, we investigate the morphological changes introduced in the fluoropolymer surfaces by ion beams as the energy of the beams is increased. When an FEP sample was irradiated with a nitrogen ion beam with an energy of less than 350 keV at 1.0 μA/cm 2 , protrusions were formed with a density between 2 × 10 7 /cm 2 and 2 × 10 8 /cm 2 . However, at energies higher than 350 keV, the protrusions became sparse, and the density dropped to 5 × 10 2 /cm 2 . Protrusions appeared sporadically during irradiation at high energies, and the top of the protrusions appeared as spots inside the sample, which were difficult to etch and became elongated as the erosion of the surface progressed. Erosion was caused by sputtering of FEP molecules and evaporation at notably elevated temperatures on the surface. Analysis based on attenuated total reflectance/Fourier transform infrared spectroscopy showed the presence of C=C bonds as well as –COOH, –C=O, and –OH bonds on all irradiated samples. Their concentration on the surface densely covered with micro-protrusions was higher than that on the surface with sparse protrusions after irradiation at energies exceeding 350 keV. Thus, we determined a suitable range for the ion energy for creating FEP surfaces densely covered with protrusions
Elasto-hydrodynamic lubrication
Dowson, D; Hopkins, D W
1977-01-01
Elasto-Hydrodynamic Lubrication deals with the mechanism of elasto-hydrodynamic lubrication, that is, the lubrication regime in operation over the small areas where machine components are in nominal point or line contact. The lubrication of rigid contacts is discussed, along with the effects of high pressure on the lubricant and bounding solids. The governing equations for the solution of elasto-hydrodynamic problems are presented.Comprised of 13 chapters, this volume begins with an overview of elasto-hydrodynamic lubrication and representation of contacts by cylinders, followed by a discussio
Elementary classical hydrodynamics
Chirgwin, B H; Langford, W J; Maxwell, E A; Plumpton, C
1967-01-01
Elementary Classical Hydrodynamics deals with the fundamental principles of elementary classical hydrodynamics, with emphasis on the mechanics of inviscid fluids. Topics covered by this book include direct use of the equations of hydrodynamics, potential flows, two-dimensional fluid motion, waves in liquids, and compressible flows. Some general theorems such as Bernoulli's equation are also considered. This book is comprised of six chapters and begins by introducing the reader to the fundamental principles of fluid hydrodynamics, with emphasis on ways of studying the motion of a fluid. Basic c
Lotic Water Hydrodynamic Model
Energy Technology Data Exchange (ETDEWEB)
Judi, David Ryan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tasseff, Byron Alexander [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2015-01-23
Water-related natural disasters, for example, floods and droughts, are among the most frequent and costly natural hazards, both socially and economically. Many of these floods are a result of excess rainfall collecting in streams and rivers, and subsequently overtopping banks and flowing overland into urban environments. Floods can cause physical damage to critical infrastructure and present health risks through the spread of waterborne diseases. Los Alamos National Laboratory (LANL) has developed Lotic, a state-of-the-art surface water hydrodynamic model, to simulate propagation of flood waves originating from a variety of events. Lotic is a two-dimensional (2D) flood model that has been used primarily for simulations in which overland water flows are characterized by movement in two dimensions, such as flood waves expected from rainfall-runoff events, storm surge, and tsunamis. In 2013, LANL developers enhanced Lotic through several development efforts. These developments included enhancements to the 2D simulation engine, including numerical formulation, computational efficiency developments, and visualization. Stakeholders can use simulation results to estimate infrastructure damage and cascading consequences within other sets of infrastructure, as well as to inform the development of flood mitigation strategies.
Room-temperature growth of a carbon nanofiber on the tip of conical carbon protrusions
International Nuclear Information System (INIS)
Tanemura, Masaki; Okita, T.; Yamauchi, H.; Tanemura, S.; Morishima, R.
2004-01-01
Glassy carbon was Ar + -ion bombarded with a simultaneous Mo supply under ultrahigh vacuum conditions using a microprotrusion fabrication system that consists of a differentially pumped ion gun and a seed-material supply source. Conical protrusions were formed by sputtering with a seed supply, and carbon nanofibers (CNFs) grew on the tips even at room temperature. The length of CNFs reached up to ∼10 μm, and their diameter was almost uniform (50 nm) in the growth direction. The short CNFs aligned in the ion beam direction, whereas the long ones were non-aligned. The CNF growth on a glassy carbon surface was ascribed to the enhanced surface texturing and to the massive redeposition of C atoms onto cones, both of which are specific to the oblique ion bombardment: The former would lead to an increase in the number of possible nucleation sites for the CNF growth, and the C atoms arising from the latter process would migrate toward the conical tips, thus forming CNFs
Chrysler Upset Protrusion Joining Techniques for Joining Dissimilar Metals
Energy Technology Data Exchange (ETDEWEB)
Logan, Stephen [FCA US LLC, Auburn Hills, MI (United States)
2017-09-28
The project goal was to develop and demonstrate a robust, cost effective, and versatile joining technique, known as Upset Protrusion Joining (UPJ), for joining challenging dissimilar metal com-binations, especially those where one of the metals is a die cast magnesium (Mg) component. Since two of the key obstacles preventing more widespread use of light metals (especially in high volume automotive applications) are 1) a lack of robust joining techniques and 2) susceptibility to galvanic corrosion, and since the majority of the joint combinations evaluated in this project include die cast Mg (the lightest structural metal) as one of the two materials being joined, and since die casting is the most common and cost effective process for producing Mg components, then successful project completion provides a key enabler to high volume application of lightweight materials, thus potentially leading to reduced costs, and encouraging implementation of lightweight multi-material vehicles for significant reductions in energy consumption and reduced greenhouse gas emissions. Eco-nomic benefits to end-use consumers are achieved primarily via the reduction in fuel consumption. Unlike currently available commercial processes, the UPJ process relies on a very robust mechanical joint rather than intermetallic bonding, so the more cathodic material can be coated prior to joining, thus creating a robust isolation against galvanic attack on the more anodic material. Additionally, since the UPJ protrusion is going through a hole that can be pre-drilled or pre-punched prior to coating, the UPJ process is less likely to damage the coating when the joint is being made. Further-more, since there is no additional cathodic material (such as a steel fastener) used to create the joint, there is no joining induced galvanic activity beyond that of the two parent materials. In accordance with its originally proposed plan, this project has successfully developed process variants of UPJ to enable
Alvarez, Diego E; Agaisse, Hervé
2016-06-01
Listeria monocytogenes is an intracellular pathogen that disseminates within the intestinal epithelium through acquisition of actin-based motility and formation of plasma membrane protrusions that project into adjacent cells. The resolution of membrane protrusions into vacuoles from which the pathogen escapes results in bacterial spread from cell to cell. This dissemination process relies on the mlp-actA-plcB operon, which encodes ActA, a bacterial nucleation-promoting factor that mediates actin-based motility, and PlcB, a phospholipase that mediates vacuole escape. Here we investigated the role of the metalloprotease Mpl in the dissemination process. In agreement with previous findings showing that Mpl is required for PlcB activation, infection of epithelial cells with the ΔplcB or Δmpl strains resulted in the formation of small infection foci. As expected, the ΔplcB strain displayed a strong defect in vacuole escape. However, the Δmpl strain showed an unexpected defect in the resolution of protrusions into vacuoles, in addition to the expected but mild defect in vacuole escape. The Δmpl strain displayed increased levels of ActA on the bacterial surface in protrusions. We mapped an Mpl-dependent processing site in ActA between amino acid residues 207 to 238. Similar to the Δmpl strain, the ΔactA207-238 strain displayed increased levels of ActA on the bacterial surface in protrusions. Although the ΔactA207-238 strain displayed wild-type actin-based motility, it formed small infection foci and failed to resolve protrusions into vacuoles. We propose that, in addition to its role in PlcB processing and vacuole escape, the metalloprotease Mpl is required for ActA processing and protrusion resolution. Copyright © 2016, American Society for Microbiology. All Rights Reserved.
Chen, Si; An, Tong; Qin, Fei; Chen, Pei
2017-10-01
Through-silicon vias (TSVs) have become an important technology for three-dimensional integrated circuit (3D IC) packaging. Protrusion of electroplated Cu-filled vias is a critical reliability issue for TSV technology. In this work, thermal cycling tests were carried out to identify how the microstructure affects protrusion during thermal cycling. Cu protrusion occurs when the loading temperature is higher than 149°C. During the first five thermal cycles, the grain size of Cu plays a dominant role in the protrusion behavior. Larger Cu grain size before thermal cycling results in greater Cu protrusion. With increasing thermal cycle number, the effect of the Cu grain size reduces and the microstrain begins to dominate the Cu protrusion behavior. Higher magnitude of microstrain within Cu results in greater protrusion increment during subsequent thermal cycles. When the thermal cycle number reaches 25, the protrusion rate of Cu slows down due to strain hardening. After 30 thermal cycles, the Cu protrusion stabilizes within the range of 1.92 μm to 2.09 μm.
Unique Asymmetric Protrusion of Nerve Cord in the Amphioxus, Branchiostoma belcheri
Nozaki, Masumi; Terakado, Kiyoshi; Kubokawa, Kaoru
The amphioxus is the only surviving prevertebrate segmented chordate. In this animal Hatschek's pit has long been regarded as a putative homologue of the adenohypophysis because of the presence of secretory granules and immunoreactive cells to vertebrate gonadotrophic hormone in this organ. We found that the nerve cord extends a protrusion to the pit along the right side of the notochord. Furthermore, secretory granules were found not only in the pit but also in the protrusion of the nerve cord. These results suggest that Hatschek's pit and the nerve protrusion are homologous to the adenohypophysis and neurohypophysis, respectively. We believe that this is an evidence for the presence of the neuroendocrine link between the central nervous system and Hatschek's pit in the amphioxus.
Short Lives with Long-Lasting Effects: Filopodia Protrusions in Neuronal Branching Morphogenesis.
Directory of Open Access Journals (Sweden)
George Leondaritis
Full Text Available The branching behaviors of both dendrites and axons are part of a neuronal maturation process initiated by the generation of small and transient membrane protrusions. These are highly dynamic, actin-enriched structures, collectively called filopodia, which can mature in neurons to form stable branches. Consequently, the generation of filopodia protrusions is crucial during the formation of neuronal circuits and involves the precise control of an interplay between the plasma membrane and actin dynamics. In this issue of PLOS Biology, Hou and colleagues identify a Ca2+/CaM-dependent molecular machinery in dendrites that ensures proper targeting of branch formation by activation of the actin nucleator Cobl.
Agenesis of mandibular second premolar in patient with dental bimaxillary protrusion
Directory of Open Access Journals (Sweden)
Carlos Alberto Estevanell Tavares
Full Text Available ABSTRACT The present study reports the treatment carried out in a patient with mandibular second premolar agenesis associated with early loss of a deciduous second molar, deep overbite, severe overjet and dentoalveolar bimaxillary protrusion, which led to lip incompetence and a convex facial profile. The main objectives of this treatment were: to eliminate the spaces in mandibular arch, correct overbite, as well as eliminate bimaxillary protrusion and lip incompetence, thus leading to a balanced profile. The case was presented to the Brazilian Board of Orthodontics and Dentofacial Orthopedics (BBO as part of the requirements to obtain the title of BBO diplomate.
Directory of Open Access Journals (Sweden)
Hugo Trevisi
2013-01-01
Full Text Available Bimaxillary protrusion cases are common in orthodontic practice. For the best facial outcome, the biomechanics can often be challenging. A class I bimaxillary protrusion case is presented below illustrating the careful application of extractions and bracket prescription. The case highlights how self-ligating brackets and high precision bracket positioning can reduce the need for additional anchorage.
Observation of a Ag protrusion on a Ag2S island using a scanning tunneling microscope
Directory of Open Access Journals (Sweden)
Takeo Ohno
2015-01-01
Full Text Available A silver sulfide (Ag2S island as an ionic conductor in resistive switching memories was formed and a protrusion of silver from the Ag2S formed by an electrochemical reaction was observed using a scanning tunneling microscope.
Preferential control of basal dendritic protrusions by EphB2.
Directory of Open Access Journals (Sweden)
Matthew S Kayser
2011-02-01
Full Text Available The flow of information between neurons in many neural circuits is controlled by a highly specialized site of cell-cell contact known as a synapse. A number of molecules have been identified that are involved in central nervous system synapse development, but knowledge is limited regarding whether these cues direct organization of specific synapse types or on particular regions of individual neurons. Glutamate is the primary excitatory neurotransmitter in the brain, and the majority of glutamatergic synapses occur on mushroom-shaped protrusions called dendritic spines. Changes in the morphology of these structures are associated with long-lasting modulation of synaptic strength thought to underlie learning and memory, and can be abnormal in neuropsychiatric disease. Here, we use rat cortical slice cultures to examine how a previously-described synaptogenic molecule, the EphB2 receptor tyrosine kinase, regulates dendritic protrusion morphology in specific regions of the dendritic arbor in cortical pyramidal neurons. We find that alterations in EphB2 signaling can bidirectionally control protrusion length, and knockdown of EphB2 expression levels reduces the number of dendritic spines and filopodia. Expression of wild-type or dominant negative EphB2 reveals that EphB2 preferentially regulates dendritic protrusion structure in basal dendrites. Our findings suggest that EphB2 may act to specify synapse formation in a particular subcellular region of cortical pyramidal neurons.
PROTRUSION OF THE DEVICE - A COMPLICATION OF CATHETER CLOSURE OF PATENT DUCTUS-ARTERIOSUS
OTTENKAMP, J; HESS, J; TALSMA, MD; BUISLIEM, TN
Objective-To assess the medium term results of percutaneous transvenous closure of patent ductus arteriosus, in particular with regard to protrusion of the device with or without turbulence of the bloodflow. Design-Clinical examination and echocardiographic study (cross sectional Doppler, and colour
Energy Technology Data Exchange (ETDEWEB)
Singh, Raman Deep, E-mail: Takhter.Ramandeep@mayo.edu; Schroeder, Andreas S.; Scheffer, Luana; Holicky, Eileen L.; Wheatley, Christine L.; Marks, David L., E-mail: Marks.david@mayo.edu; Pagano, Richard E.
2013-05-10
Highlights: •Prominin-2 expression induced protrusions that co-localized with lipid raft markers. •Prominin-2 expression decreased caveolae, caveolar endocytosis and increased pCav1. •Prominin-2 expression inhibited fluid phase endocytosis by inactivation of Cdc42. •These endocytic effects can be reversed by adding exogenous cholesterol. •Caveolin1 knockdown restored fluid phase endocytosis in Prominin2 expressing cells. -- Abstract: Background: Membrane protrusions play important roles in biological processes such as cell adhesion, wound healing, migration, and sensing of the external environment. Cell protrusions are a subtype of membrane microdomains composed of cholesterol and sphingolipids, and can be disrupted by cholesterol depletion. Prominins are pentaspan membrane proteins that bind cholesterol and localize to plasma membrane (PM) protrusions. Prominin-1 is of great interest as a marker for stem and cancer cells, while Prominin-2 (Prom2) is reportedly restricted to epithelial cells. Aim: To characterize the effects of Prom-2 expression on PM microdomain organization. Methods: Prom2-fluorescent protein was transfected in human skin fibroblasts (HSF) and Chinese hamster ovary (CHO) cells for PM raft and endocytic studies. Caveolae at PM were visualized using transmission electron microscopy. Cdc42 activation was measured and caveolin-1 knockdown was performed using siRNAs. Results: Prom2 expression in HSF and CHO cells caused extensive Prom2-positive protrusions that co-localized with lipid raft markers. Prom2 expression significantly decreased caveolae at the PM, reduced caveolar endocytosis and increased caveolin-1 phosphorylation. Prom2 expression also inhibited Cdc42-dependent fluid phase endocytosis via decreased Cdc42 activation. Effects on endocytosis were reversed by addition of cholesterol. Knockdown of caveolin-1 by siRNA restored Cdc42 dependent fluid phase endocytosis in Prom2-expressing cells. Conclusions: Prom2 protrusions primarily
Effect of Coriolis forces in a rotating channel with dimples and protrusions
International Nuclear Information System (INIS)
Elyyan, Mohammad A.; Tafti, Danesh K.
2010-01-01
Large-eddy simulations are used to investigate the effect of Coriolis forces and dimple depth on heat transfer and friction in a channel with dimples and protrusions on either side. Two geometries with two different dimple-protrusion depths, δ = 0.2 and 0.3 of channel height are investigated over a wide range of rotation numbers, Ro b = -0.77 to 1.10 based on mean velocity and channel height. It is found that the dimple side of the channel is much more sensitive to destabilizing rotational Coriolis forces than the protrusion side of the channel, although both dimples and protrusions react to the stabilizing effects of Coriolis forces on the leading side. The dimpled surface on the trailing side experiences a large increase in heat transfer coefficient from an augmentation ratio of 1.9 for stationary flow to 3.5 at Ro b = 0.77 for δ = 0.2, and from 2.3 to a maximum of 3.8 for δ = 0.3. Placing protrusion on the trailing side, however, only increases the augmentation ratio to between 3.25 and 3.7 from the stationary values of 3.0 and 3.4 for δ = 0.2 and 0.3, respectively. The dimpled leading side experiences a large drop in heat transfer to between augmentation ratios of 1.1 and 1.4 for the two dimple depths. The protrusion surface on the leading side also experiences a large drop in augmentation from 3.0 for a stationary channel to 1.3 at Ro b = 0.77 for δ = 0.2 and from 3.4 to 1.8 at Ro b = 1.1 for δ = 0.3. The results lead to the conclusion that for low rotation numbers |Ro b | b | > 0.2, dimples on the trailing side of the duct give better overall performance. Between the two depths, the deeper dimple/protrusion (δ = 0.3) gives higher heat transfer augmentation at the price of more frictional losses ranging from 6 to 10 versus 3 to 5 for depth δ = 0.2.
Hydrodynamic optical soliton tunneling
Sprenger, P.; Hoefer, M. A.; El, G. A.
2018-03-01
A notion of hydrodynamic optical soliton tunneling is introduced in which a dark soliton is incident upon an evolving, broad potential barrier that arises from an appropriate variation of the input signal. The barriers considered include smooth rarefaction waves and highly oscillatory dispersive shock waves. Both the soliton and the barrier satisfy the same one-dimensional defocusing nonlinear Schrödinger (NLS) equation, which admits a convenient dispersive hydrodynamic interpretation. Under the scale separation assumption of nonlinear wave (Whitham) modulation theory, the highly nontrivial nonlinear interaction between the soliton and the evolving hydrodynamic barrier is described in terms of self-similar, simple wave solutions to an asymptotic reduction of the Whitham-NLS partial differential equations. One of the Riemann invariants of the reduced modulation system determines the characteristics of a soliton interacting with a mean flow that results in soliton tunneling or trapping. Another Riemann invariant yields the tunneled soliton's phase shift due to hydrodynamic interaction. Soliton interaction with hydrodynamic barriers gives rise to effects that include reversal of the soliton propagation direction and spontaneous soliton cavitation, which further suggest possible methods of dark soliton control in optical fibers.
Tannamala, Pavan Kumar; Pulagam, Mahesh; Pottem, Srinivas R; Swapna, B
2012-04-01
The purpose of this study was to compare the sagittal condylar angles set in the Hanau articulator by use of a method of obtaining an intraoral protrusive record to those angles found using a panoramic radiographic image. Ten patients, free of signs and symptoms of temporomandibular disorder and with intact dentition were selected. The dental stone casts of the subjects were mounted on a Hanau articulator with a springbow and poly(vinyl siloxane) interocclusal records. For all patients, the protrusive records were obtained when the mandible moved forward by approximately 6 mm. All procedures for recording, mounting, and setting were done in the same session. The condylar guidance angles obtained were tabulated. A panoramic radiographic image of each patient was made with the Frankfurt horizontal plane parallel to the floor of the mouth. Tracings of the radiographic images were made. The horizontal reference line was marked by joining the orbitale and porion. The most superior and most inferior points of the curvatures were identified. These two lines were connected by a straight line representing the mean curvature line. Angles made by the intersection of the mean curvature line and the horizontal reference line were measured. The results were subjected to statistical analysis with a significance level of p record method. The mean condylar guidance angle between the right and left side by both the methods was not statistically significant. The comparison of mean condylar guidance angles between the right side of the protrusive record method and the right side of the panoramic radiographic method and the left side of the protrusive record method and the left side of the panoramic radiographic method (p= 0.071 and p= 0.057, respectively) were not statistically significant. Within the limitations of this study, it was concluded that the protrusive condylar guidance angles obtained by panoramic radiograph may be used in programming semi-adjustable articulators. © 2012
Soyama, H.; Hoshino, J.
2016-04-01
In this paper, we used a Venturi tube for generating hydrodynamic cavitation, and in order to obtain the optimum conditions for this to be used in chemical processes, the relationship between the aggressive intensity of the cavitation and the downstream pressure where the cavitation bubbles collapse was investigated. The acoustic power and the luminescence induced by the bubbles collapsing were investigated under various cavitating conditions, and the relationships between these and the cavitation number, which depends on the upstream pressure, the downstream pressure at the throat of the tube and the vapor pressure of the test water, was found. It was shown that the optimum downstream pressure, i.e., the pressure in the region where the bubbles collapse, increased the aggressive intensity by a factor of about 100 compared to atmospheric pressure without the need to increase the input power. Although the optimum downstream pressure varied with the upstream pressure, the cavitation number giving the optimum conditions was constant for all upstream pressures.
Directory of Open Access Journals (Sweden)
H. Soyama
2016-04-01
Full Text Available In this paper, we used a Venturi tube for generating hydrodynamic cavitation, and in order to obtain the optimum conditions for this to be used in chemical processes, the relationship between the aggressive intensity of the cavitation and the downstream pressure where the cavitation bubbles collapse was investigated. The acoustic power and the luminescence induced by the bubbles collapsing were investigated under various cavitating conditions, and the relationships between these and the cavitation number, which depends on the upstream pressure, the downstream pressure at the throat of the tube and the vapor pressure of the test water, was found. It was shown that the optimum downstream pressure, i.e., the pressure in the region where the bubbles collapse, increased the aggressive intensity by a factor of about 100 compared to atmospheric pressure without the need to increase the input power. Although the optimum downstream pressure varied with the upstream pressure, the cavitation number giving the optimum conditions was constant for all upstream pressures.
Energy Technology Data Exchange (ETDEWEB)
Bożek, Piotr, E-mail: piotr.bozek@fis.agh.edu.pl
2016-12-15
The scenario assuming a collective expansion stage in collisions of small systems, p-A, d-Au, and {sup 3}He-Au is discussed. A review of the observables predicted in relativistic hydrodynamic models in comparison with experimental data is presented, with arguments indicating the presence of collective expansion. The limits of applicability of the hydrodynamic model are addressed. We briefly indicate possible applications of the collective flow in small systems to study the space-time dynamics at very small scales in relativistic collisions.
Hydrodynamical description of collective flow
Huovinen, Pasi
2003-01-01
I review how hydrodynamical flow is related to the observed flow in ultrarelativistic heavy ion collisions and how initial conditions, equation of state and freeze-out temperature affect flow in hydrodynamical models.
Dissipative relativistic hydrodynamics
International Nuclear Information System (INIS)
Imshennik, V.S.; Morozov, Yu.I.
1989-01-01
Using the comoving reference frame in the general non-inertial case, the relativistic hydrodynamics equations are derived with an account for dissipative effects in the matter. From the entropy production equation, the exact from for the dissipative tensor components is obtained. As a result, the closed system of equations of dissipative relativistic hydrodynamics is obtained in the comoving reference frame as a relativistic generalization of the known Navier-Stokes equations for Lagrange coordinates. Equations of relativistic hydrodynamics with account for dissipative effects in the matter are derived using the assocoated reference system in general non-inertial case. True form of the dissipative tensor components is obtained from entropy production equation. Closed system of equations for dissipative relativistic hydrodynamics is obtained as a result in the assocoated reference system (ARS) - relativistic generalization of well-known Navier-Stokes equations for Lagrange coordinates. Equation system, obtained in this paper for ARS, may be effectively used in numerical models of explosive processes with 10 51 erg energy releases which are characteristic for flashes of supernovae, if white dwarf type compact target suggested as presupernova
Energy Technology Data Exchange (ETDEWEB)
Matzen, Gehard W. [Univ. of California, Berkeley, CA (United States)
1997-01-01
Three-dimensional creeping flow around single, axisymmetric protrusions is studied numerically using the boundary-integral technique. Emphasis is placed upon cylindrical protrusions on plane walls for various height-to-radius (h-to-a) aspect ratios, but cones and sections of spheres protruding from plane walls are also briefly examined. The presented items include shear-stress distributions, shear-stress contours, extents of the fluid-flow disturbance, total forces and torques on the cylinders, streamlines, and skin-friction lines. Also included is a discussion of flow topology around axisymmetric geometries. No flow reversal is observed for cylindrical protrusions with aspect ratios greater than 2.4 to 2.6. At higher aspect ratios, the fluid tends to be swept around cylindrical protrusions with little vertical motion. At lower aspect ratios, the strength of the recirculation increases, and the recirculation region becomes wider in the transverse direction and narrower in the flow direction. Also, the recirculation pattern begins to resemble the closed streamline patterns in two-dimensional flow over square ridges. However, unlike two-dimensional flow, closed streamline patterns are not observed. For arbitrary axisymmetric geometries, the extent of the fluid-flow disturbance can be estimated with the total force that is exerted on the protrusion. When the same force is exerted on protrusions with different aspect ratios, the protrusion with the higher aspect ratio tends to have a greater disturbance in the flow direction and a smaller disturbance in the transverse direction. The total force exerted on cylindrical protrusions with rounded corners is only slightly lower than the total force exerted on cylindrical protrusions with sharp corners.
Arisha, Mohammed J; Hsiung, Ming C; Ahmad, Amier; Nanda, Navin C; Elkaryoni, Ahmed; Mohamed, Ahmed H; Yin, Wei-Hsian
2017-06-01
Ostial lesions represent a challenging clinical scenario and percutaneous intervention (PCI) of left main coronary artery ostial lesions has been associated with postintervention complications, including protrusion of deployed stents into a sinus of Valsalva or aortic root. We report a case of stent protrusion into the aortic root following aorto-ostial left main coronary artery PCI, in which three-dimensional transesophageal echocardiography (3DTEE) provided incremental benefit over standard two-dimensional images. Specifically, 3DTEE confirmed the presence of stent protrusion by allowing clear visualization of the stent scaffold, in addition to characterizing the relationship between the stent and surrounding structures. © 2017, Wiley Periodicals, Inc.
Temporomandibular joint movement; Evaluation of protrusive splint therapy with GRASS MR imaging
Energy Technology Data Exchange (ETDEWEB)
Maeda, M.; Itou, S.; Ishii, Y.; Yamamoto, K.; Kawamura, Y.; Matsuda, T.; Hayashi, N.; Ishii, J. (Dept. of Radiology, Dept. of Oral and Maxillofacial Surgery, Fukui Medical School (Japan))
1992-09-01
Ten temporomandibular joints (TMJs) of 5 healthy volunteers and 19 TMJs of internal derangements in 16 patients with splint therapy were examined with MR imaging. T1-weighted images were obtained only in the closed mouth position, and gradient recalled acquisition in steady state (GRASS) images were obtained in active opening and closing phases, allowing a pseudodynamic display of TMJ movement. All patients received protrusive splint treatment. The usefulness of MR imaging to assess the efficacy of splint therapy was evaluated. Corrected disk position with the splint in place was clearly demonstrated in 9 TMJs, corresponding with elimination of reciprocal clicking. Ten other TMJs of anterior disk displacement without reduction showed uncorrected disk position by the splint. This information could confirm the therapeutic efficacy, or suggest other treatment alternatives. GRASS MR imaging can provide accurate and physiologic information about disk function in initial and follow-up assessment of protrusive splint therapy. (orig.).
Histologic effects of mandibular protrusion splints in antigen-induced TMJ arthritis in rabbits
von Bremen, Julia; K?hler, Kernt; Siudak, Krystyna; Zahner, Daniel; Ruf, Sabine
2017-01-01
Background Although it is common clinical practice to treat children with Juvenile Idiopathic Arthritis (JIA) with functional appliances, the scientific evidence for this is limited. The aim of this study was to study the histologic effects of mandibular protrusion splints in temporomandibular joint (TMJ) arthritis in rabbits. Methods Twenty-eight ten-week old New Zealand white rabbits were randomly divided into four groups: AO (TMJ arthritis, no splint), AS (TMJ arthritis, mandibular splint ...
A Case of Maxillary Protrusion with Congenitally Missing Canine Teeth in the Mandible
松井, 啓至; 酒徳, 明彦
1996-01-01
A patient that had a maxillary protrusion with congenitally missing canine teeth in the mandible was successfully treated with the extraction of the maxillary first premolars. The patient's cooperation in wearing headgear appliance was highly favorable. Her profile changes were pronounced and esthetically pleasing. A review of her post-treatment records revealed an excellent esthetic and occlusal result even though the first premolars were aligned instead of the canine teeth in the mandible. ...
Anomalous hydrodynamics kicks neutron stars
Energy Technology Data Exchange (ETDEWEB)
Kaminski, Matthias, E-mail: mski@ua.edu [Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL 35487 (United States); Department of Physics and Astronomy, University of Victoria, Victoria, BC, V8P 5C2 (Canada); Uhlemann, Christoph F. [Department of Physics, University of Washington, Seattle, WA 98195 (United States); Bleicher, Marcus [Frankfurt Institute for Advanced Studies, Goethe-Universität Frankfurt (Germany); Institut für Theoretische Physik, Goethe Universität Frankfurt (Germany); Schaffner-Bielich, Jürgen [Institut für Theoretische Physik, Goethe Universität Frankfurt (Germany)
2016-09-10
Observations show that, at the beginning of their existence, neutron stars are accelerated briskly to velocities of up to a thousand kilometers per second. We argue that this remarkable effect can be explained as a manifestation of quantum anomalies on astrophysical scales. To theoretically describe the early stage in the life of neutron stars we use hydrodynamics as a systematic effective-field-theory framework. Within this framework, anomalies of the Standard Model of particle physics as underlying microscopic theory imply the presence of a particular set of transport terms, whose form is completely fixed by theoretical consistency. The resulting chiral transport effects in proto-neutron stars enhance neutrino emission along the internal magnetic field, and the recoil can explain the order of magnitude of the observed kick velocities.
Salient Point Detection in Protrusion Parts of 3D Object Robust to Isometric Variations
Mirloo, Mahsa; Ebrahimnezhad, Hosein
2018-03-01
In this paper, a novel method is proposed to detect 3D object salient points robust to isometric variations and stable against scaling and noise. Salient points can be used as the representative points from object protrusion parts in order to improve the object matching and retrieval algorithms. The proposed algorithm is started by determining the first salient point of the model based on the average geodesic distance of several random points. Then, according to the previous salient point, a new point is added to this set of points in each iteration. By adding every salient point, decision function is updated. Hence, a condition is created for selecting the next point in which the iterative point is not extracted from the same protrusion part so that drawing out of a representative point from every protrusion part is guaranteed. This method is stable against model variations with isometric transformations, scaling, and noise with different levels of strength due to using a feature robust to isometric variations and considering the relation between the salient points. In addition, the number of points used in averaging process is decreased in this method, which leads to lower computational complexity in comparison with the other salient point detection algorithms.
International Nuclear Information System (INIS)
Gong Weidong; Li Yazhou; Cao Wei; Yang Wei; Zhang Peng; Wang Zhimin; Wu Zhiqun
2010-01-01
Objective: To observe the clinical effects and safety of radiofrequency thermocoagulation in treating the lumbar intervertebral disc protrusion. Methods: Thirty patients with lumbar intervertebral disc protrusion, whose diagnoses were confirmed by clinical manifestations and CT findings, were involved in this study. The needle was punctured to the target point of the diseased intervertebral space under C-arm fluoroscopic guidance. After the testing of sensory nerve, motor nerve and temperature was made, the target needles were heated until the nerve radiofrequency temperature meter reached the point of 92 degree C. This point of temperature was held for 100 seconds and the procedure was repeated for four cycles. Results: Six months after the treatment, all patients showed an obvious improvement in VAS, which decreased from 7.83 ± 0.33 before operation to 2.37 ± 0.48 after treatment (P < 0.05). According to the modified Macnab therapeutic evaluation criteria, excellent result was seen in 9, good result in 12, fair result in 5 and poor result in 4 cases, with a total effective rate of 86.7%. No serious complications occurred in all patients. Conclusion: Radiofrequency thermocoagulation is an effective and safe method for the treatment of lumbar intervertebral disc protrusion. (authors)
Glenoid fossa position in Class III malocclusion associated with mandibular protrusion.
Innocenti, Cristina; Giuntini, Veronica; Defraia, Efisio; Baccetti, Tiziano
2009-04-01
Our aim in this study was to investigate the position of the glenoid fossa in subjects with Class III malocclusion associated with mandibular protrusion to better clarify the role of this craniofacial component in Class III skeletal disharmony. A sample of 30 subjects, aged 8 years +/- 6 months, with skeletal and dental Class III malocclusion associated with mandibular protrusion, normal skeletal vertical relationships, and normal mandibular dimensions, was compared with a control group of 33 subjects with skeletal and dental Class I relationships. The comparisons between the Class III group and the control group on the cephalometric measures for the assessment of glenoid fossa position were performed with the Mann-Whitney U test at P <0.05. Subjects with Class III malocclusion had a significantly more mesial position of the glenoid fossa, when compared with the control group as measured with 3 parameters. An anterior position of the glenoid fossa is a possible diagnostic anatomic feature of Class III malocclusion associated with mandibular protrusion. An effective measurement to evaluate glenoid fossa position in craniofacial relationships is the cephalometric distance from the glenoid fossa to the frontomaxillary-nasal suture.
[Treatment of adult bimaxillary arch protrusion with micro-implant anchorage].
Chen, Cheng; Zhang, Xiao-Rong
2015-02-01
In this study, micro-implants were used in 15 adult patients with mild and moderate bimaxillary arch protrusion or crowding. Cephalometric analysis was used to analyze hard and soft-tissues change before and after treatment, with the aim to investigate the effects of treatment on adult bimaxillary arch protrusion with micro-implant anchorage. Fifteen adult patients with mild and moderate bimaxillary arch protrusion were selected in this study. Micro-implants were inserted into the zygomaticoalveolar ridge of maxilla and the external oblique line of mandible. A NiTi coil spring was attached to the micro-implant to drag the whole upper and lower dentition for distal movement. Cephalometrics were taken before and after treatment, and the changes of soft and hard-tissue profile were studied. SPSS13.0 software package was used to analyze the data. (1)Sixty micro-implants remained stable.(2)SNA, SNB had no significant changes (P>0.05), and the relationship between the maxilla and the mandible did not change significantly. U1/NA, U1-NA, L1/NB, L1-NB and U1/L1 changes in hard tissue had significant difference in cephalometric measurement (PMicro-implant can provide not only excellent skeletal anchorage but also a novel way to distalize the whole dentition efficiently.
Saha, Tanumoy; Rathmann, Isabel; Galic, Milos
2017-07-11
Filopodia are dynamic, finger-like cellular protrusions associated with migration and cell-cell communication. In order to better understand the complex signaling mechanisms underlying filopodial initiation, elongation and subsequent stabilization or retraction, it is crucial to determine the spatio-temporal protein activity in these dynamic structures. To analyze protein function in filopodia, we recently developed a semi-automated tracking algorithm that adapts to filopodial shape-changes, thus allowing parallel analysis of protrusion dynamics and relative protein concentration along the whole filopodial length. Here, we present a detailed step-by-step protocol for optimized cell handling, image acquisition and software analysis. We further provide instructions for the use of optional features during image analysis and data representation, as well as troubleshooting guidelines for all critical steps along the way. Finally, we also include a comparison of the described image analysis software with other programs available for filopodia quantification. Together, the presented protocol provides a framework for accurate analysis of protein dynamics in filopodial protrusions using image analysis software.
Hydrodynamics of Turning Flocks
Yang, Xingbo; Marchetti, M. Cristina
2014-01-01
We present a hydrodynamic model of flocking that generalizes the familiar Toner-Tu equations to incorporate turning inertia of well-polarized flocks. The continuum equations controlled by only two dimensionless parameters, orientational inertia and alignment strength, are derived by coarse graining the inertial spin model recently proposed by Cavagna et al. The interplay between orientational inertia and bend elasticity of the flock yields anisotropic spin waves that mediate the propagation o...
Jung, Min-Ho
2015-09-01
To evaluate the effect of dental crowding and lip protrusion on self-esteem and quality of life (QOL) in female orthodontic patients with Class I malocclusion. The study sample consisted of 201 patients (mean age 22.6 ± 3.0 years) who sought orthodontic treatment. All the patients were evaluated before treatment in terms of their degree of dental crowding and lip protrusion. Rosenberg's Self-Esteem Scale and the Orthognathic Quality of Life Questionnaire (OQLQ) were used to determine self-esteem and QOL and to evaluate whether these values were related to malocclusion severity. The results indicated that severe crowding and severe protrusion can result in lower self-esteem and poorer QOL (P self-esteem and QOL scores than severe crowding or protrusion patients.
Hydrodynamics of insect spermatozoa
Pak, On Shun; Lauga, Eric
2010-11-01
Microorganism motility plays important roles in many biological processes including reproduction. Many microorganisms propel themselves by propagating traveling waves along their flagella. Depending on the species, propagation of planar waves (e.g. Ceratium) and helical waves (e.g. Trichomonas) were observed in eukaryotic flagellar motion, and hydrodynamic models for both were proposed in the past. However, the motility of insect spermatozoa remains largely unexplored. An interesting morphological feature of such cells, first observed in Tenebrio molitor and Bacillus rossius, is the double helical deformation pattern along the flagella, which is characterized by the presence of two superimposed helical flagellar waves (one with a large amplitude and low frequency, and the other with a small amplitude and high frequency). Here we present the first hydrodynamic investigation of the locomotion of insect spermatozoa. The swimming kinematics, trajectories and hydrodynamic efficiency of the swimmer are computed based on the prescribed double helical deformation pattern. We then compare our theoretical predictions with experimental measurements, and explore the dependence of the swimming performance on the geometric and dynamical parameters.
Milena Peixoto Nogueira de Sá; Adilson Luiz Ramos; Jacqueline Nelises Zanoni; Fabrício Dias de Souza; Daniele Esteves Pepelascov; Raquel Sano Suga Terada
2017-01-01
The aim of this study was to evaluate the histogical and morphological aspects of the condyle in response to mandibular protrusion induced by composite resin occlusal planes. Thirty five-week-old male Wistar rats were selected and randomly divided in two groups. One group received a composite resin type of oclusal plane that induced mandibular protrusion, and the other was the control group, without treatment. Animals were euthanized after experimental time intervals of 7, 21 and 30 days. For...
Shin, Kang-Jae; Gil, Young-Chun; Lee, Shin-Hyo; Kim, Jeong-Nam; Yoo, Ja-Young; Kim, Soon-Heum; Choi, Hyun-Gon; Shin, Hyun Jin; Koh, Ki-Seok; Song, Wu-Chul
2017-01-01
The aim of the present study was to assess normal eyeball protrusion from the orbital rim using two- and three-dimensional images and demonstrate the better suitability of CT images for assessment of exophthalmos. The facial computed tomographic (CT) images of Korean adults were acquired in sagittal and transverse views. The CT images were used in reconstructing three-dimensional volume of faces using computer software. The protrusion distances from orbital rims and the diameters of eyeballs were measured in the two views of the CT image and three-dimensional volume of the face. Relative exophthalmometry was calculated by the difference in protrusion distance between the right and left sides. The eyeball protrusion was 4.9 and 12.5 mm in sagittal and transverse views, respectively. The protrusion distances were 2.9 mm in the three-dimensional volume of face. There were no significant differences between right and left sides in the degree of protrusion, and the difference was within 2 mm in more than 90% of the subjects. The results of the present study will provide reliable criteria for precise diagnosis and postoperative monitoring using CT imaging of diseases such as thyroid-associated ophthalmopathy and orbital tumors.
Model of Collective Fish Behavior with Hydrodynamic Interactions
Filella, Audrey; Nadal, François; Sire, Clément; Kanso, Eva; Eloy, Christophe
2018-05-01
Fish schooling is often modeled with self-propelled particles subject to phenomenological behavioral rules. Although fish are known to sense and exploit flow features, these models usually neglect hydrodynamics. Here, we propose a novel model that couples behavioral rules with far-field hydrodynamic interactions. We show that (1) a new "collective turning" phase emerges, (2) on average, individuals swim faster thanks to the fluid, and (3) the flow enhances behavioral noise. The results of this model suggest that hydrodynamic effects should be considered to fully understand the collective dynamics of fish.
Dilepton production in schematic causal viscous hydrodynamics
International Nuclear Information System (INIS)
Song, Taesoo; Han, Kyong Chol; Ko, Che Ming
2011-01-01
Assuming that in the hot dense matter produced in relativistic heavy-ion collisions, the energy density, entropy density, and pressure as well as the azimuthal and space-time rapidity components of the shear tensor are uniform in the direction transversal to the reaction plane, we derive a set of schematic equations from the Isreal-Stewart causal viscous hydrodynamics. These equations are then used to describe the evolution dynamics of relativistic heavy-ion collisions by taking the shear viscosity to entropy density ratio of 1/4π for the initial quark-gluon plasma (QGP) phase and of 10 times this value for the later hadron-gas (HG) phase. Using the production rate evaluated with particle distributions that take into account the viscous effect, we study dilepton production in central heavy-ion collisions. Compared with results from the ideal hydrodynamics, we find that although the dilepton invariant mass spectra from the two approaches are similar, the transverse momentum spectra are significantly enhanced at high transverse momenta by the viscous effect. We also study the transverse momentum dependence of dileptons produced from QGP for a fixed transverse mass, which is essentially absent in the ideal hydrodynamics, and find that this so-called transverse mass scaling is violated in the viscous hydrodynamics, particularly at high transverse momenta.
Chiu, Grace S C; Chang, Chris H N; Roberts, W Eugene
2015-01-01
Bimaxillary protrusion in a 28-year-old woman was complicated by multiple missing, restoratively compromised, or hopeless teeth. The maxillary right central incisor had a history of avulsion and replantation that subsequently evolved into generalized external root resorption with Class III mobility and severe loss of the supporting periodontium. This complex malocclusion had a discrepancy index of 21, and 8 additional points were scored for the atrophic dental implant site (maxillary right central incisor). The comprehensive treatment plan included extraction of 4 teeth (both maxillary first premolars, the maxillary right central incisor, and the mandibular right first molar), orthodontic closure of all spaces except for the future implant site (maxillary right central incisor), augmentation of the alveolar defect with an autogenous chin-block graft, enhancement of the gingival biotype with a connective tissue graft, and an implant-supported prosthesis. Orthodontists must understand the limitations of bone grafts. Augmented alveolar defects are slow to completely turn over to living bone, so they are usually good sites for implants but respond poorly to orthodontic space closure. However, postsurgical orthodontic treatment is often indicated to optimally finish the esthetic zone before placing the final prosthesis. The latter was effectively performed for this patient, resulting in a total treatment time of about 36 months for comprehensive interdisciplinary care. An excellent functional and esthetic result was achieved. Copyright © 2015 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.
Titan's hydrodynamically escaping atmosphere
Strobel, Darrell F.
2008-02-01
The upper atmosphere of Titan is currently losing mass at a rate ˜(4-5)×10 amus, by hydrodynamic escape as a high density, slow outward expansion driven principally by solar UV heating by CH 4 absorption. The hydrodynamic mass loss is essentially CH 4 and H 2 escape. Their combined escape rates are restricted by power limitations from attaining their limiting rates (and limiting fluxes). Hence they must exhibit gravitational diffusive separation in the upper atmosphere with increasing mixing ratios to eventually become major constituents in the exosphere. A theoretical model with solar EUV heating by N 2 absorption balanced by HCN rotational line cooling in the upper thermosphere yields densities and temperatures consistent with the Huygens Atmospheric Science Investigation (HASI) data [Fulchignoni, M., and 42 colleagues, 2005. Nature 438, 785-791], with a peak temperature of ˜185-190 K between 3500-3550 km. This model implies hydrodynamic escape rates of ˜2×10 CHs and 5×10 Hs, or some other combination with a higher H 2 escape flux, much closer to its limiting value, at the expense of a slightly lower CH 4 escape rate. Nonthermal escape processes are not required to account for the loss rates of CH 4 and H 2, inferred by the Cassini Ion Neutral Mass Spectrometer (INMS) measurements [Yelle, R.V., Borggren, N., de la Haye, V., Kasprzak, W.T., Niemann, H.B., Müller-Wodarg, I., Waite Jr., J.H., 2006. Icarus 182, 567-576].
How to fake hydrodynamic signals
Energy Technology Data Exchange (ETDEWEB)
Romatschke, Paul [Department of Physics, 390 UCB, University of Colorado at Boulder, Boulder, CO (United States); Center for Theory of Quantum Matter, University of Colorado, Boulder, CO 80309 (United States)
2016-12-15
Flow signatures in experimental data from relativistic ion collisions, are usually interpreted as a fingerprint of the presence of a hydrodynamic phase during the evolution of these systems. I review some theoretical ideas to ‘fake’ this hydrodynamic behavior in p+A and A+A collisions. I find that transverse flow and femtoscopic measurements can easily be forged through non-hydrodynamic evolution, while large elliptic flow requires some non-vanishing interactions in the hot phase.
Modeling hydrodynamic cavitation
Energy Technology Data Exchange (ETDEWEB)
Kumar, P.S.; Pandit, A.B. [Mumbai Univ. (India). Chemical Engineering Div.
1999-12-01
Cavitation as a source and method of energy input for chemical processing is increasingly studied due to its ability to generate localized high temperatures and pressures under nearly ambient conditions. Compared to cavitation generated by ultrasound, hydrodynamic cavitation has been proved to be a very energy-efficient alternative. A simple and unified model has been developed to study the cavitation phenomena in hydraulic systems with emphasis on the venturi tube and high-speed homogenizer. The model has been found to be satisfactory in explaining the effect of operating variables and equipment geometry on two different modes of cavitation generation qualitatively and in some cases quantitatively. (orig.)
Hydrodynamics of Ship Propellers
DEFF Research Database (Denmark)
Breslin, John P.; Andersen, Poul
This book deals with flows over propellers operating behind ships, and the hydrodynamic forces and moments which the propeller generates on the shaft and on the ship hull.The first part of the text is devoted to fundamentals of the flow about hydrofoil sections (with and without cavitation...... of an intermittently cavitating propeller in a wake and the pressures and forces it exerts on the shaft and on the ship hull is examined. A final chapter discusses the optimization of efficiency of compound propulsors. The authors have taken care to clearly describe physical concepts and mathematical steps. Appendices...
Foundations of radiation hydrodynamics
Mihalas, Dimitri
1999-01-01
Radiation hydrodynamics is a broad subject that cuts across many disciplines in physics and astronomy: fluid dynamics, thermodynamics, statistical mechanics, kinetic theory, and radiative transfer, among others. The theory developed in this book by two specialists in the field can be applied to the study of such diverse astrophysical phenomena as stellar winds, supernova explosions, and the initial phases of cosmic expansion, as well as the physics of laser fusion and reentry vehicles. As such, it provides students with the basic tools for research on radiating flows.Largely self-contained,
A mechanism of leading-edge protrusion in the absence of Arp2/3 complex.
Suraneni, Praveen; Fogelson, Ben; Rubinstein, Boris; Noguera, Philippe; Volkmann, Niels; Hanein, Dorit; Mogilner, Alex; Li, Rong
2015-03-01
Cells employ protrusive leading edges to navigate and promote their migration in diverse physiological environments. Classical models of leading-edge protrusion rely on a treadmilling dendritic actin network that undergoes continuous assembly nucleated by the Arp2/3 complex, forming ruffling lamellipodia. Recent work demonstrated, however, that, in the absence of the Arp2/3 complex, fibroblast cells adopt a leading edge with filopodia-like protrusions (FLPs) and maintain an ability to move, albeit with altered responses to different environmental signals. We show that formin-family actin nucleators are required for the extension of FLPs but are insufficient to produce a continuous leading edge in fibroblasts lacking Arp2/3 complex. Myosin II is concentrated in arc-like regions of the leading edge in between FLPs, and its activity is required for coordinated advancement of these regions with formin-generated FLPs. We propose that actomyosin contraction acting against membrane tension advances the web of arcs between FLPs. Predictions of this model are verified experimentally. The dependence of myosin II in leading-edge advancement helps explain the previously reported defect in directional movement in the Arpc3-null fibroblasts. We provide further evidence that this defect is cell autonomous during chemotaxis. © 2015 Suraneni et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).
Mancusso, Romina; Cruz, Eduardo; Cataldi, Marcela; Mendoza, Carla; Fuchs, James; Wang, Hsin; Yang, Xiaomin; Tasayco, María Luisa
2004-04-06
Recent studies of proteins with reversed charged residues have demonstrated that electrostatic interactions on the surface can contribute significantly to protein stability. We have used the approach of reversing negatively charged residues using Arg to evaluate the effect of the electrostatics context on the transition temperature (T(m)), the unfolding Gibbs free energy change (DeltaG), and the unfolding enthalpy change (DeltaH). We have reversed negatively charged residues at a pocket (Asp9) and protrusions (Asp10, Asp20, Glu85), all located in interconnecting segments between elements of secondary structure on the surface of Arg73Ala Escherichia coli thioredoxin. DSC measurements indicate that reversal of Asp in a pocket (Asp9Arg/Arg73Ala, DeltaT(m) = -7.3 degrees C) produces a larger effect in thermal stability than reversal at protrusions: Asp10Arg/Arg73Ala, DeltaT(m) = -3.1 degrees C, Asp20Arg/Arg73Ala, DeltaT(m) = 2.0 degrees C, Glu85Arg/Arg73Ala, DeltaT(m) = 3.9 degrees ). The 3D structure of thioredoxin indicates that Asp20 and Glu85 have no nearby charges within 8 A, while Asp9 does not only have Asp10 as sequential neighbor, but it also forms a 5-A long-range ion pair with the solvent-exposed Lys69. Further DSC measurements indicate that neutralization of the individual charges of the ion pair Asp9-Lys69 with nonpolar residues produces a significant decrease in stability in both cases: Asp9Ala/Arg73Ala, DeltaT(m) = -3.7 degrees C, Asp9Met/Arg73Ala, DeltaT(m) = -5.5 degrees C, Lys69Leu/Arg73Ala, DeltaT(m) = -5.1 degrees C. However, thermodynamic analysis shows that reversal or neutralization of Asp9 produces a 9-15% decrease in DeltaH, while both reversal of Asp at protrusions and neutralization of Lys69 produce negligible changes. These results correlate well with the NMR analysis, which demonstrates that only the substitution of Asp9 produces extensive conformational changes and these changes occur in the surroundings of Lys69. Our results led us to
Nanoscale hydrodynamics near solids
Camargo, Diego; de la Torre, J. A.; Duque-Zumajo, D.; Español, Pep; Delgado-Buscalioni, Rafael; Chejne, Farid
2018-02-01
Density Functional Theory (DFT) is a successful and well-established theory for the study of the structure of simple and complex fluids at equilibrium. The theory has been generalized to dynamical situations when the underlying dynamics is diffusive as in, for example, colloidal systems. However, there is no such a clear foundation for Dynamic DFT (DDFT) for the case of simple fluids in contact with solid walls. In this work, we derive DDFT for simple fluids by including not only the mass density field but also the momentum density field of the fluid. The standard projection operator method based on the Kawasaki-Gunton operator is used for deriving the equations for the average value of these fields. The solid is described as featureless under the assumption that all the internal degrees of freedom of the solid relax much faster than those of the fluid (solid elasticity is irrelevant). The fluid moves according to a set of non-local hydrodynamic equations that include explicitly the forces due to the solid. These forces are of two types, reversible forces emerging from the free energy density functional, and accounting for impenetrability of the solid, and irreversible forces that involve the velocity of both the fluid and the solid. These forces are localized in the vicinity of the solid surface. The resulting hydrodynamic equations should allow one to study dynamical regimes of simple fluids in contact with solid objects in isothermal situations.
Anisotropic nonequilibrium hydrodynamic attractor
Strickland, Michael; Noronha, Jorge; Denicol, Gabriel S.
2018-02-01
We determine the dynamical attractors associated with anisotropic hydrodynamics (aHydro) and the DNMR equations for a 0 +1 d conformal system using kinetic theory in the relaxation time approximation. We compare our results to the nonequilibrium attractor obtained from the exact solution of the 0 +1 d conformal Boltzmann equation, the Navier-Stokes theory, and the second-order Mueller-Israel-Stewart theory. We demonstrate that the aHydro attractor equation resums an infinite number of terms in the inverse Reynolds number. The resulting resummed aHydro attractor possesses a positive longitudinal-to-transverse pressure ratio and is virtually indistinguishable from the exact attractor. This suggests that an optimized hydrodynamic treatment of kinetic theory involves a resummation not only in gradients (Knudsen number) but also in the inverse Reynolds number. We also demonstrate that the DNMR result provides a better approximation of the exact kinetic theory attractor than the Mueller-Israel-Stewart theory. Finally, we introduce a new method for obtaining approximate aHydro equations which relies solely on an expansion in the inverse Reynolds number. We then carry this expansion out to the third order, and compare these third-order results to the exact kinetic theory solution.
Load responsive hydrodynamic bearing
Kalsi, Manmohan S.; Somogyi, Dezso; Dietle, Lannie L.
2002-01-01
A load responsive hydrodynamic bearing is provided in the form of a thrust bearing or journal bearing for supporting, guiding and lubricating a relatively rotatable member to minimize wear thereof responsive to relative rotation under severe load. In the space between spaced relatively rotatable members and in the presence of a liquid or grease lubricant, one or more continuous ring shaped integral generally circular bearing bodies each define at least one dynamic surface and a plurality of support regions. Each of the support regions defines a static surface which is oriented in generally opposed relation with the dynamic surface for contact with one of the relatively rotatable members. A plurality of flexing regions are defined by the generally circular body of the bearing and are integral with and located between adjacent support regions. Each of the flexing regions has a first beam-like element being connected by an integral flexible hinge with one of the support regions and a second beam-like element having an integral flexible hinge connection with an adjacent support region. A least one local weakening geometry of the flexing region is located intermediate the first and second beam-like elements. In response to application of load from one of the relatively rotatable elements to the bearing, the beam-like elements and the local weakening geometry become flexed, causing the dynamic surface to deform and establish a hydrodynamic geometry for wedging lubricant into the dynamic interface.
Hydrodynamic Forces on Composite Structures
2014-06-01
NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public release; distribution is unlimited HYDRODYNAMIC ...Thesis 4. TITLE AND SUBTITLE HYDRODYNAMIC FORCES ON COMPOSITE STRUCTURES 5. FUNDING NUMBERS 6. AUTHOR(S) Scott C. Millhouse 7. PERFORMING...angles yields different free surface effects including vortices and the onset of cavitation . 14. SUBJECT TERMS Fluid structure interaction, FSI, finite
Black brane entropy and hydrodynamics
Booth, I.; Heller, M.P.; Spaliński, M.
2010-01-01
A generalization of entropy to near-equilibrium phenomena is provided by the notion of a hydrodynamic entropy current. Recent advances in holography have lead to the formulation of fluid-gravity duality, a remarkable connection between the hydrodynamics of certain strongly coupled media and dynamics
Black brane entropy and hydrodynamics
Booth, I.; Heller, M.P.; Spaliński, M.
2011-01-01
A generalization of entropy to near-equilibrium phenomena is provided by the notion of a hydrodynamic entropy current. Recent advances in holography have lead to the formulation of fluid-gravity duality, a remarkable connection between the hydrodynamics of certain strongly coupled media and dynamics
Degradation of chlorocarbons driven by hydrodynamic cavitation
Energy Technology Data Exchange (ETDEWEB)
Wu, Z.L.; Ondruschka, B.; Braeutigam, P. [Institut fuer Technische Chemie und Umweltchemie, Friedrich-Schiller-Universitaet Jena, Jena (Germany)
2007-05-15
To provide an efficient lab-scale device for the investigation of the degradation of organic pollutants driven by hydrodynamic cavitation, the degradation kinetics of chloroform and carbon tetrachloride and the increase of conductivity in aqueous solutions were measured. These are values which were not previously available. Under hydrodynamic cavitation conditions, the degradation kinetics for chlorocarbons was found to be pseudo first-order. Meanwhile, C-H and C-Cl bonds are broken, and Cl{sub 2}, Cl{sup .}, Cl{sup -} and other ions released can increase the conductivity and enhance the oxidation of KI in aqueous solutions. The upstream pressures of the orifice plate, the cavitation number, and the solution temperature have substantial effects on the degradation kinetics. A decreased cavitation number can result in more cavitation events and enhances the degradation of chlorocarbons and/or the oxidation of KI. A decrease in temperature is generally favorable to the cavitation chemistry. Organic products from the degradation of carbon tetrachloride and chloroform have demonstrated the formation and recombination of free radicals, e.g., CCl{sub 4}, C{sub 2}Cl{sub 4}, and C{sub 2}Cl{sub 6} are produced from the degradation of CHCl{sub 3}. CHCl{sub 3} and C{sub 2}Cl{sub 6} are produced from the degradation of CCl{sub 4}. Both the chemical mechanism and the reaction kinetics of the degradation of chlorocarbons induced by hydrodynamic cavitation are consistent with those obtained from the acoustic cavitation. Therefore, the technology of hydrodynamic cavitation should be a good candidate for the removal of organic pollutants from water. (Abstract Copyright [2007], Wiley Periodicals, Inc.)
Directory of Open Access Journals (Sweden)
Thommie Karlsson
Full Text Available All modes of cell migration require rapid rearrangements of cell shape, allowing the cell to navigate within narrow spaces in an extracellular matrix. Thus, a highly flexible membrane and a dynamic cytoskeleton are crucial for rapid cell migration. Cytoskeleton dynamics and tension also play instrumental roles in the formation of different specialized cell membrane protrusions, viz. lamellipodia, filopodia, and membrane blebs. The flux of water through membrane-anchored water channels, known as aquaporins (AQPs has recently been implicated in the regulation of cell motility, and here we provide novel evidence for the role of AQP9 in the development of various forms of membrane protrusion. Using multiple imaging techniques and cellular models we show that: (i AQP9 induced and accumulated in filopodia, (ii AQP9-associated filopodial extensions preceded actin polymerization, which was in turn crucial for their stability and dynamics, and (iii minute, local reductions in osmolarity immediately initiated small dynamic bleb-like protrusions, the size of which correlated with the reduction in osmotic pressure. Based on this, we present a model for AQP9-induced membrane protrusion, where the interplay of water fluxes through AQP9 and actin dynamics regulate the cellular protrusive and motile activity of cells.
Application of Hydrodynamic Cavitation for Food and Bioprocessing
Gogate, Parag R.
Hydrodynamic cavitation can be simply generated by the alterations in the flow field in high speed/high pressure devices and also by passage of the liquid through a constriction such as orifice plate, venturi, or throttling valve. Hydrodynamic cavitation results in the formation of local hot spots, release of highly reactive free radicals, and enhanced mass transfer rates due to turbulence generated as a result of liquid circulation currents. These conditions can be suitably applied for intensification of different bioprocessing applications in an energy-efficient manner as compared to conventionally used ultrasound-based reactors. The current chapter aims at highlighting different aspects related to hydrodynamic cavitation, including the theoretical aspects for optimization of operating parameters, reactor designs, and overview of applications relevant to food and bioprocessing. Some case studies highlighting the comparison of hydrodynamic cavitation and acoustic cavitation reactors will also be discussed.
Directory of Open Access Journals (Sweden)
Carsten Schwan
2009-10-01
Full Text Available Clostridium difficile causes antibiotic-associated diarrhea and pseudomembranous colitis by production of the Rho GTPase-glucosylating toxins A and B. Recently emerging hypervirulent Clostridium difficile strains additionally produce the binary ADP-ribosyltransferase toxin CDT (Clostridium difficile transferase, which ADP-ribosylates actin and inhibits actin polymerization. Thus far, the role of CDT as a virulence factor is not understood. Here we report by using time-lapse- and immunofluorescence microscopy that CDT and other binary actin-ADP-ribosylating toxins, including Clostridium botulinum C2 toxin and Clostridium perfringens iota toxin, induce redistribution of microtubules and formation of long (up to >150 microm microtubule-based protrusions at the surface of intestinal epithelial cells. The toxins increase the length of decoration of microtubule plus-ends by EB1/3, CLIP-170 and CLIP-115 proteins and cause redistribution of the capture proteins CLASP2 and ACF7 from microtubules at the cell cortex into the cell interior. The CDT-induced microtubule protrusions form a dense meshwork at the cell surface, which wrap and embed bacterial cells, thereby largely increasing the adherence of Clostridia. The study describes a novel type of microtubule structure caused by less efficient microtubule capture and offers a new perspective for the pathogenetic role of CDT and other binary actin-ADP-ribosylating toxins in host-pathogen interactions.
Modeling the synergy of cofilin and Arp2/3 in lamellipodial protrusive activity.
Tania, Nessy; Condeelis, John; Edelstein-Keshet, Leah
2013-11-05
Rapid polymerization of actin filament barbed ends generates protrusive forces at the cell edge, leading to cell migration. Two important regulators of free barbed ends, cofilin and Arp2/3, have been shown to work in synergy (net effect greater than additive). To explore this synergy, we model the dynamics of F-actin at the leading edge, motivated by data from EGF-stimulated mammary carcinoma cells. We study how synergy depends on the localized rates and relative timing of cofilin and Arp2/3 activation at the cell edge. The model incorporates diffusion of cofilin, membrane protrusion, F-actin capping, aging, and severing by cofilin and branch nucleation by Arp2/3 (but not G-actin recycling). In a well-mixed system, cofilin and Arp2/3 can each generate a large pulse of barbed ends on their own, but have little synergy; high synergy occurs only at low activation rates, when few barbed ends are produced. In the full spatially distributed model, both synergy and barbed-end production are significant over a range of activation rates. Furthermore, barbed-end production is greatest when Arp2/3 activation is delayed relative to cofilin. Our model supports a direct role for cofilin-mediated actin polymerization in stimulated cell migration, including chemotaxis and cancer invasion. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.
Space Closure with Loop Mechanics for Treatment of Bimaxillary Protrusion: A Case Report
Sanjay, N; Rajesh, R N G; Scindia, Rajat; Ajith, Sreedevi D
2015-01-01
This case report intends to highlight the space closure with tear drop loop mechanics for bimaxillary protrusion. Loops can be fabricated in a sectional or full arch wire, and closing loops are usually used in loop mechanics for extraction space closure. The major advantage of loop mechanics is the lack of friction between the bracket and arch wire during space closure. An adult patient with bimaxillary protrusion reported to the clinic. The patient was treated successfully by maximum retraction of maxillary and mandibular anterior teeth after extraction of all first premolars. Space closure was begun using a moment differential between posterior and anterior segments created by a Tear drop loop. Anterior teeth were moved with bodily movement, and no anchorage loss of the posterior segments was seen using a Tear drop loop spring. A stable result with normal over jet and overbite was achieved with retraction of maxillary and mandibular anterior teeth. With a Tear drop loop, individual biomechanical responses can be achieved, and it is possible to calculate force magnitude for every patient. PMID:26028908
A study on normal value of eyeball protrusion in Korean adult using CT
International Nuclear Information System (INIS)
Song, Chi Sung; Chang, Kee Hyun
1984-01-01
CT may be valuably used in determination of proptosis. Normal value of eyeball protrusion was measured in normal Koreans using CT. Among 86 Koreans, 26 have normal both eyes, but 60 have one normal eye with one abnormal eye (chiefly, proptosis and and eyeball tumor). The results of 112 eyes are as follows: Absolute measurement of 'a', that is, the distance between cornea and IZL (interzygomatic line) is 16.0±3.4 mm in male (for 63 eye), 15.7±4.0 mm in female for 49 eyes. Ratio of 'a' over 'A' (A-P diameter of eyeball) is 57±12% is male (for 63 eye), 57±14% in female (for 49 eye) Discrepancy of eyeball protrusion between both eyes is 0.67±1.5 mm (for 26 adults). Practically, normal range of eyeball prtotrusion ('a') is 12.6 mm < male < 19.4 mm, 11.7 mm < female < 19.7 mm. 'a/A' ratio over 70% and over 2mm discrepancy between both eyes are also suggested as genuine exophthalmos
The origin of X-ray protrusions in the VELA supernova remnant
Gvaramadze, V. V.
We propose a possible explanation for the formation of X-ray protrusions in the Vela SNR, recently observed by the ROSAT X-ray telescope (Aschenbach, Egger & Trumper, 1995, Nature, 373, 587). We suggest that the highly asymmetric shape of the Vela SNR is the result of the interaction of the SN ejecta/shock with the pre-existing wind-driven shell blown-up in a medium with a density gradient (perpendicular to the Galactic plane). The interaction of the radiative (north-east) half of the remnant, approaching towards the Galactic plane, with dense obstacles (cloudlets or wind zones of stars) can produce X-ray "bullets" radially moving beyond the SNR boundary. These "bullets" originate due to the cooling and condensation of a gas swept-up by converging conical shocks arising behind the dense obstacles overtaken by the SN shock. The X-ray protrusions observed in the western part of the remnant might be explained by outflows of hot gas of the SNR's interior emanating through the gaps in the shell. The origin of the X-ray "jet" (Markwardt & Ogelman, 1995, Nature, 375, 40) in the central part of the Vela SNR is also discussed.
A hydrodynamic formalism for Brownian systems
International Nuclear Information System (INIS)
Pina, E.; Rosales, M.A.
1981-01-01
A formal hydrodynamic approach to Brownian motion is presented and the corresponding equations are derived. Hydrodynamic quantities are expressed in terms of the physical variables characterizing the Brownian systems. Contact is made with the hydrodynamic model of Quantum Mechanics. (author)
Foundations of radiation hydrodynamics
Mihalas, D.; Mihalas, B. W.
This book is the result of an attempt, over the past few years, to gather the basic tools required to do research on radiating flows in astrophysics. The microphysics of gases is discussed, taking into account the equation of state of a perfect gas, the first and second law of thermodynamics, the thermal properties of a perfect gas, the distribution function and Boltzmann's equation, the collision integral, the Maxwellian velocity distribution, Boltzmann's H-theorem, the time of relaxation, and aspects of classical statistical mechanics. Other subjects explored are related to the dynamics of ideal fluids, the dynamics of viscous and heat-conducting fluids, relativistic fluid flow, waves, shocks, winds, radiation and radiative transfer, the equations of radiation hydrodynamics, and radiating flows. Attention is given to small-amplitude disturbances, nonlinear flows, the interaction of radiation and matter, the solution of the transfer equation, acoustic waves, acoustic-gravity waves, basic concepts of special relativity, and equations of motion and energy.
International Nuclear Information System (INIS)
Koehler, H.S.
1983-01-01
The Time-Dependent Hartree-Fock theory provides a microscopic approach to the scattering of heavy ions. Fundamental in this theory is a mean-(one-body) field. The calculation of this field from a two-body effective interaction makes the theory microscopic. Many-body effects are included by the Brueckner definition of this interaction; the reaction-matrix. In excited media it is in general complex allowing for decays. The imaginary part relates directly to the collision-term in a transport equation. We treat this term by the time-relaxation-method. This implies an extension of the TDHF-equation to include two-body collisions. Hydrodynamic equations are derived from this new equation. The solution of the two equations agree quantitatively for short-relaxation-times. Relaxation-times are calculated as a function of temperature. (orig.)
Hydrodynamics of Peristaltic Propulsion
Athanassiadis, Athanasios; Hart, Douglas
2014-11-01
A curious class of animals called salps live in marine environments and self-propel by ejecting vortex rings much like jellyfish and squid. However, unlike other jetting creatures that siphon and eject water from one side of their body, salps produce vortex rings by pumping water through siphons on opposite ends of their hollow cylindrical bodies. In the simplest cases, it seems like some species of salp can successfully move by contracting just two siphons connected by an elastic body. When thought of as a chain of timed contractions, salp propulsion is reminiscent of peristaltic pumping applied to marine locomotion. Inspired by salps, we investigate the hydrodynamics of peristaltic propulsion, focusing on the scaling relationships that determine flow rate, thrust production, and energy usage in a model system. We discuss possible actuation methods for a model peristaltic vehicle, considering both the material and geometrical requirements for such a system.
Hydrodynamic effects on coalescence.
Energy Technology Data Exchange (ETDEWEB)
Dimiduk, Thomas G.; Bourdon, Christopher Jay; Grillet, Anne Mary; Baer, Thomas A.; de Boer, Maarten Pieter; Loewenberg, Michael (Yale University, New Haven, CT); Gorby, Allen D.; Brooks, Carlton, F.
2006-10-01
The goal of this project was to design, build and test novel diagnostics to probe the effect of hydrodynamic forces on coalescence dynamics. Our investigation focused on how a drop coalesces onto a flat surface which is analogous to two drops coalescing, but more amenable to precise experimental measurements. We designed and built a flow cell to create an axisymmetric compression flow which brings a drop onto a flat surface. A computer-controlled system manipulates the flow to steer the drop and maintain a symmetric flow. Particle image velocimetry was performed to confirm that the control system was delivering a well conditioned flow. To examine the dynamics of the coalescence, we implemented an interferometry capability to measure the drainage of the thin film between the drop and the surface during the coalescence process. A semi-automated analysis routine was developed which converts the dynamic interferogram series into drop shape evolution data.
Directory of Open Access Journals (Sweden)
K C Prabhat
2014-01-01
Full Text Available Bimaxillary dentoalveolar protrusion is common in Asian population. In this patient with procumbent upper and lower lips, excessive lip strain, proclined and protruded maxillary and mandibular incisors with vertical growth pattern, an acceptable treatment result, was achieved with 4-first-premolar extractions. This case report is presented with the aim, to describe the treatment approach for bimaxillary dentoalveolar protrusion using miniscrew implants for anchorage in upper arch and periodontal ligament distraction for canine retraction in lower arch and then retraction of incisors into the newly formed bone distal to lateral incisor. Treatment was completed in 18 months. The patient profile was improved, with reduction in lip procumbency, decrease in lip eversion and protrusion, and decrease mentalis strain. Dentally, the interincisal angulation improved significantly because both the maxillary and mandibular incisors were uprighted after space closer.
International Nuclear Information System (INIS)
Holl, J.W.
1985-01-01
Isolated surface roughness can cause significant localized pressure reductions which can lead to premature cavitation and degradation of the cavitation performance of a marine vehicle. The characteristic velocity theory was developed to analyze the limited cavitation characteristics of isolated surface protrusions. This theory is dependent upon knowing the boundary layer velocity profile in the vicinity of the roughness and the limited cavitation number for the roughness in a uniform stream. In the investigation described in this paper, the equation for triangular surface protrusions was determined experimentally by testing sharpedged flat plates in a water tunnel. These data were then employed in the characteristic velocity theory to calculate the cavitation characteristics of a triangular protrusion in a turbulent boundary layer for comparison with experimental data
Directory of Open Access Journals (Sweden)
Junichi Ohya
2014-01-01
Full Text Available Purpose: Among extraosseous abnormalities of the vertebral artery (VA at the craniovertebral junction (CVJ, available evidence regarding "posterolateral protrusion," the VA running distant from the groove over the superior surface of the posterior arch of the atlas, is limited. The purpose of this study was to determine the optimal measurement to indicate posterolateral protrusion of the VA. Materials and Methods: Computed tomography angiography (CTA images of 40 consecutive patients with cervical disease were reviewed. Ultimately, 66 arteries were included in this study. Five parameters predicted to indicate posterolateral protrusion of the VA were defined (A-E and measured by two surgeons twice over a 2-week interval. Intraclass correlation coefficients (ICC were used to examine intra-observer reproducibility and inter-observer reliability. Receiver operating characteristic (ROC curve analysis was performed to determine the most optimal parameter to predict posterolateral protrusion of the VA. Results: Excellent inter-observer reliability and intra-observer reproducibility were obtained for all parameters (ICC = 0.87-0.99. Among them, parameter A, defined as the maximal length from the outer surface of the VA to the outer surface of the posterior arch of the atlas, was most accurately described posterolateral protrusion of the VA. The optimal cut-off value of parameter A obtained with ROC curves was 8.3 mm (sensitivity 97.5%, specificity 100%. Conclusions: The measurement in this study can quantitatively evaluate the posterolateral protrusion of the VA. Before posterior surgery at the CVJ, pre-operative CTA can help surgeons detect anomalous VA and reduce the risk of intra-operative VA injury.
Hydrodynamic cavitation for sonochemical effects.
Moholkar, V S; Kumar, P S; Pandit, A B
1999-03-01
A comparative study of hydrodynamic and acoustic cavitation has been made on the basis of numerical solutions of the Rayleigh-Plesset equation. The bubble/cavity behaviour has been studied under both acoustic and hydrodynamic cavitation conditions. The effect of varying pressure fields on the collapse of the cavity (sinusoidal for acoustic and linear for hydrodynamic) and also on the latter's dynamic behaviour has been studied. The variations of parameters such as initial cavity size, intensity of the acoustic field and irradiation frequency in the case of acoustic cavitation, and initial cavity size, final recovery pressure and time for pressure recovery in the case of hydrodynamic cavitation, have been found to have significant effects on cavity/bubble dynamics. The simulations reveal that the bubble/cavity collapsing behaviour in the case of hydrodynamic cavitation is accompanied by a large number of pressure pulses of relatively smaller magnitude, compared with just one or two pulses under acoustic cavitation. It has been shown that hydrodynamic cavitation offers greater control over operating parameters and the resultant cavitation intensity. Finally, a brief summary of the experimental results on the oxidation of aqueous KI solution with a hydrodynamic cavitation set-up is given which supports the conclusion of this numerical study. The methodology presented allows one to manipulate and optimise of specific process, either physical or chemical.
Recent development of hydrodynamic modeling
Hirano, Tetsufumi
2014-09-01
In this talk, I give an overview of recent development in hydrodynamic modeling of high-energy nuclear collisions. First, I briefly discuss about current situation of hydrodynamic modeling by showing results from the integrated dynamical approach in which Monte-Carlo calculation of initial conditions, quark-gluon fluid dynamics and hadronic cascading are combined. In particular, I focus on rescattering effects of strange hadrons on final observables. Next I highlight three topics in recent development in hydrodynamic modeling. These include (1) medium response to jet propagation in di-jet asymmetric events, (2) causal hydrodynamic fluctuation and its application to Bjorken expansion and (3) chiral magnetic wave from anomalous hydrodynamic simulations. (1) Recent CMS data suggest the existence of QGP response to propagation of jets. To investigate this phenomenon, we solve hydrodynamic equations with source term which exhibits deposition of energy and momentum from jets. We find a large number of low momentum particles are emitted at large angle from jet axis. This gives a novel interpretation of the CMS data. (2) It has been claimed that a matter created even in p-p/p-A collisions may behave like a fluid. However, fluctuation effects would be important in such a small system. We formulate relativistic fluctuating hydrodynamics and apply it to Bjorken expansion. We found the final multiplicity fluctuates around the mean value even if initial condition is fixed. This effect is relatively important in peripheral A-A collisions and p-p/p-A collisions. (3) Anomalous transport of the quark-gluon fluid is predicted when extremely high magnetic field is applied. We investigate this possibility by solving anomalous hydrodynamic equations. We found the difference of the elliptic flow parameter between positive and negative particles appears due to the chiral magnetic wave. Finally, I provide some personal perspective of hydrodynamic modeling of high energy nuclear collisions
SPECIAL RELATIVISTIC HYDRODYNAMICS WITH GRAVITATION
Energy Technology Data Exchange (ETDEWEB)
Hwang, Jai-chan [Department of Astronomy and Atmospheric Sciences, Kyungpook National University, Daegu (Korea, Republic of); Noh, Hyerim [Korea Astronomy and Space Science Institute, Daejon (Korea, Republic of)
2016-12-20
Special relativistic hydrodynamics with weak gravity has hitherto been unknown in the literature. Whether such an asymmetric combination is possible has been unclear. Here, the hydrodynamic equations with Poisson-type gravity, considering fully relativistic velocity and pressure under the weak gravity and the action-at-a-distance limit, are consistently derived from Einstein’s theory of general relativity. An analysis is made in the maximal slicing, where the Poisson’s equation becomes much simpler than our previous study in the zero-shear gauge. Also presented is the hydrodynamic equations in the first post-Newtonian approximation, now under the general hypersurface condition. Our formulation includes the anisotropic stress.
Similarity flows in relativistic hydrodynamics
International Nuclear Information System (INIS)
Blaizot, J.P.; Ollitrault, J.Y.
1986-01-01
In ultra-relativistic heavy ion collisions, one expects in particular to observe a deconfinement transition leading to a formation of quark gluon plasma. In the framework of the hydrodynamic model, experimental signatures of such a plasma may be looked for as observable consequences of a first order transition on the evolution of the system. In most of the possible scenario, the phase transition is accompanied with discontinuities in the hydrodynamic flow, such as shock waves. The method presented in this paper has been developed to treat without too much numerical effort such discontinuous flow. It relies heavily on the use of similarity solutions of the hydrodynamic equations
Directory of Open Access Journals (Sweden)
Adèle Salin-Cantegrel
Full Text Available Loss-of-function of the potassium-chloride cotransporter 3 (KCC3 causes hereditary motor and sensory neuropathy with agenesis of the corpus callosum (HMSN/ACC, a severe neurodegenerative disease associated with defective midline crossing of commissural axons in the brain. Conversely, KCC3 over-expression in breast, ovarian and cervical cancer is associated with enhanced tumor cell malignancy and invasiveness. We identified a highly conserved proline-rich sequence within the C-terminus of the cotransporter which when mutated leads to loss of the KCC3-dependent regulatory volume decrease (RVD response in Xenopus Laevis oocytes. Using SH3 domain arrays, we found that this poly-proline motif is a binding site for SH3-domain containing proteins in vitro. This approach identified the guanine nucleotide exchange factor (GEF Vav2 as a candidate partner for KCC3. KCC3/Vav2 physical interaction was confirmed using GST-pull down assays and immuno-based experiments. In cultured cervical cancer cells, KCC3 co-localized with the active form of Vav2 in swelling-induced actin-rich protruding sites and within lamellipodia of spreading and migrating cells. These data provide evidence of a molecular and functional link between the potassium-chloride co-transporters and the Rho GTPase-dependent actin remodeling machinery in RVD, cell spreading and cell protrusion dynamics, thus providing new insights into KCC3's involvement in cancer cell malignancy and in corpus callosum agenesis in HMSN/ACC.
Biswas, Sondip K; Lee, Jai Eun; Brako, Lawrence; Jiang, Jean X; Lo, Woo-Kuen
2010-11-09
Ball-and-sockets and protrusions are specialized interlocking membrane domains between lens fibers of all species studied. Ball-and-sockets and protrusions are similar in their shape, size, and surface morphology, and are traditionally believed to play a key role in maintaining fiber-to-fiber stability. Here, we evaluate the hypothesis that ball-and-sockets and protrusions possess important structural and functional differences during fiber cell differentiation and maturation. Intact lenses of leghorn chickens (E7 days to P62 weeks old) and rhesus monkeys (1.5-20 years old) were studied with SEM, freeze-fracture TEM, freeze-fracture immunogold labeling (FRIL), and filipin cytochemistry for membrane cholesterol detection. SEM showed that ball-and-sockets were distributed along the long and short sides of hexagonal fiber cells, whereas protrusions were located along the cell corners, from superficial to deep cortical regions in both chicken and monkey lenses. Importantly, by freeze-fracture TEM, we discovered the selective association of gap junctions with all ball-and-sockets examined, but not with protrusions, in both species. In the embryonic chicken lens (E18), the abundant distribution of ball-and-socket gap junctions was regularly found in an approximate zone extending at least 300 μm deep from the equatorial surface of the superficial cortical fibers. Many ball-and-socket gap junctions often protruded deeply into neighboring cells. However, in the mature fibers of monkey lenses, several ball-and-sockets exhibited only partial occupancy of gap junctions with disorganized connexons, possibly due to degradation of gap junctions during fiber maturation and aging. FRIL analysis confirmed that both connexin46 (Cx46) and connexin50 (Cx50) antibodies specifically labeled ball-and-socket gap junctions, but not protrusions. Furthermore, filipin cytochemistry revealed that the ball-and-socket gap junctions contained different amounts of cholesterol (i.e., cholesterol
Directory of Open Access Journals (Sweden)
Mohd Ayaz
2016-01-01
Full Text Available This case report deals with the successful orthodontic treatment of a 14-year-old female patient having Class II malocclusion with bidental protrusion using standard edgewise prescription. She reported with forwardly placed upper front teeth and difficulty in closing lips. She had prognathic maxilla, retrognathic mandible, and full cusp Class II molar and canine relation bilaterally with overjet of 7 mm. She was in cervical vertebrae maturation indicator Stage IV. The case was treated by fixed extraction mechanotherapy. Interarch Class II mechanics was used to retract the upper incisor and to mesialize the lower molars. Simultaneously, Class I mechanics was used to upright lower incisors. Tip back bend, curve of Spee, and extra palatal root torque were incorporated in upper archwire to maintain molars in upright position and prevent extrusion and deepening of bite, respectively. There was satisfactory improvement in facial profile at the end of 24 months. After a follow-up of 6 months, occlusion was stable.
Choi, Nak-Chun; Park, Young-Chel; Jo, Yong-Min; Lee, Kee-Joon
2009-05-01
The increasing demand for esthetic orthodontic treatment has led to the development of tooth-colored and even "invisible" appliances. Although sequential removable clear aligners have several advantages over conventional bracket systems, they have some limitations in extraction treatment. This case report presents the esthetic extraction treatment of a patient with bialveolar protrusion; conventional brackets were not used. The treatment was completed in 2 steps. The first step involved segmental retraction of the anterior teeth by using miniscrews and an anterior lingual splint with a clear lever arm. The second step involved alignment and finishing by using sequential removable clear aligners. The patient's esthetic demands were fulfilled successfully during treatment, and satisfactory facial profile and occlusion were achieved after treatment.
Hydrodynamics of rotating superfluids
International Nuclear Information System (INIS)
Chandler, E.A.
1981-01-01
In this thesis, a coarse grained hydrodynamics is developed from the exact description of Tkachenko. To account for the dynamics of the vortex lattice, the macroscopic vortex displacement field is treated as an independent degree of freedom. The conserved energy is written in terms of the coarse-grained normal fluid, superfluid, and vortex velocities and includes an elastic energy associated with deformations of the vortex lattice. Equations of motion consistent with the conservation of energy, entropy and vorticity and containing mutual friction terms arising from microscopic interactions between normal fluid excitations and the vortex lines are derived. When the vortex velocity is eliminated from the damping terms, this system of equations becomes essentially that of BK with added elastic terms in the momentum stress tensor and energy current. The dispersion relation and damping of the first and second sound modes and the two transverse modes sustained by the system are investigated. It is shown that mutual friction mixes the transverse modes of the normal and superfluid components and damps the transverse mode associated with the relative velocity of these components, making this wave evanescent in the plane perpendicular to the rotation axis. The wave associated with transverse motion of the total mass current is a generalized Tkachenko mode, whose dispersion relation reduces to that derived by Tkachenko wave when the wavevector lies in this plane
Advanced in Macrostatistical Hydrodynamics
International Nuclear Information System (INIS)
Graham, A.L.; Tetlow, N.; Abbott, J.R.; Mondy, L.S.; Brenner, H.
1993-01-01
An overview is presented of research that focuses on slow flows of suspensions in which colloidal and inertial effects are negligibly small (Macrostatistical Hydrodynamics). First, we describe nuclear magnetic resonance imaging experiments to quantitatively measure particle migration occurring in concentrated suspensions undergoing a flow with a nonuniform shear rate. These experiments address the issue of how the flow field affects the microstructure of suspensions. In order to understand the local viscosity in a suspension with such a flow-induced, spatially varying concentration, one must know how the viscosity of a homogeneous suspension depends on such variables as solids concentration and particle orientation. We suggest the technique of falling ball viscometry, using small balls, as a method to determine the effective viscosity of a suspension without affecting the original microstructure significantly. We also describe data from experiments in which the detailed fluctuations of a falling ball's velocity indicate the noncontinuum nature of the suspension and may lead to more insights into the effects of suspension microstructure on macroscopic properties. Finally, we briefly describe other experiments that can be performed in quiescent suspensions (in contrast to the use of conventional shear rotational viscometers) in order to learn more about the microstructure and boundary effects in concentrated suspensions
Engineering Hydrodynamic AUV Hulls
Allen, J.
2016-12-01
AUV stands for autonomous underwater vehicle. AUVs are used in oceanography and are similar to gliders. MBARIs AUVs as well as other AUVs map the ocean floor which is very important. They also measure physical characteristics of the water, such as temperature and salinity. My science fair project for 4th grade was a STEM activity in which I built and tested 3 different AUV bodies. I wanted to find out which design was the most hydrodynamic. I tested three different lengths of AUV hulls to see which AUV would glide the farthest. The first was 6 inches. The second was 12 inches and the third was 18 inches. I used clay for the nosecone and cut a ruler into two and made it the fin. Each AUV used the same nosecone and fin. I tested all three designs in a pool. I used biomimicry to create my hypothesis. When I was researching I found that long slim animals swim fastest. So, my hypothesis is the longer AUV will glide farthest. In the end I was right. The longer AUV did glide the farthest.
Ko, Jeong-Min; Paik, Cheol-Ho; Choi, Simon; Baek, Seung-Hak
2014-05-01
To present a patient treated with submerging autotransplantation (SA) of an immature premolar and subsequent orthodontic space closure (OSC) and to report a 10-year follow-up result. A 10-year-old boy had multiple missing premolars with an asymmetric pattern (maxillary right first and second premolars, teeth 14 and 15; maxillary left second premolar, tooth 25; and mandibular right second premolar, tooth 45). After considering several treatment options, tooth 35 with immature root development underwent SA into the missing site of tooth 15 at a depth 5 mm below the occlusal plane and was stabilized with sutures to create a symmetric missing condition of the premolars in the four quadrants. Three months after autotransplantation, spontaneous eruption of the transplanted tooth was observed. Nine months after autotransplantation, presence of the lamina dura of the transplanted tooth was confirmed with a periapical radiograph. Active orthodontic treatment was initiated to reduce lip protrusion by closing the missing spaces of teeth 14, 25, 35, and 45 and to correct dental midline deviation. After 33 months of active orthodontic treatment, Class I canine and molar relationships were obtained. During the 10-year follow-up, the pulp vitality of the transplanted tooth was maintained without any pathologic findings, including root resorption or pulp canal obliteration. In a patient with lip protrusion and multiple congenitally missing premolars with an asymmetric pattern, SA of one premolar from the normal quadrant into the quadrant missing two premolars with subsequent OSC of the missing sites of the other premolars can be an effective treatment modality.
Hydrodynamics in a swarm of rising bubbles
International Nuclear Information System (INIS)
Riboux, G.
2007-04-01
In many applications, bubbles are used to agitate a liquid in order to enhance mixing and transfer. This work is devoted to the study of the hydrodynamics in a stable bubble column. Experimentally, we have determined the properties of the velocity fluctuations inside and behind a homogeneous swarm of rising bubbles for different bubble sizes and gas volume fractions α: self-similarity in α 0,4 , spectrum in k -3 and integral length scale controlled by buoyancy. Numerically, we have reproduced these properties by means of large-scale simulations, the bubbles being modeled by volume-forces. This confirms that the dynamics is controlled by wake interactions. (author)
Hydrodynamics of electrons in graphene
Lucas, Andrew; Chung Fong, Kin
2018-02-01
Generic interacting many-body quantum systems are believed to behave as classical fluids on long time and length scales. Due to rapid progress in growing exceptionally pure crystals, we are now able to experimentally observe this collective motion of electrons in solid-state systems, including graphene. We present a review of recent progress in understanding the hydrodynamic limit of electronic motion in graphene, written for physicists from diverse communities. We begin by discussing the ‘phase diagram’ of graphene, and the inevitable presence of impurities and phonons in experimental systems. We derive hydrodynamics, both from a phenomenological perspective and using kinetic theory. We then describe how hydrodynamic electron flow is visible in electronic transport measurements. Although we focus on graphene in this review, the broader framework naturally generalizes to other materials. We assume only basic knowledge of condensed matter physics, and no prior knowledge of hydrodynamics.
Analytic approaches to relativistic hydrodynamics
Energy Technology Data Exchange (ETDEWEB)
Hatta, Yoshitaka
2016-12-15
I summarize our recent work towards finding and utilizing analytic solutions of relativistic hydrodynamic. In the first part I discuss various exact solutions of the second-order conformal hydrodynamics. In the second part I compute flow harmonics v{sub n} analytically using the anisotropically deformed Gubser flow and discuss its dependence on n, p{sub T}, viscosity, the chemical potential and the charge.
Hydrodynamic aspects of flotation separation
Directory of Open Access Journals (Sweden)
Peleka Efrosyni N.
2016-01-01
Full Text Available Flotation separation is mainly used for removing particulates from aqueous dispersions. It is widely used for ore beneficiation and recovering valuable materials. This paper reviews the hydrodynamics of flotation separations and comments on selected recent publications. Units are distinguished as cells of ideal and non-ideal flow. A brief introduction to hydrodynamics is included to explain an original study of the hybrid flotation-microfiltration cell, effective for heavy metal ion removal.
An introduction to astrophysical hydrodynamics
Shore, Steven N
1992-01-01
This book is an introduction to astrophysical hydrodynamics for both astronomy and physics students. It provides a comprehensive and unified view of the general problems associated with fluids in a cosmic context, with a discussion of fluid dynamics and plasma physics. It is the only book on hydrodynamics that addresses the astrophysical context. Researchers and students will find this work to be an exceptional reference. Contents include chapters on irrotational and rotational flows, turbulence, magnetohydrodynamics, and instabilities.
International Nuclear Information System (INIS)
Isu, Toyohiko; Iwasaki, Yoshinobu; Abe, Hiroshi; Miyasaka, Kazuo; Tashiro, Kunio; Tsuru, Mitsuo; Ito, Terufumi.
1985-01-01
In the cervical disc disease, computed tomography (CT) myelographic and conventional myelographic findings were surgically confirmed. The authors classified the disc protrusion into two types, and demonstrated the characteristic features of these two types in CT myelography and conventional myelography. Moreover, the correlation with the localization of the disc protrusion and the laterality of the myelopathy are discussed. All cases were obtained using a late generation scanner and the patient in the supine position with the neck in the neutral position. Using conventional myelography, all examinations were obtained with the neck in a flexion, neutral and extended positions. Twenty-two patients with cervical disc disease operated on by an anterior approach were studied by CT myelography and conventional myelography. According to the style of the compression on the spinal cord, the cervical disc protrusion was classified into two main groups, the subligamentous type and epiligamentous type. This study included 10 patients of the subligamentous type and 12 patients of the epiligamentous type. The localization of the disc protrusion and the laterality of the myelopathy often corresponded with each other. Not only the localization of the lesion, but also the pincer effect, especially the oblique pincer effect, which is reinforced by dynamic factors, are important in the understanding of the manifestations of myelopathy. In the subligamentous type, the main cause of the myelopathy is considered to be the mechanical pressure by the prolapsed nucleus pulposus. In the epiligamentous type, on the other hand, it is believed to be the pincer effect, reinforced by dynamic factors. (author)
Directory of Open Access Journals (Sweden)
Sezar Gülbaz
2015-01-01
Full Text Available The land development and increase in urbanization in a watershed affect water quantityand water quality. On one hand, urbanization provokes the adjustment of geomorphicstructure of the streams, ultimately raises peak flow rate which causes flood; on theother hand, it diminishes water quality which results in an increase in Total SuspendedSolid (TSS. Consequently, sediment accumulation in downstream of urban areas isobserved which is not preferred for longer life of dams. In order to overcome thesediment accumulation problem in dams, the amount of TSS in streams and inwatersheds should be taken under control. Low Impact Development (LID is a BestManagement Practice (BMP which may be used for this purpose. It is a land planningand engineering design method which is applied in managing storm water runoff inorder to reduce flooding as well as simultaneously improve water quality. LID includestechniques to predict suspended solid loads in surface runoff generated over imperviousurban surfaces. In this study, the impact of LID-BMPs on surface runoff and TSS isinvestigated by employing a calibrated hydrodynamic model for Sazlidere Watershedwhich is located in Istanbul, Turkey. For this purpose, a calibrated hydrodynamicmodel was developed by using Environmental Protection Agency Storm WaterManagement Model (EPA SWMM. For model calibration and validation, we set up arain gauge and a flow meter into the field and obtain rainfall and flow rate data. Andthen, we select several LID types such as retention basins, vegetative swales andpermeable pavement and we obtain their influence on peak flow rate and pollutantbuildup and washoff for TSS. Consequently, we observe the possible effects ofLID on surface runoff and TSS in Sazlidere Watershed.
Hydrodynamic escape from planetary atmospheres
Tian, Feng
Hydrodynamic escape is an important process in the formation and evolution of planetary atmospheres. Due to the existence of a singularity point near the transonic point, it is difficult to find transonic steady state solutions by solving the time-independent hydrodynamic equations. In addition to that, most previous works assume that all energy driving the escape flow is deposited in one narrow layer. This assumption not only results in less accurate solutions to the hydrodynamic escape problem, but also makes it difficult to include other chemical and physical processes in the hydrodynamic escape models. In this work, a numerical model describing the transonic hydrodynamic escape from planetary atmospheres is developed. A robust solution technique is used to solve the time dependent hydrodynamic equations. The method has been validated in an isothermal atmosphere where an analytical solution is available. The hydrodynamic model is applied to 3 cases: hydrogen escape from small orbit extrasolar planets, hydrogen escape from a hydrogen rich early Earth's atmosphere, and nitrogen/methane escape from Pluto's atmosphere. Results of simulations on extrasolar planets are in good agreement with the observations of the transiting extrasolar planet HD209458b. Hydrodynamic escape of hydrogen from other hypothetical close-in extrasolar planets are simulated and the influence of hydrogen escape on the long-term evolution of these extrasolar planets are discussed. Simulations on early Earth suggest that hydrodynamic escape of hydrogen from a hydrogen rich early Earth's atmosphere is about two orders magnitude slower than the diffusion limited escape rate. A hydrogen rich early Earth's atmosphere could have been maintained by the balance between the hydrogen escape and the supply of hydrogen into the atmosphere by volcanic outgassing. Origin of life may have occurred in the organic soup ocean created by the efficient formation of prebiotic molecules in the hydrogen rich early
Soliton Gases and Generalized Hydrodynamics
Doyon, Benjamin; Yoshimura, Takato; Caux, Jean-Sébastien
2018-01-01
We show that the equations of generalized hydrodynamics (GHD), a hydrodynamic theory for integrable quantum systems at the Euler scale, emerge in full generality in a family of classical gases, which generalize the gas of hard rods. In this family, the particles, upon colliding, jump forward or backward by a distance that depends on their velocities, reminiscent of classical soliton scattering. This provides a "molecular dynamics" for GHD: a numerical solver which is efficient, flexible, and which applies to the presence of external force fields. GHD also describes the hydrodynamics of classical soliton gases. We identify the GHD of any quantum model with that of the gas of its solitonlike wave packets, thus providing a remarkable quantum-classical equivalence. The theory is directly applicable, for instance, to integrable quantum chains and to the Lieb-Liniger model realized in cold-atom experiments.
Anomalous hydrodynamics of Weyl materials
Monteiro, Gustavo; Abanov, Alexander
Kinetic theory is a useful tool to study transport in Weyl materials when the band-touching points are hidden inside a Fermi surface. It accounts, for example, for the negative magnetoresistance caused by the chiral magnetic effect and quantum oscillations (SdH effect) in the magnetoresistance together within the same framework. As an alternative approach to kinetic theory we also consider the regime of strong interactions where hydrodynamics can be applicable. A variational principle of these hydrodynamic equations can be found in and provide a natural framework to study hydrodynamic surface modes which correspond to the strongly-interacting physics signature of Fermi arcs. G.M. acknowledges the financial support from FAPESP.
Brownian dynamics with hydrodynamic interactions
International Nuclear Information System (INIS)
Ermak, D.L.; McCammon, J.A.
1978-01-01
A method for simulating the Brownian dynamics of N particles with the inclusion of hydrodynamic interactions is described. The particles may also be subject to the usual interparticle or external forces (e.g., electrostatic) which have been included in previous methods for simulating Brownian dynamics of particles in the absence of hydrodynamic interactions. The present method is derived from the Langevin equations for the N particle assembly, and the results are shown to be consistent with the corresponding Fokker--Planck results. Sample calculations on small systems illustrate the importance of including hydrodynamic interactions in Brownian dynamics simulations. The method should be useful for simulation studies of diffusion limited reactions, polymer dynamics, protein folding, particle coagulation, and other phenomena in solution
Abnormal pressures as hydrodynamic phenomena
Neuzil, C.E.
1995-01-01
So-called abnormal pressures, subsurface fluid pressures significantly higher or lower than hydrostatic, have excited speculation about their origin since subsurface exploration first encountered them. Two distinct conceptual models for abnormal pressures have gained currency among earth scientists. The static model sees abnormal pressures generally as relict features preserved by a virtual absence of fluid flow over geologic time. The hydrodynamic model instead envisions abnormal pressures as phenomena in which flow usually plays an important role. This paper develops the theoretical framework for abnormal pressures as hydrodynamic phenomena, shows that it explains the manifold occurrences of abnormal pressures, and examines the implications of this approach. -from Author
Anisotropic hydrodynamics: Motivation and methodology
Energy Technology Data Exchange (ETDEWEB)
Strickland, Michael
2014-06-15
In this proceedings contribution I review recent progress in our understanding of the bulk dynamics of relativistic systems that possess potentially large local rest frame momentum-space anisotropies. In order to deal with these momentum-space anisotropies, a reorganization of relativistic viscous hydrodynamics can be made around an anisotropic background, and the resulting dynamical framework has been dubbed “anisotropic hydrodynamics”. I also discuss expectations for the degree of momentum-space anisotropy of the quark–gluon plasma generated in relativistic heavy ion collisions at RHIC and LHC from second-order viscous hydrodynamics, strong-coupling approaches, and weak-coupling approaches.
Hydrodynamics of oceans and atmospheres
Eckart, Carl
1960-01-01
Hydrodynamics of Oceans and Atmospheres is a systematic account of the hydrodynamics of oceans and atmospheres. Topics covered range from the thermodynamic functions of an ideal gas and the thermodynamic coefficients for water to steady motions, the isothermal atmosphere, the thermocline, and the thermosphere. Perturbation equations, field equations, residual equations, and a general theory of rays are also presented. This book is comprised of 17 chapters and begins with an introduction to the basic equations and their solutions, with the aim of illustrating the laws of dynamics. The nonlinear
Hydrodynamic constants from cosmic censorship
International Nuclear Information System (INIS)
Nakamura, Shin
2008-01-01
We study a gravity dual of Bjorken flow of N=4 SYM-theory plasma. We point out that the cosmic censorship hypothesis may explain why the regularity of the dual geometry constrains the hydrodynamic constants. We also investigate the apparent horizon of the dual geometry. We find that the dual geometry constructed on Fefferman-Graham (FG) coordinates is not appropriate for examination of the apparent horizon since the coordinates do not cover the trapped region. However, the preliminary analysis on FG coordinates suggests that the location of the apparent horizon is very sensitive to the hydrodynamic parameters. (author)
Hydrodynamic simulation of elliptic flow
Kolb, P F; Ruuskanen, P V; Heinz, Ulrich W
1999-01-01
We use a hydrodynamic model to study the space-time evolution transverse to the beam direction in ultrarelativistic heavy-ion collisions with nonzero impact parameters. We focus on the influence of early pressure on the development of radial and elliptic flow. We show that at high energies elliptic flow is generated only during the initial stages of the expansion while radial flow continues to grow until freeze-out. Quantitative comparisons with SPS data from semiperipheral Pb+Pb collisions suggest the applicability of hydrodynamical concepts already $\\approx$ 1 fm/c after impact.
An overview of hydrodynamic studies of mineralization
Directory of Open Access Journals (Sweden)
Guoxiang Chi
2011-07-01
Full Text Available Fluid flow is an integral part of hydrothermal mineralization, and its analysis and characterization constitute an important part of a mineralization model. The hydrodynamic study of mineralization deals with analyzing the driving forces, fluid pressure regimes, fluid flow rate and direction, and their relationships with localization of mineralization. This paper reviews the principles and methods of hydrodynamic studies of mineralization, and discusses their significance and limitations for ore deposit studies and mineral exploration. The driving forces of fluid flow may be related to fluid overpressure, topographic relief, tectonic deformation, and fluid density change due to heating or salinity variation, depending on specific geologic environments and mineralization processes. The study methods may be classified into three types, megascopic (field observations, microscopic analyses, and numerical modeling. Megascopic features indicative of significantly overpressured (especially lithostatic or supralithostatic fluid systems include horizontal veins, sand injection dikes, and hydraulic breccias. Microscopic studies, especially microthermometry of fluid inclusions and combined stress analysis and microthermometry of fluid inclusion planes (FIPs can provide important information about fluid temperature, pressure, and fluid-structural relationships, thus constraining fluid flow models. Numerical modeling can be carried out to solve partial differential equations governing fluid flow, heat transfer, rock deformation and chemical reactions, in order to simulate the distribution of fluid pressure, temperature, fluid flow rate and direction, and mineral precipitation or dissolution in 2D or 3D space and through time. The results of hydrodynamic studies of mineralization can enhance our understanding of the formation processes of hydrothermal deposits, and can be used directly or indirectly in mineral exploration.
Asymptotic solutions for flow in microchannels with ridged walls and arbitrary meniscus protrusion
Kirk, Toby
2017-11-01
Flow over structured surfaces exhibiting apparent slip, such as parallel ridges, have received much attention experimentally and numerically, but analytical and asymptotic solutions that account for the microstructure have so far been limited to unbounded geometries such as shear-driven flows. Analysis for channel flows has been limited to (close to) flat interfaces spanning the grooves between ridges, but in applications the interfaces (menisci) can highly protrude and have a significant impact on the apparent slip. In this presentation, we consider pressure-driven flow through a microchannel with longitudinal ridges patterning one or both walls. With no restriction on the meniscus protrusion, we develop explicit formulae for the slip length using a formal matched asymptotic expansion. Assuming the ratio of channel height to ridge period is large, the periodicity is confined to an inner layer close to the ridges, and the expansion is found to all algebraic orders. As a result, the error is exponentially small and, under a further ``diluteness'' assumption, the explicit formulae are compared to finite element solutions. They are found to have a very wide range of validity in channel height (even when the menisci can touch the opposing wall) and so are useful for practitioners.
Directory of Open Access Journals (Sweden)
Milena Peixoto Nogueira de Sá
2017-08-01
Full Text Available The aim of this study was to evaluate the histogical and morphological aspects of the condyle in response to mandibular protrusion induced by composite resin occlusal planes. Thirty five-week-old male Wistar rats were selected and randomly divided in two groups. One group received a composite resin type of oclusal plane that induced mandibular protrusion, and the other was the control group, without treatment. Animals were euthanized after experimental time intervals of 7, 21 and 30 days. For histological analysis, thickness of the proliferative, serial and hypertrophic layers was measured, as well as each layer separately. The highest difference in cartilage thickness was observed at day 21, showing a significant increase of the proliferative layer. There were also other histomorphological changes related to occlusal plane interference. Condylar forward repositioning induced by composite occlusal planes influenced the endochondral ossification, increasing the proliferative layer.
Anomalous hydrodynamics in two dimensions
Indian Academy of Sciences (India)
Abstract. A new approach is presented to discuss two-dimensional hydrodynamics with gauge and gravitational anomalies. Exact constitutive relations for the stress tensor and charge current are obtained. Also, a connection between response parameters and anomaly coefficients is discussed. These are new results which, ...
Topics in fluctuating nonlinear hydrodynamics
International Nuclear Information System (INIS)
Milner, S.T.
1986-01-01
Models of fluctuating nonlinear hydrodynamics have enjoyed much success in explaining the effect of long-wavelength fluctuations in diverse hydrodynamic systems. This thesis explores two such problems; in both, the body of hydrodynamic assumptions powerfully constrains the predictions of a well-posed theory. The effects of layer fluctuations in smectic-A liquid crystals are first examined. The static theory (introduced by Grinstein and Pelcovits) is reviewed. Ward identities, resulting from the arbitrariness of the layering direction, are derived and exploited. The static results motivate an examination of dynamic fluctuation effects. A new sound-damping experiment is proposed that would probe singular dependence of viscosities on applied stress. A theory of Procaccia and Gitterman that reaction rates of chemically reacting binary mixtures are drastically reduced near their thermodynamic critical points is analyzed. Hydrodynamic arguments and Van Hove theory are applied, concluding that the PG idea is drastically slowed, and spatially varying composition fluctuations are at best slowed down over a narrow range of wavenumbers
Radiation hydrodynamics in the laboratory
International Nuclear Information System (INIS)
1985-12-01
This report contains a collection of five preprints devoted to the subject of laser induced phenomena of radiation hydrodynamics. These preprints cover approximately the contents of the presentations made by the MPQ experimental laser-plasma group at the 17th European Conference on Laser Interaction with Matter (ECLIM), Rome, November 18-22, 1985. (orig.)
Numerical Hydrodynamics in General Relativity
Directory of Open Access Journals (Sweden)
Font José A.
2003-01-01
Full Text Available The current status of numerical solutions for the equations of ideal general relativistic hydrodynamics is reviewed. With respect to an earlier version of the article, the present update provides additional information on numerical schemes, and extends the discussion of astrophysical simulations in general relativistic hydrodynamics. Different formulations of the equations are presented, with special mention of conservative and hyperbolic formulations well-adapted to advanced numerical methods. A large sample of available numerical schemes is discussed, paying particular attention to solution procedures based on schemes exploiting the characteristic structure of the equations through linearized Riemann solvers. A comprehensive summary of astrophysical simulations in strong gravitational fields is presented. These include gravitational collapse, accretion onto black holes, and hydrodynamical evolutions of neutron stars. The material contained in these sections highlights the numerical challenges of various representative simulations. It also follows, to some extent, the chronological development of the field, concerning advances on the formulation of the gravitational field and hydrodynamic equations and the numerical methodology designed to solve them.
Hydrodynamics of a quark droplet
DEFF Research Database (Denmark)
Bjerrum-Bohr, Johan J.; Mishustin, Igor N.; Døssing, Thomas
2012-01-01
We present a simple model of a multi-quark droplet evolution based on the hydrodynamical description. This model includes collective expansion of the droplet, effects of the vacuum pressure and surface tension. The hadron emission from the droplet is described following Weisskopf's statistical...
Hydrodynamic instabilities in inertial fusion
International Nuclear Information System (INIS)
Hoffman, N.M.
1994-01-01
This report discusses topics on hydrodynamics instabilities in inertial confinement: linear analysis of Rayleigh-Taylor instability; ablation-surface instability; bubble rise in late-stage Rayleigh-Taylor instability; and saturation and multimode interactions in intermediate-stage Rayleigh-Taylor instability
Liu, H H; Weng, S E; Chen, R J
1995-12-01
In the treatment of growing bimaxillary protrusion patients,Edgewise technique auxillary with extra oral anchorage and class III elastic help to improve the patient's chin shape,recover his beauty of lower facial part and get a good occlusion along with the growing of mandible.The purpose of this study is:analysis the force system in the treatment and evaluate the result of the treatment with some typical cases.
Mix and hydrodynamic instabilities on NIF
Smalyuk, V. A.; Robey, H. F.; Casey, D. T.; Clark, D. S.; Döppner, T.; Haan, S. W.; Hammel, B. A.; MacPhee, A. G.; Martinez, D.; Milovich, J. L.; Peterson, J. L.; Pickworth, L.; Pino, J. E.; Raman, K.; Tipton, R.; Weber, C. R.; Baker, K. L.; Bachmann, B.; Berzak Hopkins, L. F.; Bond, E.; Caggiano, J. A.; Callahan, D. A.; Celliers, P. M.; Cerjan, C.; Dixit, S. N.; Edwards, M. J.; Felker, S.; Field, J. E.; Fittinghoff, D. N.; Gharibyan, N.; Grim, G. P.; Hamza, A. V.; Hatarik, R.; Hohenberger, M.; Hsing, W. W.; Hurricane, O. A.; Jancaitis, K. S.; Jones, O. S.; Khan, S.; Kroll, J. J.; Lafortune, K. N.; Landen, O. L.; Ma, T.; MacGowan, B. J.; Masse, L.; Moore, A. S.; Nagel, S. R.; Nikroo, A.; Pak, A.; Patel, P. K.; Remington, B. A.; Sayre, D. B.; Spears, B. K.; Stadermann, M.; Tommasini, R.; Widmayer, C. C.; Yeamans, C. B.; Crippen, J.; Farrell, M.; Giraldez, E.; Rice, N.; Wilde, C. H.; Volegov, P. L.; Gatu Johnson, M.
2017-06-01
Several new platforms have been developed to experimentally measure hydrodynamic instabilities in all phases of indirect-drive, inertial confinement fusion implosions on National Ignition Facility. At the ablation front, instability growth of pre-imposed modulations was measured with a face-on, x-ray radiography platform in the linear regime using the Hydrodynamic Growth Radiography (HGR) platform. Modulation growth of "native roughness" modulations and engineering features (fill tubes and capsule support membranes) were measured in conditions relevant to layered DT implosions. A new experimental platform was developed to measure instability growth at the ablator-ice interface. In the deceleration phase of implosions, several experimental platforms were developed to measure both low-mode asymmetries and high-mode perturbations near peak compression with x-ray and nuclear techniques. In one innovative technique, the self-emission from the hot spot was enhanced with argon dopant to "self-backlight" the shell in-flight. To stabilize instability growth, new "adiabat-shaping" techniques were developed using the HGR platform and applied in layered DT implosions.
Fraley, Stephanie I.; Wu, Pei-Hsun; He, Lijuan; Feng, Yunfeng; Krisnamurthy, Ranjini; Longmore, Gregory D.; Wirtz, Denis
2015-10-01
Multiple attributes of the three-dimensional (3D) extracellular matrix (ECM) have been independently implicated as regulators of cell motility, including pore size, crosslink density, structural organization, and stiffness. However, these parameters cannot be independently varied within a complex 3D ECM protein network. We present an integrated, quantitative study of these parameters across a broad range of complex matrix configurations using self-assembling 3D collagen and show how each parameter relates to the others and to cell motility. Increasing collagen density resulted in a decrease and then an increase in both pore size and fiber alignment, which both correlated significantly with cell motility but not bulk matrix stiffness within the range tested. However, using the crosslinking enzyme Transglutaminase II to alter microstructure independently of density revealed that motility is most significantly predicted by fiber alignment. Cellular protrusion rate, protrusion orientation, speed of migration, and invasion distance showed coupled biphasic responses to increasing collagen density not predicted by 2D models or by stiffness, but instead by fiber alignment. The requirement of matrix metalloproteinase (MMP) activity was also observed to depend on microstructure, and a threshold of MMP utility was identified. Our results suggest that fiber topography guides protrusions and thereby MMP activity and motility.
Fu, Qiuling; Huang, Yu; Wan, Chunhe; Fu, Guanghua; Qi, Baomin; Cheng, Longfei; Shi, Shaohua; Chen, Hongmei; Liu, Rongchang; Chen, Zhenhai
2017-12-01
In 2008, clinical cases of short beak and dwarfism syndrome (SBDS) caused by Muscovy duck parvovirus (MDPV) infection were found in mule duck and Taiwan white duck farms in Fujian, China. A MDPV LH strain causing duck SBDS without tongue protrusion was isolated in this study. Phylogenetic analysis show that the MDPV LH strain was clustered together with other MDPV strains, but divergent from GPV isolates. Two major fragment deletions were found in the inverted terminal repeats (ITR) of MDPV LH similar to the ones in the ITR of MDPV GX5, YY and SAAS-SHNH strains. To investigate the pathogenicity of the MDPV LH strain, virus infection of young mule ducks was performed. The infected ducks showed SBDS symptoms including retard growth and shorten beaks without tongue protrusion. Atrophy of thymus, spleen and bursa of Fabricius was identified in the infected ducks. The results show that MDPV LH strain is moderately pathogenic to mule duck, leading to occurrence of SBDS. As far as we know, it is the first study showing that SBDS without tongue protrusion, and atrophy of thymus, spleen and bursa of Fabricius possibly associated with immunosuppression were found in the MDPV-infected ducks. The established duck-MDPV-SBDS system will help us to further work on the virus pathogenesis and develop efficacious vaccine against MDPV infection. Copyright © 2017. Published by Elsevier Ltd.
Wu, Xin; Liu, Guo-yuan; Jiang, Yong-lian
2015-10-01
To investigate the differences in anchorage effects between micro-implants and J hook in treating patients with Class II division 1 maxillary protrusion. Thirty-one cases of adult patients with Class II division 1 maxillary protrusion were treated. They were divided into 2 groups depending on their selection. The first group included 17 patients for micro-implant anchorage, who adopted micro-implant and sliding mechanism to close maxillary extraction space and depress the mandibular molar. The second group encompassed 14 cases for J hook, who adopted sliding mechanism, J hooks in high traction and Class II intermaxillary traction to close extraction space. X-ray lateral cephalometric radiographs were measured before and after treatment, and SPSS16.0 software package was employed to compare the differences in soft and hard tissue changes before and after treatment between 2 groups. There were statistically significant differences in SNB, ANB, MP-FH, U1-Y, U6-Y, L6-MP, NLA, and UL-Y between the 2 groups before and after treatment, while there was no significant difference in SNA, U1-SN, U1-X, and U6-X between the 2 groups. In treating patients with Class II division 1 maxillary protrusion, micro-implant has stronger anchorage effects than J hook, while at the same time depressing the mandibular molars, and making it more favorable to improve Class II faces.
Chen, Wen-Jing; Li, Qing-Yi; Gong, Ai-Xiu; Hu, Fang; Gu, Yong-Jia
2008-02-01
To compare the difference between J-hook and micro-implant anchorage in the treatment of patient with bimaxillary protrusion. Thirty patients with bimaxillary protrusion were divided into two groups (J-hook and micro-implant groups) and treated with MBT appliance. Four first premolars were extracted in all patients. Cephalometric analyses were carried out before and after treatment. In J-hook group and micro-implant group,computerized cephalometric analysis revealed that before treatment U6C-PP was (12.4 +/- 0.2) mm and (12.5 +/- 0.1) mm, respectively,and after treatment U6C-PP was (12.6 +/- 0.1) mm and (12.8 +/- 0.1) mm,respectively. The difference between J-hook group and microimplant group was significant (P micro-implant group was not significant. Both J-hook and micro-implant could provide adequate anchorage in the treatment of patients with bimaxillary protrusion.
International Nuclear Information System (INIS)
R Paul Drake
2004-01-01
OAK-B135 This is the final report from the project Hydrodynamics by High-Energy-Density Plasma Flow and Hydrodynamics and Radiation Hydrodynamics with Astrophysical Applications. This project supported a group at the University of Michigan in the invention, design, performance, and analysis of experiments using high-energy-density research facilities. The experiments explored compressible nonlinear hydrodynamics, in particular at decelerating interfaces, and the radiation hydrodynamics of strong shock waves. It has application to supernovae, astrophysical jets, shock-cloud interactions, and radiative shock waves
Degradation of dichlorvos using hydrodynamic cavitation based treatment strategies.
Joshi, Ravi K; Gogate, Parag R
2012-05-01
The degradation of an aqueous solution of dichlorvos, a commonly used pesticide in India, has been systematically investigated using hydrodynamic cavitation reactor. All the experiments have been carried out using a 20 ppm solution of commercially available dichlorvos. The effect of important operating parameters such as inlet pressure (over a range 3-6 bar), temperature (31 °C, 36 °C and 39 °C) and pH (natural pH = 5.7 and acidic pH = 3) on the extent of degradation has been investigated initially. It has been observed that an optimum value of pressure gives maximum degradation whereas low temperature and pH of 3 are favorable. Intensification studies have been carried out using different additives such as hydrogen peroxide, carbon tetrachloride, and Fenton's reagent. Use of hydrogen peroxide and carbon tetrachloride resulted in the enhancement of the extent of degradation at optimized conditions but significant enhancement was obtained with the combined use of hydrodynamic cavitation and Fenton's chemistry. The maximum extent of degradation as obtained by using a combination of hydrodynamic cavitation and Fenton's chemistry was 91.5% in 1h of treatment time. The present work has conclusively established that hydrodynamic cavitation in combination with Fenton's chemistry can be effectively used for the degradation of dichlorvos. Copyright © 2011 Elsevier B.V. All rights reserved.
Modeling the Excess Cell Surface Stored in a Complex Morphology of Bleb-Like Protrusions.
Directory of Open Access Journals (Sweden)
Maryna Kapustina
2016-03-01
Full Text Available Cells transition from spread to rounded morphologies in diverse physiological contexts including mitosis and mesenchymal-to-amoeboid transitions. When these drastic shape changes occur rapidly, cell volume and surface area are approximately conserved. Consequently, the rounded cells are suddenly presented with a several-fold excess of cell surface whose area far exceeds that of a smooth sphere enclosing the cell volume. This excess is stored in a population of bleb-like protrusions (BLiPs, whose size distribution is shown by electron micrographs to be skewed. We introduce three complementary models of rounded cell morphologies with a prescribed excess surface area. A 2D Hamiltonian model provides a mechanistic description of how discrete attachment points between the cell surface and cortex together with surface bending energy can generate a morphology that satisfies a prescribed excess area and BLiP number density. A 3D random seed-and-growth model simulates efficient packing of BLiPs over a primary rounded shape, demonstrating a pathway for skewed BLiP size distributions that recapitulate 3D morphologies. Finally, a phase field model (2D and 3D posits energy-based constitutive laws for the cell membrane, nematic F-actin cortex, interior cytosol, and external aqueous medium. The cell surface is equipped with a spontaneous curvature function, a proxy for the cell surface-cortex couple, that is a priori unknown, which the model "learns" from the thin section transmission electron micrograph image (2D or the "seed and growth" model image (3D. Converged phase field simulations predict self-consistent amplitudes and spatial localization of pressure and stress throughout the cell for any posited stationary morphology target and cell compartment constitutive properties. The models form a general framework for future studies of cell morphological dynamics in a variety of biological contexts.
Intra-vesical Prostatic Protrusion (IPP) Can Be Reduced by Prostatic Artery Embolization
Energy Technology Data Exchange (ETDEWEB)
Lin, Yen-Ting, E-mail: ymerically@gmail.com; Amouyal, Grégory, E-mail: gregamouyal@hotmail.com [Assistance Publique Hôpitaux de Paris, Hôpital Européen Georges-Pompidou, Vascular and Oncological Interventional Radiology (France); Thiounn, Nicolas, E-mail: nicolas.thiounn@egp.aphp.fr [Assistance Publique Hopitaux de Paris, Hôpital Européen Georges-Pompidou, Urology (France); Pellerin, Olivier, E-mail: olivier.pellerin@aphp.fr [Université Paris Descartes, Sorbonne Paris-Cité (France); Pereira, Héléna, E-mail: helena.pereira@aphp.fr; Giudice, Costantino Del, E-mail: costantino.del-giudice@egp.aphp.fr; Déan, Carole, E-mail: carole.dean@aphp.fr [Assistance Publique Hôpitaux de Paris, Hôpital Européen Georges-Pompidou, Vascular and Oncological Interventional Radiology (France); Sapoval, Marc, E-mail: marc.sapoval2@aphp.fr [Université Paris Descartes, Sorbonne Paris-Cité (France)
2016-05-15
BackgroundProstate artery embolization (PAE) is a new approach to improve lower urinary tract symptoms (LUTS) related to benign prostatic hyperplasia. PAE results in global reduction of prostate volume (PV). There are no data available on the efficacy of PAE in reducing intra-vesical prostatic protrusion (IPP), an anatomic feature that is clinically related with bladder outlet obstruction and LUTS.ObjectiveTo assess the results of PAE in patients with significant IPP due to median lobe hyperplasia and to compare the IPSS decrease and IPP change.Material and MethodsProspective analysis of 18 consecutive patients with significant IPP (>5 mm) related to median lobe hyperplasia undergoing PAE using 30–500-μm-calibrated trisacryl microspheres. We measured IPP on sagittal T2-weighted images before and 3 months after PAE. IPSS and clinical results were also evaluated at 3 months.ResultsPAE resulted in significant IPP reduction (1.57 cm ± 0.55 before PAE and 1.30 cm ± 0.46 after PAE, p = 0.0005) (Fig. 1) with no complication. IPSS, quality of life (QoL), total prostate-specific antigen (PSA) level, and PV showed significant reduction after PAE, and maximum urinary flow rate (Q{sub max}) showed significant increase after PAE. No significant change of International Index of Erectile Function (IIEF) for clinical evaluation after PAE. A significant correlation was found between the IPP change and the IPSS change (r = 0.636, p = 0.0045).ConclusionPatients had significant IPP reduction as well as significant symptomatic improvement after PAE, and these improvements were positively correlated.
Khyzniak, M V; Pryĭmak, E V
2013-11-01
Clinico-neurological signs of the discogenic pain syndromes, caused by intervertebral disc (IVD) protrusion in a lumbar portion of vertebral column, were analyzed. The strict indications were substantiated for application of the puncture treatment methods for the discogenic pain syndromes in patients of various ages. Clinico-neurological signs of the IVD protrusions constitute the important criterion while the treatment method selection. Differentiated application of the puncture methods permits to improve the treatment results in the patients of various age.
Analytic solutions of hydrodynamics equations
International Nuclear Information System (INIS)
Coggeshall, S.V.
1991-01-01
Many similarity solutions have been found for the equations of one-dimensional (1-D) hydrodynamics. These special combinations of variables allow the partial differential equations to be reduced to ordinary differential equations, which must then be solved to determine the physical solutions. Usually, these reduced ordinary differential equations are solved numerically. In some cases it is possible to solve these reduced equations analytically to obtain explicit solutions. In this work a collection of analytic solutions of the 1-D hydrodynamics equations is presented. These can be used for a variety of purposes, including (i) numerical benchmark problems, (ii) as a basis for analytic models, and (iii) to provide insight into more complicated solutions
Laser driven hydrodynamic instability experiments
International Nuclear Information System (INIS)
Remington, B.A.; Weber, S.V.; Haan, S.W.; Kilkenny, J.D.; Glendinning, S.G.; Wallace, R.J.; Goldstein, W.H.; Wilson, B.G.; Nash, J.K.
1993-01-01
An extensive series of experiments has been conducted on the Nova laser to measure hydrodynamic instabilities in planar foils accelerated by x-ray ablation. Single mode experiments allow a measurement of the fundamental growth rates from the linear well into the nonlinear regime. Two-mode foils allow a first direct observation of mode coupling. Surface-finish experiments allow a measurement of the evolution of a broad spectrum of random initial modes
Rapidity correlations test stochastic hydrodynamics
International Nuclear Information System (INIS)
Zin, C; Gavin, S; Moschelli, G
2017-01-01
We show that measurements of the rapidity dependence of transverse momentum correlations can be used to determine the characteristic time τ π that dictates the rate of isotropization of the stress energy tensor, as well as the shear viscosity ν = η/sT . We formulate methods for computing these correlations using second order dissipative hydrodynamics with noise. Current data are consistent with τ π /ν ∼ 10 but targeted measurements can improve this precision. (paper)
Hydrodynamic simulations of expanding shells
Czech Academy of Sciences Publication Activity Database
Wünsch, Richard; Palouš, Jan; Ehlerová, Soňa
2004-01-01
Roč. 289, 3-4 (2004), s. 35-36 ISSN 0004-640X. [From observation to self-consistent modelling of the ISM in galaxies. Porto, 03.09.2002-05.09.2002] R&D Projects: GA AV ČR KSK1048102 Keywords : hydrodynamic simulations * ISM * star formation Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 0.597, year: 2004
Hydrodynamic Limit of Multiple SLE
Hotta, Ikkei; Katori, Makoto
2018-04-01
Recently del Monaco and Schleißinger addressed an interesting problem whether one can take the limit of multiple Schramm-Loewner evolution (SLE) as the number of slits N goes to infinity. When the N slits grow from points on the real line R in a simultaneous way and go to infinity within the upper half plane H, an ordinary differential equation describing time evolution of the conformal map g_t(z) was derived in the N → ∞ limit, which is coupled with a complex Burgers equation in the inviscid limit. It is well known that the complex Burgers equation governs the hydrodynamic limit of the Dyson model defined on R studied in random matrix theory, and when all particles start from the origin, the solution of this Burgers equation is given by the Stieltjes transformation of the measure which follows a time-dependent version of Wigner's semicircle law. In the present paper, first we study the hydrodynamic limit of the multiple SLE in the case that all slits start from the origin. We show that the time-dependent version of Wigner's semicircle law determines the time evolution of the SLE hull, K_t \\subset H\\cup R, in this hydrodynamic limit. Next we consider the situation such that a half number of the slits start from a>0 and another half of slits start from -a exact solutions, we will discuss the universal long-term behavior of the multiple SLE and its hull K_t in the hydrodynamic limit.
Hydrodynamical model with massless constituents
International Nuclear Information System (INIS)
Chiu, C.B.; Wang, K.H.
1974-01-01
Within the constituent hydrodynamical model, it is shown that the total number of constituents is conserved, if these constituents are massless and satisfy the Fermi-Dirac distribution. A simple scheme for the transition from the constituent-phase to the hadron-phase is suggested, and the hadron inclusive momentum spectra are presented for this case. This phase transition scheme predicts the average transverse momentum of meson resonances which is compatible with the data. (U.S.)
Black Hole Scrambling from Hydrodynamics.
Grozdanov, Sašo; Schalm, Koenraad; Scopelliti, Vincenzo
2018-06-08
We argue that the gravitational shock wave computation used to extract the scrambling rate in strongly coupled quantum theories with a holographic dual is directly related to probing the system's hydrodynamic sound modes. The information recovered from the shock wave can be reconstructed in terms of purely diffusionlike, linearized gravitational waves at the horizon of a single-sided black hole with specific regularity-enforced imaginary values of frequency and momentum. In two-derivative bulk theories, this horizon "diffusion" can be related to late-time momentum diffusion via a simple relation, which ceases to hold in higher-derivative theories. We then show that the same values of imaginary frequency and momentum follow from a dispersion relation of a hydrodynamic sound mode. The frequency, momentum, and group velocity give the holographic Lyapunov exponent and the butterfly velocity. Moreover, at this special point along the sound dispersion relation curve, the residue of the retarded longitudinal stress-energy tensor two-point function vanishes. This establishes a direct link between a hydrodynamic sound mode at an analytically continued, imaginary momentum and the holographic butterfly effect. Furthermore, our results imply that infinitely strongly coupled, large-N_{c} holographic theories exhibit properties similar to classical dilute gases; there, late-time equilibration and early-time scrambling are also controlled by the same dynamics.
Numerical Hydrodynamics in Special Relativity.
Martí, José Maria; Müller, Ewald
2003-01-01
This review is concerned with a discussion of numerical methods for the solution of the equations of special relativistic hydrodynamics (SRHD). Particular emphasis is put on a comprehensive review of the application of high-resolution shock-capturing methods in SRHD. Results of a set of demanding test bench simulations obtained with different numerical SRHD methods are compared. Three applications (astrophysical jets, gamma-ray bursts and heavy ion collisions) of relativistic flows are discussed. An evaluation of various SRHD methods is presented, and future developments in SRHD are analyzed involving extension to general relativistic hydrodynamics and relativistic magneto-hydrodynamics. The review further provides FORTRAN programs to compute the exact solution of a 1D relativistic Riemann problem with zero and nonzero tangential velocities, and to simulate 1D relativistic flows in Cartesian Eulerian coordinates using the exact SRHD Riemann solver and PPM reconstruction. Supplementary material is available for this article at 10.12942/lrr-2003-7 and is accessible for authorized users.
Entropy-limited hydrodynamics: a novel approach to relativistic hydrodynamics
Guercilena, Federico; Radice, David; Rezzolla, Luciano
2017-07-01
We present entropy-limited hydrodynamics (ELH): a new approach for the computation of numerical fluxes arising in the discretization of hyperbolic equations in conservation form. ELH is based on the hybridisation of an unfiltered high-order scheme with the first-order Lax-Friedrichs method. The activation of the low-order part of the scheme is driven by a measure of the locally generated entropy inspired by the artificial-viscosity method proposed by Guermond et al. (J. Comput. Phys. 230(11):4248-4267, 2011, doi: 10.1016/j.jcp.2010.11.043). Here, we present ELH in the context of high-order finite-differencing methods and of the equations of general-relativistic hydrodynamics. We study the performance of ELH in a series of classical astrophysical tests in general relativity involving isolated, rotating and nonrotating neutron stars, and including a case of gravitational collapse to black hole. We present a detailed comparison of ELH with the fifth-order monotonicity preserving method MP5 (Suresh and Huynh in J. Comput. Phys. 136(1):83-99, 1997, doi: 10.1006/jcph.1997.5745), one of the most common high-order schemes currently employed in numerical-relativity simulations. We find that ELH achieves comparable and, in many of the cases studied here, better accuracy than more traditional methods at a fraction of the computational cost (up to {˜}50% speedup). Given its accuracy and its simplicity of implementation, ELH is a promising framework for the development of new special- and general-relativistic hydrodynamics codes well adapted for massively parallel supercomputers.
Cooper, W James; Carter, Casey B; Conith, Andrew J; Rice, Aaron N; Westneat, Mark W
2017-02-15
Most species-rich lineages of aquatic organisms have undergone divergence between forms that feed from the substrate (benthic feeding) and forms that feed from the water column (pelagic feeding). Changes in trophic niche are frequently accompanied by changes in skull mechanics, and multiple fish lineages have evolved highly specialized biomechanical configurations that allow them to protrude their upper jaws toward the prey during feeding. Damselfishes (family Pomacentridae) are an example of a species-rich lineage with multiple trophic morphologies and feeding ecologies. We sought to determine whether bentho-pelagic divergence in the damselfishes is tightly coupled to changes in jaw protrusion ability. Using high-speed video recordings and kinematic analysis, we examined feeding performance in 10 species that include three examples of convergence on herbivory, three examples of convergence on omnivory and two examples of convergence on planktivory. We also utilized morphometrics to characterize the feeding morphology of an additional 40 species that represent all 29 damselfish genera. Comparative phylogenetic analyses were then used to examine the evolution of trophic morphology and biomechanical performance. We find that pelagic-feeding damselfishes (planktivores) are strongly differentiated from extensively benthic-feeding species (omnivores and herbivores) by their jaw protrusion ability, upper jaw morphology and the functional integration of upper jaw protrusion with lower jaw abduction. Most aspects of cranial form and function that separate these two ecological groups have evolved in correlation with each other and the evolution of the functional morphology of feeding in damselfishes has involved repeated convergence in form, function and ecology. © 2017. Published by The Company of Biologists Ltd.
Guan, Erjia; Wang, Tianxiang; Wang, Zhipeng; Gao, Changyou
2013-09-01
It was found previously that the Schiff base bonds in poly(allylamine hydrochloride)-g-pyrene (PAH-Py) microcapsules (MCs) are hydrolyzed at pH 2 within 1 h, leading to disassembly of the MCs and protrusion of pyrene aldehyde (Py) nanorods (NRs) on the capsule surface. Herein, we found a new way to modulate the protrusion of NRs by addition of 1-pyrenesulfonic acid sodium salt (PySO3Na). Along with the increase in PySO3Na to Py molar ratio in the MCs solution, the protrusion of NRs was progressively blocked and even inhibited at a ratio of 2.3, and at this condition, the microcapsules were stable under pH 2 for 24 h. After the composite microcapsules with excess PySO3Na were washed with a pH 10 solution and then incubated in a pH 2 solution, the NRs could be protruded from the MCs again. The fluorescence peak position of the PAH-Py/PySO3Na MCs gradually red-shifted with a decrease in pH value, and a sharp transition occurred at p H3.6, demonstrating the formation of pyrene excimers between the PySO3Na small molecules and the pendant Py groups on the PAH chain. The formed excimers take the role of blocking the self-assembly of cleaved Py molecules instead of inhibiting the hydrolysis of the Schiff base, whereas the MCs were stabilized by the charge interaction between PySO3Na and PAH backbone and the hydrophobic interaction between the pyrene rings. Copyright © 2013 Elsevier Inc. All rights reserved.
International Nuclear Information System (INIS)
Odenwald, Matthew A; Prosperi, Jenifer R; Goss, Kathleen H
2013-01-01
The APC tumor suppressor is mutated or downregulated in many tumor types, and is prominently localized to punctate clusters at protrusion tips in migratory cells, such as in astrocytes where it has been implicated in directed cell motility. Although APC loss is considered an initiating event in colorectal cancer, for example, it is less clear what role APC plays in tumor cell motility and whether loss of APC might be an important promoter of tumor progression in addition to initiation. The localization of APC and β-catenin was analyzed in multiple cell lines, including non-transformed epithelial lines treated with a proteasome inhibitor or TGFβ to induce an epithelial-to-mesenchymal transition (EMT), as well as several breast cancer lines, by immunofluorescence. APC expression was knocked down in 4T07 mammary tumor cells using lentiviral-mediated delivery of APC-specific short-hairpin (sh) RNAs, and assessed using quantitative (q) reverse-transcriptase (RT)-PCR and western blotting. Tumor cell motility was analyzed by performing wound-filling assays, and morphology via immunofluorescence (IF) and phase-contrast microscopy. Additionally, proliferation was measured using BrdU incorporation, and TCF reporter assays were performed to determine β-catenin/TCF-mediated transcriptional activity. APC/β-catenin-rich complexes were observed at protrusion ends of migratory epithelial cells treated with a proteasome inhibitor or when EMT has been induced and in tumor cells with a mesenchymal, spindle-like morphology. 4T07 tumor cells with reduced APC levels were significantly less motile and had a more rounded morphology; yet, they did not differ significantly in proliferation or β-catenin/TCF transcriptional activity. Furthermore, we found that APC/β-catenin-rich complexes at protrusion ends were dependent upon an intact microtubule cytoskeleton. These findings indicate that membrane protrusions with APC/β-catenin-containing puncta control the migratory potential and
Epinette, J-A; Mertl, P; Combourieu, B; Goncalves, H; Blairon, A; Ehlinger, M; Tabutin, J
2015-10-01
The outcome of revision total hip arthroplasty (THA) for intra-pelvic cup protrusion is unclear. Hence, we conducted a large retrospective study to clarify the surgical strategy (hip lever arm and cup mechanical fixation) and the outcomes of reconstruction for severe intra-pelvic cup protrusion. We hypothesized that restoration of the anatomic hip centre in such acetabular revisions decreased the risk of recurrent loosening. The study included 246 THA procedures (in 220 patients), with a follow-up of 5.2 ± 4.9 years (1-24.2) after the index surgery. Bone loss was estimated using the SOFCOT classification (grade III or IV in 80% of cases) and the Paprosky classification (IIIA or IIIB in 58% of cases). Quality of the reconstruction was assessed on X-rays according to the correction of the protrusion and position of the hip centre of rotation. After a clinical follow-up of at least 5 years, with a mean of 9.9 ± 4.1 years (5-24 years), the mean Postel-Merle d'Aubigné score was 14.2 ± 3.1 and the mean Harris Hip Score was 78.0 ± 18.7. Cup protrusion was partially or completely corrected in every case and cup position was normal in 27 (11%) cases. The centre of rotation was within 10mm of the physiological position in 158 (64.2%) cases, acceptable in 77 (31.3%) cases, ascended in 9 (3.7%) cases, and worsened in 1 (0.4%) case. Revision for cup or cup and femoral failures was required in 24 (9.8%) cases. Cumulative survival rates with cup loosening as the endpoint were 88.5% after 5 years, 79.9% after 10 years, and 63.9% at last follow-up at 13.6 years. Our hypothesis that restoration of anatomic hip centre decreased the risk of recurrent loosening was not verified: success or failure in restoring the normal centre of rotation did not correlate significantly with final cup status. Recurrent aseptic loosening was the cause of failure in 9.8% of cases. Ensuring long-term effective mechanical stability had a greater impact on global outcomes than restoring an ideal
Directory of Open Access Journals (Sweden)
M. Arab
2006-10-01
Full Text Available Introduction: Botyroide sarcoma is one of the rhabdomyosarcoma which is usually seen in infant's vagina. However, it rarely originates from uterine cervix. Rhabdomyosarcoma is a heterogenic tumor and it is usually diagnosed in second decade of life.Case Report: The patient was a 17 years old virgin girl with the complaint of a mass protrusion from vagina with bleeding and vaginal discharge. Biopsy samples and immunohistochemistry assessments showed embryonal rhabdomyosarcoma. Surgery combined with chemotherapy, significantly increased the survival of patients with uterine cervical rhabdomyosarcoma. Conclusion: The patient underwent radical hysterectomy with restored ovaries and then combined chemotherapy. In the 9 months follow up recurrence has not been observed yet.
2013-01-01
Background The APC tumor suppressor is mutated or downregulated in many tumor types, and is prominently localized to punctate clusters at protrusion tips in migratory cells, such as in astrocytes where it has been implicated in directed cell motility. Although APC loss is considered an initiating event in colorectal cancer, for example, it is less clear what role APC plays in tumor cell motility and whether loss of APC might be an important promoter of tumor progression in addition to initiation. Methods The localization of APC and β-catenin was analyzed in multiple cell lines, including non-transformed epithelial lines treated with a proteasome inhibitor or TGFβ to induce an epithelial-to-mesenchymal transition (EMT), as well as several breast cancer lines, by immunofluorescence. APC expression was knocked down in 4T07 mammary tumor cells using lentiviral-mediated delivery of APC-specific short-hairpin (sh) RNAs, and assessed using quantitative (q) reverse-transcriptase (RT)-PCR and western blotting. Tumor cell motility was analyzed by performing wound-filling assays, and morphology via immunofluorescence (IF) and phase-contrast microscopy. Additionally, proliferation was measured using BrdU incorporation, and TCF reporter assays were performed to determine β-catenin/TCF-mediated transcriptional activity. Results APC/β-catenin-rich complexes were observed at protrusion ends of migratory epithelial cells treated with a proteasome inhibitor or when EMT has been induced and in tumor cells with a mesenchymal, spindle-like morphology. 4T07 tumor cells with reduced APC levels were significantly less motile and had a more rounded morphology; yet, they did not differ significantly in proliferation or β-catenin/TCF transcriptional activity. Furthermore, we found that APC/β-catenin-rich complexes at protrusion ends were dependent upon an intact microtubule cytoskeleton. Conclusions These findings indicate that membrane protrusions with APC/β-catenin-containing puncta
On the Hydrodynamics of Anomalocaris Tail Fins.
Sheppard, K A; Rival, D E; Caron, J-B
2018-04-25
Anomalocaris canadensis, a soft-bodied stem-group arthropod from the Burgess Shale, is considered the largest predator of the Cambrian period. Thanks to a series of lateral flexible lobes along its dorso-ventrally compressed body, it is generally regarded as an efficient swimmer, well-adapted to its predatory lifestyle. Previous theoretical hydrodynamic simulations have suggested a possible optimum in swimming performance when the lateral lobes performed as a single undulatory lateral fin, comparable to the pectoral fins in skates and rays. However, the role of the unusual fan-like tail of Anomalocaris has not been previously explored. Swimming efficiency and maneuverability deduced from direct hydrodynamic analysis are here studied in a towing tank facility using a three-vane physical model designed as an abstraction of the tail fin. Through direct force measurements, it was found that the model exhibited a region of steady-state lift and drag enhancement at angles of attack greater than 25° when compared to a triangular-shaped reference model. This would suggest that the resultant normal force on the tail fin of Anomalocaris made it well-suited for turning maneuvers, giving it the ability to turn quickly and through small radii of curvature. These results are consistent with an active predatory lifestyle, although detailed kinematic studies integrating the full organism, including the lateral lobes, would be required to test the effect of the tail fin on overall swimming performance. This study also highlights a possible example of evolutionary convergence between the tails of Anomalocaris and birds, which, in both cases, are well-adapted to efficient turning maneuvers.
Solitonic Dispersive Hydrodynamics: Theory and Observation
Maiden, Michelle D.; Anderson, Dalton V.; Franco, Nevil A.; El, Gennady A.; Hoefer, Mark A.
2018-04-01
Ubiquitous nonlinear waves in dispersive media include localized solitons and extended hydrodynamic states such as dispersive shock waves. Despite their physical prominence and the development of thorough theoretical and experimental investigations of each separately, experiments and a unified theory of solitons and dispersive hydrodynamics are lacking. Here, a general soliton-mean field theory is introduced and used to describe the propagation of solitons in macroscopic hydrodynamic flows. Two universal adiabatic invariants of motion are identified that predict trapping or transmission of solitons by hydrodynamic states. The result of solitons incident upon smooth expansion waves or compressive, rapidly oscillating dispersive shock waves is the same, an effect termed hydrodynamic reciprocity. Experiments on viscous fluid conduits quantitatively confirm the soliton-mean field theory with broader implications for nonlinear optics, superfluids, geophysical fluids, and other dispersive hydrodynamic media.
Annual Report: Hydrodynamics and Radiative Hydrodynamics with Astrophysical Applications
Energy Technology Data Exchange (ETDEWEB)
R. Paul Drake
2005-12-01
We report the ongoing work of our group in hydrodynamics and radiative hydrodynamics with astrophysical applications. During the period of the existing grant, we have carried out two types of experiments at the Omega laser. One set of experiments has studied radiatively collapsing shocks, obtaining high-quality scaling data using a backlit pinhole and obtaining the first (ever, anywhere) Thomson-scattering data from a radiative shock. Other experiments have studied the deeply nonlinear development of the Rayleigh-Taylor (RT) instability from complex initial conditions, obtaining the first (ever, anywhere) dual-axis radiographic data using backlit pinholes and ungated detectors. All these experiments have applications to astrophysics, discussed in the corresponding papers either in print or in preparation. We also have obtained preliminary radiographs of experimental targets using our x-ray source. The targets for the experiments have been assembled at Michigan, where we also prepare many of the simple components. The above activities, in addition to a variety of data analysis and design projects, provide good experience for graduate and undergraduates students. In the process of doing this research we have built a research group that uses such work to train junior scientists.
Hydrodynamic interactions in active colloidal crystal microrheology
Weeber, R; Harting, JDR Jens
2012-01-01
In dense colloids it is commonly assumed that hydrodynamic interactions do not play a role. However, a found theoretical quantification is often missing. We present computer simulations that are motivated by experiments where a large colloidal particle is dragged through a colloidal crystal. To qualify the influence of long-ranged hydrodynamics, we model the setup by conventional Langevin dynamics simulations and by an improved scheme with limited hydrodynamic interactions. This scheme signif...
Disruptive Innovation in Numerical Hydrodynamics
Energy Technology Data Exchange (ETDEWEB)
Waltz, Jacob I. [Los Alamos National Laboratory
2012-09-06
We propose the research and development of a high-fidelity hydrodynamic algorithm for tetrahedral meshes that will lead to a disruptive innovation in the numerical modeling of Laboratory problems. Our proposed innovation has the potential to reduce turnaround time by orders of magnitude relative to Advanced Simulation and Computing (ASC) codes; reduce simulation setup costs by millions of dollars per year; and effectively leverage Graphics Processing Unit (GPU) and future Exascale computing hardware. If successful, this work will lead to a dramatic leap forward in the Laboratory's quest for a predictive simulation capability.
Laser driven hydrodynamic instability experiments
International Nuclear Information System (INIS)
Remington, B.A.; Weber, S.V.; Haan, S.W.; Kilkenny, J.D.; Glendinning, S.G.; Wallace, R.J.; Goldstein, W.H.; Wilson, B.G.; Nash, J.K.
1992-01-01
We have conducted an extensive series of experiments on the Nova laser to measure hydrodynamic instabilities in planar foils accelerated by x-ray ablation. Single mode experiments allow a measurement of the fundamental growth rates from the linear well into the nonlinear regime; multimode foils allow an assessment of the degree of mode coupling; and surface-finish experiments allow a measurement of the evolution of a broad spectrum of random initial modes. Experimental results and comparisons with theory and simulations are presented
Hydrodynamics of post CHF region
International Nuclear Information System (INIS)
Ishii, M.; De Jarlais, G.
1984-04-01
Among various two-phase flow regimes, the inverted flow in the post-dryout region is relatively less well understood due to its special heat transfer conditions. The review of existing data indicates further research is needed in the areas of basic hydrodynamics related to liquid core disintegration mechanisms, slug and droplet formations, entrainment, and droplet size distributions. In view of this, the inverted flow is studied in detail both analytically and experimentally. Criteria for initial flow regimes in the post-dryout region are given. Preliminary models for subsequent flow regime transition criteria are derived together with correlations for a mean droplet diameter based on the adiabatic simulation data
Problems in astrophysical radiation hydrodynamics
International Nuclear Information System (INIS)
Castor, J.I.
1983-01-01
The basic equations of radiation hydrodynamics are discussed in the regime that the radiation is dynamically as well as thermally important. Particular attention is paid to the question of what constitutes an acceptable approximate non-relativistic system of dynamical equations for matter and radiation in this regime. Further discussion is devoted to two classes of application of these ideas. The first class consists of problems dominated by line radiation, which is sensitive to the velocity field through the Doppler effect. The second class is of problems in which the advection of radiation by moving matter dominates radiation diffusion
Hydrodynamics and stellar winds an introduction
Maciel, Walter J
2014-01-01
Stellar winds are a common phenomenon in the life of stars, from the dwarfs like the Sun to the red giants and hot supergiants, constituting one of the basic aspects of modern astrophysics. Stellar winds are a hydrodynamic phenomenon in which circumstellar gases expand towards the interstellar medium. This book presents an elementary introduction to the fundamentals of hydrodynamics with an application to the study of stellar winds. The principles of hydrodynamics have many other applications, so that the book can be used as an introduction to hydrodynamics for students of physics, astrophysics and other related areas.
Hydrodynamic interactions in active colloidal crystal microrheology.
Weeber, R; Harting, J
2012-11-01
In dense colloids it is commonly assumed that hydrodynamic interactions do not play a role. However, a found theoretical quantification is often missing. We present computer simulations that are motivated by experiments where a large colloidal particle is dragged through a colloidal crystal. To qualify the influence of long-ranged hydrodynamics, we model the setup by conventional Langevin dynamics simulations and by an improved scheme with limited hydrodynamic interactions. This scheme significantly improves our results and allows to show that hydrodynamics strongly impacts the development of defects, the crystal regeneration, as well as the jamming behavior.
Anisotropic hydrodynamics with a scalar collisional kernel
Almaalol, Dekrayat; Strickland, Michael
2018-04-01
Prior studies of nonequilibrium dynamics using anisotropic hydrodynamics have used the relativistic Anderson-Witting scattering kernel or some variant thereof. In this paper, we make the first study of the impact of using a more realistic scattering kernel. For this purpose, we consider a conformal system undergoing transversally homogenous and boost-invariant Bjorken expansion and take the collisional kernel to be given by the leading order 2 ↔2 scattering kernel in scalar λ ϕ4 . We consider both classical and quantum statistics to assess the impact of Bose enhancement on the dynamics. We also determine the anisotropic nonequilibrium attractor of a system subject to this collisional kernel. We find that, when the near-equilibrium relaxation-times in the Anderson-Witting and scalar collisional kernels are matched, the scalar kernel results in a higher degree of momentum-space anisotropy during the system's evolution, given the same initial conditions. Additionally, we find that taking into account Bose enhancement further increases the dynamically generated momentum-space anisotropy.
Hydrodynamic clustering of droplets in turbulence
Kunnen, Rudie; Yavuz, Altug; van Heijst, Gertjan; Clercx, Herman
2017-11-01
Small, inertial particles are known to cluster in turbulent flows: particles are centrifuged out of eddies and gather in the strain-dominated regions. This so-called preferential concentration is reflected in the radial distribution function (RDF; a quantitative measure of clustering). We study clustering of water droplets in a loudspeaker-driven turbulence chamber. We track the motion of droplets in 3D and calculate the RDF. At moderate scales (a few Kolmogorov lengths) we find the typical power-law scaling of preferential concentration in the RDF. However, at even smaller scales (a few droplet diameters), we encounter a hitherto unobserved additional clustering. We postulate that the additional clustering is due to hydrodynamic interactions, an effect which is typically disregarded in modeling. Using a perturbative expansion of inertial effects in a Stokes-flow description of two interacting spheres, we obtain an expression for the RDF which indeed includes the additional clustering. The additional clustering enhances the collision probability of droplets, which enhances their growth rate due to coalescence. The additional clustering is thus an essential effect in precipitation modeling.
Directory of Open Access Journals (Sweden)
Zsuzsanna Szepesi
Full Text Available Dendritic spines are are small membranous protrusions that extend from neuronal dendrites and harbor the majority of excitatory synapses. Increasing evidence has shown that matrix metalloproteinases (MMPs, a family of extracellularly acting and Zn(2+-dependent endopeptidases, are able to rapidly modulate dendritic spine morphology. Spine head protrusions (SHPs are filopodia-like processes that extend from the dendritic spine head, representing a form of postsynaptic structural remodeling in response to altered neuronal activity. Herein, we show that chemically induced long-term potentiation (cLTP in dissociated hippocampal cultures upregulates MMP-9 activity that controls the formation of SHPs. Blocking of MMPs activity or microtubule dynamics abolishes the emergence of SHPs. In addition, autoactive recombinant MMP-9, promotes the formation of SHPs in organotypic hippocampal slices. Furthermore, spines with SHPs gained postsynaptic α-amino-3-hydroxyl-5-methyl-4-isoxazole propionic acid (AMPA receptors upon cLTP and the synaptic delivery of AMPA receptors was controlled by MMPs. The present results strongly imply that MMP-9 is functionally involved in the formation of SHPs and the control of postsynaptic receptor distribution upon cLTP.
International Nuclear Information System (INIS)
Ferapontov, E.V.
2002-01-01
Hydrodynamic surfaces are solutions of hydrodynamic-type systems viewed as non-parametrized submanifolds of the hodograph space. We propose an invariant differential-geometric characterization of hydrodynamic surfaces by expressing the curvature form of the characteristic web in terms of the reciprocal invariants. (author)
An introduction to relativistic hydrodynamics
Energy Technology Data Exchange (ETDEWEB)
Font, Jose A [Departamento de AstronomIa y AstrofIsica, Universidad de Valencia, Dr. Moliner 50, 46100 Burjassot (Valencia) (Spain)
2007-11-15
We review formulations of the equations of (inviscid) general relativistic hydrodynamics and (ideal) magnetohydrodynamics, along with methods for their numerical solution. Both systems can be cast as first-order, hyperbolic systems of conservation laws, following the explicit choice of an Eulerian observer and suitable fluid and magnetic field variables. During the last fifteen years, the so-called (upwind) high-resolution shock-capturing schemes based on Riemann solvers have been successfully extended from classical to relativistic fluid dynamics, both special and general. Nowadays, general relativistic hydrodynamical simulations in relativistic astrophysics are routinely performed, particularly within the test-fluid approximation but also for dynamical spacetimes. While such advances also hold true in the case of the MHD equations, the astrophysical applications investigated so far are still limited, yet the field is bound to witness major developments in the near future. The article also presents a brief overview of numerical techniques, providing state-of-the-art examples of their applicability to general relativistic fluids and magneto-fluids in characteristic scenarios of relativistic astrophysics.
Inducer Hydrodynamic Load Measurement Devices
Skelley, Stephen E.; Zoladz, Thomas F.
2002-01-01
Marshall Space Flight Center (MSFC) has demonstrated two measurement devices for sensing and resolving the hydrodynamic loads on fluid machinery. The first - a derivative of the six component wind tunnel balance - senses the forces and moments on the rotating device through a weakened shaft section instrumented with a series of strain gauges. This "rotating balance" was designed to directly measure the steady and unsteady hydrodynamic loads on an inducer, thereby defining both the amplitude and frequency content associated with operating in various cavitation modes. The second device - a high frequency response pressure transducer surface mounted on a rotating component - was merely an extension of existing technology for application in water. MSFC has recently completed experimental evaluations of both the rotating balance and surface-mount transducers in a water test loop. The measurement bandwidth of the rotating balance was severely limited by the relative flexibility of the device itself, resulting in an unexpectedly low structural bending mode and invalidating the higher frequency response data. Despite these limitations, measurements confirmed that the integrated loads on the four-bladed inducer respond to both cavitation intensity and cavitation phenomena. Likewise, the surface-mount pressure transducers were subjected to a range of temperatures and flow conditions in a non-rotating environment to record bias shifts and transfer functions between the transducers and a reference device. The pressure transducer static performance was within manufacturer's specifications and dynamic response accurately followed that of the reference.
CHASM Challenge Problem: Lagrangian Hydrodynamics
Energy Technology Data Exchange (ETDEWEB)
Hornung, R [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Keasler, J [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Gokhale, M [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2010-09-10
Computer simulations of many science and engineering problems require modeling the equations of hydrodynamics which describe the motion of materials relative to each other induced by various forces. Many important DoD simulation problems involve complex multi-material systems that undergo large deformations. Examples include the analysis of armor defense, penetration mechanics, blast effects, structural integrity, and conventional munitions such as shaped charges and explosively formed projectiles. Indeed, the original motivation for developing codes that solve the equations of hydrodynamics, herein referred to as “hydrocodes”, was to solve problems with defense applications. The FY2010 Requirements Analysis Report issued by the DoD High Performance Computing Modernization Program (HPCMP) Office shows that a major portion of DoD HPC activities involves hydrocodes [HPCMP2010]. The report surveyed 496 projects across the Services and various Agencies, representing 4,050 HPCMP users at more than 125 locations, including government, contractors, and academia, and grouped each project into one of ten categories.
Fluctuating hydrodynamics for ionic liquids
Energy Technology Data Exchange (ETDEWEB)
Lazaridis, Konstantinos [Department of Mathematics and Statistics, Washington State University, Pullman, 99163 (United States); Wickham, Logan [Department of Computer Science, Washington State University, Richland, 99354 (United States); Voulgarakis, Nikolaos, E-mail: n.voulgarakis@wsu.edu [Department of Mathematics and Statistics, Washington State University, Pullman, 99163 (United States)
2017-04-25
We present a mean-field fluctuating hydrodynamics (FHD) method for studying the structural and transport properties of ionic liquids in bulk and near electrified surfaces. The free energy of the system consists of two competing terms: (1) a Landau–Lifshitz functional that models the spontaneous separation of the ionic groups, and (2) the standard mean-field electrostatic interaction between the ions in the liquid. The numerical approach used to solve the resulting FHD-Poisson equations is very efficient and models thermal fluctuations with remarkable accuracy. Such density fluctuations are sufficiently strong to excite the experimentally observed spontaneous formation of liquid nano-domains. Statistical analysis of our simulations provides quantitative information about the properties of ionic liquids, such as the mixing quality, stability, and the size of the nano-domains. Our model, thus, can be adequately parameterized by directly comparing our prediction with experimental measurements and all-atom simulations. Conclusively, this work can serve as a practical mathematical tool for testing various theories and designing more efficient mixtures of ionic liquids. - Highlights: • A new fluctuating hydrodynamics method for ionic liquids. • Description of ionic liquid morphology in bulk and near electrified surfaces. • Direct comparison with experimental measurements.
Low torque hydrodynamic lip geometry for rotary seals
Dietle, Lannie L.; Schroeder, John E.
2015-07-21
A hydrodynamically lubricating geometry for the generally circular dynamic sealing lip of rotary seals that are employed to partition a lubricant from an environment. The dynamic sealing lip is provided for establishing compressed sealing engagement with a relatively rotatable surface, and for wedging a film of lubricating fluid into the interface between the dynamic sealing lip and the relatively rotatable surface in response to relative rotation that may occur in the clockwise or the counter-clockwise direction. A wave form incorporating an elongated dimple provides the gradual convergence, efficient impingement angle, and gradual interfacial contact pressure rise that are conducive to efficient hydrodynamic wedging. Skewed elevated contact pressure zones produced by compression edge effects provide for controlled lubricant movement within the dynamic sealing interface between the seal and the relatively rotatable surface, producing enhanced lubrication and low running torque.
Hydrodynamic Overview at Hot Quarks 2016
International Nuclear Information System (INIS)
Noronha-Hostler, Jacquelyn
2017-01-01
Event-by-event relativistic hydrodynamics has been extremely successful in describing flow observables in heavy-ion collisions. However, the initial state and viscosity simultaneously affect comparisons to data so a discussion of experimental observables that help to distinguish the two follows. Specific problems that arise in the hydrodynamical modeling at the Beam Energy Scan are also addressed. (paper)
Two-fluid hydrodynamic model for semiconductors
DEFF Research Database (Denmark)
Maack, Johan Rosenkrantz; Mortensen, N. Asger; Wubs, Martijn
2018-01-01
The hydrodynamic Drude model (HDM) has been successful in describing the optical properties of metallic nanostructures, but for semiconductors where several different kinds of charge carriers are present an extended theory is required. We present a two-fluid hydrodynamic model for semiconductors...
Masri, Samer; El Rassi, Issam; Arabi, Mariam; Tabbakh, Anas; Bitar, Fadi
2015-08-01
To compare the efficacy and safety of Amplatzer Duct Occluder II (ADOII) among the various patent ductus arteriosus (PDA) types, and to assess the association between development of aortic obstruction and the PDA type in terms of measurable parameters as the device angulation and distance of upper end protrusion into the aortic lumen. Retrospective cohort study involving 50 consecutive subjects who underwent ADO II device closure of PDA. The median age and weight at intervention were 13 months (5.5 months to 18 years) and 11 (6-67) kg respectively. The median smallest ductal diameter by angiography was 3.2 (1.9-5.4) mm. Thirty two patients had type A PDA, 5 had type C, 5 had type D, and 8 had type E. Residual shunt was seen in only 1 patient who had a tubular PDA and resolved within 2 months of the procedure. No device embolization or pulmonary side protrusion were noted. There was a 16% aortic protrusion rate. The median distance of protrusion of the upper end of the device into the aortic lumen was 3.1 (0-9) mm and the median angle formed between the aortic end of the device and the PDA take-off was 10.4 (0-80.6) degrees. These latter parameters of aortic obstruction were significantly higher in the non-conical PDA group as compared to the conical PDA. Nevertheless, there was no significant coarctation due to aortic retention disc protrusion. Device closure of PDA using the ADO II is a safe procedure for chosen types of PDA. We demonstrated a novel technique for objective assessment of device protrusion into the descending aorta based on measurable parameters. ADOII device closure of non-conical PDAs warrants closer follow ups. © 2015 Wiley Periodicals, Inc.
Hemolytic potential of hydrodynamic cavitation.
Chambers, S D; Bartlett, R H; Ceccio, S L
2000-08-01
The purpose of this study was to determine the hemolytic potentials of discrete bubble cavitation and attached cavitation. To generate controlled cavitation events, a venturigeometry hydrodynamic device, called a Cavitation Susceptibility Meter (CSM), was constructed. A comparison between the hemolytic potential of discrete bubble cavitation and attached cavitation was investigated with a single-pass flow apparatus and a recirculating flow apparatus, both utilizing the CSM. An analytical model, based on spherical bubble dynamics, was developed for predicting the hemolysis caused by discrete bubble cavitation. Experimentally, discrete bubble cavitation did not correlate with a measurable increase in plasma-free hemoglobin (PFHb), as predicted by the analytical model. However, attached cavitation did result in significant PFHb generation. The rate of PFHb generation scaled inversely with the Cavitation number at a constant flow rate, suggesting that the size of the attached cavity was the dominant hemolytic factor.
Deterministic hydrodynamics: Taking blood apart
Davis, John A.; Inglis, David W.; Morton, Keith J.; Lawrence, David A.; Huang, Lotien R.; Chou, Stephen Y.; Sturm, James C.; Austin, Robert H.
2006-10-01
We show the fractionation of whole blood components and isolation of blood plasma with no dilution by using a continuous-flow deterministic array that separates blood components by their hydrodynamic size, independent of their mass. We use the technology we developed of deterministic arrays which separate white blood cells, red blood cells, and platelets from blood plasma at flow velocities of 1,000 μm/sec and volume rates up to 1 μl/min. We verified by flow cytometry that an array using focused injection removed 100% of the lymphocytes and monocytes from the main red blood cell and platelet stream. Using a second design, we demonstrated the separation of blood plasma from the blood cells (white, red, and platelets) with virtually no dilution of the plasma and no cellular contamination of the plasma. cells | plasma | separation | microfabrication
The hydrodynamic theory of detonation
Langweiler, Heinz
1939-01-01
This report derives equations containing only directly measurable constants for the quantities involved in the hydrodynamic theory of detonation. The stable detonation speed, D, is revealed as having the lowest possible value in the case of positive material velocity, by finding the minimum of the Du curve (u denotes the speed of the gases of combustion). A study of the conditions of energy and impulse in freely suspended detonating systems leads to the disclosure of a rarefaction front traveling at a lower speed behind the detonation front; its velocity is computed. The latent energy of the explosive passes into the steadily growing detonation zone - the region between the detonation front and the rarefaction front. The conclusions lead to a new definition of the concept of shattering power. The calculations are based on the behavior of trinitrotoluene.
Fluctuating nonlinear hydrodynamics of flocking
Yadav, Sunil Kumar; Das, Shankar P.
2018-03-01
Starting from a microscopic model, the continuum field theoretic description of the dynamics of a system of active ingredients or "particles" is presented. The equations of motion for the respective collective densities of mass and momentum follow exactly from that of a single element in the flock. The single-particle dynamics has noise and anomalous momentum dependence in its frictional terms. The equations for the collective densities are averaged over a local equilibrium distribution to obtain the corresponding coarse grained equations of fluctuating nonlinear hydrodynamics (FNH). The latter are the equations used frequently for describing active systems on the basis of intuitive arguments. The transport coefficients which appear in the macroscopic FNH equations are determined in terms of the parameters of the microscopic dynamics.
Hydrodynamics and phases of flocks
International Nuclear Information System (INIS)
Toner, John; Tu Yuhai; Ramaswamy, Sriram
2005-01-01
We review the past decade's theoretical and experimental studies of flocking: the collective, coherent motion of large numbers of self-propelled 'particles' (usually, but not always, living organisms). Like equilibrium condensed matter systems, flocks exhibit distinct 'phases' which can be classified by their symmetries. Indeed, the phases that have been theoretically studied to date each have exactly the same symmetry as some equilibrium phase (e.g., ferromagnets, liquid crystals). This analogy with equilibrium phases of matter continues in that all flocks in the same phase, regardless of their constituents, have the same 'hydrodynamic'-that is, long-length scale and long-time behavior, just as, e.g., all equilibrium fluids are described by the Navier-Stokes equations. Flocks are nonetheless very different from equilibrium systems, due to the intrinsically nonequilibrium self-propulsion of the constituent 'organisms'. This difference between flocks and equilibrium systems is most dramatically manifested in the ability of the simplest phase of a flock, in which all the organisms are, on average moving in the same direction (we call this a 'ferromagnetic' flock; we also use the terms 'vector-ordered' and 'polar-ordered' for this situation) to exist even in two dimensions (i.e., creatures moving on a plane), in defiance of the well-known Mermin-Wagner theorem of equilibrium statistical mechanics, which states that a continuous symmetry (in this case, rotation invariance, or the ability of the flock to fly in any direction) can not be spontaneously broken in a two-dimensional system with only short-ranged interactions. The 'nematic' phase of flocks, in which all the creatures move preferentially, or are simply oriented preferentially, along the same axis, but with equal probability of moving in either direction, also differs dramatically from its equilibrium counterpart (in this case, nematic liquid crystals). Specifically, it shows enormous number fluctuations, which
Hydrodynamic dispersion within porous biofilms
Davit, Y.
2013-01-23
Many microorganisms live within surface-associated consortia, termed biofilms, that can form intricate porous structures interspersed with a network of fluid channels. In such systems, transport phenomena, including flow and advection, regulate various aspects of cell behavior by controlling nutrient supply, evacuation of waste products, and permeation of antimicrobial agents. This study presents multiscale analysis of solute transport in these porous biofilms. We start our analysis with a channel-scale description of mass transport and use the method of volume averaging to derive a set of homogenized equations at the biofilm-scale in the case where the width of the channels is significantly smaller than the thickness of the biofilm. We show that solute transport may be described via two coupled partial differential equations or telegrapher\\'s equations for the averaged concentrations. These models are particularly relevant for chemicals, such as some antimicrobial agents, that penetrate cell clusters very slowly. In most cases, especially for nutrients, solute penetration is faster, and transport can be described via an advection-dispersion equation. In this simpler case, the effective diffusion is characterized by a second-order tensor whose components depend on (1) the topology of the channels\\' network; (2) the solute\\'s diffusion coefficients in the fluid and the cell clusters; (3) hydrodynamic dispersion effects; and (4) an additional dispersion term intrinsic to the two-phase configuration. Although solute transport in biofilms is commonly thought to be diffusion dominated, this analysis shows that hydrodynamic dispersion effects may significantly contribute to transport. © 2013 American Physical Society.
Directory of Open Access Journals (Sweden)
NR Yuliawati Zenab
2009-07-01
Full Text Available The purpose of this study was to find out whether there were changes in occlusal plane inclination after fixed orthodontic treatment of bimaxillary protrusion cases where extraction of four first premolars was needed using the standard Edgewise appliances. The sample was fourteen orthodontic patients, aged above sixteen years old, no sexual discrimination, treated with fixed appliances at Orthodontic Specialist Clinic Faculty of Dentistry Universitas Padjadjaran. The method was a pre-post design which compared occlusal plane inclination obtained from tracings of lateral cephalograms before and after orthodontic treatment. The results were calculated with the paired t-test analysis. The study revealed that there were no significant changes in occlusal plane inclination after the orthodontic treatment.
Energy Technology Data Exchange (ETDEWEB)
Ishihara, Makiko; Kobayashi, Hisashi; Ichikawa, Taro; Cho, Keiichi; Gemma, Kazuhito; Kumazaki, Tatsuo [Nippon Medical School, Tokyo (Japan)
1997-12-01
CT characteristics of spontaneous rupture of HCC (n=13) were reviewed retrospectively, and the value of emergency CT studies in this disease was evaluated. Especially, tumor protrusion ratio (TPR) and ascitic CT numbers were measured to for comparison with the data for unruptured HCCs and ordinary, (e.g., non-hemorrhagic) ascites (n=13). As a result, except for diffuse type HCCs, the TPR was significantly higher than for the unruptured HCCs. Nine cases had intraperitoneal HDAs, and the laterality of the HDAs corresponded with that of the ruptured tumors in 8 cases. Also, the ascitic CT numbers apart from the HDA were still higher than the ordinary ascites. Therefore, a high TPR, HDAs adjacent to the tumor, and elevated ascitic CT numbers are important CT manifestations indicating HCC rupture. Diffuse HCCs, however, require careful clinical evaluation. (author)
International Nuclear Information System (INIS)
Ishihara, Makiko; Kobayashi, Hisashi; Ichikawa, Taro; Cho, Keiichi; Gemma, Kazuhito; Kumazaki, Tatsuo
1997-01-01
CT characteristics of spontaneous rupture of HCC (n=13) were reviewed retrospectively, and the value of emergency CT studies in this disease was evaluated. Especially, tumor protrusion ratio (TPR) and ascitic CT numbers were measured to for comparison with the data for unruptured HCCs and ordinary, (e.g., non-hemorrhagic) ascites (n=13). As a result, except for diffuse type HCCs, the TPR was significantly higher than for the unruptured HCCs. Nine cases had intraperitoneal HDAs, and the laterality of the HDAs corresponded with that of the ruptured tumors in 8 cases. Also, the ascitic CT numbers apart from the HDA were still higher than the ordinary ascites. Therefore, a high TPR, HDAs adjacent to the tumor, and elevated ascitic CT numbers are important CT manifestations indicating HCC rupture. Diffuse HCCs, however, require careful clinical evaluation. (author)
Kuo, Tricia L C; Teo, Jonathan S M; Foo, K T
2016-04-01
Intravesical prostatic protrusion (IPP) may be an underutilized modality for the assessment of bladder outlet obstruction (BOO). Pressure flow studies or urodynamics have long been the gold standard for the evaluation of lower urinary tract symptoms (LUTS) in men but are invasive, time-consuming and costly. Potentially, IPP may be a useful adjunct prior to performing urodynamics. Measurement of IPP is taken in the sagittal view, using the transabdominal ultrasound. It is the vertical height from the tip of the protrusion to the base of the prostate. This technique was previously described. We reviewed previous publications that studied the accuracy, positive predictive value and clinical use of IPP. In addition, we noted the comments regarding the challenges of using this technique. IPP has been shown to have a positive predictive value of 72% for BOO. It has been calculated to have an area under curve (AUC) value of 0.71 and 0.84 in some stuies. Clinically, it may be used to predict the outcome of a trial without catheter following acute retention of urine. Patients with higher IPP grade were noted to have a higher risk of clinical progression. Studies have also shown that men with higher IPP are poorer responders to medical treatment such as α-blockers. Compared to other modalities, the advantage of IPP in assessing BOO may be its easy applicability and non-invasive nature. Therefore, there is a consideration for a larger role of IPP in bedside assessment and management of BOO in daily practice. Neurourol. Urodynam. 35:535-537, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.
Plasma hydrodynamics of the intense laser-cluster interaction*
Milchberg, Howard
2002-11-01
We present a 1D hydrodynamic model of the intense laser-cluster interaction in which the laser field is treated self-consistently. We find that for clusters initially as small as 25Å in radius, for which the hydrodynamic model is appropriate, nonuniform expansion of the heated material results in long-time resonance of the laser field at the critical density plasma layer. A significant result of this is that the ponderomotive force, which is enhanced at the critical density surface, can be large enough to strongly modify the plasma hydrodynamics, even at laser intensities as low as 10^15 W/cm^2 for 800 nm laser pulses. Recent experiments in EUV and x-ray generation as a function of laser pulsewidth [1], and femtosecond time-resolved measurements of cluster transient polarizability [2] provide strong support for the basic physics of this model. Recent results using a 2D hybrid fluid/PIC code show qualitative agreement with the 1D hydrocode [3]. *Work supported by the National Science Foundation and the EUV-LLC. 1. E. Parra, I. Alexeev, J. Fan, K. Kim, S.J. McNaught, and H. M. Milchberg, Phys. Rev. E 62, R5931 (2000). 2. K.Y. Kim, I. Alexeev, E. Parra, and H.M. Milchberg, submitted for publication. 3. T. Taguchi, T. Antonsen, and H.M Milchberg, this meeting.
Relativistic conformal magneto-hydrodynamics from holography
International Nuclear Information System (INIS)
Buchbinder, Evgeny I.; Buchel, Alex
2009-01-01
We use the AdS/CFT correspondence to study first-order relativistic viscous magneto-hydrodynamics of (2+1)-dimensional conformal magnetic fluids. It is shown that the first order magneto-hydrodynamics constructed following Landau and Lifshitz from the positivity of the entropy production is inconsistent. We propose additional contributions to the entropy motivated dissipative current and, correspondingly, new dissipative transport coefficients. We use the strongly coupled M2-brane plasma in external magnetic field to show that the new magneto-hydrodynamics leads to self-consistent results in the shear and sound wave channels.
Dileptons from transport and hydrodynamical models
International Nuclear Information System (INIS)
Huovinen, P.; Koch, V.
2000-01-01
Transport and hydrodynamical models used to describe the expansion stage of a heavy-ion collision at the CERN SPS give different dilepton spectrum even if they are tuned to reproduce the observed hadron spectra. To understand the origin of this difference we compare the dilepton emission from transport and hydrodynamical models using similar initial states in both models. We find that the requirement of pion number conservation in a hydrodynamical model does not change the dilepton emission. Also the mass distribution from the transport model indicates faster cooling and longer lifetime of the fireball
Tuning bacterial hydrodynamics with magnetic fields
Pierce, C. J.; Mumper, E.; Brown, E. E.; Brangham, J. T.; Lower, B. H.; Lower, S. K.; Yang, F. Y.; Sooryakumar, R.
2017-06-01
Magnetotactic bacteria are a group of motile prokaryotes that synthesize chains of lipid-bound, magnetic nanoparticles called magnetosomes. This study exploits their innate magnetism to investigate previously unexplored facets of bacterial hydrodynamics at surfaces. Through use of weak, uniform, external magnetic fields and local, micromagnetic surface patterns, the relative strength of hydrodynamic, magnetic, and flagellar force components is tuned through magnetic control of the bacteria's orientation. The resulting swimming behaviors provide a means to experimentally determine hydrodynamic parameters and offer a high degree of control over large numbers of living microscopic entities. The implications of this controlled motion for studies of bacterial motility near surfaces and for micro- and nanotechnology are discussed.
Khizhniak, M V; Priĭmak, E V
2013-03-01
Experience of application of intralaminar epidural pharmacotherapy for the treatment of the pain syndrome in the patients, suffering osteochondrosis of lumbar portion of vertebral column, complicated by intervertebral discs protrusion, was summarized. The method introduction permits to escape the operative intervention performance for complicated osteochondrosis.
Briggs, Laura E.; Phelps, Aimee L.; Brown, Elizabeth; Kakarla, Jayant; Anderson, Robert H.; van den Hoff, Maurice J. B.; Wessels, Andy
2013-01-01
The dorsal mesenchymal protrusion (DMP) is a prong of mesenchyme derived from the second heart field (SHF) located at the venous pole of the developing heart. Recent studies have shown that perturbation of its development is associated with the pathogenesis of atrioventricular (AV) septal defect.
Energy Technology Data Exchange (ETDEWEB)
Moon, Sung Kyoung; Kim, Hyoung Jung; Lim, Joo Won; Lee, Dong Ho; Ko, Young Tae [Kyung Hee University Hospital, Seoul (Korea, Republic of)
2008-06-15
To evaluate the proper volume measurement of prostate with focal intravesical protrusion of enlarged central gland by comparison between methods using craniocaudal length from top of protruded central gland and from prostate base near bladder neck to prostate apex. We made 20 prostate models with focal intravesical protrusion (volume range: 20{approx}50 mL, height of protrusion: about 1 cm) using devil's tongue jelly. Two radiologists measured volume of models 3 times by two kinds of methods using craniocaudal length from top of protruded central gland (method 1) and from prostate base near bladder neck (method 2) by transrectal ultrasound. The accuracy of volume measurement of models was evaluated statistically by comparing their average volume to true volume. Intra- and interobserver agreement was also evaluated. Average true volume of models was 31.05 mL. Each average volume using method 1 by two observers was 37.07 mL and 38.56 mL. Each average volume using method 2 was 30.69 mL and 31.55 mL. Volume measurement using method 2 was approximated to true volume of prostate statistically (p = .654, .823). There was no significant inter- and intra-observer variation in both methods. To measure the accurate volume of prostate with focal intravesical protrusion of enlarged central gland, its craniocaudal length should be measured from prostate base near bladder neck
Badve, Mandar P; Gogate, Parag R; Pandit, Aniruddha B; Csoka, Levente
2014-01-01
The present work deals with application of hydrodynamic cavitation for intensification of delignification of wheat straw as an essential step in the paper manufacturing process. Wheat straw was first treated with potassium hydroxide (KOH) for 48 h and subsequently alkali treated wheat straw was subjected to hydrodynamic cavitation. Hydrodynamic cavitation reactor used in the work is basically a stator and rotor assembly, where the rotor is provided with indentations and cavitational events are expected to occur on the surface of rotor as well as within the indentations. It has been observed that treatment of alkali treated wheat straw in hydrodynamic cavitation reactor for 10-15 min increases the tensile index of the synthesized paper sheets to about 50-55%, which is sufficient for paper board manufacture. The final mechanical properties of the paper can be effectively managed by controlling the processing parameters as well as the cavitational parameters. It has also been established that hydrodynamic cavitation proves to be an effective method over other standard digestion techniques of delignification in terms of electrical energy requirements as well as the required time for processing. Overall, the work is first of its kind application of hydrodynamic cavitation for enhancing the effectiveness of delignification and presents novel results of significant interest to the paper and pulp industry opening an entirely new area of application of cavitational reactors. Copyright © 2013 Elsevier B.V. All rights reserved.
Activity-induced clustering in model dumbbell swimmers: the role of hydrodynamic interactions.
Furukawa, Akira; Marenduzzo, Davide; Cates, Michael E
2014-08-01
Using a fluid-particle dynamics approach, we numerically study the effects of hydrodynamic interactions on the collective dynamics of active suspensions within a simple model for bacterial motility: each microorganism is modeled as a stroke-averaged dumbbell swimmer with prescribed dipolar force pairs. Using both simulations and qualitative arguments, we show that, when the separation between swimmers is comparable to their size, the swimmers' motions are strongly affected by activity-induced hydrodynamic forces. To further understand these effects, we investigate semidilute suspensions of swimmers in the presence of thermal fluctuations. A direct comparison between simulations with and without hydrodynamic interactions shows these to enhance the dynamic clustering at a relatively small volume fraction; with our chosen model the key ingredient for this clustering behavior is hydrodynamic trapping of one swimmer by another, induced by the active forces. Furthermore, the density dependence of the motility (of both the translational and rotational motions) exhibits distinctly different behaviors with and without hydrodynamic interactions; we argue that this is linked to the clustering tendency. Our study illustrates the fact that hydrodynamic interactions not only affect kinetic pathways in active suspensions, but also cause major changes in their steady state properties.
Conformal invariance in hydrodynamic turbulence
International Nuclear Information System (INIS)
Falkovich, Gregory
2007-01-01
This short survey is written by a physicist. It contains neither theorems nor precise definitions. Its main content is a description of the results of numerical solution of the equations of fluid mechanics in the regime of developed turbulence. Due to limitations of computers, the results are not very precise. Despite being neither exact nor rigorous, the findings may nevertheless be of interest for mathematicians. The main result is that the isolines of some scalar fields (vorticity, temperature) in two-dimensional turbulence belong to the class of conformally invariant curves called SLE (Scramm-Loewner evolution) curves. First, this enables one to predict and find a plethora of quantitative relations going far beyond what was known previously about turbulence. Second, it suggests relations between phenomena that seemed unrelated, like the Euler equation and critical percolation. Third, it shows that one is able to get exact analytic results in statistical hydrodynamics. In short, physicists have found something unexpected and hope that mathematicians can help to explain it.
The hydrodynamics of swimming microorganisms
International Nuclear Information System (INIS)
Lauga, Eric; Powers, Thomas R
2009-01-01
Cell motility in viscous fluids is ubiquitous and affects many biological processes, including reproduction, infection and the marine life ecosystem. Here we review the biophysical and mechanical principles of locomotion at the small scales relevant to cell swimming, tens of micrometers and below. At this scale, inertia is unimportant and the Reynolds number is small. Our emphasis is on the simple physical picture and fundamental flow physics phenomena in this regime. We first give a brief overview of the mechanisms for swimming motility, and of the basic properties of flows at low Reynolds number, paying special attention to aspects most relevant for swimming such as resistance matrices for solid bodies, flow singularities and kinematic requirements for net translation. Then we review classical theoretical work on cell motility, in particular early calculations of swimming kinematics with prescribed stroke and the application of resistive force theory and slender-body theory to flagellar locomotion. After examining the physical means by which flagella are actuated, we outline areas of active research, including hydrodynamic interactions, biological locomotion in complex fluids, the design of small-scale artificial swimmers and the optimization of locomotion strategies.
Framing Camera Improvements and hydrodynamic Experiments
National Research Council Canada - National Science Library
Drake, R. P
2007-01-01
.... We also propose to participate in hydrodynamic experiments at NRL whenever they occur, to prepare for an experiment for NIKE to study the onset of turbulence via the Kelvin Helmholtz instability...
Hydrodynamic limit of interacting particle systems
International Nuclear Information System (INIS)
Landim, C.
2004-01-01
We present in these notes two methods to derive the hydrodynamic equation of conservative interacting particle systems. The intention is to present the main ideas in the simplest possible context and refer for details and references. (author)
Directory of Open Access Journals (Sweden)
Martin I. Bayala
2014-06-01
Full Text Available Land Surface Temperature (LST is a key parameter in the energy balance model. However, the spatial resolution of the retrieved LST from sensors with high temporal resolution is not accurate enough to be used in local-scale studies. To explore the LST–Normalised Difference Vegetation Index relationship potential and obtain thermal images with high spatial resolution, six enhanced image sharpening techniques were assessed: the disaggregation procedure for radiometric surface temperatures (TsHARP, the Dry Edge Quadratic Function, the Difference of Edges (Ts∗DL and three models supported by the relationship of surface temperature and water stress of vegetation (Normalised Difference Water Index, Normalised Difference Infrared Index and Soil wetness index. Energy Balance Station data and in situ measurements were used to validate the enhanced LST images over a mixed agricultural landscape in the sub-humid Pampean Region of Argentina (PRA, during 2006–2010. Landsat Thematic Mapper (TM and Moderate Resolution Imaging Spectroradiometer (EOS-MODIS thermal datasets were assessed for different spatial resolutions (e.g., 960, 720 and 240 m and the performances were compared with global and local TsHARP procedures. Results suggest that the Ts∗DL technique is the most adequate for simulating LST to high spatial resolution over the heterogeneous landscape of a sub-humid region, showing an average root mean square error of less than 1 K.
Hydrodynamic approach to electronic transport in graphene
Energy Technology Data Exchange (ETDEWEB)
Narozhny, Boris N. [Institute for Theoretical Condensed Matter Physics, Karlsruhe Institute of Technology, Karlsruhe (Germany); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation); Gornyi, Igor V. [Institute for Theoretical Condensed Matter Physics, Karlsruhe Institute of Technology, Karlsruhe (Germany); Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe (Germany); Ioffe Physical Technical Institute, St. Petersburg (Russian Federation); Mirlin, Alexander D. [Institute for Theoretical Condensed Matter Physics, Karlsruhe Institute of Technology, Karlsruhe (Germany); Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe (Germany); Petersburg Nuclear Physics Institute, St. Petersburg (Russian Federation); Schmalian, Joerg [Institute for Theoretical Condensed Matter Physics, Karlsruhe Institute of Technology, Karlsruhe (Germany); Institute for Solid State Physics, Karlsruhe Institute of Technology, Karlsruhe (Germany)
2017-11-15
The last few years have seen an explosion of interest in hydrodynamic effects in interacting electron systems in ultra-pure materials. In this paper we briefly review the recent advances, both theoretical and experimental, in the hydrodynamic approach to electronic transport in graphene, focusing on viscous phenomena, Coulomb drag, non-local transport measurements, and possibilities for observing nonlinear effects. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Improvements to SOIL: An Eulerian hydrodynamics code
International Nuclear Information System (INIS)
Davis, C.G.
1988-04-01
Possible improvements to SOIL, an Eulerian hydrodynamics code that can do coupled radiation diffusion and strength of materials, are presented in this report. Our research is based on the inspection of other Eulerian codes and theoretical reports on hydrodynamics. Several conclusions from the present study suggest that some improvements are in order, such as second-order advection, adaptive meshes, and speedup of the code by vectorization and/or multitasking. 29 refs., 2 figs
Relabeling symmetries in hydrodynamics and magnetohydrodynamics
International Nuclear Information System (INIS)
Padhye, N.; Morrison, P.J.
1996-04-01
Lagrangian symmetries and concomitant generalized Bianchi identities associated with the relabeling of fluid elements are found for hydrodynamics and magnetohydrodynamics (MHD). In hydrodynamics relabeling results in Ertel's theorem of conservation of potential vorticity, while in MHD it yields the conservation of cross helicity. The symmetries of the reduction from Lagrangian (material) to Eulerian variables are used to construct the Casimir invariants of the Hamiltonian formalism
Chaotic hydrodynamics of fluidized beds
Energy Technology Data Exchange (ETDEWEB)
Van der Stappen, M.L.M. [Unit Process and Systems Engineering, Advanced Manufacturing Technology Group, Unilever Research Laboratorium, Vlaardingen (Netherlands)
1996-12-31
The major goals of this thesis are: (1) to develop and evaluate an analysis method based on techniques from non-linear chaos theory to characterize the nonlinear hydrodynamics of gas-solids fluidized beds quantitatively; and (2) to determine the dependence of the chaotic invariants on the operating conditions and investigate how the chaos analysis method can be profitably applied to improve scale-up and design of gas-solids fluidized bed reactors. Chaos theory is introduced in chapter 2 with emphasis on analysis techniques for (experimental) time series, known from literature at the start of this work (1990-1991). In chapter 3, the testing of existing and newly developed techniques on both model and fluidized bed data is described. This leads to the development of the chaos analysis method to analyze measured pressure fluctuations time series of a fluidized bed. Following, in chapter 4, this method is tested and all choices for the parameters are evaluated. The influence of the experimental parameters and external disturbances on the measurements and analysis results is discussed and quantified. The result is a chaos measurement and analysis protocol, which is further used in this work. In chapter 5, the applications to fluidized beds are discussed. It is shown that the entropy is a good measure for the characterization of the dynamical behavior of gas-solids bubbling/slugging fluidized beds. Entropy is applied to characterize the influence of the operating conditions, to assess regime transitions and to analyze dimensionless similar beds of different scale. Quantitative design correlations that relate entropy to the operating parameters (including the bed diameter) are described. Finally, it is discussed how the results of this work might be used in scaling up the chaotic dynamics of fluidized beds. The overall conclusions and outlook from this work are presented in chapter 6. 182 refs.
Hydrodynamics of soft active matter
Marchetti, M. C.; Joanny, J. F.; Ramaswamy, S.; Liverpool, T. B.; Prost, J.; Rao, Madan; Simha, R. Aditi
2013-07-01
This review summarizes theoretical progress in the field of active matter, placing it in the context of recent experiments. This approach offers a unified framework for the mechanical and statistical properties of living matter: biofilaments and molecular motors in vitro or in vivo, collections of motile microorganisms, animal flocks, and chemical or mechanical imitations. A major goal of this review is to integrate several approaches proposed in the literature, from semimicroscopic to phenomenological. In particular, first considered are “dry” systems, defined as those where momentum is not conserved due to friction with a substrate or an embedding porous medium. The differences and similarities between two types of orientationally ordered states, the nematic and the polar, are clarified. Next, the active hydrodynamics of suspensions or “wet” systems is discussed and the relation with and difference from the dry case, as well as various large-scale instabilities of these nonequilibrium states of matter, are highlighted. Further highlighted are various large-scale instabilities of these nonequilibrium states of matter. Various semimicroscopic derivations of the continuum theory are discussed and connected, highlighting the unifying and generic nature of the continuum model. Throughout the review, the experimental relevance of these theories for describing bacterial swarms and suspensions, the cytoskeleton of living cells, and vibrated granular material is discussed. Promising extensions toward greater realism in specific contexts from cell biology to animal behavior are suggested, and remarks are given on some exotic active-matter analogs. Last, the outlook for a quantitative understanding of active matter, through the interplay of detailed theory with controlled experiments on simplified systems, with living or artificial constituents, is summarized.
Directory of Open Access Journals (Sweden)
Cecilia Ambrosi
Full Text Available Outer membrane protein A (OmpA is a multifaceted predominant outer membrane protein of Escherichia coli and other Enterobacteriaceae whose role in the pathogenesis of various bacterial infections has recently been recognized. Here, the role of OmpA on the virulence of Shigella flexneri has been investigated. An ompA mutant of wild-type S. flexneri 5a strain M90T was constructed (strain HND92 and it was shown to be severely impaired in cell-to-cell spreading since it failed to plaque on HeLa cell monolayers. The lack of OmpA significantly reduced the levels of IcsA while the levels of cell associated and released IcsP-cleaved 95 kDa amino-terminal portion of the mature protein were similar. Nevertheless, the ompA mutant displayed IcsA exposed across the entire bacterial surface. Surprisingly, the ompA mutant produced proper F-actin comet tails, indicating that the aberrant IcsA exposition at bacterial lateral surface did not affect proper activation of actin-nucleating proteins, suggesting that the absence of OmpA likely unmasks mature or cell associated IcsA at bacterial lateral surface. Moreover, the ompA mutant was able to invade and to multiply within HeLa cell monolayers, although internalized bacteria were found to be entrapped within the host cell cytoplasm. We found that the ompA mutant produced significantly less protrusions than the wild-type strain, indicating that this defect could be responsible of its inability to plaque. Although we could not definitely rule out that the ompA mutation might exert pleiotropic effects on other S. flexneri genes, complementation of the ompA mutation with a recombinant plasmid carrying the S. flexneri ompA gene clearly indicated that a functional OmpA protein is required and sufficient for proper IcsA exposition, plaque and protrusion formation. Moreover, an independent ompA mutant was generated. Since we found that both mutants displayed identical virulence profile, these results further supported the
Hernandez, L Patricia; Staab, Katie Lynn
2015-07-01
While much of the functional work on suction feeding has involved members of Acanthopterygii, an earlier cypriniform radiation led to over 3200 species filling nearly every freshwater trophic niche. Within the great majority of acanthomorph clades that have been investigated suction feeding and the underlying morphology responsible for the generation of rapid suction have been largely conserved. This conserved feeding-apparatus is often associated with increasing the force experienced by the prey item, thus making a strike on elusive prey more effective. Cypriniforms' trophic anatomy is comprised of a number of novelties used for benthic feeding, which characterized early members of this clade. The modified cypriniform structure of the oral jaws represents a situation in which a particular type of suction feeding allowed for probing the benthos with a more functionally maneuverable anatomy. Requisite evolutionary modifications included origin and elongation of a median kinethmoid, duplications of certain divisions of the muscles of the adductor mandibulae, and origin of a dorsal, intra-buccal muscular palatal organ used in winnowing detritus. The elongated kinethmoid (coupled with modified adductor muscles) allowed for a type of premaxillary protrusion that decoupled the upper and lower jaws, enabled premaxillary protrusions with a closed mouth, and facilitated benthic feeding by increasing functional flexibility. The resultant flow of fluid generated by cypriniforms is also quite flexible, with multiple instances of peak flow in a single feeding event. This greatly modified morphology allowed for a degree of kinematic maneuverability not seen within most acanthomorphs. Later cypriniform radiations into piscivorous, insectivorous, or planktivorous feeding guilds were associated with shortening of the kinethmoid and with simplified morphology of the adductor, likely involving an emphasis on ram feeding. Although this suite of morphological novelties seemingly
Directory of Open Access Journals (Sweden)
Carla Maria Melleiro Gimenez
2007-12-01
Full Text Available OBJETIVO: o presente trabalho tem o propósito de apresentar uma revisão da literatura acerca do tratamento da má oclusão de Classe II, divisão 1 de Angle, tendo a protrusão maxilar como o principal componente dessa má oclusão, durante a fase de crescimento e desenvolvimento craniofacial. Serão apresentadas as características de cada um desses aparelhos, os seus componentes, a forma adequada de utilização, os seus mecanismos de ação e, principalmente, os seus efeitos em todo o complexo dentofacial. CONCLUSÃO: nos casos em que se verifica apenas a protrusão maxilar, sem envolvimento mandibular, e se faz necessário o controle vertical, pode ser indicado o AEB, conjugado ao aparelho removível derivado do aparelho preconizado por Thurow. Já nas situações de combinação da protrusão maxilar com a retrusão mandibular, uma opção de tratamento é o ativador combinado à ancoragem extrabucal.AIM: The purpose of this research is to review the literature about the treatment of Class II, division 1 malocclusion with maxillary protrusion, during the growth and development period. This review addresses the characteristics of these appliances, their components, correct use, action mechanisms, and mainly their consequences in dentofacial complex. CONCLUSIONS: In patients with maxillary protrusion and with no mandibular component, it may be indicated the use of a maxillary splint similar to the one suggested by Thurow. However, in patients with maxillary protrusion and mandibular retrusion, it may be indicated an activator associated with extra oral anchorage.
Intensification of biogas production using pretreatment based on hydrodynamic cavitation.
Patil, Pankaj N; Gogate, Parag R; Csoka, Levente; Dregelyi-Kiss, Agota; Horvath, Miklos
2016-05-01
The present work investigates the application of hydrodynamic cavitation (HC) for the pretreatment of wheat straw with an objective of enhancing the biogas production. The hydrodynamic cavitation reactor is based on a stator and rotor assembly. The effect of three different speeds of rotor (2300, 2500, 2700 rpm), wheat straw to water ratios (0.5%, 1% and 1.5% wt/wt) and also treatment times as 2, 4 and 6 min have been investigated in the work using the design of experiments (DOE) approach. It was observed that the methane yield of 31.8 ml was obtained with untreated wheat straw whereas 77.9 ml was obtained with HC pre-treated wheat straw confirming the favourable changes during the pre-treatment. The combined pre-treatment using KOH and HC gave maximum yield of biogas as 172.3 ml. Overall, it has been established that significant enhancement in the biogas production can be obtained due to the pretreatment using HC which can also be further intensified by combination with chemical treatment. Copyright © 2015 Elsevier B.V. All rights reserved.
International Nuclear Information System (INIS)
Yen, Yu-Ting; Wang, Yi-Chung; Chen, Chia-Wei; Tsai, Hung-Wei; Chen, Yu-Ze; Hu, Fan; Chueh, Yu-Lun
2015-01-01
Highlights: • CuIn(S,Se)_2 nano-protrusions were demonstrated on 36-cm"2 flexible substrates. • Nano-protrusions were created by ion erosion on selenized CuInS_2 nanocrystal precursor inks. • Tilt orientations and remarkable anti-reflectance characteristics of nano-protrusions can be precisely controlled. - Abstract: In this work, an approach to achieve surface nano-protrusions on a chalcopyrite CuIn(S,Se)_2 thin film was demonstrated. Home-made CuInS_2 nanocrystals with average diameter of 20 nm were prepared and characterized. By applying ion erosion process on the CuIn(S,Se)_2 film, large-area self-aligned nano-protrusions can be formed. Interestingly, the process can be applied on flexible substrate where the CuIn(S,Se)_2 film remains intact with no visible cracking after several bending tests. In addition, reflectance spectra reveal the extraordinary anti-reflectance characteristics of nano-protrusions on the CuIn(S,Se)_2 film with the incident light from 350 to 2000 nm. A 36-cm"2 CuIn(S,Se)_2 film with nano-protrusions on flexible molybdenum foil substrate has been demonstrated, which demonstrated the feasibility of developing low cost with a high optical absorption CuIn(S,Se)_2 flexible thin film.
Shin, Kang-Jae; Lee, Shin-Hyo; Koh, Ki-Seok; Song, Wu-Chul
2017-03-01
This study investigated the topographic relationships among the eyeball and four orbital margins with the aim of identifying the correlation between orbital geometry and eyeball protrusion in Koreans. Three-dimensional (3D) volume rendering of the face was performed using serial computed-tomography images of 141 Koreans, and several landmarks on the bony orbit and the cornea were directly marked on the 3D volumes. The anterior-posterior distances from the apex of the cornea to each orbital margin and between the orbital margins were measured in both eyes. The distances from the apex of the cornea to the superior, medial, inferior, and lateral orbital margins were 5.8, 5.8, 12.0, and 17.9 mm, respectively. Differences between sides were observed in all of the orbital margins, and the distances from the apex of the cornea to the superior and inferior orbital margins were significantly greater in females than in males. The anterior-posterior distance between the superior and inferior orbital margins did not differ significantly between males (6.3 mm) and females (6.2 mm). The data obtained in this study will be useful when developing practical guidelines applicable to forensic facial reconstruction and orbitofacial surgeries.
Re-examination of Oostenbroek et al. (2016): evidence for neonatal imitation of tongue protrusion.
Meltzoff, Andrew N; Murray, Lynne; Simpson, Elizabeth; Heimann, Mikael; Nagy, Emese; Nadel, Jacqueline; Pedersen, Eric J; Brooks, Rechele; Messinger, Daniel S; Pascalis, Leonardo De; Subiaul, Francys; Paukner, Annika; Ferrari, Pier F
2017-09-27
The meaning, mechanism, and function of imitation in early infancy have been actively discussed since Meltzoff and Moore's (1977) report of facial and manual imitation by human neonates. Oostenbroek et al. (2016) claim to challenge the existence of early imitation and to counter all interpretations so far offered. Such claims, if true, would have implications for theories of social-cognitive development. Here we identify 11 flaws in Oostenbroek et al.'s experimental design that biased the results toward null effects. We requested and obtained the authors' raw data. Contrary to the authors' conclusions, new analyses reveal significant tongue-protrusion imitation at all four ages tested (1, 3, 6, and 9 weeks old). We explain how the authors missed this pattern and offer five recommendations for designing future experiments. Infant imitation raises fundamental issues about action representation, social learning, and brain-behavior relations. The debate about the origins and development of imitation reflects its importance to theories of developmental science. © 2017 John Wiley & Sons Ltd.
Energy Technology Data Exchange (ETDEWEB)
Boulet, J.A.M. [Tennessee Univ., Knoxville, TN (United States)
1992-04-01
An initial investigation of the influence of protrusion interference on the fracture toughness required to prevent unstable propagation of a Griffith crack in a brittle material is described. The interference is caused by relative shear displacement of the crack faces when subjected to remote biaxial stress with neither principal stress parallel to the crack. It is shown that for room temperature cracks smaller than about one centimeter in silicon carbide, or about one millimeter in silicon nitride, the presence of interference changes the fracture stress. A mathematical model based on linear elasticity solutions and including multiple interference sites at arbitrarily specified positions on the crack is presented. Computations of the change in required fracture toughness and its dependence on wedge geometry (size and vertex angle), applied stresses (orientation and magnitude), and location of the interference site are discussed. Results indicate that a single interference site has only a slight effect on required toughness. However, the influence of interference increases monotonically with the number of interference sites. The two-dimensional model described herein is not accurate when the interference sites are closely spaced.
Directory of Open Access Journals (Sweden)
Sheila Laverty
2015-04-01
Full Text Available We studied changes in articular calcified cartilage (ACC and subchondral bone (SCB in the third carpal bones (C3 of Standardbred racehorses with naturally-occurring repetitive loading-induced osteoarthritis (OA. Two osteochondral cores were harvested from dorsal sites from each of 15 post-mortem C3 and classified as control or as showing early or advanced OA changes from visual inspection. We re-examined X-ray micro-computed tomography (µCT image sets for the presence of high-density mineral infill (HDMI in ACC cracks and possible high-density mineralized protrusions (HDMP from the ACC mineralizing (tidemark front (MF into hyaline articular cartilage (HAC. We hypothesized and we show that 20-µm µCT resolution in 10-mm diameter samples is sufficient to detect HDMI and HDMP: these are lost upon tissue decalcification for routine paraffin wax histology owing to their predominant mineral content. The findings show that µCT is sufficient to discover HDMI and HDMP, which were seen in 2/10 controls, 6/9 early OA and 8/10 advanced OA cases. This is the first report of HDMI and HDMP in the equine carpus and in the Standardbred breed and the first to rely solely on µCT. HDMP are a candidate cause for mechanical tissue destruction in OA.
Anisotropic hydrodynamics for conformal Gubser flow
Energy Technology Data Exchange (ETDEWEB)
Strickland, Michael; Nopoush, Mohammad [Kent State University, Kent OH 44242 (United States); Ryblewski, Radoslaw [The H. Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, PL-31342 Kraków (Poland)
2016-12-15
In this proceedings contribution, we review the exact solution of the anisotropic hydrodynamics equations for a system subject to Gubser flow. For this purpose, we use the leading-order anisotropic hydrodynamics equations which assume that the distribution function is ellipsoidally symmetric in local-rest-frame momentum. We then prove that the SO(3){sub q} symmetry in de Sitter space constrains the anisotropy tensor to be of spheroidal form with only one independent anisotropy parameter remaining. As a consequence, the exact solution reduces to the problem of solving two coupled non-linear differential equations. We show that, in the limit that the relaxation time goes to zero, one obtains Gubser's ideal hydrodynamic solution and, in the limit that the relaxation time goes to infinity, one obtains the exact free streaming solution obtained originally by Denicol et al. For finite relaxation time, we solve the equations numerically and compare to the exact solution of the relaxation-time-approximation Boltzmann equation subject to Gubser flow. Using this as our standard, we find that anisotropic hydrodynamics describes the spatio-temporal evolution of the system better than all currently known dissipative hydrodynamics approaches.
Hydrodynamic Modeling and Its Application in AUC.
Rocco, Mattia; Byron, Olwyn
2015-01-01
The hydrodynamic parameters measured in an AUC experiment, s(20,w) and D(t)(20,w)(0), can be used to gain information on the solution structure of (bio)macromolecules and their assemblies. This entails comparing the measured parameters with those that can be computed from usually "dry" structures by "hydrodynamic modeling." In this chapter, we will first briefly put hydrodynamic modeling in perspective and present the basic physics behind it as implemented in the most commonly used methods. The important "hydration" issue is also touched upon, and the distinction between rigid bodies versus those for which flexibility must be considered in the modeling process is then made. The available hydrodynamic modeling/computation programs, HYDROPRO, BEST, SoMo, AtoB, and Zeno, the latter four all implemented within the US-SOMO suite, are described and their performance evaluated. Finally, some literature examples are presented to illustrate the potential applications of hydrodynamics in the expanding field of multiresolution modeling. © 2015 Elsevier Inc. All rights reserved.
Anisotropic hydrodynamics for conformal Gubser flow
International Nuclear Information System (INIS)
Strickland, Michael; Nopoush, Mohammad; Ryblewski, Radoslaw
2016-01-01
In this proceedings contribution, we review the exact solution of the anisotropic hydrodynamics equations for a system subject to Gubser flow. For this purpose, we use the leading-order anisotropic hydrodynamics equations which assume that the distribution function is ellipsoidally symmetric in local-rest-frame momentum. We then prove that the SO(3)_q symmetry in de Sitter space constrains the anisotropy tensor to be of spheroidal form with only one independent anisotropy parameter remaining. As a consequence, the exact solution reduces to the problem of solving two coupled non-linear differential equations. We show that, in the limit that the relaxation time goes to zero, one obtains Gubser's ideal hydrodynamic solution and, in the limit that the relaxation time goes to infinity, one obtains the exact free streaming solution obtained originally by Denicol et al. For finite relaxation time, we solve the equations numerically and compare to the exact solution of the relaxation-time-approximation Boltzmann equation subject to Gubser flow. Using this as our standard, we find that anisotropic hydrodynamics describes the spatio-temporal evolution of the system better than all currently known dissipative hydrodynamics approaches.
Density waves in a lattice hydrodynamic traffic flow model with the anticipation effect
International Nuclear Information System (INIS)
Zhao Min; Sun Di-Hua; Tian Chuan
2012-01-01
By introducing the traffic anticipation effect in the real world into the original lattice hydrodynamic model, we present a new anticipation effect lattice hydrodynamic (AELH) model, and obtain the linear stability condition of the model by applying the linear stability theory. Through nonlinear analysis, we derive the Burgers equation and Korteweg-de Vries (KdV) equation, to describe the propagating behaviour of traffic density waves in the stable and the metastable regions, respectively. The good agreement between simulation results and analytical results shows that the stability of traffic flow can be enhanced when the anticipation effect is considered. (interdisciplinary physics and related areas of science and technology)
Impact of hydrodynamics on effective interactions in suspensions of active and passive matter.
Krafnick, Ryan C; García, Angel E
2015-02-01
Passive particles exhibit unique properties when immersed in an active bath of self-propelling entities. In particular, an effective attraction can appear between particles that repel each other when in a passive solution. Here we numerically study the effect of hydrodynamics on an active-passive hybrid system, where we observe qualitative differences as compared to simulations with excluded volume effects alone. The results shed light on an existing discrepancy in pair lifetimes between simulation and experiment, due to the hydrodynamically enhanced stability of coupled passive particles.
Hydrodynamics of stratified epithelium: Steady state and linearized dynamics
Yeh, Wei-Ting; Chen, Hsuan-Yi
2016-05-01
A theoretical model for stratified epithelium is presented. The viscoelastic properties of the tissue are assumed to be dependent on the spatial distribution of proliferative and differentiated cells. Based on this assumption, a hydrodynamic description of tissue dynamics at the long-wavelength, long-time limit is developed, and the analysis reveals important insights into the dynamics of an epithelium close to its steady state. When the proliferative cells occupy a thin region close to the basal membrane, the relaxation rate towards the steady state is enhanced by cell division and cell apoptosis. On the other hand, when the region where proliferative cells reside becomes sufficiently thick, a flow induced by cell apoptosis close to the apical surface enhances small perturbations. This destabilizing mechanism is general for continuous self-renewal multilayered tissues; it could be related to the origin of certain tissue morphology, tumor growth, and the development pattern.
A theoretical study of hydrodynamic cavitation.
Arrojo, S; Benito, Y
2008-03-01
The optimization of hydrodynamic cavitation as an AOP requires identifying the key parameters and studying their effects on the process. Specific simulations of hydrodynamic bubbles reveal that time scales play a major role on the process. Rarefaction/compression periods generate a number of opposing effects which have demonstrated to be quantitatively different from those found in ultrasonic cavitation. Hydrodynamic cavitation can be upscaled and offers an energy efficient way of generating cavitation. On the other hand, the large characteristic time scales hinder bubble collapse and generate a low number of cavitation cycles per unit time. By controlling the pressure pulse through a flexible cavitation chamber design these limitations can be partially compensated. The chemical processes promoted by this technique are also different from those found in ultrasonic cavitation. Properties such as volatility or hydrophobicity determine the potential applicability of HC and therefore have to be taken into account.
Shear viscosity, cavitation and hydrodynamics at LHC
International Nuclear Information System (INIS)
Bhatt, Jitesh R.; Mishra, Hiranmaya; Sreekanth, V.
2011-01-01
We study evolution of quark-gluon matter in the ultrarelativistic heavy-ion collisions within the frame work of relativistic second-order viscous hydrodynamics. In particular, by using the various prescriptions of a temperature-dependent shear viscosity to the entropy ratio, we show that the hydrodynamic description of the relativistic fluid becomes invalid due to the phenomenon of cavitation. For most of the initial conditions relevant for LHC, the cavitation sets in very early stage. The cavitation in this case is entirely driven by the large values of shear viscosity. Moreover we also demonstrate that the conformal terms used in equations of the relativistic dissipative hydrodynamic can influence the cavitation time.
The RAGE radiation-hydrodynamic code
Energy Technology Data Exchange (ETDEWEB)
Gittings, Michael; Clover, Michael; Betlach, Thomas; Byrne, Nelson; Ranta, Dale [Science Applications International Corp. MS A-1, 10260 Campus Point Drive, San Diego, CA 92121 (United States); Weaver, Robert; Coker, Robert; Dendy, Edward; Hueckstaedt, Robert; New, Kim; Oakes, W Rob [Los Alamos National Laboratory, MS T087, PO Box 1663, Los Alamos, NM 87545 (United States); Stefan, Ryan [TaylorMade-adidas Golf, 5545 Fermi Court, Carlsbad, CA 92008-7324 (United States)], E-mail: michael.r.clover@saic.com
2008-10-01
We describe RAGE, the 'radiation adaptive grid Eulerian' radiation-hydrodynamics code, including its data structures, its parallelization strategy and performance, its hydrodynamic algorithm(s), its (gray) radiation diffusion algorithm, and some of the considerable amount of verification and validation efforts. The hydrodynamics is a basic Godunov solver, to which we have made significant improvements to increase the advection algorithm's robustness and to converge stiffnesses in the equation of state. Similarly, the radiation transport is a basic gray diffusion, but our treatment of the radiation-material coupling, wherein we converge nonlinearities in a novel manner to allow larger timesteps and more robust behavior, can be applied to any multi-group transport algorithm.
The RAGE radiation-hydrodynamic code
International Nuclear Information System (INIS)
Gittings, Michael; Clover, Michael; Betlach, Thomas; Byrne, Nelson; Ranta, Dale; Weaver, Robert; Coker, Robert; Dendy, Edward; Hueckstaedt, Robert; New, Kim; Oakes, W Rob; Stefan, Ryan
2008-01-01
We describe RAGE, the 'radiation adaptive grid Eulerian' radiation-hydrodynamics code, including its data structures, its parallelization strategy and performance, its hydrodynamic algorithm(s), its (gray) radiation diffusion algorithm, and some of the considerable amount of verification and validation efforts. The hydrodynamics is a basic Godunov solver, to which we have made significant improvements to increase the advection algorithm's robustness and to converge stiffnesses in the equation of state. Similarly, the radiation transport is a basic gray diffusion, but our treatment of the radiation-material coupling, wherein we converge nonlinearities in a novel manner to allow larger timesteps and more robust behavior, can be applied to any multi-group transport algorithm
Impact of hydrodynamic stresses on bacterial flagella
Das, Debasish; Riley, Emily; Lauga, Eric
2017-11-01
The locomotion of bacteria powered by helical filaments, such as Escherichia coli, critically involves the generation of flows and hydrodynamic stresses which lead to forces and moments balanced by the moment applied by the bacterial rotary motor (which is embedded in the cell wall) and the deformation of the short flexible hook. In this talk we use numerical computations to accurately compute these hydrodynamic stresses, to show how they critically lead to fluid-structure instabilities at the whole-cell level, and enquire if they can be used to rationalise experimental measurements of bacterial motor torques. ERC Consolidator Grant.
Hydrodynamics of quark-gluon plasmas
International Nuclear Information System (INIS)
Blaizot, J.P.
1986-06-01
This paper reviews some aspects of the hydrodynamics of quark-gluon plasmas. Various stages of ultra-relativistic heavy ion collisions are described. Several estimates of the maximum energy density expected to be achieved in these collisions are compared. Discontinuities which may be induced in the hydrodynamic flow by a phase transition are described and a convenient numerical method designed to deal with such discontinuous flows is briefly presented. Finally, the correlations between particle transverse momenta and multiplicities are analyzed and one discusses to which extent these correlations could signal the occurrence of a phase transition in heavy ion collisions
FDTD for Hydrodynamic Electron Fluid Maxwell Equations
Directory of Open Access Journals (Sweden)
Yingxue Zhao
2015-05-01
Full Text Available In this work, we develop a numerical method for solving the three dimensional hydrodynamic electron fluid Maxwell equations that describe the electron gas dynamics driven by an external electromagnetic wave excitation. Our numerical approach is based on the Finite-Difference Time-Domain (FDTD method for solving the Maxwell’s equations and an explicit central finite difference method for solving the hydrodynamic electron fluid equations containing both electron density and current equations. Numerical results show good agreement with the experiment of studying the second-harmonic generation (SHG from metallic split-ring resonator (SRR.
Modeling of laser-driven hydrodynamics experiments
di Stefano, Carlos; Doss, Forrest; Rasmus, Alex; Flippo, Kirk; Desjardins, Tiffany; Merritt, Elizabeth; Kline, John; Hager, Jon; Bradley, Paul
2017-10-01
Correct interpretation of hydrodynamics experiments driven by a laser-produced shock depends strongly on an understanding of the time-dependent effect of the irradiation conditions on the flow. In this talk, we discuss the modeling of such experiments using the RAGE radiation-hydrodynamics code. The focus is an instability experiment consisting of a period of relatively-steady shock conditions in which the Richtmyer-Meshkov process dominates, followed by a period of decaying flow conditions, in which the dominant growth process changes to Rayleigh-Taylor instability. The use of a laser model is essential for capturing the transition. also University of Michigan.
Fish stocking density impacts tank hydrodynamics
DEFF Research Database (Denmark)
Rasmussen, Michael R.; Lunger, Angela; Laursen, Jesper
2006-01-01
The effect of stocking density upon the hydrodynamics of a circular tank, configured in a recirculation system, was investigated. Red drums Sciaenops ocellatus of approximately 140 g wet weight, were stocked at five rates varying from 0 to 12 kg m-3. The impact of the presence of fish upon tank...... hydrodynamics was established using in-tank-based Rhodamine WT fluorometry at a flow rate of 0.23 l s-1 (tank exchange rate of 1.9 h-1). With increasing numbers of animals, curvilinear relationships were observed for dispersion coefficients and tank mixing times. Stocking densities of 3, 6, 9 and 12 kg m-3...
Introduction to physics mechanics, hydrodynamics thermodynamics
Frauenfelder, P
2013-01-01
Introduction of Physics: Mechanics , Hydrodynamics, Thermodynamics covers the principles of matter and its motion through space and time, as well as the related concepts of energy and force. This book is composed of eleven chapters, and begins with an introduction to the basic principles of mechanics, hydrodynamics, and thermodynamics. The subsequent chapters deal with the statics of rigid bodies and the dynamics of particles and rigid bodies. These topics are followed by discussions on elasticity, mechanics of fluids, the basic concept of thermodynamic, kinetic theory, and crystal structure o
Shadowfax: Moving mesh hydrodynamical integration code
Vandenbroucke, Bert
2016-05-01
Shadowfax simulates galaxy evolution. Written in object-oriented modular C++, it evolves a mixture of gas, subject to the laws of hydrodynamics and gravity, and any collisionless fluid only subject to gravity, such as cold dark matter or stars. For the hydrodynamical integration, it makes use of a (co-) moving Lagrangian mesh. The code has a 2D and 3D version, contains utility programs to generate initial conditions and visualize simulation snapshots, and its input/output is compatible with a number of other simulation codes, e.g. Gadget2 (ascl:0003.001) and GIZMO (ascl:1410.003).
Bagal, Manisha V; Gogate, Parag R
2014-05-01
Diclofenac sodium, a widely detected pharmaceutical drug in wastewater samples, has been selected as a model pollutant for degradation using novel combined approach of hydrodynamic cavitation and heterogeneous photocatalysis. A slit venturi has been used as cavitating device in the hydrodynamic cavitation reactor. The effect of various operating parameters such as inlet fluid pressure (2-4 bar) and initial pH of the solution (4-7.5) on the extent of degradation have been studied. The maximum extent of degradation of diclofenac sodium was obtained at inlet fluid pressure of 3 bar and initial pH as 4 using hydrodynamic cavitation alone. The loadings of TiO2 and H2O2 have been optimised to maximise the extent of degradation of diclofenac sodium. Kinetic study revealed that the degradation of diclofenac sodium fitted first order kinetics over the selected range of operating protocols. It has been observed that combination of hydrodynamic cavitation with UV, UV/TiO2 and UV/TiO2/H2O2 results in enhanced extents of degradation as compared to the individual schemes. The maximum extent of degradation as 95% with 76% reduction in TOC has been observed using hydrodynamic cavitation in conjunction with UV/TiO2/H2O2 under the optimised operating conditions. The diclofenac sodium degradation byproducts have been identified using LC/MS analysis. Copyright © 2013 Elsevier B.V. All rights reserved.
Jin, Chao; Ren, Carolyn L; Emelko, Monica B
2016-04-19
It is widely believed that media surface roughness enhances particle deposition-numerous, but inconsistent, examples of this effect have been reported. Here, a new mathematical framework describing the effects of hydrodynamics and interaction forces on particle deposition on rough spherical collectors in absence of an energy barrier was developed and validated. In addition to quantifying DLVO force, the model includes improved descriptions of flow field profiles and hydrodynamic retardation functions. This work demonstrates that hydrodynamic effects can significantly alter particle deposition relative to expectations when only the DLVO force is considered. Moreover, the combined effects of hydrodynamics and interaction forces on particle deposition on rough, spherical media are not additive, but synergistic. Notably, the developed model's particle deposition predictions are in closer agreement with experimental observations than those from current models, demonstrating the importance of inclusion of roughness impacts in particle deposition description/simulation. Consideration of hydrodynamic contributions to particle deposition may help to explain discrepancies between model-based expectations and experimental outcomes and improve descriptions of particle deposition during physicochemical filtration in systems with nonsmooth collector surfaces.
Dey, Ranabir; Raj M, Kiran; Bhandaru, Nandini; Mukherjee, Rabibrata; Chakraborty, Suman
2014-05-21
The present work comprehensively addresses the hydrodynamic characteristics through microchannels with lotus leaf replica (exhibiting low adhesion and superhydrophobic properties) walls. The lotus leaf replica is fabricated following an efficient, two-step, soft-molding process and is then integrated with rectangular microchannels. The inherent biomimetic, superhydrophobic surface-liquid interfacial hydrodynamics, and the consequential bulk flow characteristics, are critically analyzed by the micro-particle image velocimetry technique. It is observed that the lotus leaf replica mediated microscale hydrodynamics comprise of two distinct flow regimes even within the low Reynolds number paradigm, unlike the commonly perceived solely apparent slip-stick dominated flows over superhydrophobic surfaces. While the first flow regime is characterized by an apparent slip-stick flow culminating in an enhanced bulk throughput rate, the second flow regime exhibits a complete breakdown of the aforementioned laminar and uni-axial flow model, leading to a predominantly no-slip flow. Interestingly, the critical flow condition dictating the transition between the two hydrodynamic regimes is intrinsically dependent on the micro-confinement effect. In this regard, an energetically consistent theoretical model is also proposed to predict the alterations in the critical flow condition with varying microchannel configurations, by addressing the underlying biomimetic surface-liquid interfacial conditions. Hence, the present research endeavour provides a new design-guiding paradigm for developing multi-functional microfluidic devices involving biomimetic, superhydrophobic surfaces, by judicious exploitation of the tunable hydrodynamic characteristics in the two regimes.
Dynamics of zonal shear collapse with hydrodynamic electrons
Hajjar, R. J.; Diamond, P. H.; Malkov, M. A.
2018-06-01
This paper presents a theory for the collapse of the edge zonal shear layer, as observed at the density limit at low β. This paper investigates the scaling of the transport and mean profiles with the adiabaticity parameter α, with special emphasizes on fluxes relevant to zonal flow (ZF) generation. We show that the adiabaticity parameter characterizes the strength of production of zonal flows and so determines the state of turbulence. A 1D reduced model that self-consistently describes the spatiotemporal evolution of the mean density n ¯ , the azimuthal flow v¯ y , and the turbulent potential enstrophy ɛ=⟨(n˜ -∇2ϕ˜ ) 2/2 ⟩ —related to fluctuation intensity—is presented. Quasi-linear analysis determines how the particle flux Γn and vorticity flux Π=-χy∇2vy+Πre s scale with α, in both hydrodynamic and adiabatic regimes. As the plasma response passes from adiabatic (α > 1) to hydrodynamic (α y=Πre s/χy —representative of the strength of the shear—also drops. The shear layer then collapses and turbulence is enhanced. The collapse is due to a decrease in ZF production, not an increase in damping. A physical picture for the onset of collapse is presented. The findings of this paper are used to motivate an explanation of the phenomenology of low β density limit evolution. A change from adiabatic ( α=kz2vth 2/(|ω|νei)>1 ) to hydrodynamic (α < 1) electron dynamics is associated with the density limit.
Impact of Hydrodynamics on Oral Biofilm Strength
Paramonova, E.; Kalmykowa, O. J.; van der Mei, H. C.; Busscher, H. J.; Sharma, P. K.
2009-01-01
Mechanical removal of oral biofilms is ubiquitously accepted as the best way to prevent caries and periodontal diseases. Removal effectiveness strongly depends on biofilm strength. To investigate the influence of hydrodynamics on oral biofilm strength, we grew single- and multi-species biofilms of
Hydrodynamic states of phonons in insulators
Directory of Open Access Journals (Sweden)
S.A. Sokolovsky
2012-12-01
Full Text Available The Chapman-Enskog method is generalized for accounting the effect of kinetic modes on hydrodynamic evolution. Hydrodynamic states of phonon system of insulators have been studied in a small drift velocity approximation. For simplicity, the investigation was carried out for crystals of the cubic class symmetry. It has been found that in phonon hydrodynamics, local equilibrium is violated even in the approximation linear in velocity. This is due to the absence of phonon momentum conservation law that leads to a drift velocity relaxation. Phonon hydrodynamic equations which take dissipative processes into account have been obtained. The results were compared with the standard theory based on the local equilibrium validity. Integral equations have been obtained for calculating the objects of the theory (including viscosity and heat conductivity. It has been shown that in low temperature limit, these equations are solvable by iterations. Steady states of the system have been considered and an expression for steady state heat conductivity has been obtained. It coincides with the famous result by Akhiezer in the leading low temperature approximation. It has been established that temperature distribution in the steady state of insulator satisfies a condition of heat source absence.
Magneto-hydrodynamical model for plasma
Liu, Ruikuan; Yang, Jiayan
2017-10-01
Based on the Newton's second law and the Maxwell equations for the electromagnetic field, we establish a new 3-D incompressible magneto-hydrodynamics model for the motion of plasma under the standard Coulomb gauge. By using the Galerkin method, we prove the existence of a global weak solution for this new 3-D model.
Statistical analysis of hydrodynamic cavitation events
Gimenez, G.; Sommer, R.
1980-10-01
The frequency (number of events per unit time) of pressure pulses produced by hydrodynamic cavitation bubble collapses is investigated using statistical methods. The results indicate that this frequency is distributed according to a normal law, its parameters not being time-evolving.
Filter-Feeding Zoobenthos and Hydrodynamics
DEFF Research Database (Denmark)
Riisgård, Hans Ulrik; Larsen, Poul Scheel
2017-01-01
interplay between benthic filter feeders and hydrodynamics. Starting from the general concept of grazing potential and typical data on benthic population densities its realization is considered, first at the level of the individual organism through the processes of pumping and trapping of food particles...
does earthworms density really modify soil's hydrodynamic ...
African Journals Online (AJOL)
N. Ababsa,, M. Kribaa, D. Addad, L. Tamrabet and M. Baha
1 mai 2016 ... Journal of Fundamental and Applied Sciences is licensed under a Creative Commons Attribution-NonCommercial 4.0. International License. Libraries Resource Directory. We are listed under Research Associations category. DOES EARTHWORMS DENSITY REALLY MODIFY SOIL'S HYDRODYNAMIC.
PHANTOM: Smoothed particle hydrodynamics and magnetohydrodynamics code
Price, Daniel J.; Wurster, James; Nixon, Chris; Tricco, Terrence S.; Toupin, Stéven; Pettitt, Alex; Chan, Conrad; Laibe, Guillaume; Glover, Simon; Dobbs, Clare; Nealon, Rebecca; Liptai, David; Worpel, Hauke; Bonnerot, Clément; Dipierro, Giovanni; Ragusa, Enrico; Federrath, Christoph; Iaconi, Roberto; Reichardt, Thomas; Forgan, Duncan; Hutchison, Mark; Constantino, Thomas; Ayliffe, Ben; Mentiplay, Daniel; Hirsh, Kieran; Lodato, Giuseppe
2017-09-01
Phantom is a smoothed particle hydrodynamics and magnetohydrodynamics code focused on stellar, galactic, planetary, and high energy astrophysics. It is modular, and handles sink particles, self-gravity, two fluid and one fluid dust, ISM chemistry and cooling, physical viscosity, non-ideal MHD, and more. Its modular structure makes it easy to add new physics to the code.
Microflow Cytometers with Integrated Hydrodynamic Focusing
Directory of Open Access Journals (Sweden)
Martin Schmidt
2013-04-01
Full Text Available This study demonstrates the suitability of microfluidic structures for high throughput blood cell analysis. The microfluidic chips exploit fully integrated hydrodynamic focusing based on two different concepts: Two-stage cascade focusing and spin focusing (vortex principle. The sample—A suspension of micro particles or blood cells—is injected into a sheath fluid streaming at a substantially higher flow rate, which assures positioning of the particles in the center of the flow channel. Particle velocities of a few m/s are achieved as required for high throughput blood cell analysis. The stability of hydrodynamic particle positioning was evaluated by measuring the pulse heights distributions of fluorescence signals from calibration beads. Quantitative assessment based on coefficient of variation for the fluorescence intensity distributions resulted in a value of about 3% determined for the micro-device exploiting cascade hydrodynamic focusing. For the spin focusing approach similar values were achieved for sample flow rates being 1.5 times lower. Our results indicate that the performances of both variants of hydrodynamic focusing suit for blood cell differentiation and counting. The potential of the micro flow cytometer is demonstrated by detecting immunologically labeled CD3 positive and CD4 positive T-lymphocytes in blood.
Numerical methods for hydrodynamic stability problems
International Nuclear Information System (INIS)
Fujimura, Kaoru
1985-11-01
Numerical methods for solving the Orr-Sommerfeld equation, which is the fundamental equation of the hydrodynamic stability theory for various shear flows, are reviewed and typical numerical results are presented. The methods of asymptotic solution, finite difference methods, initial value methods and expansions in orthogonal functions are compared. (author)
Hydrodynamic relaxations in dissipative particle dynamics
Hansen, J. S.; Greenfield, Michael L.; Dyre, Jeppe C.
2018-01-01
This paper studies the dynamics of relaxation phenomena in the standard dissipative particle dynamics (DPD) model [R. D. Groot and P. B. Warren, J. Chem. Phys. 107, 4423 (1997)]. Using fluctuating hydrodynamics as the framework of the investigation, we focus on the collective transverse and longitudinal dynamics. It is shown that classical hydrodynamic theory predicts the transverse dynamics at relatively low temperatures very well when compared to simulation data; however, the theory predictions are, on the same length scale, less accurate for higher temperatures. The agreement with hydrodynamics depends on the definition of the viscosity, and here we find that the transverse dynamics are independent of the dissipative and random shear force contributions to the stress. For high temperatures, the spectrum for the longitudinal dynamics is dominated by the Brillouin peak for large length scales and the relaxation is therefore governed by sound wave propagation and is athermal. This contrasts the results at lower temperatures and small length scale, where the thermal process is clearly present in the spectra. The DPD model, at least qualitatively, re-captures the underlying hydrodynamical mechanisms, and quantitative agreement is excellent at intermediate temperatures for the transverse dynamics.
Hydrodynamic dispersion of microswimmers in suspension
Martin, Matthieu; Rafaï, Salima; Peyla, Philippe
2014-11-01
In our laboratory, we study hydrodynamics of suspensions of micro-swimmers. These micro-organisms are unicellular algae Chlamydomonas Rheinhardii which are able to swim by using their flagella. The swimming dynamics of these micro-swimmers can be seen as a random walk, in absence of any kind of interaction. In addition, these algae have the property of being phototactic, i.e. they swim towards the light. Combining this property with a hydrodynamic flow, we were able to reversibly separate algae from the rest of the fluid. But for sufficiently high volume fraction, these active particles interact with each other. We are now interested in how the coupling of hydrodynamic interactions between swimmers and phototaxis can modify the swimming dynamics at the scale of the suspension. To this aim, we conduct experiments in microfluidic devices to study the dispersion of the micro-organisms in a the liquid phase as a function of the volume fraction. We show that the dispersion of an assembly of puller type microswimmers is quantitatively affected by hydrodynamics interactions. Phd student.
Hydrodynamic modelling of hydrostatic magnesium extrusion
Moodij, Ellen; de Rooij, Matthias B.; Schipper, Dirk J.
2006-01-01
Wilson’s hydrodynamic model of the hydrostatic extrusion process is extended to meet the geometry found on residual billets. The transition from inlet to work zone of the process is not considered sharp as in the model of Wilson but as a rounded edge, modelled by a parabolic function. It is shown
Hydrodynamic forces on inundated bridge decks
2009-05-01
The hydrodynamic forces experienced by an inundated bridge deck have great importance in the design of bridges. Specifically, the drag force, lift force, and the moment acting on the bridge deck under various levels of inundation and a range of flow ...
The quantum hydrodynamics of the Sutherland model
International Nuclear Information System (INIS)
Stone, Michael; Gutman, Dmitry
2008-01-01
We show that the form of the chiral condition found by Abanov et al in the quantum hydrodynamics of the Sutherland model arises because there are two distinct inner products with respect to which the chiral Hamiltonian is Hermitian, but only one with respect to which the full, non-chiral, Hamiltonian is Hermitian
Hydrodynamic impact response, a flexible view
Vredeveldt, A.W.; Hoogeland, M.; Janssen, G.Th.M.
2001-01-01
The popularity of high-speed craft is steadily increasing. Until now, much attention has been focussed on the hydrodynamic aspects of these craft. The structural design of these vessels is usually considered in a quasi static sense. However, due to the requirement of light ship structures, fast ship
Universal hydrodynamics of non-conformal branes
International Nuclear Information System (INIS)
Kanitscheider, Ingmar; Skenderis, Kostas
2009-01-01
We examine the hydrodynamic limit of non-conformal branes using the recently developed precise holographic dictionary. We first streamline the discussion of holography for backgrounds that asymptote locally to non-conformal brane solutions by showing that all such solutions can be obtained from higher dimensional asymptotically locally AdS solutions by suitable dimensional reduction and continuation in the dimension. As a consequence, many holographic results for such backgrounds follow from the corresponding results of the Asymptotically AdS case. In particular, the hydrodynamics of non-conformal branes is fully determined in terms of conformal hydrodynamics. Using previous results on the latter we predict the form of the non-conformal hydrodynamic stress tensor to second order in derivatives. Furthermore we show that the ratio between bulk and shear viscosity is fixed by the generalized conformal structure to be ζ/η = 2(1/(d-1)-c s 2 ), where c s is the speed of sound in the fluid.
Detailed simulation of morphodynamics : 1. Hydrodynamic model
Nabi, M.; De Vriend, H.J.; Mosselman, E.; Sloff, C.J.; Shimizu, Y.
2012-01-01
We present a three-dimensional high-resolution hydrodynamic model for unsteady incompressible flow over an evolving bed topography. This is achieved by using a multilevel Cartesian grid technique that allows the grid to be refined in high-gradient regions and in the vicinity of the river bed. The
Radiation hydrodynamical instabilities in cosmological and galactic ionization fronts
Whalen, Daniel J.; Norman, Michael L.
2011-11-01
Ionization fronts, the sharp radiation fronts behind which H/He ionizing photons from massive stars and galaxies propagate through space, were ubiquitous in the universe from its earliest times. The cosmic dark ages ended with the formation of the first primeval stars and galaxies a few hundred Myr after the Big Bang. Numerical simulations suggest that stars in this era were very massive, 25-500 solar masses, with H(II) regions of up to 30,000 light-years in diameter. We present three-dimensional radiation hydrodynamical calculations that reveal that the I-fronts of the first stars and galaxies were prone to violent instabilities, enhancing the escape of UV photons into the early intergalactic medium (IGM) and forming clumpy media in which supernovae later exploded. The enrichment of such clumps with metals by the first supernovae may have led to the prompt formation of a second generation of low-mass stars, profoundly transforming the nature of the first protogalaxies. Cosmological radiation hydrodynamics is unique because ionizing photons coupled strongly to both gas flows and primordial chemistry at early epochs, introducing a hierarchy of disparate characteristic timescales whose relative magnitudes can vary greatly throughout a given calculation. We describe the adaptive multistep integration scheme we have developed for the self-consistent transport of both cosmological and galactic ionization fronts.
A hydrodynamically active flipper-stroke in humpback whales.
Segre, Paolo S; Seakamela, S Mduduzi; Meÿer, Michael A; Findlay, Ken P; Goldbogen, Jeremy A
2017-07-10
A central paradigm of aquatic locomotion is that cetaceans use fluke strokes to power their swimming while relying on lift and torque generated by the flippers to perform maneuvers such as rolls, pitch changes and turns [1]. Compared to other cetaceans, humpback whales (Megaptera novaeangliae) have disproportionately large flippers with added structural features to aid in hydrodynamic performance [2,3]. Humpbacks use acrobatic lunging maneuvers to attack dense aggregations of krill or small fish, and their large flippers are thought to increase their maneuverability and thus their ability to capture prey. Immediately before opening their mouths, humpbacks will often rapidly move their flippers, and it has been hypothesized that this movement is used to corral prey [4,5] or to generate an upward pitching moment to counteract the torque caused by rapid water engulfment [6]. Here, we demonstrate an additional function for the rapid flipper movement during lunge feeding: the flippers are flapped using a complex, hydrodynamically active stroke to generate lift and increase propulsive thrust. We estimate that humpback flipper-strokes are capable of producing large forward oriented forces, which may be used to enhance lunge feeding performance. This behavior is the first observation of a lift-generating flipper-stroke for propulsion cetaceans and provides an additional function for the uniquely shaped humpback whale flipper. Copyright © 2017 Elsevier Ltd. All rights reserved.
Enhancing of optic phonon contribution in hydrodynamic phonon transport
de Tomas, C.; Cantarero, A.; Lopeandia, A. F.; Alvarez, F. X.
2015-10-01
In the framework of the kinetic-collective model of phonon heat transport, we analyze how each range of the phonon frequency spectrum contributes to the total thermal conductivity both in the macro and the nanoscale. For this purpose, we use two case study samples: naturally occurring bulk silicon and a 115 nm of diameter silicon nanowire. We show that the contribution of high-energy phonons (optic branches) is non-negligible only when N-collisions are strongly present. This contribution increases when the effective size of the sample decreases, and it is found to be up to a 10% at room temperature for the 115 nm nanowire, corroborating preliminar ab-initio predictions.
Hydrodynamic Energy Saving Enhancements for DDG 51 Class Ships
2012-02-01
temperature and pressure in the hydraulic pitch control system, expansion and contraction of the pitch control rods, improper pitch calibration procedure ...outdated pitch calibration, etc. Experience during hot pitch calibration procedures conducted by NSWCCD prior to powering trials has indicated that...18% increase in power.10 Sea trials conducted during a long-term evaluation on the USS WHIPPLE (FF 1062), showed that by 800 days out of drydock
Doyon, Benjamin; Dubail, Jérôme; Konik, Robert; Yoshimura, Takato
2017-11-01
The theory of generalized hydrodynamics (GHD) was recently developed as a new tool for the study of inhomogeneous time evolution in many-body interacting systems with infinitely many conserved charges. In this Letter, we show that it supersedes the widely used conventional hydrodynamics (CHD) of one-dimensional Bose gases. We illustrate this by studying "nonlinear sound waves" emanating from initial density accumulations in the Lieb-Liniger model. We show that, at zero temperature and in the absence of shocks, GHD reduces to CHD, thus for the first time justifying its use from purely hydrodynamic principles. We show that sharp profiles, which appear in finite times in CHD, immediately dissolve into a higher hierarchy of reductions of GHD, with no sustained shock. CHD thereon fails to capture the correct hydrodynamics. We establish the correct hydrodynamic equations, which are finite-dimensional reductions of GHD characterized by multiple, disjoint Fermi seas. We further verify that at nonzero temperature, CHD fails at all nonzero times. Finally, we numerically confirm the emergence of hydrodynamics at zero temperature by comparing its predictions with a full quantum simulation performed using the NRG-TSA-abacus algorithm. The analysis is performed in the full interaction range, and is not restricted to either weak- or strong-repulsion regimes.
Hydrodynamic schooling of flapping swimmers
International Nuclear Information System (INIS)
Becker, Alexander D.; Masoud, Hassan; Newbolt, Joel W.; Shelley, Michael; Ristroph, Leif
2015-01-01
Fish schools and bird flocks are fascinating examples of collective behaviours in which many individuals generate and interact with complex flows. Motivated by animal groups on the move, here we explore how the locomotion of many bodies emerges from their flow-mediated interactions. Through experiments and simulations of arrays of flapping wings that propel within a collective wake, we discover distinct modes characterized by the group swimming speed and the spatial phase shift between trajectories of neighbouring wings. For identical flapping motions, slow and fast modes coexist and correspond to constructive and destructive wing-wake interactions. Simulations show that swimming in a group can enhance speed and save power, and we capture the key phenomena in a mathematical model based on memory or the storage and recollection of information in the flow field. Lastly, these results also show that fluid dynamic interactions alone are sufficient to generate coherent collective locomotion, and thus might suggest new ways to characterize the role of flows in animal groups
Hydrodynamic schooling of flapping swimmers
Becker, Alexander D.; Masoud, Hassan; Newbolt, Joel W.; Shelley, Michael; Ristroph, Leif
2015-10-01
Fish schools and bird flocks are fascinating examples of collective behaviours in which many individuals generate and interact with complex flows. Motivated by animal groups on the move, here we explore how the locomotion of many bodies emerges from their flow-mediated interactions. Through experiments and simulations of arrays of flapping wings that propel within a collective wake, we discover distinct modes characterized by the group swimming speed and the spatial phase shift between trajectories of neighbouring wings. For identical flapping motions, slow and fast modes coexist and correspond to constructive and destructive wing-wake interactions. Simulations show that swimming in a group can enhance speed and save power, and we capture the key phenomena in a mathematical model based on memory or the storage and recollection of information in the flow field. These results also show that fluid dynamic interactions alone are sufficient to generate coherent collective locomotion, and thus might suggest new ways to characterize the role of flows in animal groups.
Numerical modelling of extreme waves by Smoothed Particle Hydrodynamics
Directory of Open Access Journals (Sweden)
M. H. Dao
2011-02-01
Full Text Available The impact of extreme/rogue waves can lead to serious damage of vessels as well as marine and coastal structures. Such extreme waves in deep water are characterized by steep wave fronts and an energetic wave crest. The process of wave breaking is highly complex and, apart from the general knowledge that impact loadings are highly impulsive, the dynamics of the breaking and impact are still poorly understood. Using an advanced numerical method, the Smoothed Particle Hydrodynamics enhanced with parallel computing is able to reproduce well the extreme waves and their breaking process. Once the waves and their breaking process are modelled successfully, the dynamics of the breaking and the characteristics of their impact on offshore structures could be studied. The computational methodology and numerical results are presented in this paper.
Modelling hydrodynamic parameters to predict flow assisted corrosion
International Nuclear Information System (INIS)
Poulson, B.; Greenwell, B.; Chexal, B.; Horowitz, J.
1992-01-01
During the past 15 years, flow assisted corrosion has been a worldwide problem in the power generating industry. The phenomena is complex and depends on environment, material composition, and hydrodynamic factors. Recently, modeling of flow assisted corrosion has become a subject of great importance. A key part of this effort is modeling the hydrodynamic aspects of this issue. This paper examines which hydrodynamic parameter should be used to correlate the occurrence and rate of flow assisted corrosion with physically meaningful parameters, discusses ways of measuring the relevant hydrodynamic parameter, and describes how the hydrodynamic data is incorporated into the predictive model
Hydrodynamic Cavitation-Assisted Synthesis of Nanocalcite
Directory of Open Access Journals (Sweden)
Shirish H. Sonawane
2010-01-01
Full Text Available A systematic study was made on the synthesis of nanocalcite using a hydrodynamic cavitation reactor. The effects of various parameters such as diameter and geometry of orifice, CO2 flow rate, and Ca(OH2 concentration were investigated. It was observed that the orifice diameter and its geometry had significant effect on the carbonation process. The reaction rate was significantly faster than that observed in a conventional carbonation process. The particle size was significantly affected by the reactor geometry. The results showed that an orifice with 5 holes of 1 mm size resulted in the particle size reduction to 37 nm. The experimental investigation reveals that hydrodynamic cavitation may be more energy efficient.
Application of hydrodynamics to heavy ion collisions
Energy Technology Data Exchange (ETDEWEB)
Felsberger, Lukas
2014-12-02
The Bjorken model is a simple tool for making rough predictions of the hydrodynamic evolution of the thermalized matter created in a heavy ion collision. The advantage of the model clearly lies in its simplicity, rather than accuracy. As it is still used for making rough estimations 'by hand', in this thesis, I investigate in which cases the Bjorken model gives useful results and in which it is not recommended. For central collisions, I show which critical size the nuclei should have so that the Bjorken model can be applied. For non-central collisions, I demonstrate that using Glauber initial conditions combined with the Bjorken evolution, leads to reasonable results up to large impact parameters. Finally, I study the case of a non-ideal (viscous) description of the thermalized matter which leads to strongly differing results if first- or second-order hydrodynamics is applied.
Hyperbolic metamaterial lens with hydrodynamic nonlocal response
DEFF Research Database (Denmark)
Yan, Wei; Mortensen, N. Asger; Wubs, Martijn
2013-01-01
We investigate the effects of hydrodynamic nonlocal response in hyperbolic metamaterials (HMMs), focusing on the experimentally realizable parameter regime where unit cells are much smaller than an optical wavelength but much larger than the wavelengths of the longitudinal pressure waves...... of the free-electron plasma in the metal constituents. We derive the nonlocal corrections to the effective material parameters analytically, and illustrate the noticeable nonlocal effects on the dispersion curves numerically. As an application, we find that the focusing characteristics of a HMM lens...... in the local-response approximation and in the hydrodynamic Drude model can differ considerably. In particular, the optimal frequency for imaging in the nonlocal theory is blueshifted with respect to that in the local theory. Thus, to detect whether nonlocal response is at work in a hyperbolic metamaterial, we...
Application of hydrodynamics to heavy ion collisions
International Nuclear Information System (INIS)
Felsberger, Lukas
2014-01-01
The Bjorken model is a simple tool for making rough predictions of the hydrodynamic evolution of the thermalized matter created in a heavy ion collision. The advantage of the model clearly lies in its simplicity, rather than accuracy. As it is still used for making rough estimations 'by hand', in this thesis, I investigate in which cases the Bjorken model gives useful results and in which it is not recommended. For central collisions, I show which critical size the nuclei should have so that the Bjorken model can be applied. For non-central collisions, I demonstrate that using Glauber initial conditions combined with the Bjorken evolution, leads to reasonable results up to large impact parameters. Finally, I study the case of a non-ideal (viscous) description of the thermalized matter which leads to strongly differing results if first- or second-order hydrodynamics is applied.
Hydrodynamic interaction between bacteria and passive sphere
Zhang, Bokai; Ding, Yang; Xu, Xinliang
2017-11-01
Understanding hydrodynamic interaction between bacteria and passive sphere is important for identifying rheological properties of bacterial and colloidal suspension. Over the past few years, scientists mainly focused on bacterial influences on tracer particle diffusion or hydrodynamic capture of a bacteria around stationary boundary. Here, we use superposition of singularities and regularized method to study changes in bacterial swimming velocity and passive sphere diffusion, simultaneously. On this basis, we present a simple two-bead model that gives a unified interpretation of passive sphere diffusion and bacterial swimming. The model attributes both variation of passive sphere diffusion and changes of speed of bacteria to an effective mobility. Using the effective mobility of bacterial head and tail as an input function, the calculations are consistent with simulation results at a broad range of tracer diameters, incident angles and bacterial shapes.
Granular Gases: Probing the Boundaries of Hydrodynamics
International Nuclear Information System (INIS)
Goldhirsch, I.
1999-01-01
The dissipative nature of the particle interactions in granular systems renders granular gases mesoscopic and bearing some similarities to regular gases in the ''continuum transition regime'' where shear rates and/or thermal gradients are very large). The following properties of granular gases support the above claim: (i). Mean free times are of the same order as macroscopic time scales (inverse shear rates); (ii). Mean free paths can be macroscopic and comparable to the system's dimensions; (iii). Typical flows are supersonic; (iv). Shear rates are typically ''large''; (v). Stress fields are scale (resolution) dependent; (vi). Burnett and super-Burnett corrections to both the constitutive relations and the boundary conditions are of importance; (vii). Single particle distribution functions can be far from Gaussian. It is concluded that while hydrodynamic descriptions of granular gases are relevant, they are probing the boundaries of applicability of hydrodynamics and perhaps slightly beyond
The role of Weyl symmetry in hydrodynamics
Diles, Saulo
2018-04-01
This article is dedicated to the analysis of Weyl symmetry in the context of relativistic hydrodynamics. Here is discussed how this symmetry is properly implemented using the prescription of minimal coupling: ∂ → ∂ + ωA. It is shown that this prescription has no problem to deal with curvature since it gives the correct expressions for the commutator of covariant derivatives. In hydrodynamics, Weyl gauge connection emerges from the degrees of freedom of the fluid: it is a combination of the expansion and entropy gradient. The remaining degrees of freedom, shear, vorticity and the metric tensor, are see in this context as charged fields under the Weyl gauge connection. The gauge nature of the connection provides natural dynamics to it via equations of motion analogous to the Maxwell equations for electromagnetism. As a consequence, a charge for the Weyl connection is defined and the notion of local charge is analyzed generating the conservation law for the Weyl charge.
Heat capacity of liquids: A hydrodynamic approach
Directory of Open Access Journals (Sweden)
T. Bryk
2015-03-01
Full Text Available We study autocorrelation functions of energy, heat and entropy densities obtained by molecular dynamics simulations of supercritical Ar and compare them with the predictions of the hydrodynamic theory. It is shown that the predicted by the hydrodynamic theory single-exponential shape of the entropy density autocorrelation functions is perfectly reproduced for small wave numbers by the molecular dynamics simulations and permits the calculation of the wavenumber-dependent specific heat at constant pressure. The estimated wavenumber-dependent specific heats at constant volume and pressure, Cv(k and Cp(k, are shown to be in the long-wavelength limit in good agreement with the macroscopic experimental values of Cv and Cp for the studied thermodynamic points of supercritical Ar.
Hydrodynamics of ultra-relativistic bubble walls
Directory of Open Access Journals (Sweden)
Leonardo Leitao
2016-04-01
Full Text Available In cosmological first-order phase transitions, gravitational waves are generated by the collisions of bubble walls and by the bulk motions caused in the fluid. A sizeable signal may result from fast-moving walls. In this work we study the hydrodynamics associated to the fastest propagation modes, namely, ultra-relativistic detonations and runaway solutions. We compute the energy injected by the phase transition into the fluid and the energy which accumulates in the bubble walls. We provide analytic approximations and fits as functions of the net force acting on the wall, which can be readily evaluated for specific models. We also study the back-reaction of hydrodynamics on the wall motion, and we discuss the extrapolation of the friction force away from the ultra-relativistic limit. We use these results to estimate the gravitational wave signal from detonations and runaway walls.
Hydrodynamics of ultra-relativistic bubble walls
Energy Technology Data Exchange (ETDEWEB)
Leitao, Leonardo, E-mail: lleitao@mdp.edu.ar; Mégevand, Ariel, E-mail: megevand@mdp.edu.ar
2016-04-15
In cosmological first-order phase transitions, gravitational waves are generated by the collisions of bubble walls and by the bulk motions caused in the fluid. A sizeable signal may result from fast-moving walls. In this work we study the hydrodynamics associated to the fastest propagation modes, namely, ultra-relativistic detonations and runaway solutions. We compute the energy injected by the phase transition into the fluid and the energy which accumulates in the bubble walls. We provide analytic approximations and fits as functions of the net force acting on the wall, which can be readily evaluated for specific models. We also study the back-reaction of hydrodynamics on the wall motion, and we discuss the extrapolation of the friction force away from the ultra-relativistic limit. We use these results to estimate the gravitational wave signal from detonations and runaway walls.
Hyperbolic metamaterial lens with hydrodynamic nonlocal response.
Yan, Wei; Mortensen, N Asger; Wubs, Martijn
2013-06-17
We investigate the effects of hydrodynamic nonlocal response in hyperbolic metamaterials (HMMs), focusing on the experimentally realizable parameter regime where unit cells are much smaller than an optical wavelength but much larger than the wavelengths of the longitudinal pressure waves of the free-electron plasma in the metal constituents. We derive the nonlocal corrections to the effective material parameters analytically, and illustrate the noticeable nonlocal effects on the dispersion curves numerically. As an application, we find that the focusing characteristics of a HMM lens in the local-response approximation and in the hydrodynamic Drude model can differ considerably. In particular, the optimal frequency for imaging in the nonlocal theory is blueshifted with respect to that in the local theory. Thus, to detect whether nonlocal response is at work in a hyperbolic metamaterial, we propose to measure the near-field distribution of a hyperbolic metamaterial lens.
Smoothed Particle Hydrodynamics Coupled with Radiation Transfer
Susa, Hajime
2006-04-01
We have constructed a brand-new radiation hydrodynamics solver based upon Smoothed Particle Hydrodynamics, which works on a parallel computer system. The code is designed to investigate the formation and evolution of first-generation objects at z ≳ 10, where the radiative feedback from various sources plays important roles. The code can compute the fraction of chemical species e, H+, H, H-, H2, and H+2 by by fully implicit time integration. It also can deal with multiple sources of ionizing radiation, as well as radiation at Lyman-Werner band. We compare the results for a few test calculations with the results of one-dimensional simulations, in which we find good agreements with each other. We also evaluate the speedup by parallelization, which is found to be almost ideal, as long as the number of sources is comparable to the number of processors.
Transversal expansion study in the Landau hydrodynamic
International Nuclear Information System (INIS)
Pottag, F.W.
1984-01-01
The system of equations in the frame of Landau's hydrodynamical model for multiparticle production at high energies is studied. Taking as a first approximation the one-dimensional exact due to Khalatnikov, and a special set of curvilinear coordinates, the radial part is separated from the longitudinal one in the equations of motion, and a system of partial differential equations (non-linear, hyperbolic) is obtained for the radial part. These equations are solved numerically by the method of caracteristics. The hydrodynamical variables are obtained over all the three-dimensional-flow region as well as its variation with the mass of the initially expanding system. Both, the transverse rapidity distribution of the fluid and the inclusive particle distribution at 90 0 in the center of mass system, are calculated. The last one is compared with recent experimental data. (author) [pt
Numerical Hydrodynamics and Magnetohydrodynamics in General Relativity
Directory of Open Access Journals (Sweden)
Font José A.
2008-09-01
Full Text Available This article presents a comprehensive overview of numerical hydrodynamics and magnetohydrodynamics (MHD in general relativity. Some significant additions have been incorporated with respect to the previous two versions of this review (2000, 2003, most notably the coverage of general-relativistic MHD, a field in which remarkable activity and progress has occurred in the last few years. Correspondingly, the discussion of astrophysical simulations in general-relativistic hydrodynamics is enlarged to account for recent relevant advances, while those dealing with general-relativistic MHD are amply covered in this review for the first time. The basic outline of this article is nevertheless similar to its earlier versions, save for the addition of MHD-related issues throughout. Hence, different formulations of both the hydrodynamics and MHD equations are presented, with special mention of conservative and hyperbolic formulations well adapted to advanced numerical methods. A large sample of numerical approaches for solving such hyperbolic systems of equations is discussed, paying particular attention to solution procedures based on schemes exploiting the characteristic structure of the equations through linearized Riemann solvers. As previously stated, a comprehensive summary of astrophysical simulations in strong gravitational fields is also presented. These are detailed in three basic sections, namely gravitational collapse, black-hole accretion, and neutron-star evolutions; despite the boundaries, these sections may (and in fact do overlap throughout the discussion. The material contained in these sections highlights the numerical challenges of various representative simulations. It also follows, to some extent, the chronological development of the field, concerning advances in the formulation of the gravitational field, hydrodynamics and MHD equations and the numerical methodology designed to solve them. To keep the length of this article reasonable
On an incompressible model in radiation hydrodynamics
Czech Academy of Sciences Publication Activity Database
Ducomet, B.; Nečasová, Šárka
2015-01-01
Roč. 38, č. 4 (2015), s. 765-774 ISSN 0170-4214 R&D Projects: GA ČR GA13-00522S Institutional support: RVO:67985840 Keywords : radiation hydrodynamics * incompressible Navier-Stokes-Fourier system * weak solution Subject RIV: BA - General Mathematics Impact factor: 1.002, year: 2015 http://onlinelibrary.wiley.com/doi/10.1002/mma.3107/abstract
Relativistic charged fluids: hydrodynamic and kinetic approaches
International Nuclear Information System (INIS)
Debbasch, F.; Bonnaud, G.
1991-10-01
This report gives a rigorous and consistent hydrodynamic and kinetic description of a charged fluid and the basis equations, in a relativistic context. This study should lead to a reliable model, as much analytical as numerical, of relativistic plasmas which will appear in the interaction of a strong laser field with a plasma. For simplicity, we limited our study to a perfect fluid or, in other words, we disregarded the energy dissipation processes inside the fluid [fr
Resolution of hydrodynamical equations for transverse expansions
International Nuclear Information System (INIS)
Hama, Y.; Pottag, F.W.
1984-01-01
The three-dimensional hydrodynamical expansion is treated with a method similar to that of Milekhin, but more explicit. Although in the final stage one have to appeal to numerical calculation, the partial differential equations governing the transverse expansions are treated without transforming them into ordinary equations with an introduction of averaged quantities. It is only concerned with the formalism and the numerical results will be given in the next paper. (Author) [pt
Viscosity effect in Landau's hydrodynamical model
International Nuclear Information System (INIS)
Hoang, T.F.; Phua, K.K.; Nanyang Univ., Singapore
1979-01-01
The Bose-Einstein distribution is used to investigate Landau's hydrodynamical model with viscosity. In case the viscosity dependence on the temperature is T 3 , the correction to the multiplicity behaves like I/E and is found to be negligible for the pp data. A discussion is presented on a possibility of reconciling E 1 / 2 and logE dependence of the multiplicity law. (orig.)
On the convexity of relativistic hydrodynamics
International Nuclear Information System (INIS)
Ibáñez, José M; Martí, José M; Cordero-Carrión, Isabel; Miralles, Juan A
2013-01-01
The relativistic hydrodynamic system of equations for a perfect fluid obeying a causal equation of state is hyperbolic (Anile 1989 Relativistic Fluids and Magneto-Fluids (Cambridge: Cambridge University Press)). In this report, we derive the conditions for this system to be convex in terms of the fundamental derivative of the equation of state (Menikoff and Plohr1989 Rev. Mod. Phys. 61 75). The classical limit is recovered. Communicated by L Rezzolla (note)
Determining the hydrodynamic indices of contractions
International Nuclear Information System (INIS)
Blagov, Eh.E.
2002-01-01
The new dependences, making it possible only by measuring the flow rate and pressure drop on the contraction device (CD) with the known geometry, including the regulatory organ, in the non-crisis mode of the turbulent flow to calculate all the hydrodynamic indices of this device, including the pressure reduction in the jet contraction, are obtained. This simplifies and accelerates the CD hydraulic tests of all types. The new methodology for determining the cavitation factual start on the CD is proposed [ru
Towards granular hydrodynamics in two dimensions
International Nuclear Information System (INIS)
Grossman, E.L.; Zhou, T.; Ben-Naim, E.; Ben-Naim, E.
1997-01-01
We study steady-state properties of inelastic gases in two dimensions in the presence of an energy source. We generalize previous hydrodynamic treatments to situations where high and low density regions coexist. The theoretical predictions compare well with numerical simulations in the nearly elastic limit. It is also seen that the system can achieve a nonequilibrium steady state with asymmetric velocity distributions, and we discuss the conditions under which such situations occur. copyright 1997 The American Physical Society
Stochastic Hydrodynamic Synchronization in Rotating Energy Landscapes
Koumakis, N.; Di Leonardo, R.
2013-01-01
Hydrodynamic synchronization provides a general mechanism for the spontaneous emergence of coherent beating states in independently driven mesoscopic oscillators. A complete physical picture of those phenomena is of definite importance to the understanding of biological cooperative motions of cilia and flagella. Moreover, it can potentially suggest novel routes to exploit synchronization in technological applications of soft matter. We demonstrate that driving colloidal particles in rotating ...
Hyperbolic metamaterial lens with hydrodynamic nonlocal response
Yan, Wei; Mortensen, N. Asger; Wubs, Martijn
2013-01-01
We investigate the effects of hydrodynamic nonlocal response in hyperbolic metamaterials (HMMs), focusing on the experimentally realizable parameter regime where unit cells are much smaller than an optical wavelength but much larger than the wavelengths of the longitudinal pressure waves of the free-electron plasma in the metal constituents. We derive the nonlocal corrections to the effective material parameters analytically, and illustrate the noticeable nonlocal effects on the dispersion cu...
Hydrodynamic attraction of swimming microorganisms by surfaces
Berke, Allison P.; Turner, Linda; Berg, Howard C.; Lauga, Eric
2008-01-01
Cells swimming in confined environments are attracted by surfaces. We measure the steady-state distribution of smooth-swimming bacteria (Escherichia coli) between two glass plates. In agreement with earlier studies, we find a strong increase of the cell concentration at the boundaries. We demonstrate theoretically that hydrodynamic interactions of the swimming cells with solid surfaces lead to their re-orientation in the direction parallel to the surfaces, as well as their attraction by the c...
Resolution of hydrodynamical equations for transverse expansions
International Nuclear Information System (INIS)
Hama, Y.; Pottag, F.W.
1985-01-01
The three-dimensional hydrodynamical expansion is treated with a method similar to that of Milekhin, but more explicit. Although in the final stage we have to appeal to numerical calculation, the partial differential equations governing the transverse expansions are treated without transforming them into ordinary equations with an introduction of averaged quantities. The present paper is concerned with the formalism and the numerical results will be reported in another paper. (Author) [pt
Hydrodynamic Modeling of Santa Marta's Big Marsh
International Nuclear Information System (INIS)
Saldarriaga, Juan
1991-01-01
The ecological degradation of Santa Marta's Big Marsh and their next areas it has motivated the realization of diagnosis studies and design by several state and private entities. One of the recommended efforts for international advisory it was to develop an ecological model that allowed the handling of the water body and the economic test of alternative of solution to those ecological problems. The first part of a model of this type is in turn a model that simulates the movement of the water inside the marsh, that is to say, a hydrodynamic model. The realization of this was taken charge to the civil engineering department, on the part of Colciencias. This article contains a general explanation of the hydrodynamic pattern that this being developed by a professors group. The ecological causes are described and antecedent, the parts that conform the complex of the Santa Marta big Marsh The marsh modeling is made and it is explained in qualitative form the model type Hydrodynamic used
Hydrodynamic model research in Waseda group
International Nuclear Information System (INIS)
Muroya, Shin
2010-01-01
Constructing 'High Energy Material Science' had been proposed by Namiki as the guiding principle for the scientists of the high energy physics group lead by himself in Waseda University when the author started to study multiple particle production in 1980s toward the semi-phenomenological model for the quark gluon plasma (QGP). Their strategy was based on three stages to build an intermediate one between the fundamental theory of QCD and the phenomenological model. The quantum theoretical Langevin equation was taken up as the semi-phenomenological model at the intermediate stage and the Landau hydrodynamic model was chosen as the phenomenological model to focus on the 'phase transition' of QGP. A review is given here over the quantum theoretical Langevin equation formalism developed there and followed by the further progress with the 1+1 dimensional viscous fluid model as well as the hydrodynamic model with cylindrical symmetry. The developments of the baryon fluid model and Hanbury-Brown Twiss effect are also reviewed. After 1995 younger generation physicists came to the group to develop those models further. Activities by Hirano, Nonaka and Morita beyond the past generation's hydrodynamic model are picked up briefly. (S. Funahashi)
Towards the concept of hydrodynamic cavitation control
Chatterjee, Dhiman; Arakeri, Vijay H.
1997-02-01
A careful study of the existing literature available in the field of cavitation reveals the potential of ultrasonics as a tool for controlling and, if possible, eliminating certain types of hydrodynamic cavitation through the manipulation of nuclei size present in a flow. A glass venturi is taken to be an ideal device to study the cavitation phenomenon at its throat and its potential control. A piezoelectric transducer, driven at the crystal resonant frequency, is used to generate an acoustic pressure field and is termed an ‘ultrasonic nuclei manipulator (UNM)’. Electrolysis bubbles serve as artificial nuclei to produce travelling bubble cavitation at the venturi throat in the absence of a UNM but this cavitation is completely eliminated when a UNM is operative. This is made possible because the nuclei, which pass through the acoustic field first, cavitate, collapse violently and perhaps fragment and go into dissolution before reaching the venturi throat. Thus, the potential nuclei for travelling bubble cavitation at the venturi throat seem to be systematically destroyed through acoustic cavitation near the UNM. From the solution to the bubble dynamics equation, it has been shown that the potential energy of a bubble at its maximum radius due to an acoustic field is negligible compared to that for the hydrodynamic field. Hence, even though the control of hydrodynamic macro cavitation achieved in this way is at the expense of acoustic micro cavitation, it can still be considered to be a significant gain. These are some of the first results in this direction.
The hydrodynamic size of polymer stabilized nanocrystals
Energy Technology Data Exchange (ETDEWEB)
Krueger, Karl M; Al-Somali, Ali M; Mejia, Michelle; Colvin, Vicki L [Department of Chemistry, Rice University, MS-60 6100 Main Street, Houston, TX 77005 (United States)
2007-11-28
For many emerging applications, nanocrystals are surface functionalized with polymers to control self-assembly, prevent aggregation, and promote incorporation into polymer matrices and biological systems. The hydrodynamic diameter of these nanoparticle-polymer complexes is a critical factor for many applications, and predicting this size is complicated by the fact that the structure of the grafted polymer at a nanocrystalline interface is not generally established. In this work we evaluate using size-exclusion chromatography the overall hydrodynamic diameter of nanocrystals (Au, CdSe, d<5 nm) surface coated with polystyrene of varying molecular weight. The polymer is tethered to the nanoparticles via a terminal thiol to provide strong attachment. Our data show that at full coverage the polymer assumes a brush conformation and is 44% longer than the unbound polymer in solution. The brush conformation is confirmed by comparison with models used to describe polymer brushes at flat interfaces. From this work, we suggest an empirical formula which predicts the hydrodynamic diameter of polymer coated nanoparticles based on the size of the nanoparticle core and the size of the randomly coiled unbound polymer in solution.
Hydrodynamic slip length as a surface property
Ramos-Alvarado, Bladimir; Kumar, Satish; Peterson, G. P.
2016-02-01
Equilibrium and nonequilibrium molecular dynamics simulations were conducted in order to evaluate the hypothesis that the hydrodynamic slip length is a surface property. The system under investigation was water confined between two graphite layers to form nanochannels of different sizes (3-8 nm). The water-carbon interaction potential was calibrated by matching wettability experiments of graphitic-carbon surfaces free of airborne hydrocarbon contamination. Three equilibrium theories were used to calculate the hydrodynamic slip length. It was found that one of the recently reported equilibrium theories for the calculation of the slip length featured confinement effects, while the others resulted in calculations significantly hindered by the large margin of error observed between independent simulations. The hydrodynamic slip length was found to be channel-size independent using equilibrium calculations, i.e., suggesting a consistency with the definition of a surface property, for 5-nm channels and larger. The analysis of the individual trajectories of liquid particles revealed that the reason for observing confinement effects in 3-nm nanochannels is the high mobility of the bulk particles. Nonequilibrium calculations were not consistently affected by size but by noisiness in the smallest systems.
Hydrodynamic instabilities in astrophysics and ICF
International Nuclear Information System (INIS)
Paul Drake, R.
2005-01-01
Inertial fusion systems and astrophysical systems both involve hydrodynamic effects, including sources of pressure, shock waves, rarefactions, and plasma flows. In the evolution of such systems, hydrodynamic instabilities naturally evolve. As a result, a fundamental understanding of hydrodynamic instabilities is necessary to understand their behavior. In addition, high-energy-density facilities designed for ICF purposes can be used to provide and experimental basis for understanding astrophysical processes. In this talk. I will discuss the instabilities that appear in astrophysics and ICF from the common perspective of the basic mechanisms at work. Examples will be taken from experiments aimed at ICF, from astrophysical systems, and from experiments using ICF systems to address issues in astrophysics. The high-energy-density research facilities of today can accelerate small but macroscopic amounts of material to velocities above 100 km/s, can heat such material to temperature above 100 eV, can produce pressures far above a million atmospheres (10''12 dybes/cm''2 or 0.1 TPascal), and can do experiments under these conditions that address basic physics issues. This enables on to devise experiments aimed directly at important process such as the Rayleigh Taylor instability at an ablating surface or at an embedded interface that is accelerating, the Richtmeyer Meshkov evolution of shocked interfaces, and the Kelvin-Helmholtz instability of shear flows. The talk will include examples of such phenomena from the laboratory and from astrophysics, and will discuss experiments to study them. (Author)
Harutyunyan, A. V.; Petrosyan, H. M.
2010-05-01
In the basis of multiple geological and geophysical data, also on the results of investigations seismic and density properties of rocks at high termobaric conditions, we proposed the petrophisical section and model of evolution of Earth crust of the territory of Armenia. On the proposed model the following interrelated problems are debated: forming of ophiolite belts and volcanic centers, genesis of hydrocarbons by organic and inorganic ways, and also reasons of originating of seismic centers. The reasons of originating of seismic centers in different depths of Earth crust, are miscellaneous. According to the model of Earth crust evolution the ophiolite belts are formed due to permanent protrusive intrusion of serpentinized masses from the foot of the crust (35-50km) into upper horizons. It is natural to assume, that the permanent intrusion of serpentinizd masses through deep faults has drastically occurred accompanying with seismic shakings. This process encourages the development of deep faults. The protrusive intrusion of serpentinized masse accompanied with partial dehydration of serpentinites and serpentinized ultrabasites and new mineral formation. The processes was accompanied also with drastic change of seismic waves and volumes up to 30%. Experiments at high termobaric conditions show, that some minerals undergone polymorphous transformations, accompanied with phase change and drastic change of rocks volume. Particularly plastic calcite, included in the composition of metamorphic rocks to run into the cracks expends and diversifies them. The process described cause some general effects similar to those of the process of dilatancy. Therefore, the protrusive intrusion of serpentinized masses into upper horizons, it dehydrations and polymorphous transformations in different minerals, may be cause of geo-dynamic processes at different depths of Earth crust. It may be assumed, that those processes permanently occur nowadays as well. Comparing the maps of
Hydrodynamic studies on two traveling wavy foils in tandem arrangement
Deng, Jian; Shao, Xue-Ming; Yu, Zhao-Sheng
2007-11-01
In this study, the hydrodynamic interactions between two tandem foils undergoing fishlike swimming motion are investigated numerically by solving the Navier-Stokes equations with the immersed-boundary method. The two foils represent two tandem propellers attached on a concept ship. The thrusts and efficiencies at three typical Strouhal numbers, i.e., St =0.4, 0.6, and 0.8, are investigated. The results show that a fish situated directly behind another one does not always undergo a lower thrust. Whether it experiences a thrust enhancement or reduction depends on the Strouhal number. At a relatively low Strouhal number (e.g., St =0.4), the usual wake drag-reduction effect predominates over the drag-enhancement effect caused by the reverse von Kármán vortices, resulting in a thrust enhancement. The opposite happens at a relatively high Strouhal number (e.g., St =0.8). The downstream fish can benefit from the upstream one by slalom between the vortices rather than through them. For the upstream fish, the thrusts and efficiencies for all Strouhal numbers studied are higher than those for a single fish when the two fish are closely spaced, and approach those for a single fish as the spacing is increased.
Stochastic-hydrodynamic model of halo formation in charged particle beams
Directory of Open Access Journals (Sweden)
Nicola Cufaro Petroni
2003-03-01
Full Text Available The formation of the beam halo in charged particle accelerators is studied in the framework of a stochastic-hydrodynamic model for the collective motion of the particle beam. In such a stochastic-hydrodynamic theory the density and the phase of the charged beam obey a set of coupled nonlinear hydrodynamic equations with explicit time-reversal invariance. This leads to a linearized theory that describes the collective dynamics of the beam in terms of a classical Schrödinger equation. Taking into account space-charge effects, we derive a set of coupled nonlinear hydrodynamic equations. These equations define a collective dynamics of self-interacting systems much in the same spirit as in the Gross-Pitaevskii and Landau-Ginzburg theories of the collective dynamics for interacting quantum many-body systems. Self-consistent solutions of the dynamical equations lead to quasistationary beam configurations with enhanced transverse dispersion and transverse emittance growth. In the limit of a frozen space-charge core it is then possible to determine and study the properties of stationary, stable core-plus-halo beam distributions. In this scheme the possible reproduction of the halo after its elimination is a consequence of the stationarity of the transverse distribution which plays the role of an attractor for every other distribution.
Behafarid, Farhad; Brasseur, James G.
2017-11-01
Following tablet disintegration, clouds of drug particles 5-200 μm in diameter pass through the intestines where drug molecules are absorbed into the blood. Release rate depends on particle size, drug solubility, local drug concentration and the hydrodynamic environment driven by patterned gut contractions. To analyze the dynamics underlying drug release and absorption, we use a 3D lattice Boltzmann model of the velocity and concentration fields driven by peristaltic contractions in vivo, combined with a mathematical model of dissolution-rate from each drug particle transported through the grid. The model is empirically extended for hydrodynamic enhancements to release rate by local convection and shear-rate, and incorporates heterogeneity in bulk concentration. Drug dosage and solubility are systematically varied along with peristaltic wave speed and volume. We predict large hydrodynamic enhancements (35-65%) from local shear-rate with minimal enhancement from convection. With high permeability boundary conditions, a quasi-equilibrium balance between release and absorption is established with volume and wave-speed dependent transport time scale, after an initial transient and before a final period of dissolution/absorption. Supported by FDA.
Poitelon, Yannick; Feltri, M Laura
2018-01-01
In the peripheral nervous system, axons dictate the differentiation state of Schwann cells. Most of this axonal influence on Schwann cells is due to juxtacrine interactions between axonal transmembrane molecules (e.g., the neuregulin growth factor) and receptors on the Schwann cell (e.g., the ErbB2/ErbB3 receptor). The fleeting nature of this interaction together with the lack of synchronicity in the development of the Schwann cell population limits our capability to study this phenomenon in vivo. Here we present a simple Boyden Chamber-based method to study this important cell-cell interaction event. We isolate the early protrusions of Schwann cells that are generated in response to juxtacrine stimulation by sensory neuronal membranes. This method is compatible with a large array of current biochemical analyses and provides an effective approach to study biomolecules that are differentially localized in Schwann cell protrusions and cell bodies in response to axonal signals. A similar approach can be extended to different kinds of cell-cell interactions.
Imamura, Toshihiro; Kokai, Satoshi; Ono, Takashi
2018-01-01
For patients with bimaxillary protrusion, significant retraction and intrusion of the anterior teeth are sometimes essential to improve the facial profile. However, severe root resorption of the maxillary incisors occasionally occurs after treatment because of various factors. For instance, it has been reported that approximation or invasion of the incisive canal by the anterior tooth roots during retraction may cause apical root damage. Thus, determination of the position of the maxillary incisors is key for orthodontic diagnosis and treatment planning in such cases. Cone-beam computed tomography (CBCT) may be useful for simulating the post-treatment position of the maxillary incisors and surrounding structures in order to ensure safe teeth movement. Here, we present a case of Class II malocclusion with bimaxillary protrusion, wherein apical root damage due to treatment was minimized by pretreatment evaluation of the anatomical structures and simulation of the maxillary central incisor movement using CBCT. Considerable retraction and intrusion of the maxillary incisors, which resulted in a significant improvement in the facial profile and smile, were achieved without severe root resorption. Our findings suggest that CBCT-based diagnosis and treatment simulation may facilitate safe and dynamic orthodontic tooth movement, particularly in patients requiring maximum anterior tooth retraction. PMID:29732305
Frey, Roland; Volodin, Ilya; Volodina, Elena; Carranza, Juan; Torres-Porras, Jerónimo
2012-03-01
Roaring in rutting Iberian red deer stags Cervus elaphus hispanicus is unusual compared to other subspecies of red deer, which radiated from the Iberian refugium after the last glacial maximum. In all red deer stags, the larynx occupies a permanent low mid-neck resting position and is momentarily retracted almost down to the rostral end of the sternum during the production of rutting calls. Simultaneous with the retraction of the larynx, male Iberian red deer pronouncedly protrude the tongue during most of their rutting roars. This poses a mechanical challenge for the vocal tract (vt) and for the hyoid apparatus, as tongue and larynx are strongly pulled in opposite directions. This study (i) examines the vocal anatomy and the acoustics of the rutting roars in free-ranging male C. e. hispanicus; (ii) establishes a potential mechanism of simultaneous tongue protrusion and larynx retraction by applying a two-dimensional model based on graphic reconstructions in single video frames of unrestrained animals; and (iii) advances a hypothesis of evaporative cooling by tongue protrusion in the males of a subspecies of red deer constrained to perform all of the exhausting rutting activities, including acoustic display, in a hot and arid season. © 2012 The Authors. Journal of Anatomy © 2012 Anatomical Society.
Assessment for hydrodynamic masses of HANARO flow tubes
Energy Technology Data Exchange (ETDEWEB)
Ryu, Jeong Soo; Cho, Yeong Garp; Kim, Doo Kie; Woo, Jong Sug; Park, Jin Ho
2000-06-01
The effect of hydrodynamic masses is investigated in dynamic characteristics and seismic response analyses of the submerged HANARO hexagonal flow tubes. Consistent hydrodynamic masses of the surrounding water are evaluated by the prepared program using the finite element method, in which arbitrary cross-sections of submerged structures and boundary conditions of the surrounding fluid can be considered. Also lumped hydrodynamic masses are calculated using simple formula applied to hexagonal flow tubes in the infinite fluid. Modal analyses and seismic response spectrum analyses were performed using hydrodynamic masses obtained by the finite element method and the simple formula. The results of modal analysis were verified by comparing the results measured from modal tests. And the displacement results of the seismic response spectrum analysis were assessed by comparing the consistent and the lumped hydrodynamic masses obtained by various methods. Finally practical criteria based on parametric studies are proposed as the lumped hydrodynamic masses for HANARO flow tubes.
Assessment for hydrodynamic masses of HANARO flow tubes
International Nuclear Information System (INIS)
Ryu, Jeong Soo; Cho, Yeong Garp; Kim, Doo Kie; Woo, Jong Sug; Park, Jin Ho
2000-06-01
The effect of hydrodynamic masses is investigated in dynamic characteristics and seismic response analyses of the submerged HANARO hexagonal flow tubes. Consistent hydrodynamic masses of the surrounding water are evaluated by the prepared program using the finite element method, in which arbitrary cross-sections of submerged structures and boundary conditions of the surrounding fluid can be considered. Also lumped hydrodynamic masses are calculated using simple formula applied to hexagonal flow tubes in the infinite fluid. Modal analyses and seismic response spectrum analyses were performed using hydrodynamic masses obtained by the finite element method and the simple formula. The results of modal analysis were verified by comparing the results measured from modal tests. And the displacement results of the seismic response spectrum analysis were assessed by comparing the consistent and the lumped hydrodynamic masses obtained by various methods. Finally practical criteria based on parametric studies are proposed as the lumped hydrodynamic masses for HANARO flow tubes
Hydrodynamic evolution of neutron star merger remnants
Liu, Men-Quan; Zhang, Jie
2017-11-01
Based on the special relativistic hydrodynamic equations and updated cooling function, we investigate the long-term evolution of neutron stars merger (NSM) remnants by a one-dimensional hydrodynamic code. Three NSM models from one soft equation of state, SFHo, and two stiff equations of state, DD2 and TM1, are used to compare their influences on the hydrodynamic evolution of remnants. We present the luminosity, mass and radius of remnants, as well as the velocity, temperature and density of shocks. For a typical interstellar medium (ISM) density with solar metallicity, we find that the NSM remnant from the SFHo model makes much more changes to ISM in terms of velocity, density and temperature distributions, compared with the case of DD2 and TM1 models. The maximal luminosity of the NSM remnant from the SFHo model is 3.4 × 1038 erg s-1, which is several times larger than that from DD2 and TM1 models. The NSM remnant from the SFHo model can maintain high luminosity (>1038 erg s-1) for 2.29 × 104 yr. Furthermore, the density and temperature of remnants at the maximal luminosity are not sensitive to the power of the original remnant. For the ISM with the solar metallicity and nH = 1 cm- 3, the density of the first shock ∼10-23 g cm-3 and the temperature ∼3 × 105 K in the maximal luminosity phase; The temperature of the first shock decreases and there is a thin 'dense' shell with density ∼10-21 g cm-3 after the maximal luminosity. These characteristics may be helpful for future observations of NSM remnants.
Computer simulation of the fire-tube boiler hydrodynamics
Directory of Open Access Journals (Sweden)
Khaustov Sergei A.
2015-01-01
Full Text Available Finite element method was used for simulating the hydrodynamics of fire-tube boiler with the ANSYS Fluent 12.1.4 engineering simulation software. Hydrodynamic structure and volumetric temperature distribution were calculated. The results are presented in graphical form. Complete geometric model of the fire-tube boiler based on boiler drawings was considered. Obtained results are suitable for qualitative analysis of hydrodynamics and singularities identification in fire-tube boiler water shell.
Measurement of beam driven hydrodynamic turbulence
International Nuclear Information System (INIS)
Norem, J.; Black, E.; Bandura, L.; Errede, D.; Cummings, M. A. C.
2003-01-01
Cooling intense muon beams in liquid hydrogen absorbers introduces kW of heating to the cold fluid, which will drive turbulent flow. The amount of turbulence may be sufficient to help cool the liquid, but calculations are difficult. We have used a 20 MeV electron beam in a water tank to look at the scale of the beam driven convection and turbulence. The density and flow measurements are made with schlieren and Ronchi systems. We describe the optical systems and the turbulence measured. These data are being used to calibrate hydrodynamic calculations of convection driven and forced flow cooling in muon cooling absorbers
The frontal method in hydrodynamics simulations
Walters, R.A.
1980-01-01
The frontal solution method has proven to be an effective means of solving the matrix equations resulting from the application of the finite element method to a variety of problems. In this study, several versions of the frontal method were compared in efficiency for several hydrodynamics problems. Three basic modifications were shown to be of value: 1. Elimination of equations with boundary conditions beforehand, 2. Modification of the pivoting procedures to allow dynamic management of the equation size, and 3. Storage of the eliminated equations in a vector. These modifications are sufficiently general to be applied to other classes of problems. ?? 1980.
Hydrodynamic instabilities in inertial confinement fusion
International Nuclear Information System (INIS)
Hoffman, N.M.
1995-01-01
The focus of these (two) lectures is on buoyancy-driven instabilities of the Rayleigh-Taylor type, which are commonly regarded as the most important kind of hydrodynamic instability in inertial-confinement-fusion implosions. The paper is intended to be pedagogical rather than research-oriented, and so is by no means a comprehensive review of work in this field. Rather, it is hoped that the student will find here a foundation on which to build an understanding of current research, and the experienced researcher will find a compilation of useful results. (author)
Hydrodynamic Study Of Column Bioleaching Processes
Directory of Open Access Journals (Sweden)
Sadowski Zygmunt
2015-06-01
Full Text Available The modelling of flow leaching solution through the porous media has been considered. The heap bioleaching process can be tested using the column experimental equipment. This equipment was employed to the hydrodynamic studies of copper ore bioleaching. The copper ore (black shale ore with the support, inertial materials (glass small balls and polyethylene beads was used to the bioleaching tests. The packed beds were various composition, the ore/support ratio was changed. The correlation between the bed porosity and bioleaching kinetics, and copper recovery was investigated.
Hydrodynamic instabilities in an ablation front
International Nuclear Information System (INIS)
Piriz, A R; Portugues, R F
2004-01-01
The hydrodynamic stability of an ablation front is studied for situations in which the wavelength of the perturbations is larger than the distance to the critical surface where the driving radiation is absorbed. An analytical model is presented, and it shows that under conditions in which the thermal flux is limited within the supercritical region of the ablative corona, the front may behave like a flame or like an ablation front, depending on the perturbation wavelength. For relatively long wavelengths the critical and ablation surfaces practically lump together into a unique surface and the front behaves like a flame, whereas for the shortest wavelengths the ablation front substructure is resolved
Hydrodynamic instabilities in an ablation front
Energy Technology Data Exchange (ETDEWEB)
Piriz, A R; Portugues, R F [E.T.S.I. Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain)
2004-06-01
The hydrodynamic stability of an ablation front is studied for situations in which the wavelength of the perturbations is larger than the distance to the critical surface where the driving radiation is absorbed. An analytical model is presented, and it shows that under conditions in which the thermal flux is limited within the supercritical region of the ablative corona, the front may behave like a flame or like an ablation front, depending on the perturbation wavelength. For relatively long wavelengths the critical and ablation surfaces practically lump together into a unique surface and the front behaves like a flame, whereas for the shortest wavelengths the ablation front substructure is resolved.
Self-acting and hydrodynamic shaft seals
Ludwig, L. P.
1973-01-01
Self-acting and hydrodynamic seals are described. The analytical procedures are outlined for obtaining a seal force balance and the operating film thickness. Particular attention is given to primary ring response (seal vibration) to rotating seat face runout. This response analysis revealed three different vibration modes. Proposed applications of self-acting seals in gas turbine engines and in rocket vehicle turbopumps are described. Also experimental data on self-acting face seals operating under simulated gas turbine conditions are given; these data show the feasibility of operating the seal at conditions of 345 newtons per square centimeter (500 psi) and 152 meters per second (500 ft/sec) sliding speed.
Hydrodynamics and Elasticity of Charged Black Branes
DEFF Research Database (Denmark)
Gath, Jakob
We consider long-wavelength perturbations of charged black branes to first order in a uidelastic derivative expansion. At first order the perturbations decouple and we treat the hydrodynamic and elastic perturbations separately. To put the results in a broader perspective, we present the rst...... as a seed solution, we obtain a class of charged black brane geometries carrying smeared Maxwell charge in Einstein-Maxwell-dilaton theory. In the specific case of ten-dimensional space-time we furthermore use T-duality to generate bent black branes with higher-form charge, including smeared D...
Control of hydrodynamic cavitation using ultrasonic
Chatterjee, Dhiman; Arakeri, Vijay H.
2003-11-01
Hydrodynamic cavitation is known to have many harmful effects like surface damage and generation of noise. We investigated the use of ultrasonics to control traveling bubble cavitation. Ultrasonic pressure field, produced by a piezoelectric crystal, was applied to modify the nuclei size distribution. Effects of continuous-wave (CW) and pulsed excitations were studied. At low dissolved gas content the CW-mode performed better than the pulsed one, whereas for high gas content the pulsed one was more effective. The dominant mechanisms were Bjerknes force and rectified diffusion in these two cases. Simultaneous excitation by two crystals in CW and pulsed modes was seen to control cavitation better.
Hydrodynamic bearing lubricated with magnetic fluids
International Nuclear Information System (INIS)
Urreta, H; Leicht, Z; Sanchez, A; Agirre, A; Kuzhir, P; Magnac, G
2009-01-01
This paper summarizes the work carried out in the development of hydrodynamic lubricated journal bearings with magnetic fluids. Two different fluids have been analyzed, one ferrofluid from FERROTEC APG s10n and one magnetorheological fluid from LORD Corp., MRF122-2ED. Theoretical analysis has been carried out with numerical solutions of Reynolds equation, based on apparent viscosity modulation for ferrofluid and Bingham model for MR fluid. To validate this model, one test bench has been designed, manufactured and set up, where preliminary results shown in this paper demonstrate that magnetic fluids can be used to develop active journal bearings.
Experimental hydrodynamics of swimming in fishes
Tytell, Eric Daniel
2005-11-01
The great diversity of fish body shapes suggests that they have adapted to different selective pressures. For many fishes, the pressures include hydrodynamic demands: swimming efficiently or accelerating rapidly, for instance. However, the hydrodynamic advantages or disadvantages to specific morphologies are poorly understood. In particular, eels have been considered inefficient swimmers, but they migrate long distances without feeding, a task that requires efficient swimming. This dissertation, therefore, begins with an examination of the swimming hydrodynamics of American eels, Anguilla rostrata, at steady swimming speeds from 0.5 to 2 body lengths (L) per second and during accelerations from -1.4 to 1.3 L s -2. The final chapter examines the hydrodynamic effects of body shape directly by describing three-dimensional flow around swimming bluegill sunfish, Lepomis macrochirus. In all chapters, flow is quantified using digital particle image velocimetry, and simultaneous kinematics are measured from high-resolution digital video. The wake behind a swimming eel in the horizontal midline plane is described first. Rather than producing a wake with fluid jets angled backwards, like in fishes such as sunfish, eels have a wake with exclusively lateral jets. The lack of downstream momentum indicates that eels balance the axial forces of thrust and drag evenly over time and over their bodies, and therefore do not change axial fluid momentum. This even balance, present at all steady swimming speeds, is probably due to the relatively uniform body shape of eels. As eels accelerate, thrust exceeds drag, axial momentum increases, and the wake approaches that of other fishes. During steady swimming, though, the lack of axial momentum prevents direct efficiency estimation. The effect of body shape was examined directly by measuring flow in multiple transverse planes along the body of bluegill sunfish swimming at 1.2 L s-1. The dorsal and anal fin, neglected in many previous
Hydrodynamization and transient modes of expanding plasma in kinetic theory
Heller, Michal P.; Spalinski, Michal
2016-01-01
We study the transition to hydrodynamics in a weakly-coupled model of quark-gluon plasma given by kinetic theory in the relaxation time approximation. Our studies uncover qualitative similarities to the results on hydrodynamization in strongly coupled gauge theories. In particular, we demonstrate that the gradient expansion in this model has vanishing radius of convergence. The asymptotic character of the hydrodynamic gradient expansion is crucial for the recently discovered applicability of hydrodynamics at large gradients. Furthermore, the analysis of the resurgent properties of the series provides, quite remarkably, indication for the existence of a novel transient, damped oscillatory mode of expanding plasmas in kinetic theory.
Hydrodynamics in a Degenerate, Strongly Attractive Fermi Gas
Thomas, John E.; Kinast, Joseph; Hemmer, Staci; Turlapov, Andrey; O'Hara, Ken; Gehm, Mike; Granade, Stephen
2004-01-01
In summary, we use all-optical methods with evaporative cooling near a Feshbach resonance to produce a strongly interacting degenerate Fermi gas. We observe hydrodynamic behavior in the expansion dynamics. At low temperatures, collisions may not explain the expansion dynamics. We observe hydrodynamics in the trapped gas. Our observations include collisionally-damped excitation spectra at high temperature which were not discussed above. In addition, we observe weakly damped breathing modes at low temperature. The observed temperature dependence of the damping time and hydrodynamic frequency are not consistent with collisional dynamics nor with collisionless mean field interactions. These observations constitute the first evidence for superfluid hydrodynamics in a Fermi gas.
Taming axial dispersion in hydrodynamic chromatography columns through wall patterning
Adrover, Alessandra; Cerbelli, Stefano; Giona, Massimiliano
2018-04-01
A well-known limitation of hydrodynamic chromatography arises from the synergistic interaction between transverse diffusion and streamwise convection, which enhances axial dispersion through the Taylor-Aris mechanism. We show that a periodic sequence of slip/no-slip conditions at the channel walls (e.g., representing wall indentations hosting stable air pockets) can significantly reduce axial dispersion, thus enhancing separation performance. The theoretical/numerical analysis is based on a generalization of Brenner's macrotransport approach to solute transport, here modified to account for the finite-size of the suspended particles. The most effective dispersion-taming outcome is observed when the alternating sequence of slip/no-slip conditions yields non-vanishing cross-sectional flow components. The combination of these components with the hindering interaction between the channel boundaries and the finite-sized particles gives rise to a non-trivial solution of Brenner's problem on the unit periodic cell, where the cross-sectional particle number density departs from the spatially homogeneous condition. In turn, this effect impacts upon the solution of the so-called b-field defining the large-scale dispersion tensor, with an overall decremental effect on the axial dispersion coefficient and on the Height Equivalent of a Theoretical Plate.
Interaction mechanism of double bubbles in hydrodynamic cavitation
Li, Fengchao; Cai, Jun; Huai, Xiulan; Liu, Bin
2013-06-01
Bubble-bubble interaction is an important factor in cavitation bubble dynamics. In this paper, the dynamic behaviors of double cavitation bubbles driven by varying pressure field downstream of an orifice plate in hydrodynamic cavitation reactor are examined. The bubble-bubble interaction between two bubbles with different radii is considered. We have shown the different dynamic behaviors between double cavitation bubbles and a single bubble by solving two coupling nonlinear equations using the Runge-Kutta fourth order method with adaptive step size control. The simulation results indicate that, when considering the role of the neighbor smaller bubble, the oscillation of the bigger bubble gradually exhibits a lag in comparison with the single-bubble case, and the extent of the lag becomes much more obvious as time goes by. This phenomenon is more easily observed with the increase of the initial radius of the smaller bubble. In comparison with the single-bubble case, the oscillation of the bigger bubble is enhanced by the neighbor smaller bubble. Especially, the pressure pulse of the bigger bubble rises intensely when the sizes of two bubbles approach, and a series of peak values for different initial radii are acquired when the initial radius ratio of two bubbles is in the range of 0.9˜1.0. Although the increase of the center distance between two bubbles can weaken the mutual interaction, it has no significant influence on the enhancement trend. On the one hand, the interaction between two bubbles with different radii can suppress the growth of the smaller bubble; on the other hand, it also can enhance the growth of the bigger one at the same time. The significant enhancement effect due to the interaction of multi-bubbles should be paid more attention because it can be used to reinforce the cavitation intensity for various potential applications in future.
Improved Swimming Performance in Hydrodynamically- coupled Airfoils
Heydari, Sina; Shelley, Michael J.; Kanso, Eva
2017-11-01
Collective motion is a widespread phenomenon in the animal kingdom from fish schools to bird flocks. Half of the known fish species are thought to exhibit schooling behavior during some phase of their life cycle. Schooling likely occurs to serve multiple purposes, including foraging for resources and protection from predators. Growing experimental and theoretical evidence supports the hypothesis that fish can benefit from the hydrodynamic interactions with their neighbors, but it is unclear whether this requires particular configurations or regulations. Here, we propose a physics-based approach that account for hydrodynamic interactions among swimmers based on the vortex sheet model. The benefit of this model is that it is scalable to a large number of swimmers. We start by examining the case of two swimmers, heaving plates, moving in parallel and in tandem. We find that for the same heaving amplitude and frequency, the coupled-swimmers move faster and more efficiently. This increase in velocity depends strongly on the configuration and separation distance between the swimmers. Our results are consistent with recent experimental findings on heaving airfoils and underline the role of fluid dynamic interactions in the collective behavior of swimmers.
Hydrodynamic optical-field-ionized plasma channels
Shalloo, R. J.; Arran, C.; Corner, L.; Holloway, J.; Jonnerby, J.; Walczak, R.; Milchberg, H. M.; Hooker, S. M.
2018-05-01
We present experiments and numerical simulations which demonstrate that fully ionized, low-density plasma channels could be formed by hydrodynamic expansion of plasma columns produced by optical field ionization. Simulations of the hydrodynamic expansion of plasma columns formed in hydrogen by an axicon lens show the generation of 200 mm long plasma channels with axial densities of order ne(0 ) =1 ×1017cm-3 and lowest-order modes of spot size WM≈40 μ m . These simulations show that the laser energy required to generate the channels is modest: of order 1 mJ per centimeter of channel. The simulations are confirmed by experiments with a spherical lens which show the formation of short plasma channels with 1.5 ×1017cm-3≲ne(0 ) ≲1 ×1018cm-3 and 61 μ m ≳WM≳33 μ m . Low-density plasma channels of this type would appear to be well suited as multi-GeV laser-plasma accelerator stages capable of long-term operation at high pulse repetition rates.
A web portal for hydrodynamical, cosmological simulations
Ragagnin, A.; Dolag, K.; Biffi, V.; Cadolle Bel, M.; Hammer, N. J.; Krukau, A.; Petkova, M.; Steinborn, D.
2017-07-01
This article describes a data centre hosting a web portal for accessing and sharing the output of large, cosmological, hydro-dynamical simulations with a broad scientific community. It also allows users to receive related scientific data products by directly processing the raw simulation data on a remote computing cluster. The data centre has a multi-layer structure: a web portal, a job control layer, a computing cluster and a HPC storage system. The outer layer enables users to choose an object from the simulations. Objects can be selected by visually inspecting 2D maps of the simulation data, by performing highly compounded and elaborated queries or graphically by plotting arbitrary combinations of properties. The user can run analysis tools on a chosen object. These services allow users to run analysis tools on the raw simulation data. The job control layer is responsible for handling and performing the analysis jobs, which are executed on a computing cluster. The innermost layer is formed by a HPC storage system which hosts the large, raw simulation data. The following services are available for the users: (I) CLUSTERINSPECT visualizes properties of member galaxies of a selected galaxy cluster; (II) SIMCUT returns the raw data of a sub-volume around a selected object from a simulation, containing all the original, hydro-dynamical quantities; (III) SMAC creates idealized 2D maps of various, physical quantities and observables of a selected object; (IV) PHOX generates virtual X-ray observations with specifications of various current and upcoming instruments.
Hydrodynamic instability experiments on the Nova laser
International Nuclear Information System (INIS)
Remington, B.A.; Glendinning, S.G.; Kalantar, D.H.
1996-08-01
Hydrodynamic instabilities in compressible plasmas play a critical role in the fields of inertial confinement fusion (ICF), astrophysics, and high energy-density physics. We are, investigating hydrodynamic instabilities such as the Rayleigh-Taylor (RT) instability, at high compression at the Nova laser in a series of experiments, both in planar and in spherical geometry. In the indirect drive approach, a thermal x-ray drive is generated by focusing the Nova laser beams into a Au cylindrical radiation cavity (hohlraum). Issues in the instability evolution that we are examining are shock propagation and foil compression, RT growth of 2D versus 3D single-mode perturbations, drive pulse shape, perturbation location at the ablation front versus at an embedded interface, and multimode perturbation growth and nonlinear saturation. The effects of convergence on RT growth are being investigated both with hemispherical implosions of packages mounted on the hohlraum wall and with spherical implosions of capsules at the center of the hohlraum. Single-mode perturbations are pre-imposed at the ablation front of these capsules as a seed for the RT growth. In our direct drive experiments, we are investigating the effect of laser imprinting and subsequent RT growth on planar foils, both at λ Laser = 1/3 μm and 1/2 μm. An overview is given describing recent progress in each of these areas
Mesoscale simulations of hydrodynamic squirmer interactions.
Götze, Ingo O; Gompper, Gerhard
2010-10-01
The swimming behavior of self-propelled microorganisms is studied by particle-based mesoscale simulations. The simulation technique includes both hydrodynamics and thermal fluctuations that are both essential for the dynamics of microswimmers. The swimmers are modeled as squirmers, i.e., spherical objects with a prescribed tangential surface velocity, where the focus of thrust generation can be tuned from pushers to pullers. For passive squirmers (colloids), we show that the velocity autocorrelation function agrees quantitatively with the Boussinesq approximation. Single active squirmers show a persistent random-walk behavior, determined by forward motion, lateral diffusion, and orientational fluctuations, in agreement with theoretical predictions. For pairs of squirmers, which are initially swimming in parallel, we find an attraction for pushers and a repulsion for pullers, as expected. The hydrodynamic force between squirmer pairs is calculated as a function of the center-to-center distances d(cm) and is found to be consistent with a logarithmic distance dependence for d(cm) less than about two sphere diameters; here, the force is considerably stronger than expected from the far-field expansion. The dependence of the force strength on the asymmetry of the polar surface velocity is obtained. During the collision process, thermal fluctuations turn out to be very important and to strongly affect the postcollision velocity directions of both squirmers.
The Coupling of Radiation and Hydrodynamics
International Nuclear Information System (INIS)
Lowrie, R.B.; Morel, J.E.; Hittinger, J.A.
1999-01-01
The coupling of radiation transport and hydrodynamics is discussed for the Eulerian frame. The discussion is aimed at developing a suitable set of equations for nonrelativistic radiation hydrodynamics (RHD) that can be numerically integrated using high-resolution methods for conservation laws. We outline how numerical methods based on a wave decomposition may be developed, along with the importance of conservation, particularly in the equilibrium regime. The properties of the RHD equations are examined through asymptotic and dispersion analyses. The conditions required to obtain the classical equilibrium limit are rigorously studied. The results show that a simple coupling term developed recently by Morel, which retains a minimum of relativistic corrections, may be sufficient for nonrelativistic flows. We also give two constraints on the relativistic corrections that result in retaining terms on the order of the truncation. In addition, the dispersion results for the P 1 approximation are studied in detail and are compared with both the exact-transport results and a full relativistic treatment. We also examine some nonintuitive behavior in the dispersion results. copyright copyright 1999. The American Astronomical Society
Hydrodynamic Forces from Steep Waves in Rivers
Energy Technology Data Exchange (ETDEWEB)
Loevoll, A.
1996-12-31
The reservoir behind a hydroelectric power production dam has an enormous potential for destruction in case of a dam break. The present doctoral thesis evaluates the hydrodynamic forces from steep waves in rivers. In the laboratory, forces on a structure shaped as a vertical cylinder of rectangular cross section were measured, and the threshold condition for the bed sediment was investigated. A wave parameter {alpha} is introduced to describe the gradient of a wave front. The flow condition in the flume was reproduced by a 3-D numerical model. For various values of the wave parameter the forces were measured and compared to the drag force calculated from measured depth and velocity. From these comparisons the hydrodynamic force can be calculated as drag only, even in the case of a breaking wave front. The contribution from inertia relative to drag depends on the size of the structure. For larger structures the contributions may be important in steep waves. To study the initiation of motion (of sediments) under unsteady flow, waves of various parameter values were passed over a gravel covered bed. The initiation of motion starts before the peak of the wave, and is given by Shield`s relation if the friction slope is applied. No dependence upon the wave gradient was found. A relation was established which gives the critical shear stress if the friction slope is estimated by the bottom slope. 65 refs., 41 figs., 10 tabs.
Hydrodynamic Forces from Steep Waves in Rivers
International Nuclear Information System (INIS)
Loevoll, A.
1996-01-01
The reservoir behind a hydroelectric power production dam has an enormous potential for destruction in case of a dam break. The present doctoral thesis evaluates the hydrodynamic forces from steep waves in rivers. In the laboratory, forces on a structure shaped as a vertical cylinder of rectangular cross section were measured, and the threshold condition for the bed sediment was investigated. A wave parameter α is introduced to describe the gradient of a wave front. The flow condition in the flume was reproduced by a 3-D numerical model. For various values of the wave parameter the forces were measured and compared to the drag force calculated from measured depth and velocity. From these comparisons the hydrodynamic force can be calculated as drag only, even in the case of a breaking wave front. The contribution from inertia relative to drag depends on the size of the structure. For larger structures the contributions may be important in steep waves. To study the initiation of motion (of sediments) under unsteady flow, waves of various parameter values were passed over a gravel covered bed. The initiation of motion starts before the peak of the wave, and is given by Shield's relation if the friction slope is applied. No dependence upon the wave gradient was found. A relation was established which gives the critical shear stress if the friction slope is estimated by the bottom slope. 65 refs., 41 figs., 10 tabs
Hydrodynamic modeling and explosive compaction of ceramics
International Nuclear Information System (INIS)
Hoenig, C.; Holt, A.; Finger, M.; Kuhl, W.
1977-01-01
High-density ceramics with high-strength microstructure were achieved by explosive compaction. Well-characterized Al 2 O 3 , AlN, and boron powders were explosively compacted in both cylindrical and flat plate geometries. In cylindrical geometries compacted densities between 91 and 98 percent of theoretical were achieved. Microhardness measurements indicated that the strength and integrity of the microstructure were comparable to conventionally fabricated ceramics, even though all samples with densities greater than 90 percent theoretical contained macrocracks. Fractured surfaces evaluated by SEM showed evidence of boundary melting. Equation of state data for porous Al 2 O 3 were used to calculate the irreversible work done on the sample as a function of pressure. This was expressed as a percentage of the total sample which could be melted. Calculations show that very little melting can be expected in samples shocked to less than 3 GPa. Significant melting and grain boundary fusion can be expected in samples shocked to pressures greater than 8 GPa. Hydrodynamic modeling of right cylinder compaction with detonation at one end was attempted by using a two-dimensional computer code. The complications of this analysis led to experiments using plane shock waves. Flat-plate compaction assemblies were designed and analyzed by 2-D hydrodynamic codes. The use of porous shock attenuators was evaluated. Experiments were performed on aluminum oxide powders in plane wave geometry. Microstructure evaluations were made as a function of location in the flat plate samples. 11 figures, 1 table
Directory of Open Access Journals (Sweden)
Dalei Jing
2017-07-01
Full Text Available In the present study, a modified Reynolds equation including the electrical double layer (EDL-induced electroviscous effect of lubricant is established to investigate the effect of the EDL on the hydrodynamic lubrication of a 1D slider bearing. The theoretical model is based on the nonlinear Poisson–Boltzmann equation without the use of the Debye–Hückel approximation. Furthermore, the variation in the bulk electrical conductivity of the lubricant under the influence of the EDL is also considered during the theoretical analysis of hydrodynamic lubrication. The results show that the EDL can increase the hydrodynamic load capacity of the lubricant in a 1D slider bearing. More importantly, the hydrodynamic load capacity of the lubricant under the influence of the EDL shows a non-monotonic trend, changing from enhancement to attenuation with a gradual increase in the absolute value of the zeta potential. This non-monotonic hydrodynamic lubrication is dependent on the non-monotonic electroviscous effect of the lubricant generated by the EDL, which is dominated by the non-monotonic electrical field strength and non-monotonic electrical body force on the lubricant. The subject of the paper is the theoretical modeling and the corresponding analysis.
Low torque hydrodynamic lip geometry for bi-directional rotation seals
Dietle, Lannie L [Houston, TX; Schroeder, John E [Richmond, TX
2009-07-21
A hydrodynamically lubricating geometry for the generally circular dynamic sealing lip of rotary seals that are employed to partition a lubricant from an environment. The dynamic sealing lip is provided for establishing compressed sealing engagement with a relatively rotatable surface, and for wedging a film of lubricating fluid into the interface between the dynamic sealing lip and the relatively rotatable surface in response to relative rotation that may occur in the clockwise or the counter-clockwise direction. A wave form incorporating an elongated dimple provides the gradual convergence, efficient impingement angle, and gradual interfacial contact pressure rise that are conducive to efficient hydrodynamic wedging. Skewed elevated contact pressure zones produced by compression edge effects provide for controlled lubricant movement within the dynamic sealing interface between the seal and the relatively rotatable surface, producing enhanced lubrication and low running torque.
Numerical analysis of the texture effect on the hydrodynamic performance of a mechanical seal
Adjemout, M.; Brunetiere, N.; Bouyer, J.
2016-03-01
The purpose of this paper is to analyze the effect of the main geometrical characteristics of texture on the hydrodynamic lubrication of a mechanical seal. A parametric study was carried out in order to improve the performance of a mechanical seal. The numerical model used in this study solves the Reynolds equation coupled with a mass conservative model which takes into account the cavitation phenomenon. It is shown that among the six dimple shapes tested herein, namely cylinder, square, triangle, truncated cone, truncated pyramid, and spherical cap, the triangular dimples placed symmetrically with respect to their bases are more effective for enhancing the hydrodynamic performance of the mechanical seal. The effect of the area and depth ratios is studied and optimized as well. The optimized solution is able to minimize friction and leakage under a range of operating conditions.
Hydrodynamic cavitation: a bottom-up approach to liquid aeration
Raut, J.S.; Stoyanov, S.D.; Duggal, C.; Pelan, E.G.; Arnaudov, L.N.; Naik, V.M.
2012-01-01
We report the use of hydrodynamic cavitation as a novel, bottom-up method for continuous creation of foams comprising of air microbubbles in aqueous systems containing surface active ingredients, like proteins or particles. The hydrodynamic cavitation was created using a converging-diverging nozzle.
Hydrodynamics of ponderomotive interactions in a collisionless plasma
International Nuclear Information System (INIS)
Kono, M.; Skoric, M.M.; ter Haar, D.
1987-01-01
A hydrodynamic treatment of ponderomotive interactions in a collisionless plasma is presented and it is shown that consistent hydrodynamics leads to the correct expression for the solenoidal ponderomotive electron current density, a result previously thought to be derivable only in the framework of the warm-plasma kinetic theory
Three aspects of critical phenomenons: fundamental, hydrodynamic, conceptual
International Nuclear Information System (INIS)
Beysens, D.
1993-01-01
After a recall of the leading results relative to the universality class of fluids, examples of how well known universal prevision are held in check by fluids specificities, especially hydrodynamics. Applications of critical phenomenons tool to damping, hydrodynamic instabilities, turbulence are described. (A.B.). 11 refs., 7 figs., 1 tab
Hydrodynamics of a Multistage Wet Scrubber Incineration Conditions
Said, M. M.; Manyele, S. V.; Raphael, M. L.
2012-01-01
The objective of the study was to determine the hydrodynamics of the two stage counter-current cascade wet scrubbers used during incineration of medical waste. The dependence of the hydrodynamics on two main variables was studied: Inlet air flow rate and inlet liquid flow rate. This study introduces a new wet scrubber operating features, which are…
Behavior of passive admixture in a vortical hydrodynamic field
Bobrov, R.O.; Kyrylyuk, A.V; Zatovsky, A.V.
2006-01-01
The motion of passive admixture of spherical particles in the stationary hydrodynamic field of a swirling flow is studied. A spherical particle of a given mass in the hydrodynamic field of a swirling flow is located on a certain circular orbit, where the centrifugal force is compensated by the
Inami, Toru; Ito, Goshi; Miyazawa, Ken; Tabuchi, Masako; Goto, Shigemi
2018-05-02
This case report demonstrates the treatment of a skeletal Class II high-angle adult patient with bimaxillary protrusion, angle Class I occlusion, and crowded anterior teeth. A ribbon-wise arch wire and a customized lingual appliance with anterior vertical slots were used to achieve proper torque control of the maxillary anterior teeth. An orthodontic anchor screw and a palatal bar were used for vertical control to avoid increasing the Frankfort-mandibular plane angle (FMA) by maxillary molar extrusion. Through the combined use of the ribbon-wise customized lingual appliance, palatal bar, and orthodontic anchor screw, vertical control and an excellent treatment result were achieved without the vertical and horizontal bowing effects peculiar to conventional lingual treatment.
Liu, Qiang; Zhu, Yunkai; Liu, Jianping; Qi, Jun; Kang, Jian
2017-03-01
Intravesical prostatic protrusion (IPP) is a type of benign prostatic hyperplasia (BPH) adenoma, and it plays a critical role in the pathogenesis of bladder outlet obstruction in patients with lower urinary tract syndromes (LUTS/BPH). The goal of this study was to investigate the effect of a combination therapy with finasteride and doxazosin on IPP in BPU/LUTS patients. A total of 322 BPH patients with enlarged prostatic volume as well as moderate to severe symptom scores were enrolled and divided into four groups according to the degree of IPP (IPP > 10 mm, 5-10 mm, 0.05). Failure rates of the medication differed significantly among the four groups. The study indicated that the combination therapy using finasteride and doxazosin could not reduce the degree of IPP. LUTS/BPH patients with IPP which contributes to the failure of medication tend to have a higher risk of progression.
Hydrodynamic Coefficients Identification and Experimental Investigation for an Underwater Vehicle
Directory of Open Access Journals (Sweden)
Shaorong XIE
2014-02-01
Full Text Available Hydrodynamic coefficients are the foundation of unmanned underwater vehicles modeling and controller design. In order to reduce identification complexity and acquire necessary hydrodynamic coefficients for controllers design, the motion of the unmanned underwater vehicle was separated into vertical motion and horizontal motion models. Hydrodynamic coefficients were regarded as mapping parameters from input forces and moments to output velocities and acceleration of the unmanned underwater vehicle. The motion models of the unmanned underwater vehicle were nonlinear and Genetic Algorithm was adopted to identify those hydrodynamic coefficients. To verify the identification quality, velocities and acceleration of the unmanned underwater vehicle was measured using inertial sensor under the same conditions as Genetic Algorithm identification. Curves similarity between measured velocities and acceleration and those identified by Genetic Algorithm were used as optimizing standard. It is found that the curves similarity were high and identified hydrodynamic coefficients of the unmanned underwater vehicle satisfied the measured motion states well.
McClung, J R; Goldberg, S J
2000-12-01
This anatomical investigation in the rat was designed to illustrate the detailed organization of the tongue's muscles and their innervation in order to elucidate the actions of the muscles of the higher mammalian tongue and thereby clarify the protrusor subdivision of the hypoglossal-tongue complex. The hypoglossal innervated, extrinsic styloglossus, hyoglossus, and genioglossus and the intrinsic transversus, verticalis and longitudinalis linguae muscles were observed by microdissection and analysis of serial transverse-sections of the tongue. Sihler's staining technique was applied to whole rat tongues to demonstrate the hypoglossal nerve branching patterns. Dissections of the tongue demonstrate the angles at which the extrinsic muscles act on the base of the tongue. The Sihler stained hypoglossal nerves demonstrate branches to the styloglossus and hyoglossus emanating from its lateral division while branches to the genioglossus muscle exit from its medial division. The largest portions of both XIIth nerve divisions can be seen to enter the body of the tongue to innervate the intrinsic muscles. Transverse sections of the tongue demonstrate the organization of the intrinsic muscle fibers of the tongue. Longitudinal muscle fibers run along the entire circumference of the tongue. Alternating sheets of transverse lingual and vertical lingual muscles can be observed to insert into the circumference of the tongue. Most importantly in clarifying tongue protrusion, we demonstrate the transversus muscle fibers enveloping the most superior and inferior portions of the longitudinalis muscles. Longitudinal muscle fascicles are completely encircled and thus are likely to be compressed by transverse muscle fascicles resulting in elongation of the tongue. We discuss our findings in relation to biomechanical studies, that describe the tongue as a muscular hydrostat and thereby define the "elongation-protrusion apparatus" of the mammalian tongue. In so doing, we clarify the
Microscopic hydrodynamics study with nuclear track membrane
International Nuclear Information System (INIS)
Shilun Guo; Yuhua Zhao; Yulan Wang; Hiuhong Hao; Brandt, R.; Vater, P.
1988-01-01
Microscopic hydrodynamics has been studied using different liquids and nuclear track membranes with pores perpendicularly piercing through them. The flow rate of water and alcohol has been studied with polycarbonate track membranes with pore diameters 1.48 micrometres and 1.08 micrometres. It has been shown that the flow rate both for water and alcohol on a microscopic scale can be determined by the Poiseuille law which characterizes macroscopic laminar flow. The Reynolds number used in macroscopic fluid flow has been calculated from the flow rate and parameters of the liquids and the geometry of the pores. It has been shown that this Reynolds number can also be used to characterize microscopic flow. Based on the above results, the filtration capacity (or limit) of polycarbonate track microfilters for water had been calculated. Some possible limits on the application of the calculation are pointed out and discussed. (author)
Generalized hydrodynamic correlations and fractional memory functions
Rodríguez, Rosalio F.; Fujioka, Jorge
2015-12-01
A fractional generalized hydrodynamic (GH) model of the longitudinal velocity fluctuations correlation, and its associated memory function, for a complex fluid is analyzed. The adiabatic elimination of fast variables introduces memory effects in the transport equations, and the dynamic of the fluctuations is described by a generalized Langevin equation with long-range noise correlations. These features motivate the introduction of Caputo time fractional derivatives and allows us to calculate analytic expressions for the fractional longitudinal velocity correlation function and its associated memory function. Our analysis eliminates a spurious constant term in the non-fractional memory function found in the non-fractional description. It also produces a significantly slower power-law decay of the memory function in the GH regime that reduces to the well-known exponential decay in the non-fractional Navier-Stokes limit.
Hydrodynamic advantages of swimming by salp chains.
Sutherland, Kelly R; Weihs, Daniel
2017-08-01
Salps are marine invertebrates comprising multiple jet-propelled swimming units during a colonial life-cycle stage. Using theory, we show that asynchronous swimming with multiple pulsed jets yields substantial hydrodynamic benefit due to the production of steady swimming velocities, which limit drag. Laboratory comparisons of swimming kinematics of aggregate salps ( Salpa fusiformis and Weelia cylindrica ) using high-speed video supported that asynchronous swimming by aggregates results in a smoother velocity profile and showed that this smoother velocity profile is the result of uncoordinated, asynchronous swimming by individual zooids. In situ flow visualizations of W. cylindrica swimming wakes revealed that another consequence of asynchronous swimming is that fluid interactions between jet wakes are minimized. Although the advantages of multi-jet propulsion have been mentioned elsewhere, this is the first time that the theory has been quantified and the role of asynchronous swimming verified using experimental data from the laboratory and the field. © 2017 The Author(s).
Tears of Venom: Hydrodynamics of Reptilian Envenomation
Young, Bruce A.; Herzog, Florian; Friedel, Paul; Rammensee, Sebastian; Bausch, Andreas; van Hemmen, J. Leo
2011-05-01
In the majority of venomous snakes, and in many other reptiles, venom is conveyed from the animal’s gland to the prey’s tissue through an open groove on the surface of the teeth and not through a tubular fang. Here we focus on two key aspects of the grooved delivery system: the hydrodynamics of venom as it interacts with the groove geometry, and the efficiency of the tooth-groove-venom complex as the tooth penetrates the prey’s tissue. We show that the surface tension of the venom is the driving force underlying the envenomation dynamics. In so doing, we explain not only the efficacy of the open groove, but also the prevalence of this mechanism among reptiles.
Modeling the hydrodynamics of Phloem sieve plates
DEFF Research Database (Denmark)
Jensen, Kaare Hartvig; Mullendore, Daniel Leroy; Holbrook, Noel Michele
2012-01-01
Sieve plates have an enormous impact on the efficiency of the phloem vascular system of plants, responsible for the distribution of photosynthetic products. These thin plates, which separate neighboring phloem cells, are perforated by a large number of tiny sieve pores and are believed to play...... understood. We propose a theoretical model for quantifying the effect of sieve plates on the phloem in the plant, thus unifying and improving previous work in the field. Numerical simulations of the flow in real and idealized phloem channels verify our model, and anatomical data from 19 plant species...... a crucial role in protecting the phloem sap from intruding animals by blocking flow when the phloem cell is damaged. The resistance to the flow of viscous sap in the phloem vascular system is strongly affected by the presence of the sieve plates, but the hydrodynamics of the flow through them remains poorly...
An analytical model of flagellate hydrodynamics
DEFF Research Database (Denmark)
Dölger, Julia; Bohr, Tomas; Andersen, Anders Peter
2017-01-01
solution by Oseen for the low Reynolds number flow due to a point force outside a no-slip sphere. The no-slip sphere represents the cell and the point force a single flagellum. By superposition we are able to model a freely swimming flagellate with several flagella. For biflagellates with left......–right symmetric flagellar arrangements we determine the swimming velocity, and we show that transversal forces due to the periodic movements of the flagella can promote swimming. For a model flagellate with both a longitudinal and a transversal flagellum we determine radius and pitch of the helical swimming......Flagellates are unicellular microswimmers that propel themselves using one or several beating flagella. We consider a hydrodynamic model of flagellates and explore the effect of flagellar arrangement and beat pattern on swimming kinematics and near-cell flow. The model is based on the analytical...
Flow stabilization with active hydrodynamic cloaks.
Urzhumov, Yaroslav A; Smith, David R
2012-11-01
We demonstrate that fluid flow cloaking solutions, based on active hydrodynamic metamaterials, exist for two-dimensional flows past a cylinder in a wide range of Reynolds numbers (Re's), up to approximately 200. Within the framework of the classical Brinkman equation for homogenized porous flow, we demonstrate using two different methods that such cloaked flows can be dynamically stable for Re's in the range of 5-119. The first highly efficient method is based on a linearization of the Brinkman-Navier-Stokes equation and finding the eigenfrequencies of the least stable eigenperturbations; the second method is a direct numerical integration in the time domain. We show that, by suppressing the von Kármán vortex street in the weakly turbulent wake, porous flow cloaks can raise the critical Reynolds number up to about 120 or five times greater than for a bare uncloaked cylinder.
Hydrodynamic Interactions in Active and Passive Matter
Krafnick, Ryan C.
Active matter is present at all biological length scales, from molecular apparatuses interior to cells, to swimming microscopic organisms, to birds, fish, and people. Its properties are varied and its applications diverse, but our understanding of the fundamental driving forces of systems with these constituents remains incomplete. This thesis examines active matter suspensions, exploring the role of hydrodynamic interactions on the unique and emergent properties therein. Both qualitative and quantitative impacts are considered, and care is taken in determining the physical origin of the results in question. It is found that fluid dynamical interactions are fundamentally, qualitatively important, and much of the properties of a system can be explained with an effective energy density defined via the fluid fields arising from the embedded self-propelling entities themselves.
Using river locks to teach hydrodynamic concepts
Carvalho-Santos, Vagson L.; Mendes, Thales C.; Silva, Enisvaldo C.; Rios, Márcio L.; Silva, Anderson A. P.
2013-11-01
In this work, the use of a river lock as a non-formal setting for teaching hydrodynamical concepts is proposed. In particular, we describe the operation of a river lock situated at the Sobradinho dam, on the São Francisco River (Brazil). A model to represent and to analyse the dynamics of river lock operation is presented and we derive the dynamical equations for the rising of the water column as an example to understand the Euler equation. Furthermore, with this activity, we enable the integration of content initially introduced in the classroom with practical applications, thereby allowing the association of physical themes to content relevant in disciplines such as history and geography. In addition, experiences of this kind enable teachers to talk about the environmental and social impacts caused by the construction of a dam and, consequently, a crossover of concepts has been made possible, leading to more meaningful learning for the students.
Hydrodynamics of compressible superfluids in confined geometries
International Nuclear Information System (INIS)
Malmi-Kakkada, Abdul N; Valls, Oriol T; Dasgupta, Chandan
2014-01-01
We present a study of the hydrodynamics of compressible superfluids in confined geometries. We use a perturbative procedure in terms of the dimensionless expansion parameter (v/v s ) 2 where v is the typical speed of the flow and v s is the speed of sound. A zero value of this parameter corresponds to the incompressible limit. We apply the procedure to two specific problems: the case of a trapped superfluid with a Gaussian profile of the local density, and that of a superfluid confined in a rotating obstructed cylinder. We find that the corrections due to finite compressibility which are, as expected, negligible for liquid He, are important but amenable to the perturbative treatment for typical ultracold atomic systems. (paper)
Using river locks to teach hydrodynamic concepts
International Nuclear Information System (INIS)
Carvalho-Santos, Vagson L; Mendes, Thales C; Silva, Enisvaldo C; Rios, Márcio L; Silva, Anderson A P
2013-01-01
In this work, the use of a river lock as a non-formal setting for teaching hydrodynamical concepts is proposed. In particular, we describe the operation of a river lock situated at the Sobradinho dam, on the São Francisco River (Brazil). A model to represent and to analyse the dynamics of river lock operation is presented and we derive the dynamical equations for the rising of the water column as an example to understand the Euler equation. Furthermore, with this activity, we enable the integration of content initially introduced in the classroom with practical applications, thereby allowing the association of physical themes to content relevant in disciplines such as history and geography. In addition, experiences of this kind enable teachers to talk about the environmental and social impacts caused by the construction of a dam and, consequently, a crossover of concepts has been made possible, leading to more meaningful learning for the students. (paper)
Hydrodynamical winds from a geometrically thin disk
International Nuclear Information System (INIS)
Fukue, Jun
1989-01-01
Hydrodynamical winds emanating from the surface of a geometrically thin disk under the gravitational field of the central object are examined. The attention is focused on the transonic nature of the flow. For a given configuration of streamlines, the flow fields are divided into three regions: the inner region where the gas near the disk plane is gravitationally bound to form a corona; the intermediate wind region where multiple critical points appear and the gas flows out from the disk passing through critical points; and the outer region where the gas is unbound to escape to infinity without passing through critical points. This behavior of disk winds is due to the shape of the gravitational potential of the central object along the streamline and due to the energy source distribution at the flow base on the disk plane where the potential in finite. (author)
Hydrodynamics, fields and constants in gravitational theory
International Nuclear Information System (INIS)
Stanyukovich, K.P.; Mel'nikov, V.N.
1983-01-01
Results of original inveatigations into problems of standard gravitation theory and its generalizations are presented. The main attention is paid to the application of methods of continuous media techniques in the gravitation theory; to the specification of the gravitation role in phenomena of macro- and microworld, accurate solutions in the case, when the medium is the matter, assigned by hydrodynamic energy-momentum tensor; and to accurate solutions for the case when the medium is the field. GRT generalizations are analyzed, such as the new cosmologic hypothesis which is based on the gravitation vacuum theory. Investigations are performed into the quantization of cosmological models, effects of spontaneous symmetry violation and particle production in cosmology. Graeity theory with fundamental Higgs field is suggested in the framework of which in the atomic unit number one can explain possible variations of the effective gravitational bonds, and in the gravitation bond, variations of masses of all particles
Hydrodynamic models for slurry bubble column reactors
Energy Technology Data Exchange (ETDEWEB)
Gidaspow, D. [IIT Center, Chicago, IL (United States)
1995-12-31
The objective of this investigation is to convert a {open_quotes}learning gas-solid-liquid{close_quotes} fluidization model into a predictive design model. This model is capable of predicting local gas, liquid and solids hold-ups and the basic flow regimes: the uniform bubbling, the industrially practical churn-turbulent (bubble coalescence) and the slugging regimes. Current reactor models incorrectly assume that the gas and the particle hold-ups (volume fractions) are uniform in the reactor. They must be given in terms of empirical correlations determined under conditions that radically differ from reactor operation. In the proposed hydrodynamic approach these hold-ups are computed from separate phase momentum balances. Furthermore, the kinetic theory approach computes the high slurry viscosities from collisions of the catalyst particles. Thus particle rheology is not an input into the model.
Formulating viscous hydrodynamics for large velocity gradients
International Nuclear Information System (INIS)
Pratt, Scott
2008-01-01
Viscous corrections to relativistic hydrodynamics, which are usually formulated for small velocity gradients, have recently been extended from Navier-Stokes formulations to a class of treatments based on Israel-Stewart equations. Israel-Stewart treatments, which treat the spatial components of the stress-energy tensor τ ij as dynamical objects, introduce new parameters, such as the relaxation times describing nonequilibrium behavior of the elements τ ij . By considering linear response theory and entropy constraints, we show how the additional parameters are related to fluctuations of τ ij . Furthermore, the Israel-Stewart parameters are analyzed for their ability to provide stable and physical solutions for sound waves. Finally, it is shown how these parameters, which are naturally described by correlation functions in real time, might be constrained by lattice calculations, which are based on path-integral formulations in imaginary time
Steady State Thermo-Hydrodynamic Analysis of Two-Axial groove and Multilobe Hydrodynamic Bearings
Directory of Open Access Journals (Sweden)
C. Bhagat
2014-12-01
Full Text Available Steady state thermo-hydrodynamic analysis of two axial groove and multi lobe oil journal bearings is performed in this paper. To study the steady state thermo-hydrodynamic characteristics Reynolds equation is solved simultaneously along with the energy equation and heat conduction equation in bush and shaft. The effect of groove geometry, cavitation in the fluid film, the recirculation of lubricant, shaft speed has also been taken into account. Film temperature in case of three-lobe bearing is found to be high as compared to other studied bearing configurations. The data obtained from this analysis can be used conveniently in the design of such bearings, which are presented in dimensionless form.
Hydrodynamical fluctuations in smooth shear flows
International Nuclear Information System (INIS)
Chagelishvili, G.D.; Khujadze, G.R.; Lominadze, J.G.
1999-11-01
Background of hydrodynamical fluctuations in a intrinsically/stochastically forced, laminar, uniform shear flow is studied. The employment of so-called nonmodal mathematical analysis makes it possible to represent the background of fluctuations in a new light and to get more insight into the physics of its formation. The basic physical processes responsible for the formation of vortex and acoustic wave fluctuation backgrounds are analyzed. Interplay of the processes at low and moderate shear rates is described. Three-dimensional vortex fluctuations around a given macroscopic state are numerically calculated. The correlation functions of the fluctuations of physical quantities are analyzed. It is shown that there exists subspace D k in the wave-number space (k-space) that is limited externally by spherical surface with radius k ν ≡ A/ν (where A is the velocity shear parameter, ν - the kinematic viscosity) in the nonequilibrium open system under study. The spatial Fourier harmonics of vortex as well as acoustic wave fluctuations are strongly subjected by flow shear (by the open character of the system) at wave-numbers satisfying the condition k ν . Specifically it is shown that in D k : The fluctuations are non-Markovian; the spatial spectral density of energy of the vortex fluctuations by far exceeds the white-noise; the term of a new type associated to the hydrodynamical fluctuation of velocity appears in the correlation function of pressure; the fluctuation background of the acoustic waves is completely different at low and moderate shear rates (at low shear rates it is reduced in D k in comparison to the uniform (non-shear) flow; at moderate shear rates it it comparable to the background of the vortex fluctuations). The fluctuation background of both the vortex and the acoustic wave modes is anisotropic. The possible significance of the fluctuation background of vortices for the subcritical transition to turbulence and Brownian motion of small macroscopic
Hydrodynamics of circulating and bubbling fluidized beds
International Nuclear Information System (INIS)
Gidaspow, D.P.; Tsuo, Y.P.; Ding, J.
1991-01-01
This paper reports that a review of modeling of the hydrodynamics of fluidization of bubbling beds showed that inviscid two-fluid models were able to predict a great deal of the behavior of bubbling beds because the dominant mechanism of energy dissipation is the drag between the particles and the fluid. The formation, the growth and the bursting of bubbles were predicted. Predicted wall-to-bed heat transfer coefficients and velocity profiles of jets agreed with measurements. Time average porosity distributions agreed with measurements done using gamma-ray densitometers without the use of any adjustable parameters. However, inviscid models could not correctly predict rates of erosion around tubes immersed into fluidized beds. To correctly model such behavior, granular stresses involving solids viscosity were added into the computer model. This viscosity arises due to random collision of particles. Several models fro this viscosity were investigated and the results compared to measurements of solids distributions in two-dimensional beds and to particle velocities reported in the literature. While in the case of bubbling beds the solids viscosity plays the role of a correction, modeling of a circulating fluidized bed (CFB) without a viscosity is not possible. Recent experimental data obtained at IIT and at IGT show that in CFB the solids viscous dissipation is responsible for as much as half of the pressure drop. From such measurement, solids viscosities were computed. These were used in the two fluid hydrodynamic model, to predict radial solids distributions and solids velocities which matched the experimental distributions. Most important, the model predicted cluster formation and transient internal circulation which is responsible for the favorable characteristics of CFBs, such as good wall-to-bed heat transfer. Video tape movies of computations compared favorably with high speed movies of the experiments
Full sphere hydrodynamic and dynamo benchmarks
Marti, P.
2014-01-26
Convection in planetary cores can generate fluid flow and magnetic fields, and a number of sophisticated codes exist to simulate the dynamic behaviour of such systems. We report on the first community activity to compare numerical results of computer codes designed to calculate fluid flow within a whole sphere. The flows are incompressible and rapidly rotating and the forcing of the flow is either due to thermal convection or due to moving boundaries. All problems defined have solutions that alloweasy comparison, since they are either steady, slowly drifting or perfectly periodic. The first two benchmarks are defined based on uniform internal heating within the sphere under the Boussinesq approximation with boundary conditions that are uniform in temperature and stress-free for the flow. Benchmark 1 is purely hydrodynamic, and has a drifting solution. Benchmark 2 is a magnetohydrodynamic benchmark that can generate oscillatory, purely periodic, flows and magnetic fields. In contrast, Benchmark 3 is a hydrodynamic rotating bubble benchmark using no slip boundary conditions that has a stationary solution. Results from a variety of types of code are reported, including codes that are fully spectral (based on spherical harmonic expansions in angular coordinates and polynomial expansions in radius), mixed spectral and finite difference, finite volume, finite element and also a mixed Fourier-finite element code. There is good agreement between codes. It is found that in Benchmarks 1 and 2, the approximation of a whole sphere problem by a domain that is a spherical shell (a sphere possessing an inner core) does not represent an adequate approximation to the system, since the results differ from whole sphere results. © The Authors 2014. Published by Oxford University Press on behalf of The Royal Astronomical Society.
Variational description of multifluid hydrodynamics: Uncharged fluids
Prix, Reinhard
2004-02-01
We present a formalism for Newtonian multifluid hydrodynamics derived from an unconstrained variational principle. This approach provides a natural way of obtaining the general equations of motion for a wide range of hydrodynamic systems containing an arbitrary number of interacting fluids and superfluids. In addition to spatial variations we use “time shifts” in the variational principle, which allows us to describe dissipative processes with entropy creation, such as chemical reactions, friction or the effects of external non-conservative forces. The resulting framework incorporates the generalization of the entrainment effect originally discussed in the case of the mixture of two superfluids by Andreev and Bashkin. In addition to the conservation of energy and momentum, we derive the generalized conservation laws of vorticity and helicity, and the special case of Ertel’s theorem for the single perfect fluid. We explicitly discuss the application of this framework to thermally conducting fluids, superfluids, and superfluid neutron star matter. The equations governing thermally conducting fluids are found to be more general than the standard description, as the effect of entrainment usually seems to be overlooked in this context. In the case of superfluid 4He we recover the Landau-Khalatnikov equations of the two-fluid model via a translation to the “orthodox” framework of superfluidity, which is based on a rather awkward choice of variables. Our two-fluid model for superfluid neutron star matter allows for dissipation via mutual friction and also “transfusion” via β reactions between the neutron fluid and the proton-electron fluid.
Hydrodynamic role of longitudinal ridges in a leatherback turtle swimming
Bang, Kyeongtae; Kim, Jooha; Lee, Sang-Im; Choi, Haecheon
2015-11-01
The leatherback sea turtle (Dermochelys coriacea), the fastest swimmer and the deepest diver among marine turtles, has five longitudinal ridges on its carapace. These ridges are the most remarkable morphological features distinguished from other marine turtles. To investigate the hydrodynamic role of these ridges in the leatherback turtle swimming, we model a carapace with and without ridges by using three dimensional surface data of a stuffed leatherback turtle in the National Science Museum, Korea. The experiment is conducted in a wind tunnel in the ranges of the real leatherback turtle's Reynolds number (Re) and angle of attack (α). The longitudinal ridges function differently according to the flow condition (i.e. Re and α). At low Re and negative α that represent the swimming condition of hatchlings and juveniles, the ridges significantly decrease the drag by generating streamwise vortices and delaying the main separation. On the other hand, at high Re and positive α that represent the swimming condition of adults, the ridges suppress the laminar separation bubble near the front part by generating streamwise vortices and enhance the lift and lift-to-drag ratio. Supported by the NRF program (2011-0028032).
Response Function of the Crayfish Caudal Photoreceptor to Hydrodynamic Stimuli
Breite, Sally; Bahar, Sonya; Neiman, Alexander; Moss, Frank
2002-03-01
In its abdominal 6th ganglion the crayfish houses 2 light-sensitive neurons (caudal photoreceptors, or CPRs). It is known that these neurons work in tandem with a mechanosensory system of tiny hairs spread across the tailfan, which make synaptic contact with the photoreceptors. A stochastic resonance effect has been shown in this system in which light enhances the transduction of a weak, periodic mechanosensory (hydrodynamic) stimulus. It is not known, however, whether an optimal response from the CPR is induced by a single sine wave cycle or some other waveform. We have experimentally investigated this favorable waveform by driving a tailfan preparation with mechanical 10 Hz correlated Ornstein-Uhlenbeck noise and calculating the response function from the spike-triggered average of the applied noise waveform. We will discuss differences in the shape of the optimal waveform under dark and light conditions, as well as what seems to be a noticeable difference in the magnitude of the animals' response to a noisy stimulus in comparison with a periodic stimulus.
Hydrodynamic studies of CNT nanofluids in helical coil heat exchanger
Babita; Sharma, S. K.; Mital Gupta, Shipra; Kumar, Arinjay
2017-12-01
Helical coils are extensively used in several industrial processes such as refrigeration systems, chemical reactors, recovery processes etc to accommodate a large heat transfer area within a smaller space. Nanofluids are getting great attention due to their enhanced heat transfer capability. In heat transfer equipments, pressure drop is one of the major factors of consideration for pumping power calculations. So, the present work is aimed to study hydrodynamics of CNT nanofluids in helical coils. In this study, pressure drop characteristics of CNT nanofluid flowing inside horizontal helical coils are investigated experimentally. The helical coil to tube diameter was varied from 11.71 to 27.34 keeping pitch of the helical coil constant. Double distilled water was used as basefluid. SDBS and GA surfactants were added to stablilize CNT nanofluids. The volumetric fraction of CNT nanofluid was varied from 0.003 vol% to 0.051 vol%. From the experimental data, it was analyzed that the friction factor in helical coils is greater than that of straight tubes. Concentration of CNT in nanofluids also has a significant influence on the pressure drop/friction factor of helical coils. At a constant concentration of CNT, decreasing helical coil to tube diameter from 27.24 to 11.71, fanning friction factor of helical coil; f c increases for a constant value of p/d t. This increase in the value of fanning friction factor can be attributed to the secondary flow of CNT nanofluid in helical coils.
Hydrodynamic aspects of thrust generation in gymnotiform swimming
Shirgaonkar, Anup A.; Curet, Oscar M.; Patankar, Neelesh A.; Maciver, Malcolm A.
2008-11-01
The primary propulsor in gymnotiform swimmers is a fin running along most of the ventral midline of the fish. The fish propagates traveling waves along this ribbon fin to generate thrust. This unique mode of thrust generation gives these weakly electric fish great maneuverability cluttered spaces. To understand the mechanical basis of gymnotiform propulsion, we investigated the hydrodynamics of a model ribbon-fin of an adult black ghost knifefish using high-resolution numerical experiments. We found that the principal mechanism of thrust generation is a central jet imparting momentum to the fluid with associated vortex rings near the free edge of the fin. The high-fidelity simulations also reveal secondary vortex rings potentially useful in rapid sideways maneuvers. We obtained the scaling of thrust with respect to the traveling wave kinematic parameters. Using a fin-plate model for a fish, we also discuss improvements to Lighthill's inviscid theory for gymnotiform and balistiform modes in terms of thrust magnitude, viscous drag on the body, and momentum enhancement.
Hydrodynamic trails produced by Daphnia: size and energetics.
Wickramarathna, Lalith N; Noss, Christian; Lorke, Andreas
2014-01-01
This study focuses on quantifying hydrodynamic trails produced by freely swimming zooplankton. We combined volumetric tracking of swimming trajectories with planar observations of the flow field induced by Daphnia of different size and swimming in different patterns. Spatial extension of the planar flow field along the trajectories was used to interrogate the dimensions (length and volume) and energetics (dissipation rate of kinetic energy and total dissipated power) of the trails. Our findings demonstrate that neither swimming pattern nor size of the organisms affect the trail width or the dissipation rate. However, we found that the trail volume increases with increasing organism size and swimming velocity, more precisely the trail volume is proportional to the third power of Reynolds number. This increase furthermore results in significantly enhanced total dissipated power at higher Reynolds number. The biggest trail volume observed corresponds to about 500 times the body volume of the largest daphnids. Trail-averaged viscous dissipation rate of the swimming daphnids vary in the range of 1.8 x 10(-6) W/kg to 3.4 x 10(-6) W/kg and the observed magnitudes of total dissipated power between 1.3 x 10(-9) W and 1 x 10(-8) W, respectively. Among other zooplankton species, daphnids display the highest total dissipated power in their trails. These findings are discussed in the context of fluid mixing and transport by organisms swimming at intermediate Reynolds numbers.
Wang, Zhen; Zheng, Yi; Mao, Yu-feng; Wang, Ya-zhou; Yu, Yan-ting; Liu, Hong-ning
2018-03-01
In the disturbance of unsteady flow field under the sea, the monitoring accuracy and precision of the bottom-mounted acoustic monitoring platform will decrease. In order to reduce the hydrodynamic interference, the platform wrapped with fairing structure and separated from the retrieval unit is described. The suppression effect evaluation based on the correlation theory of sound pressure and particle velocity for spherical wave in infinite homogeneous medium is proposed and the difference value between them is used to evaluate the hydrodynamic restraining performance of the bottom-mounted platform under far field condition. Through the sea test, it is indicated that the platform with sparse layers fairing structure (there are two layers for the fairing, in which the inside layer is 6-layers sparse metal net, and the outside layer is 1-layer polyester cloth, and then it takes sparse layers for short) has no attenuation in the sound pressure response to the sound source signal, but obvious suppression in the velocity response to the hydrodynamic noise. The effective frequency of the fairing structure is decreased below 10 Hz, and the noise magnitude is reduced by 10 dB. With the comparison of different fairing structures, it is concluded that the tighter fairing structure can enhance the performance of sound transmission and flow restraining.
Energy Technology Data Exchange (ETDEWEB)
Peralta-Ramos, J., E-mail: jperalta@ift.unesp.b [Instituto de Fisica Teorica, Universidade Estadual Paulista, Rua Doutor Bento Teobaldo Ferraz 271, Bloco II, 01140-070 Sao Paulo (Brazil); Nakwacki, M.S., E-mail: sole@iafe.uba.a [Instituto de Astronomia, Geofisica e Ciencias Atmosfericas, Universidade de Sao Paulo, Rua do Matao 1226, Cidade Universitaria, 05508-090 Sao Paulo (Brazil)
2011-02-01
We calculate the spectra of produced thermal photons in Au + Au collisions taking into account the nonequilibrium contribution to photon production due to finite shear viscosity. The evolution of the fireball is modeled by second-order as well as by divergence-type 2+1 dissipative hydrodynamics, both with an ideal equation of state and with one based on Lattice QCD that includes an analytical crossover. The spectrum calculated in the divergence-type theory is considerably enhanced with respect to the one calculated in the second-order theory, the difference being entirely due to differences in the viscous corrections to photon production. Our results show that the differences in hydrodynamic formalisms are an important source of uncertainty in the extraction of the value of {eta}/s from measured photon spectra. The uncertainty in the value of {eta}/s associated with different hydrodynamic models used to compute thermal photon spectra is larger than the one occurring in matching hadron elliptic flow to RHIC data.
Directory of Open Access Journals (Sweden)
Ling Kang
2017-03-01
Full Text Available Compared to the hydrostatic hydrodynamic model, the non-hydrostatic hydrodynamic model can accurately simulate flows that feature vertical accelerations. The model’s low computational efficiency severely restricts its wider application. This paper proposes a non-hydrostatic hydrodynamic model based on a multithreading parallel computing method. The horizontal momentum equation is obtained by integrating the Navier–Stokes equations from the bottom to the free surface. The vertical momentum equation is approximated by the Keller-box scheme. A two-step method is used to solve the model equations. A parallel strategy based on block decomposition computation is utilized. The original computational domain is subdivided into two subdomains that are physically connected via a virtual boundary technique. Two sub-threads are created and tasked with the computation of the two subdomains. The producer–consumer model and the thread lock technique are used to achieve synchronous communication between sub-threads. The validity of the model was verified by solitary wave propagation experiments over a flat bottom and slope, followed by two sinusoidal wave propagation experiments over submerged breakwater. The parallel computing method proposed here was found to effectively enhance computational efficiency and save 20%–40% computation time compared to serial computing. The parallel acceleration rate and acceleration efficiency are approximately 1.45% and 72%, respectively. The parallel computing method makes a contribution to the popularization of non-hydrostatic models.
Numerical simulations of radiation hydrodynamics and modeling of high temperature hohlraum cavities
International Nuclear Information System (INIS)
Gupta, N.K.; Godwal, B.K.
2003-10-01
A summary of our efforts towards the validation of radiation hydrodynamics and opacity models are presented. Effects of various parameters on the radiation temperature inside an inertial confinement fusion (ICF) hohlraum, the effects of non-local thermodynamic equilibrium conditions on emission and absorption, and the hydrodynamics of aluminium and gold foils driven by radiation are studied. LTE and non-LTE predictions for emitted radiation are compared with the experimental results and it is seen that non-LTE simulations show a marked improvement over LTE results. It is shown that the mixing of two high Z materials can lead to an enhancement in the Rosseland mean. An experimental study of soft x-ray emission from laser-irradiated Au-Cu mix-Z targets confirmed these predictions. It is seen that only multi group non-LTE radiation transport is able to explain experimentally observed features in the conversion efficiency of laser light to x-rays. One group radiation transport under predicts the radiation temperature. It is shown that erroneous results can be obtained if the space mesh in the hohlraum wall is not fine enough. Hydrodynamics of a wedge shaped aluminium foil driven by the hohlraum radiation is also presented and results are compared with NOVA laser experiments. Laser driven shock wave EOS and gold hohlraum experiments carried out at CAT are analyzed and they confirmed our theoretical estimates. (author)
Investigation of the hydrodynamic behavior of diatom aggregates using particle image velocimetry.
Xiao, Feng; Li, Xiaoyan; Lam, Kitming; Wang, Dongsheng
2012-01-01
The hydrodynamic behavior of diatom aggregates has a significant influence on the interactions and flocculation kinetics of algae. However, characterization of the hydrodynamics of diatoms and diatom aggregates in water is rather difficult. In this laboratory study, an advanced visualization technique in particle image velocimetry (PIV) was employed to investigate the hydrodynamic properties of settling diatom aggregates. The experiments were conducted in a settling column filled with a suspension of fluorescent polymeric beads as seed tracers. A laser light sheet was generated by the PIV setup to illuminate a thin vertical planar region in the settling column, while the motions of particles were recorded by a high speed charge-coupled device (CCD) camera. This technique was able to capture the trajectories of the tracers when a diatom aggregate settled through the tracer suspension. The PIV results indicated directly the curvilinear feature of the streamlines around diatom aggregates. The rectilinear collision model largely overestimated the collision areas of the settling particles. Algae aggregates appeared to be highly porous and fractal, which allowed streamlines to penetrate into the aggregate interior. The diatom aggregates have a fluid collection efficiency of 10%-40%. The permeable feature of aggregates can significantly enhance the collisions and flocculation between the aggregates and other small particles including algal cells in water.
On higher order and anisotropic hydrodynamics for Bjorken and Gubser flows
2018-01-01
We study the evolution of hydrodynamic and non-hydrodynamic moments of the distribution function using anisotropic and third-order Chapman-Enskog hydrodynamics for systems undergoing Bjorken and Gubser flows. The hydrodynamic results are compared with the exact solution of the Boltzmann equation with a collision term in relaxation time approximation. While the evolution of the hydrodynamic moments of the distribution function (i.e. of the energy momentum tensor) can be described with high accuracy by both hydrodynamic approximation schemes, their description of the evolution of the entropy of the system is much less precise. We attribute this to large contributions from non-hydrodynamic modes coupling into the entropy evolution which are not well captured by the hydrodynamic approximations. The differences between the exact solution and the hydrodynamic approximations are larger for the third-order Chapman-Enskog hydrodynamics than for anisotropic hydrodynamics, which effectively resums some of the dissipati...
Hydrodynamic suppression of phase separation in active suspensions.
Matas-Navarro, Ricard; Golestanian, Ramin; Liverpool, Tanniemola B; Fielding, Suzanne M
2014-09-01
We simulate with hydrodynamics a suspension of active disks squirming through a Newtonian fluid. We explore numerically the full range of squirmer area fractions from dilute to close packed and show that "motility induced phase separation," which was recently proposed to arise generically in active matter, and which has been seen in simulations of active Brownian disks, is strongly suppressed by hydrodynamic interactions. We give an argument for why this should be the case and support it with counterpart simulations of active Brownian disks in a parameter regime that provides a closer counterpart to hydrodynamic suspensions than in previous studies.
Boltzmann equation and hydrodynamics beyond Navier-Stokes.
Bobylev, A V
2018-04-28
We consider in this paper the problem of derivation and regularization of higher (in Knudsen number) equations of hydrodynamics. The author's approach based on successive changes of hydrodynamic variables is presented in more detail for the Burnett level. The complete theory is briefly discussed for the linearized Boltzmann equation. It is shown that the best results in this case can be obtained by using the 'diagonal' equations of hydrodynamics. Rigorous estimates of accuracy of the Navier-Stokes and Burnett approximations are also presented.This article is part of the theme issue 'Hilbert's sixth problem'. © 2018 The Author(s).
Connection between hydrodynamic, water bag and Vlasov models
International Nuclear Information System (INIS)
Gros, M.; Bertrand, P.; Feix, M.R.
1978-01-01
The connection between hydrodynamic, water bag and Vlasov models is still under consideration with numerical experiments. For long wavelength, slightly non linear excitations and initial preparations such as the usual adiabatic invariant Pn -3 is space independent, the hydrodynamic model is equivalent to the water bag, and for long wavelengths a nice agreement is found with the full numerical solution of the Vlasov equation. For other initial conditions when the water bag cannot be defined, the hydrodynamic approach does not represent the correct behaviour. (author)
Dynamic structurization in solutions of hydrodynamically active polymers
International Nuclear Information System (INIS)
Pogrebnyak, V.G.; Tverdokhleb, S.V.; Naumchuk, N.V.
1993-01-01
The processes of ordering and self-regulation in nonlinear systems have attracted great attention because understanding the principles of self-regulation and its thermodynamics can become a clue to many physical phenomena. In this work, it is experimentally established that, under the condition of elongational flows, dynamic structurization and periodic processes may originate in the solutions of flexible, hydrodynamically-active polymers due to self-regulation in these systems. The hydrodynamic elongational field was created using the flow of a Newtonian liquid (water, acetone, dioxane) converging to a small opening. The hydrodynamically-active polymers were polyethylene oxide or hydrolyzed polyacrylamide
Numerical Analysis of Combined Valve Hydrodynamic Characteristics for Turbine System
Energy Technology Data Exchange (ETDEWEB)
Bhowmik, P. K.; Shamim, J. A.; Gairola, A.; Arif, M.; Suh, Kune Y. [Seoul National Univ., Seoul (Korea, Republic of)
2014-05-15
Flow characteristic curves are plotted by calculating the ratio of the measured mass flow rate versus the theoretical mass flow rate. The flow characteristic curves are utilized to accurately test the performance of the control valve of turbine system to ensure the highest controllability and reliability of the power conversion system of large and small power plants. Turbine converts the kinetic energy of steam to mechanical energy of rotor blades in power conversion system. The electrical energy output from the generator of which the rotor is coupled with that of the turbine depends on the rotation velocity of the turbine bucket. The rotation velocity is proportional to the mass flow rate (steam or gas) to the turbine through valves and nozzles. The turbine comprises fast acting governing control valves and stop valves acting against the seat in the flow passage in the closed position. The turbine control valve regulates the mass flow rate entering the first nozzle of a turbine. The main function of stop valve is to close the fluid inlet rapidly in response to a fast close signal to swiftly cut off the flow through the valve inlet. Both these valves contribute attractively to improvement of the power system transient stability as well. To improve the efficiency of power conversion system many investigation have been done by researcher by focusing on the cycle layout or working fluid or by improving the flow path of the working fluid. The main focus is to find out the best option for combined cycle power plant by analyzing four different cycle configuration. Next research phase focused on different way to enhance the cycle efficiency. As the electrical power output from the generator is proportional to the mass flow rate to the turbine through the valve, it should preferably operate linearly. In reality, however, the valve has the various flow characteristics pursuant to the stem lift. Thus, the flow characteristic and control performance are needed to be designed
Numerical Analysis of Combined Valve Hydrodynamic Characteristics for Turbine System
International Nuclear Information System (INIS)
Bhowmik, P. K.; Shamim, J. A.; Gairola, A.; Arif, M.; Suh, Kune Y.
2014-01-01
Flow characteristic curves are plotted by calculating the ratio of the measured mass flow rate versus the theoretical mass flow rate. The flow characteristic curves are utilized to accurately test the performance of the control valve of turbine system to ensure the highest controllability and reliability of the power conversion system of large and small power plants. Turbine converts the kinetic energy of steam to mechanical energy of rotor blades in power conversion system. The electrical energy output from the generator of which the rotor is coupled with that of the turbine depends on the rotation velocity of the turbine bucket. The rotation velocity is proportional to the mass flow rate (steam or gas) to the turbine through valves and nozzles. The turbine comprises fast acting governing control valves and stop valves acting against the seat in the flow passage in the closed position. The turbine control valve regulates the mass flow rate entering the first nozzle of a turbine. The main function of stop valve is to close the fluid inlet rapidly in response to a fast close signal to swiftly cut off the flow through the valve inlet. Both these valves contribute attractively to improvement of the power system transient stability as well. To improve the efficiency of power conversion system many investigation have been done by researcher by focusing on the cycle layout or working fluid or by improving the flow path of the working fluid. The main focus is to find out the best option for combined cycle power plant by analyzing four different cycle configuration. Next research phase focused on different way to enhance the cycle efficiency. As the electrical power output from the generator is proportional to the mass flow rate to the turbine through the valve, it should preferably operate linearly. In reality, however, the valve has the various flow characteristics pursuant to the stem lift. Thus, the flow characteristic and control performance are needed to be designed
Onsager and the theory of hydrodynamic turbulence
International Nuclear Information System (INIS)
Eyink, Gregory L.; Sreenivasan, Katepalli R.
2006-12-01
Lars Onsager, a giant of twentieth-century science and the 1968 Nobel Laureate in Chemistry, made deep contributions to several areas of physics and chemistry. Perhaps less well known is his ground-breaking work and lifelong interest in the subject of hydrodynamic turbulence. He wrote two papers on the subject in the 1940s, one of them just a short abstract. Unbeknownst to Onsager, one of his major results was derived a few years earlier by A. N. Kolmogorov, but Onsager's work contains many gems and shows characteristic originality and deep understanding. His only full-length article on the subject in 1949 introduced two novel ideas - negative-temperature equilibria for two-dimensional ideal fluids and an energy-dissipation anomaly for singular Euler solutions - that stimulated much later work. However, a study of Onsager's letters to his peers around that time, as well as his private papers of that period and the early 1970s, shows that he had much more to say about the problem than he published. Remarkably, his private notes of the 1940s contain the essential elements of at least four major results that appeared decades later in the literature: (1) a mean-field Poisson-Boltzmann equation and other thermodynamic relations for point vortices; (2) a relation similar to Kolmogorov's 4/5 law connecting singularities and dissipation; (3) the modern physical picture of spatial intermittency of velocity increments, explaining anomalous scaling of the spectrum; and (4) a spectral turbulence closure quite similar to the modern eddy-damped quasinormal Markovian equations. This paper is a summary of Onsager's published and unpublished contributions to hydrodynamic turbulence and an account of their place in the field as the subject has evolved through the years. A discussion is also given of the historical context of the work, especially of Onsager's interactions with his contemporaries who were acknowledged experts in the subject at the time. Finally, a brief speculation is
Stark, J.; Smolders, S.; Meire, P.; Temmerman, S.
2017-11-01
Marsh restoration projects are nowadays being implemented as ecosystem-based strategies to reduce flood risks and to restore intertidal habitat along estuaries. Changes in estuarine tidal hydrodynamics are expected along with such intertidal area changes. A validated hydrodynamic model of the Scheldt Estuary is used to gain fundamental insights in the role of intertidal area characteristics on tidal hydrodynamics and tidal asymmetry in particular through several geomorphological scenarios in which intertidal area elevation and location along the estuary is varied. Model results indicate that the location of intertidal areas and their storage volume relative to the local tidal prism determine the intensity and reach along the estuary over which tidal hydrodynamics are affected. Our model results also suggest that intertidal storage areas that are located within the main estuarine channel system, and hence are part of the flow-carrying part of the estuary, may affect tidal hydrodynamics differently than intertidal areas that are side-basins of the main estuarine channel, and hence only contribute little to the flow-carrying cross-section of the estuary. If tidal flats contribute to the channel cross-section and exert frictional effects on the tidal propagation, the elevation of intertidal flats influences the magnitude and direction of tidal asymmetry along estuarine channels. Ebb-dominance is most strongly enhanced if tidal flats are around mean sea level or slightly above. Conversely, flood-dominance is enhanced if the tidal flats are situated low in the tidal frame. For intertidal storage areas at specific locations besides the main channel, flood-dominance in the estuary channel peaks in the vicinity of those areas and generally reduces upstream and downstream compared to a reference scenario. Finally, the model results indicate an along-estuary varying impact on the tidal prism as a result of adding intertidal storage at a specific location. In addition to known
A hydrodynamic model for cooperating solidary countries
De Luca, Roberto; Di Mauro, Marco; Falzarano, Angelo; Naddeo, Adele
2017-07-01
The goal of international trade theories is to explain the exchange of goods and services between different countries, aiming to benefit from it. Albeit the idea is very simple and known since ancient history, smart policy and business strategies need to be implemented by each subject, resulting in a complex as well as not obvious interplay. In order to understand such a complexity, different theories have been developed since the sixteenth century and today new ideas still continue to enter the game. Among them, the so called classical theories are country-based and range from Absolute and Comparative Advantage theories by A. Smith and D. Ricardo to Factor Proportions theory by E. Heckscher and B. Ohlin. In this work we build a simple hydrodynamic model, able to reproduce the main conclusions of Comparative Advantage theory in its simplest setup, i.e. a two-country world with country A and country B exchanging two goods within a genuine exchange-based economy and a trade flow ruled only by market forces. The model is further generalized by introducing money in order to discuss its role in shaping trade patterns. Advantages and drawbacks of the model are also discussed together with perspectives for its improvement.
Relativistic hydrodynamic evolutions with black hole excision
International Nuclear Information System (INIS)
Duez, Matthew D.; Shapiro, Stuart L.; Yo, H.-J.
2004-01-01
We present a numerical code designed to study astrophysical phenomena involving dynamical spacetimes containing black holes in the presence of relativistic hydrodynamic matter. We present evolutions of the collapse of a fluid star from the onset of collapse to the settling of the resulting black hole to a final stationary state. In order to evolve stably after the black hole forms, we excise a region inside the hole before a singularity is encountered. This excision region is introduced after the appearance of an apparent horizon, but while a significant amount of matter remains outside the hole. We test our code by evolving accurately a vacuum Schwarzschild black hole, a relativistic Bondi accretion flow onto a black hole, Oppenheimer-Snyder dust collapse, and the collapse of nonrotating and rotating stars. These systems are tracked reliably for hundreds of M following excision, where M is the mass of the black hole. We perform these tests both in axisymmetry and in full 3+1 dimensions. We then apply our code to study the effect of the stellar spin parameter J/M 2 on the final outcome of gravitational collapse of rapidly rotating n=1 polytropes. We find that a black hole forms only if J/M 2 2 >1, the collapsing star forms a torus which fragments into nonaxisymmetric clumps, capable of generating appreciable 'splash' gravitational radiation
Interface tracking for 2D hydrodynamics
International Nuclear Information System (INIS)
Bezard, Fabienne
1997-01-01
The aim of this work is to explore new methods to numerically simulate the evolution of interfaces between immiscible fluids in the context of the dynamics of compressible and non-viscous fluids. The methods currently available, to our knowledge, to deal with this type of problem are based on the Lagrange coordinates (that is to say, that follow the material in its displacements) or on the Euler coordinates (fixed during the time). In the case of Eulerian coordinates, the simplest methods involve so-called 'mixing' meshes (that is, containing several fluids). The study that is presented is based on an Eulerian method with Lagrangian interface tracking. This avoids the introduction of any model of mesh of mixture. This method combines some advantages of the previously mentioned methods, notably the precision of the Lagrangian follow-up and the robustness of the Eulerian schemes. This report describes only the algorithms of displacement and regularization of the interface, by clearly presenting the geometry around the interface. These algorithms will then be coupled with the resolution of two-dimensional hydrodynamic equations to solve multi-fluid problems. Some numerical results are proposed to illustrate the good behavior of the interface tracking algorithm [fr
Hydrodynamic excitations in hot QCD plasma
Abbasi, Navid; Allahbakhshi, Davood; Davody, Ali; Taghavi, Seyed Farid
2017-12-01
We study the long wavelength excitations in rotating QCD fluid in the presence of an external magnetic field at finite vector and axial charge densities. We consider the fluctuations of vector and axial charge currents coupled to energy and momentum fluctuations and compute the S O (3 ) covariant dispersion relations of the six corresponding hydrodynamic modes. Among them, there are always two scalar chiral-magnetic-vortical-heat (CMVH) waves; in the absence of a magnetic field (vorticity) these waves reduce to chiral-vortical-heat (CVH) [chiral-magnetic-heat (CMH)] waves. While CMVH waves are a mixture of CMH and CVH waves, they have generally different velocities compared to the sum of velocities of the latter waves. The other four modes, which are made out of scalar-vector fluctuations, are mixed sound-Alfvén waves. We show that when the magnetic field is parallel with the vorticity, these four modes are the two ordinary sound modes together with two chiral Alfvén waves propagating along the common direction of the magnetic field and vorticity.
An analytical model of flagellate hydrodynamics
International Nuclear Information System (INIS)
Dölger, Julia; Bohr, Tomas; Andersen, Anders
2017-01-01
Flagellates are unicellular microswimmers that propel themselves using one or several beating flagella. We consider a hydrodynamic model of flagellates and explore the effect of flagellar arrangement and beat pattern on swimming kinematics and near-cell flow. The model is based on the analytical solution by Oseen for the low Reynolds number flow due to a point force outside a no-slip sphere. The no-slip sphere represents the cell and the point force a single flagellum. By superposition we are able to model a freely swimming flagellate with several flagella. For biflagellates with left–right symmetric flagellar arrangements we determine the swimming velocity, and we show that transversal forces due to the periodic movements of the flagella can promote swimming. For a model flagellate with both a longitudinal and a transversal flagellum we determine radius and pitch of the helical swimming trajectory. We find that the longitudinal flagellum is responsible for the average translational motion whereas the transversal flagellum governs the rotational motion. Finally, we show that the transversal flagellum can lead to strong feeding currents to localized capture sites on the cell surface. (paper)
Modeling the hydrodynamics of phloem sieve plates
Directory of Open Access Journals (Sweden)
Kaare Hartvig Jensen
2012-07-01
Full Text Available Sieve plates have an enormous impact on the efficiency of the phloem vascular system of plants, responsible for the distribution of photosynthetic products. These thin plates, which separate neighboring phloem cells, are perforated by a large number of tiny sieve pores and are believed to play a crucial role in protecting the phloem sap from intruding animals by blocking flow when the phloem cell is damaged. The resistance to the flow of viscous sap in the phloem vascular system is strongly affected by the presence of the sieve plates, but the hydrodynamics of the flow through them remains poorly understood. We propose a theoretical model for quantifying the effect of sieve plates on the phloem in the plant, thus unifying and improving previous work in the field. Numerical simulations of the flow in real and idealized phloem channels verify our model, and anatomical data from 19 plant species are investigated. We find that the sieve plate resistance is correlated to the cell lumen resistance, and that the sieve plate and the lumen contribute almost equally to the total hydraulic resistance of the phloem translocation pathway.
Modeling hydrodynamic effects on choanoflagellate feeding
Oakes, Christian; Hguyen, Hoa; Koehl, Mimi; Fauci, Lisa
2017-11-01
Choanoflagellates are unicellular organisms whose intriguing morphology includes a set of collars/microvilli emanating from the cell body, surrounding the beating flagellum. As the closest living relative to animals, they are important for both ecological and evolutionary studies. Choanoflagellates have three unicellular types: slow swimmers, fast swimmers, and thecate (attached to a surface by a stalk). Each has different morphology and feeding rate. We use the method of regularized Stokeslets to simulate cell-fluid interactions of each type and show the hydrodynamic effects on the amount and directions of fluid flow toward the collar. After validating the swimming speeds of our models with experimental data, we calculate the rate of flow across a capture zone around the collar (flux). This sheds light on how each morphological aspect of the cell aids in bacteria capture during feeding. Among the three types, the thecate cells have the largest average flux values, implying that they take advantage of the nearby surface by creating eddies that draw bacteria into their collar for ingestion. Funding Source: FASTER Grant SURF `` National Science Foundation DUE S-STEM Award 1153796, Mach Fellowship.
A geometric viewpoint on generalized hydrodynamics
Directory of Open Access Journals (Sweden)
Benjamin Doyon
2018-01-01
Full Text Available Generalized hydrodynamics (GHD is a large-scale theory for the dynamics of many-body integrable systems. It consists of an infinite set of conservation laws for quasi-particles traveling with effective (“dressed” velocities that depend on the local state. We show that these equations can be recast into a geometric dynamical problem. They are conservation equations with state-independent quasi-particle velocities, in a space equipped with a family of metrics, parametrized by the quasi-particles' type and speed, that depend on the local state. In the classical hard rod or soliton gas picture, these metrics measure the free length of space as perceived by quasi-particles; in the quantum picture, they weigh space with the density of states available to them. Using this geometric construction, we find a general solution to the initial value problem of GHD, in terms of a set of integral equations where time appears explicitly. These integral equations are solvable by iteration and provide an extremely efficient solution algorithm for GHD.
An implicit Smooth Particle Hydrodynamic code
Energy Technology Data Exchange (ETDEWEB)
Knapp, Charles E. [Univ. of New Mexico, Albuquerque, NM (United States)
2000-05-01
An implicit version of the Smooth Particle Hydrodynamic (SPH) code SPHINX has been written and is working. In conjunction with the SPHINX code the new implicit code models fluids and solids under a wide range of conditions. SPH codes are Lagrangian, meshless and use particles to model the fluids and solids. The implicit code makes use of the Krylov iterative techniques for solving large linear-systems and a Newton-Raphson method for non-linear corrections. It uses numerical derivatives to construct the Jacobian matrix. It uses sparse techniques to save on memory storage and to reduce the amount of computation. It is believed that this is the first implicit SPH code to use Newton-Krylov techniques, and is also the first implicit SPH code to model solids. A description of SPH and the techniques used in the implicit code are presented. Then, the results of a number of tests cases are discussed, which include a shock tube problem, a Rayleigh-Taylor problem, a breaking dam problem, and a single jet of gas problem. The results are shown to be in very good agreement with analytic solutions, experimental results, and the explicit SPHINX code. In the case of the single jet of gas case it has been demonstrated that the implicit code can do a problem in much shorter time than the explicit code. The problem was, however, very unphysical, but it does demonstrate the potential of the implicit code. It is a first step toward a useful implicit SPH code.
The hydrodynamics of Type II supernove
International Nuclear Information System (INIS)
Chevalier, R.A.
1976-01-01
Observations of Type II supernovae indicate the presence of a moderately cool expanding photosphere. This situation can result from an explosion in a star with an extended envelope. The evolutionary phases of an explosion are described. Information on the propagation of the shock wave through the star can be obtained from γ=4/3 blast wave solutions. If the photon mean free path becomes large compared to the length scales of the flow, a thermal wave moves out from the shock wave and a dense shell is formed behind the shock. The arrival of the shock wave at the photosphere is accompanied by ultraviolet and X-ray burst. As the star expands, a rarefaction wave converts internal energy into kinetic energy. Detailed hydrodynamic models have been calculated, assuming an initial radius compatible with stellar evolution and an energy compatible with the observed velocities. The observed values of photospheric radius and temperature near maximum light are reproduced. Features of the models which are consistent with observation are: the ejection of a detached shell; the cooling of the photosphere from 10,000 K to 6000 K in tens of days after maximum visual light; the shape of the light curve around maximum; the decrease in the velocity of the gas at the photosphere in tens of days after maximum; and a photospheric radius of about 10/sup 14/ cm after several hundred days
Toroidal plasmoid generation via extreme hydrodynamic shear.
Gharib, Morteza; Mendoza, Sean; Rosenfeld, Moshe; Beizai, Masoud; Alves Pereira, Francisco J
2017-11-28
Saint Elmo's fire and lightning are two known forms of naturally occurring atmospheric pressure plasmas. As a technology, nonthermal plasmas are induced from artificially created electromagnetic or electrostatic fields. Here we report the observation of arguably a unique case of a naturally formed such plasma, created in air at room temperature without external electromagnetic action, by impinging a high-speed microjet of deionized water on a dielectric solid surface. We demonstrate that tribo-electrification from extreme and focused hydrodynamic shear is the driving mechanism for the generation of energetic free electrons. Air ionization results in a plasma that, unlike the general family, is topologically well defined in the form of a coherent toroidal structure. Possibly confined through its self-induced electromagnetic field, this plasmoid is shown to emit strong luminescence and discrete-frequency radio waves. Our experimental study suggests the discovery of a unique platform to support experimentation in low-temperature plasma science. Copyright © 2017 the Author(s). Published by PNAS.
Hydrodynamics of vertical jumping in Archer fish
Techet, Alexandra H.; Mendelson, Leah
2017-11-01
Vertical jumping for aerial prey from an aquatic environment requires both propulsive power and precise aim to succeed. Rapid acceleration to a ballistic velocity sufficient for reaching the prey height occurs before the fish leaves the water completely and experiences a thousandfold drop in force-producing ability. In addition to speed, accuracy and stability are crucial for successful feeding by jumping. This talk examines the physics of jumping using the archer fish as a model. Better known for their spitting abilities, archer fish will jump multiple body lengths out of the water for prey capture, from a stationary position just below the free surface. Modulation of oscillatory body kinematics and use of multiple fins for force production are identified as methods through which the fish can meet requirements for both acceleration and stabilization in limited space. Quantitative 3D PIV wake measurements reveal how variations in tail kinematics relate to thrust production throughout the course of a jumping maneuver and over a range of jump heights. By performing measurements in 3D, the timing, interactions, and relative contributions to thrust and lateral forces from each fin can be evaluated, elucidating the complex hydrodynamics that enable archer fish water exit.
Code Differentiation for Hydrodynamic Model Optimization
Energy Technology Data Exchange (ETDEWEB)
Henninger, R.J.; Maudlin, P.J.
1999-06-27
Use of a hydrodynamics code for experimental data fitting purposes (an optimization problem) requires information about how a computed result changes when the model parameters change. These so-called sensitivities provide the gradient that determines the search direction for modifying the parameters to find an optimal result. Here, the authors apply code-based automatic differentiation (AD) techniques applied in the forward and adjoint modes to two problems with 12 parameters to obtain these gradients and compare the computational efficiency and accuracy of the various methods. They fit the pressure trace from a one-dimensional flyer-plate experiment and examine the accuracy for a two-dimensional jet-formation problem. For the flyer-plate experiment, the adjoint mode requires similar or less computer time than the forward methods. Additional parameters will not change the adjoint mode run time appreciably, which is a distinct advantage for this method. Obtaining ''accurate'' sensitivities for the j et problem parameters remains problematic.
A new lattice hydrodynamic traffic flow model with a consideration of multi-anticipation effect
International Nuclear Information System (INIS)
Tian Chuan; Sun Di-Hua; Yang Shu-Hong
2011-01-01
We present a new multi-anticipation lattice hydrodynamic model based on the traffic anticipation effect in the real world. Applying the linear stability theory, we obtain the linear stability condition of the model. Through nonlinear analysis, we derive the modified Korteweg-de Vries equation to describe the propagating behaviour of a traffic density wave near the critical point. The good agreement between the simulation results and the analytical results shows that the stability of traffic flow can be enhanced when the multi-anticipation effect is considered. (interdisciplinary physics and related areas of science and technology)
Hydrodynamic potentials for the micropolar Navier-Stokes problem
International Nuclear Information System (INIS)
Martynenko, M.D.; Dimian, M.
1995-01-01
An integral representation of linear and angular velocities and pressure for the description of linear stationary flows of micropolar viscous liquid media is obtained, and on its basis hydrodynamic potentials for the micropolar Navier-Stokes problem are introduced
The effect of hydrodynamics on nitrogen accumulation and ...
African Journals Online (AJOL)
STORAGESEVER
2008-07-18
Jul 18, 2008 ... Natural water hydrodynamic conditions play an important role in the nutrients transport among water, ... stress inhibition, while Chl a and b appeared to be a little synthesized in the S flume. ..... accounting for 48.1% increase.
New theories of relativistic hydrodynamics in the LHC era
Florkowski, Wojciech; Heller, Michal P.; Spaliński, Michał
2018-04-01
The success of relativistic hydrodynamics as an essential part of the phenomenological description of heavy-ion collisions at RHIC and the LHC has motivated a significant body of theoretical work concerning its fundamental aspects. Our review presents these developments from the perspective of the underlying microscopic physics, using the language of quantum field theory, relativistic kinetic theory, and holography. We discuss the gradient expansion, the phenomenon of hydrodynamization, as well as several models of hydrodynamic evolution equations, highlighting the interplay between collective long-lived and transient modes in relativistic matter. Our aim to provide a unified presentation of this vast subject—which is naturally expressed in diverse mathematical languages—has also led us to include several new results on the large-order behaviour of the hydrodynamic gradient expansion.
Numerical Ship Hydrodynamics: An Assessment of the Gothenburg 2010 Workshop
National Research Council Canada - National Science Library
Larsson, Lars; Stern, Frederick (Professor of engineering); Visonneau, Michel
2014-01-01
"This book assesses the state-of-the-art in computational fluid dynamics (CFD) applied to ship hydrodynamics and provides guidelines for the future developments in the field based on the Gothenburg 2010 Workshop...
Flow hydrodynamics near inlet key of Piano Key Weir (PKW)
Indian Academy of Sciences (India)
Department of Water Resources Development and Management, Indian Institute ... on the hydrodynamic performance near inlet key of Piano Key Weir (PKW). ... nature of flows is clearly understood with the help of advanced instrumentation.
Viscosity and Vorticity in Reduced Magneto-Hydrodynamics
Energy Technology Data Exchange (ETDEWEB)
Joseph, Ilon [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2015-08-12
Magneto-hydrodynamics (MHD) critically relies on viscous forces in order for an accurate determination of the electric eld. For each charged particle species, the Braginskii viscous tensor for a magnetized plasma has the decomposition into matrices with special symmetries.
HYDRODYNAMICS OF OSCILLATING WING ON THE PITCH ANGLE
Directory of Open Access Journals (Sweden)
Vitalii Korobov
2017-07-01
Full Text Available Purpose: research of the hydrodynamic characteristics of a wing in a nonstationary stream. Methods: The experimental studies of the hydrodynamic load acting on the wing of 1.5 elongation, wich harmonically oscillated respect to the transversal axis in the frequency range of 0.2-2.5 Hz. The flow speed in the hydrodynamic tunnel ranged of 0.2-1.5 m/s. Results: The instantaneous values of the coefficients of lift and drag / thrust on the pitch angle at unsteady flow depends on the Strouhal number.Discussion: with increasing oscillation frequency coefficients of hydrodynamic force components significantly higher than the data for the stationary blowing out of the wing.
Local anisotropy effects in the hydrodynamical theory of multiparticle production
International Nuclear Information System (INIS)
Gorenstein, M.I.; Sinyukov, Yu.M.
1984-01-01
The stage of secondary particle formation in the hydrodynamic theory of multiparticle production is analysed. We find out that the secondary particle spectrum of the fluid element decay is anisotropic in the rest frame system of this element. (orig.)
Hydrodynamic control of microphytoplankton bloom in a coastal sea
Indian Academy of Sciences (India)
Hydrodynamic control of microphytoplankton bloom in a coastal sea ... many times more than what could be accounted for by solar insolation and nutrient levels. ... and stable water column and weak winds left undisturbed, the transient bloom.
Local anisotropy effects in the hydrodynamical theory of multiparticle production
International Nuclear Information System (INIS)
Gorenshtejn, M.I.; Sinyukov, Yu.M.
1983-01-01
The stage of final particle formation in the hydrodynamic theory of multiparticle production is analysed. It is shown, that secondary particle spectrum of the fluid element decay to be anisotropic in the rest frame system of this element
Hydrodynamical model based on a bag-like Lagrangian
International Nuclear Information System (INIS)
Chiu, C.B.; Lam, C.S.; Wang, K.H.
1976-06-01
Equations of motion of hydrodynamical model are derived from a bag-like Lagrangian by using the technique of information theory. Comments on the break-up of the system and on the properties of decay products are included
Hydrodynamic analysis application of contaminated groundwater remediation to oil hydrocarbons
Pajić Predrag R.; Čalenić Aleksandar I.; Polomčić Dušan M.; Bajić Dragoljub I.
2017-01-01
In this paper, the application of the hydrodynamic analysis in the selected ‘pumping and treatment’ remediation method of groundwater hydrocarbon pollution in the case of the Pancevo oil refinery is examined. The applied hydrodynamic analysis represents a regular and necessary approach in modern hydrogeology. Previous chemical analysis of soil and groundwater samples at observation objects revealed their pollution by oil products. New researches included the constraction of 12 piezometric bor...
Hydrodynamics automatic optimization of runner blades for reaction hydraulic turbines
Balint, D.; Câmpian, V.; Nedelcu, D.; Megheles, O.
2012-11-01
The aim of this paper is to optimize the hydrodynamics of the runner blades of hydraulic turbines. The runner presented is an axial Kaplan one, but the methodology is common also to Francis runners. The whole methodology is implemented in the in-house software QTurbo3D. The effect of the runner blades geometry modification upon its hydrodynamics is shown both from energetic and cavitation points of view.
Hydrodynamics automatic optimization of runner blades for reaction hydraulic turbines
International Nuclear Information System (INIS)
Balint, D; Câmpian, V; Nedelcu, D; Megheles, O
2012-01-01
The aim of this paper is to optimize the hydrodynamics of the runner blades of hydraulic turbines. The runner presented is an axial Kaplan one, but the methodology is common also to Francis runners. The whole methodology is implemented in the in-house software QTurbo3D. The effect of the runner blades geometry modification upon its hydrodynamics is shown both from energetic and cavitation points of view.
Kubo Formulas for Second-Order Hydrodynamic Coefficients
International Nuclear Information System (INIS)
Moore, Guy D.; Sohrabi, Kiyoumars A.
2011-01-01
At second order in gradients, conformal relativistic hydrodynamics depends on the viscosity η and on five additional ''second-order'' hydrodynamical coefficients τ Π , κ, λ 1 , λ 2 , and λ 3 . We derive Kubo relations for these coefficients, relating them to equilibrium, fully retarded three-point correlation functions of the stress tensor. We show that the coefficient λ 3 can be evaluated directly by Euclidean means and does not in general vanish.
Kerr, James R; Manes, Costantino; Kemp, Paul S
2016-11-01
It is commonly assumed that stream-dwelling fish should select positions where they can reduce energetic costs relative to benefits gained and enhance fitness. However, the selection of appropriate hydrodynamic metrics that predict space use is the subject of recent debate and a cause of controversy. This is for three reasons: (1) flow characteristics are often oversimplified, (2) confounding variables are not always controlled and (3) there is limited understanding of the explanatory mechanisms that underpin the biophysical interactions between fish and their hydrodynamic environment. This study investigated the space use of brown trout, Salmo trutta, in a complex hydrodynamic flow field created using an array of different sized vertically oriented cylinders in a large open-channel flume in which confounding variables were controlled. A hydrodynamic drag function (D) based on single-point time-averaged velocity statistics that incorporates the influence of turbulent fluctuations was used to infer the energetic cost of steady swimming. Novel hydrodynamic preference curves were developed and used to assess the appropriateness of D as a descriptor of space use compared with other commonly used metrics. Zones in which performance-enhancing swimming behaviours (e.g. Kármán gaiting, entraining and bow riding) that enable fish to hold position while reducing energetic costs (termed 'specialised behaviours') were identified and occupancy was recorded. We demonstrate that energy conservation strategies play a key role in space use in an energetically taxing environment with the majority of trout groups choosing to frequently occupy areas in which specialised behaviours may be adopted or by selecting low-drag regions. © 2016. Published by The Company of Biologists Ltd.
International Nuclear Information System (INIS)
Srinivasan, Bhuvana; Tang, Xian-Zhu
2014-01-01
In an inertial confinement fusion target, energy loss due to thermal conduction from the hot-spot will inevitably ablate fuel ice into the hot-spot, resulting in a more massive but cooler hot-spot, which negatively impacts fusion yield. Hydrodynamic mix due to Rayleigh-Taylor instability at the gas-ice interface can aggravate the problem via an increased gas-ice interfacial area across which energy transfer from the hot-spot and ice can be enhanced. Here, this mix-enhanced transport effect on hot-spot fusion-performance degradation is quantified using contrasting 1D and 2D hydrodynamic simulations, and its dependence on effective acceleration, Atwood number, and ablation speed is identified
Use of hydrodynamic cavitation in (waste)water treatment.
Dular, Matevž; Griessler-Bulc, Tjaša; Gutierrez-Aguirre, Ion; Heath, Ester; Kosjek, Tina; Krivograd Klemenčič, Aleksandra; Oder, Martina; Petkovšek, Martin; Rački, Nejc; Ravnikar, Maja; Šarc, Andrej; Širok, Brane; Zupanc, Mojca; Žitnik, Miha; Kompare, Boris
2016-03-01
The use of acoustic cavitation for water and wastewater treatment (cleaning) is a well known procedure. Yet, the use of hydrodynamic cavitation as a sole technique or in combination with other techniques such as ultrasound has only recently been suggested and employed. In the first part of this paper a general overview of techniques that employ hydrodynamic cavitation for cleaning of water and wastewater is presented. In the second part of the paper the focus is on our own most recent work using hydrodynamic cavitation for removal of pharmaceuticals (clofibric acid, ibuprofen, ketoprofen, naproxen, diclofenac, carbamazepine), toxic cyanobacteria (Microcystis aeruginosa), green microalgae (Chlorella vulgaris), bacteria (Legionella pneumophila) and viruses (Rotavirus) from water and wastewater. As will be shown, hydrodynamic cavitation, like acoustic, can manifest itself in many different forms each having its own distinctive properties and mechanisms. This was until now neglected, which eventually led to poor performance of the technique. We will show that a different type of hydrodynamic cavitation (different removal mechanism) is required for successful removal of different pollutants. The path to use hydrodynamic cavitation as a routine water cleaning method is still long, but recent results have already shown great potential for optimisation, which could lead to a low energy tool for water and wastewater cleaning. Copyright © 2015 Elsevier B.V. All rights reserved.
Frequency-dependent hydrodynamic interaction between two solid spheres
Jung, Gerhard; Schmid, Friederike
2017-12-01
Hydrodynamic interactions play an important role in many areas of soft matter science. In simulations with implicit solvent, various techniques such as Brownian or Stokesian dynamics explicitly include hydrodynamic interactions a posteriori by using hydrodynamic diffusion tensors derived from the Stokes equation. However, this equation assumes the interaction to be instantaneous which is an idealized approximation and only valid on long time scales. In the present paper, we go one step further and analyze the time-dependence of hydrodynamic interactions between finite-sized particles in a compressible fluid on the basis of the linearized Navier-Stokes equation. The theoretical results show that at high frequencies, the compressibility of the fluid has a significant impact on the frequency-dependent pair interactions. The predictions of hydrodynamic theory are compared to molecular dynamics simulations of two nanocolloids in a Lennard-Jones fluid. For this system, we reconstruct memory functions by extending the inverse Volterra technique. The simulation data agree very well with the theory, therefore, the theory can be used to implement dynamically consistent hydrodynamic interactions in the increasingly popular field of non-Markovian modeling.
International Nuclear Information System (INIS)
R. Paul Drake
2007-01-01
We report the ongoing work of our group in hydrodynamics and radiation hydrodynamics with astrophysical applications. During the period of the existing grant, we have carried out two types of experiments at the Omega laser. One set of experiments has studied radiatively collapsing shocks, obtaining data using a backlit pinhole with a 100 ps backlighter and beginning to develop the ability to look into the shock tube with optical or x-ray diagnostics. Other experiments have studied the deeply nonlinear development of the Rayleigh-Taylor (RT) instability from complex initial conditions, using dual-axis radiographic data with backlit pinholes and ungated detectors to complete the data set for a Ph.D. student. We lead a team that is developing a proposal for experiments at the National Ignition Facility and are involved in experiments at NIKE and LIL. All these experiments have applications to astrophysics, discussed in the corresponding papers. We assemble the targets for the experiments at Michigan, where we also prepare many of the simple components. We also have several projects underway in our laboratory involving our x-ray source. The above activities, in addition to a variety of data analysis and design projects, provide good experience for graduate and undergraduates students. In the process of doing this research we have built a research group that uses such work to train junior scientists
Annual Report 2006 for Hydrodynamics and Radiation Hydrodynamics with Astrophysical Applications
Energy Technology Data Exchange (ETDEWEB)
R. Paul Drake
2007-04-05
We report the ongoing work of our group in hydrodynamics and radiation hydrodynamics with astrophysical applications. During the period of the existing grant, we have carried out two types of experiments at the Omega laser. One set of experiments has studied radiatively collapsing shocks, obtaining data using a backlit pinhole with a 100 ps backlighter and beginning to develop the ability to look into the shock tube with optical or x-ray diagnostics. Other experiments have studied the deeply nonlinear development of the Rayleigh-Taylor (RT) instability from complex initial conditions, using dual-axis radiographic data with backlit pinholes and ungated detectors to complete the data set for a Ph.D. student. We lead a team that is developing a proposal for experiments at the National Ignition Facility and are involved in experiments at NIKE and LIL. All these experiments have applications to astrophysics, discussed in the corresponding papers. We assemble the targets for the experiments at Michigan, where we also prepare many of the simple components. We also have several projects underway in our laboratory involving our x-ray source. The above activities, in addition to a variety of data analysis and design projects, provide good experience for graduate and undergraduates students. In the process of doing this research we have built a research group that uses such work to train junior scientists.
Lee, Jeong-Hoon; Park, Byung-Soo; Ghang, Hyun-Gu; Song, Hyunjoon; Yang, Sung Yun
2018-04-25
Hybrid films consisting of anisotropic octahedral gold nanoparticles (AuNPs) and polymers had their surfaces functionalized and were immobilized on surface plasmon resonance (SPR) sensors for biomolecule detection. Specifically, carboxylated octahedral AuNPs (C-Oh-AuNPs) and poly(allylamine hydrochloride) (PAH) were assembled as ultrathin films by using a layer-by-layer process. The ionic strength generated from the functional groups of C-Oh-AuNP and PAH influenced the composition, its surface morphology, and the reactivity of the film toward further chemical reactions such as the synthesis of spherical AuNPs (S-AuNPs). We were thus able to control the size and the structure of the C-Oh-AuNP and S-AuNPs converted to nano-raspberry-shaped particles. This hierarchical AuNP hybrid film exhibits much more sensitive and stable detection of biomolecules than regular flat chip systems, and this result may be due to the SPR of the AuNP at its surface being able to markedly enhance the local optical field of the chip. The micropatterning of the hybrid coating was also studied by using a soft lithographic patterning method. We, in particular, worked on creating multiplex patterns having different combinations of shapes and fluorescent colors. We expect our hybrid coating system with multicode biomolecular arrays to be used as a powerful platform for biosensor applications.
Bacterial Swarming: social behaviour or hydrodynamics?
Vermant, Jan
2010-03-01
Bacterial swarming of colonies is typically described as a social phenomenon between bacteria, whereby groups of bacteria collectively move atop solid surfaces. This multicellular behavior, during which the organized bacterial populations are embedded in an extracellular slime layer, is connected to important features such as biofilm formation and virulence. Despite the possible intricate quorum sensing mechanisms that regulate swarming, several physico-chemical phenomena may play a role in the dynamics of swarming and biofilm formation. Especially the striking fingering patterns formed by some swarmer colonies on relatively soft sub phases have attracted the attention as they could be the signatures of an instability. Recently, a parallel has been drawn between the swarming patterns and the spreading of viscous drops under the influence of a surfactant, which lead to similar patterns [1]. Starting from the observation that several of the molecules, essential in swarming systems, are strong biosurfactants, the possibility of flows driven by gradients in surface tension, has been proposed. This Marangoni flows are known to lead to these characteristic patterns. For Rhizobium etli not only the pattern formation, but also the experimentally observed spreading speed has been shown to be consistent with the one expected for Marangoni flows for the surface pressures, thickness, and viscosities that have been observed [2]. We will present an experimental study of swarming colonies of the bacteria Pseudomonas aeruginosa, the pattern formation, the surfactant gradients and height profiles in comparison with predictions of a thin film hydrodynamic model.[4pt] [1] Matar O.K. and Troian S., Phys. Fluids 11 : 3232 (1999)[0pt] [2] Daniels, R et al., PNAS, 103 (40): 14965-14970 (2006)
Hydrodynamic behavior of a bare rod bundle
International Nuclear Information System (INIS)
Bartzis, J.G.; Todreas, N.E.
1977-06-01
The temperature distribution within the rod bundle of a nuclear reactor is of major importance in nuclear reactor design. However temperature information presupposes knowledge of the hydrodynamic behavior of the coolant which is the most difficult part of the problem due to complexity of the turbulence phenomena. In the present work a 2-equation turbulence model--a strong candidate for analyzing actual three dimensional turbulent flows--has been used to predict fully developed flow of infinite bare rod bundle of various aspect ratios (P/D). The model has been modified to take into account anisotropic effects of eddy viscosity. Secondary flow calculations have been also performed although the model seems to be too rough to predict the secondary flow correctly. Heat transfer calculations have been performed to confirm the importance of anisotropic viscosity in temperature predictions. All numerical calculations for flow and heat have been performed by two computer codes based on the TEACH code. Experimental measurements of the distribution of axial velocity, turbulent axial velocity, turbulent kinetic energy and radial Reynolds stresses were performed in the developing and fully developed regions. A 2-channel Laser Doppler Anemometer working on the Reference mode with forward scattering was used to perform the measurements in a simulated interior subchannel of a triangular rod array with P/D = 1.124. Comparisons between the analytical results and the results of this experiment as well as other experimental data in rod bundle array available in literature are presented. The predictions are in good agreement with the results for the high Reynolds numbers
Hydrodynamic Simulations of Kepler's Supernova Remnant
Sullivan, Jessica; Blondin, John; Borkowski, Kazik; Reynolds, Stephen
2018-01-01
Kepler’s supernova remnant contains unusual features that strongly suggest an origin in a single-degenerate Type Ia explosion, including anisotropic circumstellar medium (CSM), a strong brightness gradient, and spatially varying expansion proper motions. We present 3Dhydrodynamic simulations to test a picture in which Kepler's progenitor binary emitted a strong asymmetric wind, densest in the orbital plane, while the system moved at high velocity through the ISM. We simulate the creation of the presupernova environment as well as the supernova blast wave, using the VH-1 grid-based hydrodynamics code. We first modeled an anisotropic wind to create an asymmetric bowshock around the progenitor, then the blast wave from thesupernova. The final simulation places both previous model pieces onto a single grid and allows the blast wave to expand into the bowshock. Models were completed on a Yin-Yang grids with matching angular resolutions. By manipulating parameters that control the asymmetry of the system, we attempted to find conditions that recreated the current state of Kepler. We analyzed these models by comparing images of Kepler from the Chandra X-ray Observatory to line-of-sight projections from the model results. We also present comparisons of simulated expansion velocities with recent observations of X-ray proper motions from Chandra images. We were able to produce models that contained similar features to those seen in Kepler. We find the greatest resemblance to Kepler images with a presupernova wind with an equator-to-pole density contrast of 3 and a moderately disk-like CSM at a 5° angle between equatorial plane and system motion.
International Nuclear Information System (INIS)
Tserkovnikov, Yu.A.
2001-01-01
The regular method for deriving the equations for the Green functions in the tasks on the molecular hydrodynamics and kinetics, making it possible to account consequently the contribution into the generalized kinetics coefficients, conditioned by interaction of two, three and more hydrodynamic modes. In contrast to the general theory of perturbations by the interaction constant the consequent approximations are accomplished by the degree of accounting for the higher correlations, described by the irreducible functions [ru
Preparing for an explosion: Hydrodynamic instabilities and turbulence in presupernovae
Energy Technology Data Exchange (ETDEWEB)
Smith, Nathan; Arnett, W. David, E-mail: nathans@as.arizona.edu, E-mail: darnett@as.arizona.edu [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)
2014-04-20
Both observations and numerical simulations are discordant with predictions of conventional stellar evolution codes for the latest stages of a massive star's life before core collapse. The most dramatic example of this disconnect is in the eruptive mass loss occurring in the decade preceding Type IIn supernovae. We outline the key empirical evidence that indicates severe pre-supernova instability in massive stars, and we suggest that the chief reason that these outbursts are absent in stellar evolution models may lie in the treatment of turbulent convection in these codes. The mixing length theory that is used ignores (1) finite amplitude fluctuations in velocity and temperature and (2) their nonlinear interaction with nuclear burning. Including these fluctuations is likely to give rise to hydrodynamic instabilities in the latest burning sequences, which prompts us to discuss a number of far-reaching implications for the fates of massive stars. In particular, we explore connections to enhanced pre-supernova mass loss, unsteady nuclear burning and consequent eruptions, swelling of the stellar radius that may trigger violent interactions with a companion star, and potential modifications to the core structure that could dramatically alter calculations of the core-collapse explosion mechanism itself. These modifications may also impact detailed nucleosynthesis and measured isotopic anomalies in meteorites, as well as the interpretation of young core-collapse supernova remnants. Understanding these critical instabilities in the final stages of evolution may make possible the development of an early warning system for impending core collapse, if we can identify their asteroseismological or eruptive signatures.
Structure and hydrodynamic properties of plectin molecules.
Foisner, R; Wiche, G
1987-12-05
Plectin is a cytoskeletal, high molecular weight protein of widespread and abundant occurrence in cultured cells and tissues. To study its molecular structure, the protein was purified from rat glioma C6 cells and subjected to chemical and biophysical analyses. Plectin's polypeptide chains have an apparent molecular weight of 300,000, as shown by one-dimensional sodium dodecyl sulfate/polyacrylamide electrophoresis. Cross-linking of non-denatured plectin in solution with dimethyl suberimidate and electrophoretic analyses on sodium dodecyl sulfate/agarose gels revealed that the predominant soluble plectin species was a molecule of 1200 X 10(3) Mr consisting of four 300 X 10(3) Mr polypeptide chains. Hydrodynamic properties of plectin in solution were obtained by sedimentation velocity centrifugation and high-pressure liquid chromatography analysis yielding a sedimentation coefficient of 10 S and a Stokes radius of 27 nm. The high f/fmin ratio of 4.0 indicated a very elongated shape of plectin molecules and an axial ratio of about 50. Shadowing and negative staining electron microscopy of plectin molecules revealed multiple domains: a rigid rod of 184 nm in length and 2 nm in diameter, and two globular heads of 9 nm diameter at each end of the rod. Circular dichroism spectra suggested a composition of 30% alpha-helix, 9% beta-structure and 61% random coil or aperiodic structure. The rod-like shape, the alpha-helix content as well as the thermal transition within a midpoint of 45 degrees C and the transition enthalpy (168 kJ/mol) of secondary structure suggested a double-stranded, alpha-helical coiled coil rod domain. Based on the available data, we favor a model of native plectin as a dumb-bell-like association of four 300 X 10(3) Mr polypeptide chains. Electron microscopy and turbidity measurements showed that plectin molecules self-associate into various oligomeric states in solutions of nearly physiological ionic strength. These interactions apparently involved
Discovery of hydrodynamic behavior in high energy heavy ion collisions
International Nuclear Information System (INIS)
Hamagaki, Hideki
2010-01-01
The objective of high energy heavy ion collision experiments is creating high temperature and high density states to investigate hadron matter properties in such extreme conditions. Since the start of heavy ion collision experiments with BEVALAC, knowledge of the space-time evolution of collision has become indispensable for understanding the hadronic matter properties. This problem is reviewed here from the hydrodynamics view point. Although its importance has been generally recognized since the time of BEVALAC, the hydrodynamic description has not been successful because the hydrodynamic model assuming non-viscous or small fluid had not been considered to be enough to properly describe the space-time evolution of hadron-hadron collisions until the RHIC experiments. Items of the following titles are picked up and reviewed here: Development of heavy ion accelerations; Space-time evolution of hadron collision process and hydrodynamic model; Chemical freezing and kinematical freezing, including transverse momentum spectra at proton-proton collisions and particle spectra in heavy ion collisions; Elliptical azimuthal angle anisotropy; Discovery of hydrodynamic flow at BEVALAC; Problems of incident beam dependence of v2; Elliptic azimuthal angle anisotropy at RHIC; What is it that carries the elliptic anisotropy? Discussion of attainment of thermodynamical equilibrium state at RHIC; and finally investigations of fluid properties other than azimuthal anisotropy, such as, Fluid properties probed by heavy quarks and Observing QCD fluid responses. (S. Funahashi)
arXiv On higher order and anisotropic hydrodynamics for Bjorken and Gubser flows
Chattopadhyay, Chandrodoy; Pal, Subrata; Vujanovic, Gojko
2018-06-15
We study the evolution of hydrodynamic and nonhydrodynamic moments of the distribution function using anisotropic and third-order Chapman-Enskog hydrodynamics for systems undergoing Bjorken and Gubser flows. The hydrodynamic results are compared with the exact solution of the Boltzmann equation with a collision term in relaxation time approximation. While the evolution of the hydrodynamic moments of the distribution function (i.e., of the energy momentum tensor) can be described with high accuracy by both hydrodynamic approximation schemes, their description of the evolution of the entropy of the system is much less precise. We attribute this to large contributions from nonhydrodynamic modes coupling into the entropy evolution, which are not well captured by the hydrodynamic approximations. The differences between the exact solution and the hydrodynamic approximations are larger for the third-order Chapman-Enskog hydrodynamics than for anisotropic hydrodynamics, which effectively resums some of the dissipativ...
Zhou, Yufeng; Gao, Xiaobin Wilson
2016-09-01
High-intensity focused ultrasound (HIFU) is emerging as an effective therapeutic modality in clinics. Besides the thermal ablation, tissue disintegration is also possible because of the interaction between the distorted HIFU bursts and either bubble cloud or boiling bubble. Hydrodynamic cavitation is another type of cavitation and has been employed widely in industry, but its role in mechanical erosion to tissue is not clearly known. In this study, the bubble dynamics immediately after the termination of HIFU exposure in the transparent gel phantom was captured by high-speed photography, from which the bubble displacement towards the transducer and the changes of bubble size was quantitatively determined. The characteristics of hydrodynamic cavitation due to the release of the acoustic radiation force and relaxation of compressed surrounding medium were found to associate with the number of pulses delivered and HIFU parameters (i.e. pulse duration and pulse repetition frequency). Because of the initial big bubble (~1 mm), large bubble expansion (up to 1.76 folds), and quick bubble motion (up to ~1 m s-1) hydrodynamic cavitation is significant after HIFU exposure and may lead to mechanical erosion. The shielding effect of residual tiny bubbles would reduce the acoustic energy delivered to the pre-existing bubble at the focus and, subsequently, the hydrodynamic cavitation effect. Tadpole shape of mechanical erosion in ex vivo porcine kidney samples was similar to the contour of bubble dynamics in the gel. Liquefied tissue was observed to emit towards the transducer through the punctured tissue after HIFU exposure in the sonography. In summary, the release of HIFU exposure-induced hydrodynamic cavitation produces significant bubble expansion and motion, which may be another important mechanism of tissue erosion. Understanding its mechanism and optimizing the outcome would broaden and enhance HIFU applications.
Zhou, Yufeng; Gao, Xiaobin Wilson
2016-09-21
High-intensity focused ultrasound (HIFU) is emerging as an effective therapeutic modality in clinics. Besides the thermal ablation, tissue disintegration is also possible because of the interaction between the distorted HIFU bursts and either bubble cloud or boiling bubble. Hydrodynamic cavitation is another type of cavitation and has been employed widely in industry, but its role in mechanical erosion to tissue is not clearly known. In this study, the bubble dynamics immediately after the termination of HIFU exposure in the transparent gel phantom was captured by high-speed photography, from which the bubble displacement towards the transducer and the changes of bubble size was quantitatively determined. The characteristics of hydrodynamic cavitation due to the release of the acoustic radiation force and relaxation of compressed surrounding medium were found to associate with the number of pulses delivered and HIFU parameters (i.e. pulse duration and pulse repetition frequency). Because of the initial big bubble (~1 mm), large bubble expansion (up to 1.76 folds), and quick bubble motion (up to ~1 m s -1 ) hydrodynamic cavitation is significant after HIFU exposure and may lead to mechanical erosion. The shielding effect of residual tiny bubbles would reduce the acoustic energy delivered to the pre-existing bubble at the focus and, subsequently, the hydrodynamic cavitation effect. Tadpole shape of mechanical erosion in ex vivo porcine kidney samples was similar to the contour of bubble dynamics in the gel. Liquefied tissue was observed to emit towards the transducer through the punctured tissue after HIFU exposure in the sonography. In summary, the release of HIFU exposure-induced hydrodynamic cavitation produces significant bubble expansion and motion, which may be another important mechanism of tissue erosion. Understanding its mechanism and optimizing the outcome would broaden and enhance HIFU applications.
Xu, Ding; Yu, Yongjiang; Zhu, Yunkai; Huang, Tao; Chen, Yaqing; Qi, Jun
2014-04-01
The Prostate-specific antigen (PSA) level is largely used to diagnose prostate cancer (PCa) in last decades. However, its specificity is low in patients with a PSA level ranging from 4.0 to 10.0 ng/ml. This study aims to define the correlation between intravesical prostatic protrusion (IPP) and PSA and to establish a new model to predict PCa. A total of 339 patients order than 45 years examined between October 2010 and June 2012 were enrolled. Eligible patients were recommended for transrectal ultrasonography (TRUS)-guided prostate biopsies after measuring total prostate volume (TPV), tranzisional zone volume (TZV) and IPP. The levels of total PSA (tPSA), free PSA (fPSA) were analyzed by using Hybritech calibrated Access tPSA and fPSA assays. A new mathematical model, named IPP removed PCa predicting score (IRPPS), consists of tPSA, TZV and IPP was established. The predictive accuracy of IRPPS, PSA density (PSAD), %PSA and tPSA were compared using receiver-operator characteristic (ROC) analysis. Eighty-six patients had PSA levels of 4.0-10.0 ng/ml. Twenty of them were diagnosed as PCa. Using ROC curves, the areas under the curve for IRPPS, PSAD and %PSA and tPSA were 0.786, 0.768 and 0.664 and 0.585, respectively. We suggested IPP grade had a significant relationship with serum tPSA levels. The predictive accuracy of IRPPS was higher than the other 3 indictors.
Nonlinear hydrodynamic equations for superfluid helium in aerogel
International Nuclear Information System (INIS)
Brusov, Peter N.; Brusov, Paul P.
2003-01-01
Aerogel in superfluids is studied very intensively during last decade. The importance of these systems is connected to the fact that this allows to investigate the influence of impurities on superfluidity. We have derived for the first time nonlinear hydrodynamic equations for superfluid helium in aerogel. These equations are generalization of McKenna et al. equations for nonlinear hydrodynamics case and could be used to study sound propagation phenomena in aerogel-superfluid system, in particular--to study sound conversion phenomena. We have obtained two alternative sets of equations, one of which is a generalization of a traditional set of nonlinear hydrodynamics equations for the case of an aerogel-superfluid system and, the other one represents a la Putterman equations (equation for v→ s is replaced by equation for A→=((ρ n )/(ρσ))w→, where w→=v→ n -v→ s )
Biodiesel production through hydrodynamic cavitation and performance testing
Energy Technology Data Exchange (ETDEWEB)
Pal, Amit; Verma, Ashish; Kachhwaha, S.S.; Maji, S. [Department of Mechanical Engineering, Delhi College of Engineering, Bawana Road, Delhi 110042 (India)
2010-03-15
This paper presents the details of development of a biodiesel production test rig based on hydrodynamic cavitation followed by results of experimental investigation carried out on a four cylinder, direct injection water cooled diesel engine operating on diesel and biodiesel blend of Citrullus colocyntis (Thumba) oil. The experiment covers a wide range of engine rpm. Results show that biodiesel of Thumba oil produced through hydrodynamic cavitation technique can be used as an alternative fuel with better performance and lower emissions compared to diesel. The most significant conclusions are that (1) Biodiesel production through hydrodynamic cavitation technique seems to be a simple, efficient, time saving, eco-friendly and industrially viable process. (2) 30% biodiesel blend of Thumba oil shows relatively higher brake power, brake thermal efficiency, reduced bsfc and smoke opacity with favourable p-{theta} diagram as compared to diesel. (author)
High-order hydrodynamic algorithms for exascale computing
Energy Technology Data Exchange (ETDEWEB)
Morgan, Nathaniel Ray [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2016-02-05
Hydrodynamic algorithms are at the core of many laboratory missions ranging from simulating ICF implosions to climate modeling. The hydrodynamic algorithms commonly employed at the laboratory and in industry (1) typically lack requisite accuracy for complex multi- material vortical flows and (2) are not well suited for exascale computing due to poor data locality and poor FLOP/memory ratios. Exascale computing requires advances in both computer science and numerical algorithms. We propose to research the second requirement and create a new high-order hydrodynamic algorithm that has superior accuracy, excellent data locality, and excellent FLOP/memory ratios. This proposal will impact a broad range of research areas including numerical theory, discrete mathematics, vorticity evolution, gas dynamics, interface instability evolution, turbulent flows, fluid dynamics and shock driven flows. If successful, the proposed research has the potential to radically transform simulation capabilities and help position the laboratory for computing at the exascale.
Hydrodynamic Expansion of Pellicles Caused by e-Beam Heating
Ho, D
2000-01-01
Placing a pellicle in front of a x-ray converter target for radiographic applications can confine the backstreaming ions and target plasma to a shorter channel so that the cumulative effect on e-beam focusing is reduced. The pellicle is subject to heating by e-beam since the pellicle is placed upstream of the target. The calculation of the hydrodynamic expansion, caused by the heating, using the radiation hydrodynamics code LASNEX is presented in this report. Calculations show that mylar pellicles disintegrate at the end of a multi-pulse intense e-beam while beryllium and carbon pellicles remain intact. The expansions for the kapton-carbon multi-layered targets are also examined. Hydrodynamic expansions for pellicles with various e-beam spot radii are calculated for DARHT-II beam parameters. All the simulation results indicate that the backstreaming ions can be stopped.
Automatization of hydrodynamic modelling in a Floreon+ system
Ronovsky, Ales; Kuchar, Stepan; Podhoranyi, Michal; Vojtek, David
2017-07-01
The paper describes fully automatized hydrodynamic modelling as a part of the Floreon+ system. The main purpose of hydrodynamic modelling in the disaster management is to provide an accurate overview of the hydrological situation in a given river catchment. Automatization of the process as a web service could provide us with immediate data based on extreme weather conditions, such as heavy rainfall, without the intervention of an expert. Such a service can be used by non scientific users such as fire-fighter operators or representatives of a military service organizing evacuation during floods or river dam breaks. The paper describes the whole process beginning with a definition of a schematization necessary for hydrodynamic model, gathering of necessary data and its processing for a simulation, the model itself and post processing of a result and visualization on a web service. The process is demonstrated on a real data collected during floods in our Moravian-Silesian region in 2010.
Overview of the 9th International Conference on Hydrodynamics
Lu, Dong-qiang
2010-10-01
The 9th International Conference on Hydrodynamics (ICHD), held in Shanghai, China from 11 to 15 October, 2010, was briefly reviewed. More than 240 delegates from 23 countries and regions attended this Conference, at which three plenary lectures, two keynote lectures and more than 160 papers were delivered. A special symposium on hydrodynamics in honor of Prof. You-sheng He was jointly organized in this ICHD. The printed proceedings, edited by Y. S. Wu, S. Q. Dai, H. Liu et al. and published by China Ocean Press, collect 172 technical papers contributed from 26 countries and regions. The electronic proceedings are distributed by the Elsevier at the ScienceDirect website as "Journal of Hydrodynamics, 2010, Vol. 22, No. 5 (Supplement)".
Modeling of nanoscale liquid mixture transport by density functional hydrodynamics
Dinariev, Oleg Yu.; Evseev, Nikolay V.
2017-06-01
Modeling of multiphase compositional hydrodynamics at nanoscale is performed by means of density functional hydrodynamics (DFH). DFH is the method based on density functional theory and continuum mechanics. This method has been developed by the authors over 20 years and used for modeling in various multiphase hydrodynamic applications. In this paper, DFH was further extended to encompass phenomena inherent in liquids at nanoscale. The new DFH extension is based on the introduction of external potentials for chemical components. These potentials are localized in the vicinity of solid surfaces and take account of the van der Waals forces. A set of numerical examples, including disjoining pressure, film precursors, anomalous rheology, liquid in contact with heterogeneous surface, capillary condensation, and forward and reverse osmosis, is presented to demonstrate modeling capabilities.
Pattern formation in flocking models: A hydrodynamic description.
Solon, Alexandre P; Caussin, Jean-Baptiste; Bartolo, Denis; Chaté, Hugues; Tailleur, Julien
2015-12-01
We study in detail the hydrodynamic theories describing the transition to collective motion in polar active matter, exemplified by the Vicsek and active Ising models. Using a simple phenomenological theory, we show the existence of an infinity of propagative solutions, describing both phase and microphase separation, that we fully characterize. We also show that the same results hold specifically in the hydrodynamic equations derived in the literature for the active Ising model and for a simplified version of the Vicsek model. We then study numerically the linear stability of these solutions. We show that stable ones constitute only a small fraction of them, which, however, includes all existing types. We further argue that, in practice, a coarsening mechanism leads towards phase-separated solutions. Finally, we construct the phase diagrams of the hydrodynamic equations proposed to qualitatively describe the Vicsek and active Ising models and connect our results to the phenomenology of the corresponding microscopic models.
Origins of hydrodynamic forces on centrifugal pump impellers
Adkins, Douglas R.; Brennen, Christopher E.
1987-01-01
Hydrodynamic interactions that occur between a centrifugal pump impeller and volute are experimentally and theoretically investigated. The theoretical analysis considers the inability of the blades to perfectly guide the flow through the impeller, and also includes a quasi-one dimensional treatment of the flow in the volute. The disturbance at the impeller discharge and the resulting forces are determined by the theoretical model. The model is then extended to obtain the hydrodynamic force perturbations that are caused by the impeller whirling eccentrically in the volute. Under many operating conditions, these force perturbations were found to be destablizing. Comparisons are made between the theoretical model and the experimental measurements of pressure distributions and radial forces on the impeller. The theoretical model yields fairly accurate predictions of the radial forces caused by the flow through the impeller. However, it was found that the pressure acting on the front shroud of the impeller has a substantial effect on the destablizing hydrodynamic forces.
Vibration of a rotating shaft on hydrodynamic bearings: multi-scales surface effects
International Nuclear Information System (INIS)
Rebufa, Jocelyn
2016-01-01
The hydrodynamic bearing provides good damping properties in rotating machineries. However, the performances of rotor-bearings systems are highly impacted by nonlinear effects that are difficult to analyze. The rotor dynamics prediction requires advanced models for the flow in the bearings. The surface of the bearings seems to have a strong impact on the lubricant flow, acting on the static and dynamic properties of the rotating parts. This study aims to enhance the simulation of the bearings' surface state effect on the motion of the rotating shaft. The flexible shaft interacts with textured hydrodynamic bearings. Multi-scales homogenization is used in a multi-physics algorithm in order to describe the fluid-structure interaction. Different models are used to account for the cavitation phenomenon in the bearings. Nonlinear harmonic methods allow efficient parametric studies of periodic solutions as well as their stability. Moreover, a test rig has been designed to compare predictions to real measurements. Several textured shaft samples modified with femto-seconds LASER surface texturing are tested. In most cases the experimental study showed similar results than the simulation. Enhancements of the vibration behaviors of the rotor-bearing system have been revealed for certain texturing patterns. The self-excited vibration, also known as 'oil whirl' phenomenon, is stabilized on a wide rotating frequency range. However, the simulation tool does not predict well the enhancements that are observed. Vortices in surface texturing patterns have been revealed numerically with Navier-Stokes equation resolution. These results are opposed to the classical lubrication hypothesis. It is also a possible explanation of the enhancements that are experimentally measured with textured bearings. (author) [fr
Assessing the Hydrogeomorphic Effects of Environmental Flows using Hydrodynamic Modeling.
Gregory, Angela; Morrison, Ryan R; Stone, Mark
2018-04-13
Water managers are increasingly using environmental flows (e-flows) as a tool to improve ecological conditions downstream from impoundments. Recent studies have called for e-flow approaches that explicitly consider impacts on hydrogeomorphic processes when developing management alternatives. Process-based approaches are particularly relevant in river systems that have been highly modified and where water supplies are over allocated. One-dimensional (1D) and two-dimensional (2D) hydrodynamic models can be used to resolve hydrogeomorphic processes at different spatial and temporal scales to support the development, testing, and refinement of e-flow hypotheses. Thus, the objective of this paper is to demonstrate the use of hydrodynamic models as a tool for assisting stakeholders in targeting and assessing environmental flows within a decision-making framework. We present a case study of e-flows on the Rio Chama in northern New Mexico, USA, where 1D and 2D hydrodynamic modeling was used within a collaborative process to implement an e-flow experiment. A specific goal of the e-flow process was to improve spawning habitat for brown trout by flushing fine sediments from gravel features. The results revealed that the 2D hydrodynamic model provided much greater insight with respect to hydrodynamic and sediment transport processes, which led to a reduction in the recommended e-flow discharge. The results suggest that 2D hydrodynamic models can be useful tools for improving process understanding, developing e-flow recommendations, and supporting adaptive management even when limited or no data are available for model calibration and validation.
Hydrodynamic perception in true seals (Phocidae) and eared seals (Otariidae).
Hanke, Wolf; Wieskotten, Sven; Marshall, Christopher; Dehnhardt, Guido
2013-06-01
Pinnipeds, that is true seals (Phocidae), eared seals (Otariidae), and walruses (Odobenidae), possess highly developed vibrissal systems for mechanoreception. They can use their vibrissae to detect and discriminate objects by direct touch. At least in Phocidae and Otariidae, the vibrissae can also be used to detect and analyse water movements. Here, we review what is known about this ability, known as hydrodynamic perception, in pinnipeds. Hydrodynamic perception in pinnipeds developed convergently to the hydrodynamic perception with the lateral line system in fish and the sensory hairs in crustaceans. So far two species of pinnipeds, the harbour seal (Phoca vitulina) representing the Phocidae and the California sea lion (Zalophus californianus) representing the Otariidae, have been studied for their ability to detect local water movements (dipole stimuli) and to follow hydrodynamic trails, that is the water movements left behind by objects that have passed by at an earlier point in time. Both species are highly sensitive to dipole stimuli and can follow hydrodynamic trails accurately. In the individuals tested, California sea lions were clearly more sensitive to dipole stimuli than harbour seals, and harbour seals showed a superior trail following ability as compared to California sea lions. Harbour seals have also been shown to derive additional information from hydrodynamic trails, such as motion direction, size and shape of the object that caused the trail (California sea lions have not yet been tested). The peculiar undulated shape of the harbour seals' vibrissae appears to play a crucial role in trail following, as it suppresses self-generated noise while the animal is swimming.
Star Formation History of Dwarf Galaxies in Cosmological Hydrodynamic Simulations
Directory of Open Access Journals (Sweden)
Kentaro Nagamine
2010-01-01
Full Text Available We examine the past and current work on the star formation (SF histories of dwarf galaxies in cosmological hydrodynamic simulations. The results obtained from different numerical methods are still somewhat mixed, but the differences are understandable if we consider the numerical and resolution effects. It remains a challenge to simulate the episodic nature of SF history in dwarf galaxies at late times within the cosmological context of a cold dark matter model. More work is needed to solve the mysteries of SF history of dwarf galaxies employing large-scale hydrodynamic simulations on the next generation of supercomputers.
Hydrodynamics of long-scale-length plasmas. Summary
International Nuclear Information System (INIS)
Craxton, R.S.
1984-01-01
A summary is given relating to the importance of long-scale-length plasmas to laser fusion. Some experiments are listed in which long-scale-length plasmas have been produced and studied. This talk presents SAGE simulations of most of these experiments with the emphasis being placed on understanding the hydrodynamic conditions rather than the parametric/plasma-physics processes themselves which are not modeled by SAGE. However, interpretation of the experiments can often depend on a good understanding of the hydrodynamics, including optical ray tracing
Relativistic hydrodynamics, heavy ion reactions and antiproton annihilation
International Nuclear Information System (INIS)
Strottman, D.
1985-01-01
The application of relativistic hydrodynamics to relativistic heavy ions and antiproton annihilation is summarized. Conditions for validity of hydrodynamics are presented. Theoretical results for inclusive particle spectra, pion production and flow analysis are given for medium energy heavy ions. The two-fluid model is introduced and results presented for reactions from 800 MeV per nucleon to 15 GeV on 15 GeV per nucleon. Temperatures and densities attained in antiproton annihilation are given. Finally, signals which might indicate the presence of a quark-gluon plasma are briefly surveyed
Hydrodynamic motion of a heavy-ion-beam-heated plasma
International Nuclear Information System (INIS)
Jacoby, J.; Hoffmann, D.H.H.; Mueller, R.W.; Mahrt-Olt, K.; Arnold, R.C.; Schneider, V.; Maruhn, J.
1990-01-01
The first experimental study is reported of a plasma produced by a heavy-ion beam. Relevant parameters for heating with heavy ions are described, temperature and density of the plasma are determined, and the hydrodynamic motion in the target induced by the beam is studied. The measured temperature and the free-electron density are compared with a two-dimensional hydrodynamic-model calculation. In accordance with the model, a radial rarefaction wave reaching the center of the target was observed and the penetration velocity of the ion beam into the xenon-gas target was measured
Use of water towing tanks for aerodynamics and hydrodynamics
Gadelhak, Mohamed
1987-01-01
Wind tunnels and flumes have become standard laboratory tools for modeling a variety of aerodynamic and hydrodynamic flow problems. Less available, although by no means less useful, are facilities in which a model can be towed (or propelled) through air or water. This article emphasizes the use of the water towing tank as an experimental tool for aerodynamic and hydrodynamic studies. Its advantages and disadvantages over other flow rigs are discussed, and its usefullness is illustrated through many examples of research results obtained over the past few years in a typical towing tank facility.
Behavior of passive admixture in a vortical hydrodynamic field
Directory of Open Access Journals (Sweden)
R.O.Bobrov
2006-01-01
Full Text Available The motion of passive admixture of spherical particles in the stationary hydrodynamic field of a swirling flow is studied. A spherical particle of a given mass in the hydrodynamic field of a swirling flow is located on a certain circular orbit, where the centrifugal force is compensated by the radial drag force due to the sink. This leads to the separation of the host fluid and admixture. A theory of Brownian motion of admixture in dilute solutions with a non-uniform flow is constructed.
Hydrodynamic flow in a synaptic cleft during exocytosis.
Shneider, M N; Gimatdinov, R S; Skorinkin, A I; Kovyazina, I V; Nikolsky, E E
2012-01-01
It is shown that exocytosis in a chemical synapse may be accompanied by "microjet" formation due to the overpressure that exists in the vesicles. This mechanism may take place either at complete fusion of a vesicle with the presynaptic membrane or in the so-called kiss-and-run mode of neurotransmitter release. A simple hydrodynamic model of the viscous incompressible flow arising in the synaptic cleft is suggested. The occurrence of hydrodynamic flow (microjet) leads to more efficient transport of neurotransmitter than in the case of classical diffusive transport.
Isotropization and hydrodynamization in weakly coupled heavy-ion collisions
Kurkela, Aleksi
2015-01-01
We numerically solve 2+1D effective kinetic theory of weak coupling QCD under longitudinal expansion relevant for early stages of heavy-ion collisions. We find agreement with viscous hydrodynamics and classical Yang-Mills simulations in the regimes where they are applicable. By choosing initial conditions that are motivated by color-glass-condensate framework we find that for Q=2GeV and $\\alpha_s$=0.3 the system is approximately described by viscous hydrodynamics well before $\\tau \\lesssim 1.0$ fm/c.
Anisotropic hydrodynamics, holography and the chiral magnetic effect
International Nuclear Information System (INIS)
Gahramanov, Ilmar; Kalaydzhyan, Tigran; Kirsch, Ingo; Hamburg Univ.
2012-03-01
We discuss a possible dependence of the chiral magnetic effect (CME) on the elliptic flow coefficient υ 2 . We first study this in a hydrodynamic model for a static anisotropic plasma with multiple anomalous U(1) currents. In the case of two charges, one axial and one vector, the CME formally appears as a first-order transport coefficient in the vector current. We compute this transport coefficient and show its dependence on υ 2 . We also determine the CME-coefficient from first-order corrections to the dual AdS background using the fluid-gravity duality. For small anisotropies, we find numerical agreement with the hydrodynamic result. (orig.)
Comparisons of hydrodynamic beam models with kinetic treatments
International Nuclear Information System (INIS)
Boyd, J.K.; Mark, J.W.; Sharp, W.M.; Yu, S.S.
1983-01-01
Hydrodynamic models have been derived by Mark and Yu and by others to describe energetic self-pinched beams, such as those used in ion-beam fusion. The closure of the Mark-Yu model is obtained with adiabatic assumptions mathematically analogous to those of Chew, Goldberger, and Low for MHD. The other models treated here use an ideal gas closure and a closure by Newcomb based on an expansion in V/sub th//V/sub z/. Features of these hydrodynamic beam models are compared with a kinetic treatment
Hydrodynamic evolution and jet energy loss in Cu + Cu collisions
International Nuclear Information System (INIS)
Schenke, Bjoern; Jeon, Sangyong; Gale, Charles
2011-01-01
We present results from a hybrid description of Cu + Cu collisions using (3 + 1)-dimensional hydrodynamics (music) for the bulk evolution and a Monte Carlo simulation (martini) for the evolution of high-momentum partons in the hydrodynamical background. We explore the limits of this description by going to small system sizes and determine the dependence on different fractions of wounded nucleon and binary collisions scaling of the initial energy density. We find that Cu + Cu collisions are well described by the hybrid description at least up to 20% central collisions.
On the hydrodynamic limit of self-consistent field equations
International Nuclear Information System (INIS)
Pauli, H.C.
1980-01-01
As an approximation to the nuclear many-body problem, the hydrodynamical limit of self-consistent field equations is worked out and applied to the treatment of vibrational and rotational motion. Its validity is coupled to the value of a smallness parameter, behaving as 20Asup(-2/3) with the number of nucleons. For finite nuclei, this number is not small enough as compared to 1, and indeed one observes a discrepancy of roughly a factor of 5 between the hydrodynamic frequencies and the relevant experimental numbers. (orig.)
Challenges to Ship Hydrodynamics in the XXI Century
Directory of Open Access Journals (Sweden)
Lech Kobylinski
2014-09-01
Full Text Available The beginning of twenty-first century is characterized with important changes in world shipping and exploitation of ocean resources. Three important trends are clearly visible: environment protection, safety and economy. They materialize in important changes in the structure of world fleet where some existing ship types are going to disappear and new ship types emerge. Increasing the size of some ship types is another visible tendency. Stress on environment protection has serious impact on the hydrodynamic characteristics of ships whether with regard to safety zero accident rate is the goal. Important challenges to ship hydrodynamics caused by those tendencies are discussed in the paper.
Impact of hydrodynamic interactions on protein folding rates depends on temperature
Zegarra, Fabio C.; Homouz, Dirar; Eliaz, Yossi; Gasic, Andrei G.; Cheung, Margaret S.
2018-03-01
We investigated the impact of hydrodynamic interactions (HI) on protein folding using a coarse-grained model. The extent of the impact of hydrodynamic interactions, whether it accelerates, retards, or has no effect on protein folding, has been controversial. Together with a theoretical framework of the energy landscape theory (ELT) for protein folding that describes the dynamics of the collective motion with a single reaction coordinate across a folding barrier, we compared the kinetic effects of HI on the folding rates of two protein models that use a chain of single beads with distinctive topologies: a 64-residue α /β chymotrypsin inhibitor 2 (CI2) protein, and a 57-residue β -barrel α -spectrin Src-homology 3 domain (SH3) protein. When comparing the protein folding kinetics simulated with Brownian dynamics in the presence of HI to that in the absence of HI, we find that the effect of HI on protein folding appears to have a "crossover" behavior about the folding temperature. This means that at a temperature greater than the folding temperature, the enhanced friction from the hydrodynamic solvents between the beads in an unfolded configuration results in lowered folding rate; conversely, at a temperature lower than the folding temperature, HI accelerates folding by the backflow of solvent toward the folded configuration of a protein. Additionally, the extent of acceleration depends on the topology of a protein: for a protein like CI2, where its folding nucleus is rather diffuse in a transition state, HI channels the formation of contacts by favoring a major folding pathway in a complex free energy landscape, thus accelerating folding. For a protein like SH3, where its folding nucleus is already specific and less diffuse, HI matters less at a temperature lower than the folding temperature. Our findings provide further theoretical insight to protein folding kinetic experiments and simulations.
Degradation of reactive orange 4 dye using hydrodynamic cavitation based hybrid techniques.
Gore, Mohan M; Saharan, Virendra Kumar; Pinjari, Dipak V; Chavan, Prakash V; Pandit, Aniruddha B
2014-05-01
In the present work, degradation of reactive orange 4 dye (RO4) has been investigated using hydrodynamic cavitation (HC) and in combination with other AOP's. In the hybrid techniques, combination of hydrodynamic cavitation and other oxidizing agents such as H2O2 and ozone have been used to get the enhanced degradation efficiency through HC device. The hydrodynamic cavitation was first optimized in terms of different operating parameters such as operating inlet pressure, cavitation number and pH of the operating medium to get the maximum degradation of RO4. Following the optimization of HC parameters, the degradation of RO4 was carried out using the combination of HC with H2O2 and ozone. It has been found that the efficiency of the HC can be improved significantly by combining it with H2O2 and ozone. The mineralization rate of RO4 increases considerably with 14.67% mineralization taking place using HC alone increases to 31.90% by combining it with H2O2 and further increases to 76.25% through the combination of HC and ozone. The synergetic coefficient of greater than one for the hybrid processes of HC+H2O2 and HC+Ozone has suggested that the combination of HC with other oxidizing agents is better than the individual processes for the degradation of dye effluent containing RO4. The combination of HC with ozone proves to be the most energy efficient method for the degradation of RO4 as compared to HC alone and the hybrid process of HC and H2O2. Copyright © 2013 Elsevier B.V. All rights reserved.
Hoch, Jannis M.; Neal, Jeffrey C.; Baart, Fedor; Van Beek, Rens; Winsemius, Hessel C.; Bates, Paul D.; Bierkens, Marc F.P.
2017-01-01
We here present GLOFRIM, a globally applicable computational framework for integrated hydrological-hydrodynamic modelling. GLOFRIM facilitates spatially explicit coupling of hydrodynamic and hydrologic models and caters for an ensemble of models to be coupled. It currently encompasses the global
DEFF Research Database (Denmark)
Park, Kidong; Shim, Jeong; Solovyeva, Vita
2012-01-01
We examined the hydrodynamic loading of vertically resonating microfabricated plates immersed in liquids with different viscosities. The planar structures were patterned with focused ion beam, perforating various shapes with identical area but varying perimeters. The hydrodynamic loading of various...
Hydrodynamic modelling for relativistic heavy-ion collisions at RHIC ...
Indian Academy of Sciences (India)
model, to describe the microscopic evolution and decoupling of the hadronic ... progress on hydrodynamic modelling, investigation on the flow data and the ... and to describe and predict the soft particle physics in relativistic heavy-ion collisions [4]. It is based on the conservation laws of energy, momentum and net charge ...
Hydrodynamic processes in sharp meander bends and their morphological implications
Blanckaert, K.
2011-01-01
The migration rate of sharp meander bends exhibits large variance and indicates that some sharply curved bends tend to stabilize. These observations remain unexplained. This paper examines three hydrodynamic processes in sharp bends with fixed banks and discusses their morphological implications:
Hydrodynamics studies of cyclic voltammetry for electrochemical micro biosensors
DEFF Research Database (Denmark)
Adesokan, Bolaji James; Quan, Xueling; Evgrafov, Anton
2015-01-01
We investigate the effect of flow rate on the electrical current response to the applied voltage in a micro electrochemical system. To accomplish this, we considered an ion-transport model that is governed by the Nernst-Planck equation coupled to the Navier-Stokes equations for hydrodynamics...
Hydrodynamics of burst swimming fish larvae; a conceptual model approach
Verhagen, J.H.G.
2004-01-01
Burst swimming of fish larvae is analysed from a hydrodynamic point of view. A picture of the expected flow pattern is presented based on information in literature on unsteady-flow patterns around obstacles in the intermediate Reynolds number region. It is shown that the acceleration stage of burst
Cavitation Generation and Usage Without Ultrasound: Hydrodynamic Cavitation
Gogate, Parag R.; Pandit, Aniruddha B.
Hydrodynamic Cavitation, which was and is still looked upon as an unavoidable nuisance in the flow systems, can be a serious contender as an alternative to acoustic cavitation for harnessing the spectacular effects of cavitation in physical and chemical processing. The present chapter covers the basics of hydrodynamic cavitation including the considerations for the bubble dynamics analysis, reactor designs and recommendations for optimum operating parameters. An overview of applications in different areas of physical, chemical and biological processing on scales ranging from few grams to several hundred kilograms has also been presented. Since hydrodynamic cavitation was initially proposed as an alternative to acoustic cavitation, it is necessary to compare the efficacy of both these modes of cavitations for a variety of applications and hence comparisons have been discussed either on the basis of energy efficiency or based on the scale of operation. Overall it appears that hydrodynamic cavitation results in conditions similar to those generated using acoustic cavitation but at comparatively much larger scale of operation and with better energy efficiencies.
Modeling of hydrodynamic cavitation reactors: a unified approach
Moholkar, V.S.; Pandit, A.B.
2001-01-01
An attempt has been made to present a unified theoretical model for the cavitating flow in a hydrodynamic cavitation reactor using the nonlinear continuum mixture model for two-phase flow as the basis. This model has been used to describe the radial motion of bubble in the cavitating flow in two
Hydrodynamic analysis of anisotropic transverse flow at RHIC
International Nuclear Information System (INIS)
Hirano, Tetsufumi; Tsuda, Keiichi; Kajimoto, Kohei
2001-01-01
By using a (3+1)-dimensional relativistic hydrodynamic model, we estimate the magnitude of (differential) elliptic flow parameter υ 2 at the BNL-RHIC energy. We compare the centrality and the transverse momentum dependence of υ 2 with the experimental data observed by the STAR Collaboration. (author)
Geochemical and hydrodynamic phosphorus retention mechanisms in lowland catchments
van der Grift, B.
2017-01-01
The release of phosphorus (P) to surface water from heavily fertilised agricultural fields is of major importance for surface water quality. The research reported in this thesis examined the role of geochemical and hydrodynamic processes controlling P speciation and transport in lowland catchments
Numerical analysis of hydrodynamic journal bearings lubricated with ferrofluid
Montazeri, H.
2008-01-01
The current work focuses on studying the hydrodynamic characteristics of flow in journal bearings lubricated with ferrofluid. The bearing has an infinite length and operates under incompressible laminar flow and steady conditions. Assuming linear behaviour for the magnetic material of the
Progress and challenges in coupled hydrodynamic-ecological estuarine modeling
Ganju, Neil K.; Brush, Mark J.; Rashleigh, Brenda; Aretxabaleta, Alfredo L.; del Barrio, Pilar; Grear, Jason S.; Harris, Lora A.; Lake, Samuel J.; McCardell, Grant; O'Donnell, James; Ralston, David K.; Signell, Richard P.; Testa, Jeremy; Vaudrey, Jamie M. P.
2016-01-01
Numerical modeling has emerged over the last several decades as a widely accepted tool for investigations in environmental sciences. In estuarine research, hydrodynamic and ecological models have moved along parallel tracks with regard to complexity, refinement, computational power, and incorporation of uncertainty. Coupled hydrodynamic-ecological models have been used to assess ecosystem processes and interactions, simulate future scenarios, and evaluate remedial actions in response to eutrophication, habitat loss, and freshwater diversion. The need to couple hydrodynamic and ecological models to address research and management questions is clear because dynamic feedbacks between biotic and physical processes are critical interactions within ecosystems. In this review, we present historical and modern perspectives on estuarine hydrodynamic and ecological modeling, consider model limitations, and address aspects of model linkage, skill assessment, and complexity. We discuss the balance between spatial and temporal resolution and present examples using different spatiotemporal scales. Finally, we recommend future lines of inquiry, approaches to balance complexity and uncertainty, and model transparency and utility. It is idealistic to think we can pursue a “theory of everything” for estuarine models, but recent advances suggest that models for both scientific investigations and management applications will continue to improve in terms of realism, precision, and accuracy.
Interaction of Microphysical Aerosol Processes with Hydrodynamics Mixing
Alshaarawi, Amjad
2015-12-15
This work is concerned with the interaction between condensing aerosol dynamics and hydrodynamic mixing within ow configurations in which aerosol particles form (nucleate) from a supersaturated vapor and supersaturation is induced by the mixing of two streams (a saturated stream and a cold one). Two canonical hydrodynamic configurations are proposed for the investigation. The First is the steady one-dimensional opposed-ow configuration. The setup consists of the two (saturated and cold) streams owing from opposite nozzles. A mixing layer is established across a stagnation plane in the center where nucleation and other aerosol dynamics are triggered. The second is homogeneous isotropic turbulence in a three-dimensional periodic domain. Patches of a hot saturated gas mix with patches of a cold one. A mixing layer forms across the growing interface where the aerosol dynamics of interest occur. In both configurations, a unique analogy is observed. The results reveal a complex response to variations in the mixing rates. Depending on the mixing rate, the response of the number density falls into one of two regimes. For fast mixing rates, the maximum reached number density of the condensing droplets increases with the hydrodynamic time. We refer to this as the nucleation regime. On the contrary, for low mixing rates, the maximum reached number density decreases with the hydrodynamic time. We refer to this as the consumption regime. It is shown that vapor scavenging by the aerosol phase is key to explaining the transition between these two regimes.