Agosta, Roxana; Bilbija, Dushan; Deutsch, Marc; Gallant, David; Rose, Don; Shreve, Gene; Smario, David; Suffredini, Brian
1992-01-01
As intercontinental business and tourism volumes continue their rapid expansion, the need to reduce travel times becomes increasingly acute. The Edge Supersonic Transport Aircraft is designed to meet this demand by the year 2015. With a maximum range of 5750 nm, a payload of 294 passengers and a cruising speed of M = 2.4, The Edge will cut current international flight durations in half, while maintaining competitive first class, business class, and economy class comfort levels. Moreover, this transport will render a minimal impact upon the environment, and will meet all Federal Aviation Administration Part 36, Stage III noise requirements. The cornerstone of The Edge's superior flight performance is its aerodynamically efficient, dual-configuration design incorporating variable-geometry wingtips. This arrangement combines the benefits of a high aspect ratio wing at takeoff and low cruising speeds with the high performance of an arrow-wing in supersonic cruise. And while the structural weight concerns relating to swinging wingtips are substantial, The Edge looks to ever-advancing material technologies to further increase its viability. Heeding well the lessons of the past, The Edge design holds economic feasibility as its primary focus. Therefore, in addition to its inherently superior aerodynamic performance, The Edge uses a lightweight, largely windowless configuration, relying on a synthetic vision system for outside viewing by both pilot and passengers. Additionally, a fly-by-light flight control system is incorporated to address aircraft supersonic cruise instability. The Edge will be produced at an estimated volume of 400 aircraft and will be offered to airlines in 2015 at $167 million per transport (1992 dollars).
Tesseract supersonic business transport
Reshotko, Eli; Garbinski, Gary; Fellenstein, James; Botting, Mary; Hooper, Joan; Ryan, Michael; Struk, Peter; Taggart, Ben; Taillon, Maggie; Warzynski, Gary
1992-01-01
This year, the senior level Aerospace Design class at Case Western Reserve University developed a conceptual design of a supersonic business transport. Due to the growing trade between Asia and the United States, a transpacific range was chosen for the aircraft. A Mach number of 2.2 was chosen, too, because it provides reasonable block times and allows the use of a large range of materials without a need for active cooling. A payload of 2,500 lbs. was assumed corresponding to a complement of nine passengers and crew, plus some light cargo. With these general requirements set, the class was broken down into three groups. The aerodynamics of the aircraft were the responsibility of the first group. The second developed the propulsion system. The efforts of both the aerodynamics and propulsion groups were monitored and reviewed for weight considerations and structural feasibility by the third group. Integration of the design required considerable interaction between the groups in the final stages. The fuselage length of the final conceptual design was 107.0 ft, while the diameter of the fuselage was 7.6 ft. The delta wing design consisted of an aspect ratio of 1.9 with a wing span of 47.75 ft and mid-chord length of 61.0 ft. A SNECMA MCV 99 variable-cycle engine design was chosen for this aircraft.
Tesseract: Supersonic business transport
Reshotko, Eli; Garbinski, Gary
1992-01-01
This year, the senior level Aerospace Design class at Case Western Reserve University developed a conceptual design of a supersonic business transport. Due to the growing trade between Asia and the United States, a transpacific range has been chosen for the aircraft. A Mach number of 2.2 was chosen too because it provides reasonable block times and allows the use of a large range of materials without a need for active cooling. A payload of 2500 lbs. has been assumed corresponding to a complement of nine (passengers and crew) plus some light cargo. With these general requirements set, the class was broken down into three groups. The aerodynamics of the aircraft were the responsibility of the first group. The second developed the propulsion system. The efforts of both the aerodynamics and propulsion groups were monitored and reviewed for weight considerations and structural feasibility by the third group. Integration of the design required considerable interaction between the groups in the final stages. The fuselage length of the final conceptual design was 107.0 ft. while the diameter of the fuselage was 7.6 ft. The delta wing design consisted of an aspect ratio of 1.9 with a wing span of 47.75 ft and midcord length of 61.0 ft. A SNEMCA MCV 99 variable-cycle engine design was chosen for this aircraft.
Model predictions of latitude-dependent ozone depletion due to supersonic transport operations
Borucki, W. J.; Whitten, R. C.; Watson, V. R.; Woodward, H. T.; Riegel, C. A.; Capone, L. A.; Becker, T.
1976-01-01
Results are presented from a two-dimensional model of the stratosphere that simulates the seasonal movement of ozone by both wind and eddy transport, and contains all the chemistry known to be important. The calculated reductions in ozone due to NO2 injection from a fleet of supersonic transports are compared with the zonally averaged results of a three-dimensional model for a similar episode of injection. The agreement is good in the northern hemisphere, but is not as good in the southern hemisphere. Both sets of calculations show a strong corridor effect in that the predicted ozone depletions are largest to the north of the flight corridor for aircraft operating in the northern hemisphere.
Supersonic induction plasma jet modeling
Energy Technology Data Exchange (ETDEWEB)
Selezneva, S.E. E-mail: svetlana2@hermes.usherbS_Selezneva2@hermes.usherb; Boulos, M.I
2001-06-01
Numerical simulations have been applied to study the argon plasma flow downstream of the induction plasma torch. It is shown that by means of the convergent-divergent nozzle adjustment and chamber pressure reduction, a supersonic plasma jet can be obtained. We investigate the supersonic and a more traditional subsonic plasma jets impinging onto a normal substrate. Comparing to the subsonic jet, the supersonic one is narrower and much faster. Near-substrate velocity and temperature boundary layers are thinner, so the heat flux near the stagnation point is higher in the supersonic jet. The supersonic plasma jet is characterized by the electron overpopulation and the domination of the recombination over the dissociation, resulting into the heating of the electron gas. Because of these processes, the supersonic induction plasma permits to separate spatially different functions (dissociation and ionization, transport and deposition) and to optimize each of them. The considered configuration can be advantageous in some industrial applications, such as plasma-assisted chemical vapor deposition of diamond and polymer-like films and in plasma spraying of nanoscaled powders.
Christhilf, David M.; Pototzky, Anthony S.; Stevens, William L.
2010-01-01
The Simulink-based Simulation Architecture for Evaluating Controls for Aerospace Vehicles (SAREC-ASV) was modified to incorporate linear models representing aeroservoelastic characteristics of the SemiSpan SuperSonic Transport (S4T) wind-tunnel model. The S4T planform is for a Technology Concept Aircraft (TCA) design from the 1990s. The model has three control surfaces and is instrumented with accelerometers and strain gauges. Control laws developed for wind-tunnel testing for Ride Quality Enhancement, Gust Load Alleviation, and Flutter Suppression System functions were implemented in the simulation. The simulation models open- and closed-loop response to turbulence and to control excitation. It provides time histories for closed-loop stable conditions above the open-loop flutter boundary. The simulation is useful for assessing the potential impact of closed-loop control rate and position saturation. It also provides a means to assess fidelity of system identification procedures by providing time histories for a known plant model, with and without unmeasured turbulence as a disturbance. Sets of linear models representing different Mach number and dynamic pressure conditions were implemented as MATLAB Linear Time Invariant (LTI) objects. Configuration changes were implemented by selecting which LTI object to use in a Simulink template block. A limited comparison of simulation versus wind-tunnel results is shown.
Study of active cooling for supersonic transports
Brewer, G. D.; Morris, R. E.
1975-01-01
The potential benefits of using the fuel heat sink of hydrogen fueled supersonic transports for cooling large portions of the aircraft wing and fuselage are examined. The heat transfer would be accomplished by using an intermediate fluid such as an ethylene glycol-water solution. Some of the advantages of the system are: (1) reduced costs by using aluminum in place of titanium, (2) reduced cabin heat loads, and (3) more favorable environmental conditions for the aircraft systems. A liquid hydrogen fueled, Mach 2.7 supersonic transport aircraft design was used for the reference uncooled vehicle. The cooled aircraft designs were analyzed to determine their heat sink capability, the extent and location of feasible cooled surfaces, and the coolant passage size and spacing.
A Reynolds Number Study of Wing Leading-Edge Effects on a Supersonic Transport Model at Mach 0.3
Williams, M. Susan; Owens, Lewis R., Jr.; Chu, Julio
1999-01-01
A representative supersonic transport design was tested in the National Transonic Facility (NTF) in its original configuration with small-radius leading-edge flaps and also with modified large-radius inboard leading-edge flaps. Aerodynamic data were obtained over a range of Reynolds numbers at a Mach number of 0.3 and angles of attack up to 16 deg. Increasing the radius of the inboard leading-edge flap delayed nose-up pitching moment to a higher lift coefficient. Deflecting the large-radius leading-edge flap produced an overall decrease in lift coefficient and delayed nose-up pitching moment to even higher angles of attack as compared with the undeflected large- radius leading-edge flap. At angles of attack corresponding to the maximum untrimmed lift-to-drag ratio, lift and drag coefficients decreased while lift-to-drag ratio increased with increasing Reynolds number. At an angle of attack of 13.5 deg., the pitching-moment coefficient was nearly constant with increasing Reynolds number for both the small-radius leading-edge flap and the deflected large-radius leading-edge flap. However, the pitching moment coefficient increased with increasing Reynolds number for the undeflected large-radius leading-edge flap above a chord Reynolds number of about 35 x 10 (exp 6).
Aeroelastic Analyses of the SemiSpan SuperSonic Transport (S4T) Wind Tunnel Model at Mach 0.95
Hur, Jiyoung
2014-01-01
Detailed aeroelastic analyses of the SemiSpan SuperSonic Transport (S4T) wind tunnel model at Mach 0.95 with a 1.75deg fixed angle of attack are presented. First, a numerical procedure using the Computational Fluids Laboratory 3-Dimensional (CFL3D) Version 6.4 flow solver is investigated. The mesh update method for structured multi-block grids was successfully applied to the Navier-Stokes simulations. Second, the steady aerodynamic analyses with a rigid structure of the S4T wind tunnel model are reviewed in transonic flow. Third, the static analyses were performed for both the Euler and Navier-Stokes equations. Both the Euler and Navier-Stokes equations predicted a significant increase of lift forces, compared to the results from the rigid structure of the S4T wind-tunnel model, over various dynamic pressures. Finally, dynamic aeroelastic analyses were performed to investigate the flutter condition of the S4T wind tunnel model at the transonic Mach number. The condition of flutter was observed at a dynamic pressure of approximately 75.0-psf for the Navier-Stokes simulations. However, it was observed that the flutter condition occurred a dynamic pressure of approximately 47.27-psf for the Euler simulations. Also, the computational efficiency of the aeroelastic analyses for the S4T wind tunnel model has been assessed.
Wieseman, Carol D.; Christhilf, David; Perry, Boyd, III
2012-01-01
An important objective of the Semi-Span Super-Sonic Transport (S4T) wind tunnel model program was the demonstration of Flutter Suppression (FS), Gust Load Alleviation (GLA), and Ride Quality Enhancement (RQE). It was critical to evaluate the stability and robustness of these control laws analytically before testing them and experimentally while testing them to ensure safety of the model and the wind tunnel. MATLAB based software was applied to evaluate the performance of closed-loop systems in terms of stability and robustness. Existing software tools were extended to use analytical representations of the S4T and the control laws to analyze and evaluate the control laws prior to testing. Lessons were learned about the complex windtunnel model and experimental testing. The open-loop flutter boundary was determined from the closed-loop systems. A MATLAB/Simulink Simulation developed under the program is available for future work to improve the CPE process. This paper is one of a series of that comprise a special session, which summarizes the S4T wind-tunnel program.
The impact of emerging technologies on an advanced supersonic transport
Driver, C.; Maglieri, D. J.
1986-01-01
The effects of advances in propulsion systems, structure and materials, aerodynamics, and systems on the design and development of supersonic transport aircraft are analyzed. Efficient propulsion systems with variable-cycle engines provide the basis for improved propulsion systems; the propulsion efficienies of supersonic and subsonic engines are compared. Material advances consist of long-life damage-tolerant structures, advanced material development, aeroelastic tailoring, and low-cost fabrication. Improvements in the areas of aerodynamics and systems are examined. The environmental problems caused by engine emissions, airport noise, and sonic boom are studied. The characteristics of the aircraft designed to include these technical advances are described.
Christhilf, David M.
2014-01-01
It has long been recognized that frequency and phasing of structural modes in the presence of airflow play a fundamental role in the occurrence of flutter. Animation of simulation results for the long, slender Semi-Span Super-Sonic Transport (S4T) wind-tunnel model demonstrates that, for the case of mass-ballasted nacelles, the flutter mode can be described as a traveling wave propagating downstream. Such a characterization provides certain insights, such as (1) describing the means by which energy is transferred from the airflow to the structure, (2) identifying airspeed as an upper limit for speed of wave propagation, (3) providing an interpretation for a companion mode that coalesces in frequency with the flutter mode but becomes very well damped, (4) providing an explanation for bursts of response to uniform turbulence, and (5) providing an explanation for loss of low frequency (lead) phase margin with increases in dynamic pressure (at constant Mach number) for feedback systems that use sensors located upstream from active control surfaces. Results from simulation animation, simplified modeling, and wind-tunnel testing are presented for comparison. The simulation animation was generated using double time-integration in Simulink of vertical accelerometer signals distributed over wing and fuselage, along with time histories for actuated control surfaces. Crossing points for a zero-elevation reference plane were tracked along a network of lines connecting the accelerometer locations. Accelerometer signals were used in preference to modal displacement state variables in anticipation that the technique could be used to animate motion of the actual wind-tunnel model using data acquired during testing. Double integration of wind-tunnel accelerometer signals introduced severe drift even with removal of both position and rate biases such that the technique does not currently work. Using wind-tunnel data to drive a Kalman filter based upon fitting coefficients to
Technical and environmental challenges for the next generation supersonic transport
Energy Technology Data Exchange (ETDEWEB)
Pacull, M. [Aerospatiale (France); Hume, Ch. [British Aerospace (United Kingdom)
1994-12-31
The next century will be marked by the entry into service of new supersonic transport. The real question concerning the next generation supersonic transport is not will it happen, but when, and how. There is a general agreement that such an airplane will result from a worldwide venture. Who will participate, to what extend and how we will put the vehicle and partners together, are an interesting concern that will need some time to resolve. The other challenges will be to design, build and market an aircraft that will be a viable product: for the passenger, who wants the service of a fast airliner with a reasonable surcharge; for the airline which wants competitive operating cost so that it will make sense to introduce such an airplane in its fleet; for the manufacturer, which not only does not want to go bankruptcy, but seeks to make a profit in the long term within the environmental constraints: no adverse impact on high atmosphere ozone; compliance with noise requirements, operations compatible with sonic boom. This paper does not try to answer all these question, but rather highlight major technical and environmental issues for the next generation supersonic transport. The topics discussed are: general specification, noise, atmospheric emissions, sonic boom, aerodynamics, structures, engine integration, systems. (authors)
Hydrogen tube vehicle for supersonic transport: 2. Speed and energy
Energy Technology Data Exchange (ETDEWEB)
Miller, Arnold R. [Vehicle Projects Inc and Supersonic Tubevehicle LLC, 200 Violet St, Suite 100, Golden, CO 80401 (United States)
2010-06-15
The central concept of a new idea in high-speed transport is that operation of a vehicle in a hydrogen atmosphere, because of the low density of hydrogen, would increase sonic speed by a factor of 3.8 and decrease drag by 15 relative to air. A hydrogen atmosphere requires that the vehicle operate within a hydrogen-filled tube or pipeline, which serves as a phase separator. The supersonic tube vehicle (STV) can be supersonic with respect to air outside the tube while remaining subsonic inside. It breathes hydrogen fuel for its propulsion fuel cells from the tube itself. This paper, second in a series on the scientific foundations of the supersonic tube vehicle, tests the hypothesis that the STV will be simultaneously fast and energy efficient by comparing its predicted speed and energy consumption with that of four long-haul passenger transport modes: road, rail, maglev, and air. The study establishes the speed ranking STV >> airplane > maglev > train > coach (intercity bus) and the normalized energy consumption ranking Airplane >> coach > maglev > train > STV. Consistent with the hypothesis, the concept vehicle is both the fastest and lowest energy consuming mode. In theory, the vehicle can cruise at Mach 2.8 while consuming less than half the energy per passenger of a Boeing 747 at a cruise speed of Mach 0.81. (author)
Chemically reacting supersonic flow calculation using an assumed PDF model
Farshchi, M.
1990-01-01
This work is motivated by the need to develop accurate models for chemically reacting compressible turbulent flow fields that are present in a typical supersonic combustion ramjet (SCRAMJET) engine. In this paper the development of a new assumed probability density function (PDF) reaction model for supersonic turbulent diffusion flames and its implementation into an efficient Navier-Stokes solver are discussed. The application of this model to a supersonic hydrogen-air flame will be considered.
Morgenstern, John; Norstrud, Nicole; Stelmack, Marc; Skoch, Craig
2010-01-01
The N+3 Final Report documents the work and progress made by Lockheed Martin Aeronautics in response to the NASA sponsored program "N+3 NRA Advanced Concept Studies for Supersonic Commercial Transports Entering Service in the 2030 to 2035 Period." The key technical objective of this effort was to generate promising supersonic concepts for the 2030 to 2035 timeframe and to develop plans for maturing the technologies required to make those concepts a reality. The N+3 program is aligned with NASA's Supersonic Project and is focused on providing alternative system-level solutions capable of overcoming the efficiency, environmental, and performance barriers to practical supersonic flight
Morgenstern, John; Norstrud, Nicole; Sokhey, Jack; Martens, Steve; Alonso, Juan J.
2013-01-01
Lockheed Martin Aeronautics Company (LM), working in conjunction with General Electric Global Research (GE GR), Rolls-Royce Liberty Works (RRLW), and Stanford University, herein presents results from the "N+2 Supersonic Validations" contract s initial 22 month phase, addressing the NASA solicitation "Advanced Concept Studies for Supersonic Commercial Transports Entering Service in the 2018 to 2020 Period." This report version adds documentation of an additional three month low boom test task. The key technical objective of this effort was to validate integrated airframe and propulsion technologies and design methodologies. These capabilities aspired to produce a viable supersonic vehicle design with environmental and performance characteristics. Supersonic testing of both airframe and propulsion technologies (including LM3: 97-023 low boom testing and April-June nozzle acoustic testing) verified LM s supersonic low-boom design methodologies and both GE and RRLW's nozzle technologies for future implementation. The N+2 program is aligned with NASA s Supersonic Project and is focused on providing system-level solutions capable of overcoming the environmental and performance/efficiency barriers to practical supersonic flight. NASA proposed "Initial Environmental Targets and Performance Goals for Future Supersonic Civil Aircraft". The LM N+2 studies are built upon LM s prior N+3 100 passenger design studies. The LM N+2 program addresses low boom design and methodology validations with wind tunnel testing, performance and efficiency goals with system level analysis, and low noise validations with two nozzle (GE and RRLW) acoustic tests.
Underwood, Matthew C.; Guminsky, Michael D.
2015-01-01
Several public sector businesses and government agencies, including the National Aeronautics and Space Administration are currently working on solving key technological barriers that must be overcome in order to realize the vision of low-boom supersonic flights conducted over land. However, once these challenges are met, the manner in which this class of aircraft is integrated in the National Airspace System may become a potential constraint due to the significant environmental, efficiency, and economic repercussions that their integration may cause. Background research was performed on historic supersonic operations in the National Airspace System, including both flight deck procedures and air traffic controller procedures. Using this information, an experiment was created to test some of these historic procedures in a current-day, emerging Next Generation Air Transportation System (NextGen) environment and observe the interactions between commercial supersonic transport aircraft and modern-day air traffic. Data was gathered through batch simulations of supersonic commercial transport category aircraft operating in present-day traffic scenarios as a base-lining study to identify the magnitude of the integration problems and begin the exploration of new air traffic management technologies and architectures which will be needed to seamlessly integrate subsonic and supersonic transport aircraft operations. The data gathered include information about encounters between subsonic and supersonic aircraft that may occur when supersonic commercial transport aircraft are integrated into the National Airspace System, as well as flight time data. This initial investigation is being used to inform the creation and refinement of a preliminary Concept of Operations and for the subsequent development of technologies that will enable overland supersonic flight.
A flamelet model for turbulent diffusion combustion in supersonic flow
Institute of Scientific and Technical Information of China (English)
LEE; ChunHian
2010-01-01
In order to develop a turbulent diffusion combustion model for supersonic flow, the physical argument of the extension of the flamelet model to supersonic flow was presented, and the flow field of a hydrogen/air diffusion combustion generated by axisymmetric supersonic jets was numerically simulated by employing the flamelet model. Using the experimental data, value of the model coefficient of scalar dissipation in the flamelet model was revised specifically for supersonic flow. The computational results of the modified flamelet model were compared with the experimental results, and it was indicated that the precision of the modified flamelet model was satisfying. Based on the numerical results and flamelet theory, the influence mechanisms of turbulence fluctuation on the average state equation and chemical reaction rate were studied for the first time. It was found that the fluctuation correlation of species mass fractions and temperature has little effect on the averaged gas state equation; the temperature fluctuation decreases the product of H2O, but its effect is small; the fluctuation of species mass fractions increases the product of H2O in the region close to oxidizer while decreases the product of H2O in other regions; the fluctuation correlation of species mass fractions and temperature largely decreases the product of H2O.
Dippold, Vance F. III; Friedlander, David
2017-01-01
Reynolds-Averaged Navier-Stokes (RANS) simulations were performed for a commercial supersonic transport aircraft concept and experimental hardware models designed to represent the installed propulsion system of the conceptual aircraft in an upcoming test campaign. The purpose of the experiment is to determine the effects of jet-surface interactions from supersonic aircraft on airport community noise. RANS simulations of the commercial supersonic transport aircraft concept were performed to relate the representative experimental hardware to the actual aircraft. RANS screening simulations were performed on the proposed test hardware to verify that it would be free from potential rig noise and to predict the aerodynamic forces on the model hardware to assist with structural design. The simulations showed a large region of separated flow formed in a junction region of one of the experimental configurations. This was dissimilar with simulations of the aircraft and could invalidate the noise measurements. This configuration was modified and a subsequent RANS simulation showed that the size of the flow separation was greatly reduced. The aerodynamic forces found on the experimental models were found to be relatively small when compared to the expected loads from the model’s own weight.Reynolds-Averaged Navier-Stokes (RANS) simulations were completed for two configurations of a three-stream inverted velocity profile (IVP) nozzle and a baseline single-stream round nozzle (mixed-flow equivalent conditions). For the Sideline and Cutback flow conditions, while the IVP nozzles did not reduce the peak turbulent kinetic energy on the lower side of the jet plume, the IVP nozzles did significantly reduce the size of the region of peak turbulent kinetic energy when compared to the jet plume of the baseline nozzle cases. The IVP nozzle at Sideline conditions did suffer a region of separated flow from the inner stream nozzle splitter that did produce an intense, but small, region of
Towards an Aero-Propulso-Servo-Elasticity Analysis of a Commercial Supersonic Transport
Connolly, Joseph W.; Kopasakis, George; Chwalowski, Pawel; Sanetrik, Mark D.; Carlson, Jan-Renee; Silva, Walt A.; McNamara, Jack
2016-01-01
This paper covers the development of an aero-propulso-servo-elastic (APSE) model using computational fluid dynamics (CFD) and linear structural deformations. The APSE model provides the integration of the following two previously developed nonlinear dynamic simulations: a variable cycle turbofan engine and an elastic supersonic commercial transport vehicle. The primary focus of this study is to provide a means to include relevant dynamics of a turbomachinery propulsion system into the aeroelastic studies conducted during a vehicle design, which have historically neglected propulsion effects. A high fidelity CFD tool is used here for the integration platform. The elastic vehicle neglecting the propulsion system serves as a comparison of traditional approaches to the APSE results. An overview of the methodology is presented for integrating the propulsion system and elastic vehicle. Static aeroelastic analysis comparisons between the traditional and developed APSE models for a wing tip detection indicate that the propulsion system impact on the vehicle elastic response could increase the detection by approximately ten percent.
Mobley, B. L.; Smith, S. D.; Van Norman, J. W.; Muppidi, S.; Clark, I
2016-01-01
Provide plume induced heating (radiation & convection) predictions in support of the LDSD thermal design (pre-flight SFDT-1) Predict plume induced aerodynamics in support of flight dynamics, to achieve targeted freestream conditions to test supersonic deceleration technologies (post-flight SFDT-1, pre-flight SFDT-2)
Institute of Scientific and Technical Information of China (English)
R.E. Waltz
2007-01-01
@@ There has been remarkable progress during the past decade in understanding and modeling turbulent transport in tokamaks. With some exceptions the progress is derived from the huge increases in computational power and the ability to simulate tokamak turbulence with ever more fundamental and physically realistic dynamical equations, e.g.
Modeling supersonic combustion using a fully-implicit numerical method
Maccormack, Robert W.; Wilson, Gregory J.
1990-01-01
A fully-implicit finite-volume algorithm for two-dimensional axisymmetric flows has been coupled to a detailed hydrogen-air reaction mechanism (13 species and 33 reactions) so that supersonic combustion phenomena may be investigated. Numerical computations are compared with ballistic-range shadowgraphs of Lehr (1972) that exhibit two discontinuities caused by a blunt body as it passes through a premixed stoichiometric hydrogen-air mixture. The suitability of the numerical procedure for simulating these double-front flows is shown. The requirements for the physical formulation and the numerical modeling of these flowfields are discussed. Finally, the sensitivity of these external flowfields to changes in certain key reaction rate constants is examined.
A Direct-Fire Trajectory Model for Supersonic, Transonic, and Subsonic Projectile Flight
2014-07-01
motions of the projectile about the trajectory due to the angular motion of the projectile . For a stable projectile , these motions are typically small...A Direct-Fire Trajectory Model for Supersonic, Transonic, and Subsonic Projectile Flight by Paul Weinacht ARL-TR-6998 July 2014...Direct-Fire Trajectory Model for Supersonic, Transonic, and Subsonic Projectile Flight Paul Weinacht Weapons and Materials Research Directorate, ARL
Saitoh, Kenichi; Tamayama, Masato; Kikuchi, Takao; Machida, Shigeru; Nakamichi, Jiro
This paper reports a wind-tunnel experiment and analysis that have been conducted under the National Experimental Airplane for Supersonic Transports (NEXST-1) project of JAXA. In order to perform the flight experiment, the design of the vehicle was examined from the stand point of aeroelasticity. The aileron buzz as well as flutter was of much concern for its aileron system on the main wing. Therefore, both wind-tunnel test and analysis were carried out by using a semi-span model with fuselage. Although the buzz was not observed in the test, damping responses of the aileron rotation mode were obtained. Critical damping was observed in supersonic flow, that meant a buzz could occur in ``region C'' of Lambourne's classification. Linear unsteady aerodynamic analysis is applicable to this type of buzz and the characteristics of the buzz of the model is discussed.
Characteristic parameters of diffusive supersonic radiation transport in low density materials
Institute of Scientific and Technical Information of China (English)
Jiang Shao-En; Yang Jia-Min; Zheng Zhi-Jian; Ding Yong-Kun
2007-01-01
Diffusive heat waves play an important role in radiation hydrodynamics. In low density material, it may be possible that the radiative energy flux dominates the material energy flux and thus energy flow can be determined. In this paper by means of a simple algebraic method, the expressions characterizing the condition of diffusion approximation and supersonic transport of heat wave are found. In this case, the ratio of the radiative energy flux to the material energy flux is directly proportional to the product of Mach number M multiplied by optical depth τ. And it may also be expressed by radiation temperature heating material. The materiel density and length may be determined in order to aceve above-mentioned conditions when the driven temperature and duration are given.
Linear models for sound from supersonic reacting mixing layers
Chary, P. Shivakanth; Samanta, Arnab
2016-12-01
We perform a linearized reduced-order modeling of the aeroacoustic sound sources in supersonic reacting mixing layers to explore their sensitivities to some of the flow parameters in radiating sound. Specifically, we investigate the role of outer modes as the effective flow compressibility is raised, when some of these are expected to dominate over the traditional Kelvin-Helmholtz (K-H) -type central mode. Although the outer modes are known to be of lesser importance in the near-field mixing, how these radiate to the far-field is uncertain, on which we focus. On keeping the flow compressibility fixed, the outer modes are realized via biasing the respective mean densities of the fast (oxidizer) or slow (fuel) side. Here the mean flows are laminar solutions of two-dimensional compressible boundary layers with an imposed composite (turbulent) spreading rate, which we show to significantly alter the growth of instability waves by saturating them earlier, similar to in nonlinear calculations, achieved here via solving the linear parabolized stability equations. As the flow parameters are varied, instability of the slow modes is shown to be more sensitive to heat release, potentially exceeding equivalent central modes, as these modes yield relatively compact sound sources with lesser spreading of the mixing layer, when compared to the corresponding fast modes. In contrast, the radiated sound seems to be relatively unaffected when the mixture equivalence ratio is varied, except for a lean mixture which is shown to yield a pronounced effect on the slow mode radiation by reducing its modal growth.
Morgenstern, John; Buonanno, Michael; Yao, Jixian; Murugappan, Mugam; Paliath, Umesh; Cheung, Lawrence; Malcevic, Ivan; Ramakrishnan, Kishore; Pastouchenko, Nikolai; Wood, Trevor; Martens, Steve; Viars, Phil; Tersmette, Trevor; Lee, Jason; Simmons, Ron; Plybon, David; Alonso, Juan; Palacios, Francisco; Lukaczyk, Trent; Carrier, Gerald
2015-01-01
significant fidelity to the design of the configuration in this phase by performing a low speed wind tunnel test at our LTWT facility in Palmdale, by more complete modelling of propulsion effects in our sonic boom analysis, and by refining our configuration packaging and performance assessments. Working with General Electric, LM performed an assessment of the impact of inlet and nozzle effects on the sonic boom signature of the LM N+2 configurations. Our results indicate that inlet/exhaust streamtube boundary conditions are adequate for conceptual design studies, but realistic propulsion modeling at similar stream-tube conditions does have a small but measurable impact on the sonic boom signature. Previous supersonic transport studies have identified aeroelastic effects as one of the major challenges associated with the long, slender vehicles particularly common with shaped boom aircraft (Ref. 3). Under the Phase 2 effort, we have developed a detailed structural analysis model to evaluate the impact of flexibility and structural considerations on the feasibility of future quiet supersonic transports. We looked in particular at dynamic structural modes and flutter as a failure that must be avoided. We found that for our N+2 design in particular, adequate flutter margin existed. Our flutter margin is large enough to cover uncertainties like large increases in engine weight and the margin is relatively easy to increase with additional stiffening mass. The lack of major aeroelastic problems probably derives somewhat from an early design bias. While shaped boom aircraft require long length, they are not required to be thin. We intentionally developed our structural depths to avoid major flexibility problems. So at the end of Phase 2, we have validated that aeroelastic problems are not necessarily endemic to shaped boom designs. Experimental validation of sonic boom design and analysis techniques was the primary objective of the N+2 Supersonic Validations contract; and in this
Semi-analytical and 3D CFD DPAL modeling: feasibility of supersonic operation
Rosenwaks, Salman; Barmashenko, Boris D.; Waichman, Karol
2014-02-01
The feasibility of operating diode pumped alkali lasers (DPALs) with supersonic expansion of the gaseous laser mixture, consisting of alkali atoms, He atoms and (frequently) hydrocarbon molecules, is explored. Taking into account fluid dynamics and kinetic processes, both semi-analytical and three-dimensional (3D) computational fluid dynamics (CFD) modeling of supersonic DPALs is reported. Using the semi-analytical model, the operation of supersonic DPALs is compared with that measured and modeled in subsonic lasers for both Cs and K. The maximum power of supersonic Cs and K lasers is found to be higher than that of subsonic lasers with the same resonator and alkali density at the laser inlet by 25% and 70%, respectively. Using the 3D CFD model, the flow pattern and spatial distributions of the pump and laser intensities in the resonator are calculated for Cs DPALs. Comparison between the semi-analytical and 3D CFD models for Cs shows that the latter predicts much larger maximum achievable laser power than the former. These results indicate that for scaling-up the power of DPALs, supersonic expansion should be considered.
Wollan, M. J.
1975-01-01
The ability was examined of governmental agencies to adequately assess technological programs or projects to which they are committed. The hazards of government-sponsored activities are discussed; these include weather modification, supersonic transport noise, and the value conflicts involved in the fluoridation controversy. These three case studies indicate that the Federal vested interests in the continuation of its technological programs limit its ability to provide adequate technology assessment.
The Impact of Structural Vibration on Flying Qualities of a Supersonic Transport
Raney, David L.; Jackson, E. Bruce; Buttrill, Carey S.; Adams, William M.
2001-01-01
A piloted simulation experiment has been conducted in the NASA Langley Visual/Motion Simulator facility to address the impact of dynamic aeroelastic effects on flying qualities of a supersonic transport. The intent of this experiment was to determine the effectiveness of several measures that may be taken to reduce the impact of aircraft flexibility on piloting tasks. Potential solutions that were examined included structural stiffening, active vibration suppression, and elimination of visual cues associated with the elastic modes. A series of parametric configurations was evaluated by six test pilots for several types of maneuver tasks. During the investigation, several incidents were encountered in which cockpit vibrations due to elastic modes fed back into the control stick through involuntary motions of the pilot's upper body and arm. The phenomenon, referred to as biodynamic coupling, is evidenced by a resonant peak in the power spectrum of the pilot's stick inputs at a structural mode frequency. The results of the investigation indicate that structural stiffening and compensation of the visual display were of little benefit in alleviating the impact of elastic dynamics on the piloting tasks, while increased damping and elimination of control-effector excitation of the lowest frequency modes offered great improvements when applied in sufficient degree.
Aerodynamic Models for the Low Density Supersonic Decelerator (LDSD) Test Vehicles
Van Norman, John W.; Dyakonov, Artem; Schoenenberger, Mark; Davis, Jody; Muppidi, Suman; Tang, Chun; Bose, Deepak; Mobley, Brandon; Clark, Ian
2016-01-01
An overview of aerodynamic models for the Low Density Supersonic Decelerator (LDSD) Supersonic Flight Dynamics Test (SFDT) campaign test vehicle is presented, with comparisons to reconstructed flight data and discussion of model updates. The SFDT campaign objective is to test Supersonic Inflatable Aerodynamic Decelerator (SIAD) and large supersonic parachute technologies at high altitude Earth conditions relevant to entry, descent, and landing (EDL) at Mars. Nominal SIAD test conditions are attained by lifting a test vehicle (TV) to 36 km altitude with a helium balloon, then accelerating the TV to Mach 4 and 53 km altitude with a solid rocket motor. Test flights conducted in June of 2014 (SFDT-1) and 2015 (SFDT-2) each successfully delivered a 6 meter diameter decelerator (SIAD-R) to test conditions and several seconds of flight, and were successful in demonstrating the SFDT flight system concept and SIAD-R technology. Aerodynamic models and uncertainties developed for the SFDT campaign are presented, including the methods used to generate them and their implementation within an aerodynamic database (ADB) routine for flight simulations. Pre- and post-flight aerodynamic models are compared against reconstructed flight data and model changes based upon knowledge gained from the flights are discussed. The pre-flight powered phase model is shown to have a significant contribution to off-nominal SFDT trajectory lofting, while coast and SIAD phase models behaved much as predicted.
Kopasakis, George; Connolly, Joseph W.; Seiel, Jonathan
2016-01-01
A summary of the propulsion system modeling under NASA's High Speed Project (HSP) AeroPropulsoServoElasticity (APSE) task is provided with a focus on the propulsion system for the low-boom supersonic configuration developed by Lockheed Martin and referred to as the N+2 configuration. This summary includes details on the effort to date to develop computational models for the various propulsion system components. The objective of this paper is to summarize the model development effort in this task, while providing more detail in the modeling areas that have not been previously published. The purpose of the propulsion system modeling and the overall APSE effort is to develop an integrated dynamic vehicle model to conduct appropriate unsteady analysis of supersonic vehicle performance. This integrated APSE system model concept includes the propulsion system model, and the vehicle structural aerodynamics model. The development to date of such a preliminary integrated model will also be summarized in this report
Connolly, Joseph W.; Friedlander, David; Kopasakis, George
2015-01-01
This paper covers the development of an integrated nonlinear dynamic simulation for a variable cycle turbofan engine and nozzle that can be integrated with an overall vehicle Aero-Propulso-Servo-Elastic (APSE) model. A previously developed variable cycle turbofan engine model is used for this study and is enhanced here to include variable guide vanes allowing for operation across the supersonic flight regime. The primary focus of this study is to improve the fidelity of the model's thrust response by replacing the simple choked flow equation convergent-divergent nozzle model with a MacCormack method based quasi-1D model. The dynamic response of the nozzle model using the MacCormack method is verified by comparing it against a model of the nozzle using the conservation element/solution element method. A methodology is also presented for the integration of the MacCormack nozzle model with the variable cycle engine.
Numerical modelling of Mars supersonic disk-gap-band parachute inflation
Gao, Xinglong; Zhang, Qingbin; Tang, Qiangang
2016-06-01
The transient dynamic behaviour of supersonic disk-gap-band parachutes in a Mars entry environment involving fluid structure interactions is studied. Based on the multi-material Arbitrary Lagrange-Euler method, the coupling dynamic model between a viscous compressible fluid and a flexible large deformation structure of the parachute is solved. The inflation performance of a parachute with a fixed forebody under different flow conditions is analysed. The decelerating parameters of the parachute, including drag area, opening loads, and coefficients, are obtained from the supersonic wind tunnel test data from NASA. Meanwhile, the evolution of the three-dimensional shape of the disk-gap-band parachute during supersonic inflation is presented, and the structural dynamic behaviour of the parachute is predicted. Then, the influence of the presence of the capsule on the flow field of the parachute is investigated, and the wake of unsteady fluid and the distribution of shock wave around the supersonic parachute are presented. Finally, the structural dynamic response of the canopy fabric under high-pressure conditions is comparatively analysed. The results show that the disk-gap-band parachute is well inflated without serious collapse. As the Mach numbers increase from 2.0 to 2.5, the drag coefficients gradually decrease, along with a small decrease in inflation time, which corresponds with test results, and proves the validity of the method proposed in this paper.
DAC 22 High Speed Civil Transport Model
1992-01-01
Between tests, NASA research engineer Dave Hahne inspects a tenth-scale model of a supersonic transport model in the 30- by 60-Foot Tunnel at NASA Langley Research Center, Hampton, Virginia. The model is being used in support of NASA's High-Speed Research (HSR) program. Langley researchers are applying advance aerodynamic design methods to develop a wing leading-edge flap system which significantly improves low-speed fuel efficiency and reduces noise generated during takeoff operation. Langley is NASA's lead center for the agency's HSR program, aimed at developing technology to help U.S. industry compete in the rapidly expanding trans-oceanic transport market. A U.S. high-speed civil transport is expected to fly in about the year 2010. As envisioned, it would fly 300 passengers across the Pacific in about four hours at Mach 2.4 (approximately 1,600 mph/1950 kph) for a modest increase over business class fares.
Abort System Using Supersonic Aerodynamic Interaction for Capsule-Type Space Transportation System
小澤, 啓伺; 北村, 圭一; 花井, 勝祥; 三好, 理也; 森, 浩一; 中村, 佳朗
The space transportation system using capsule/rocket configurations such as Apollo and Soyuz are simple compared with Space Shuttle, and have several merits from the viewpoint of reliability. The capsule/rocket system will take over the Space Shuttle, after it retires in 2010. As the Space Shuttle accidents had been caused by several factors, e.g., aerodynamic interaction of shock waves ahead of its wing, advanced abort systems such as LAS (Launch Abort System) are required for the capsule/rocket system. In the present study, as a baseline configuration, a combination of a cone and a cylinder is employed as a CEV (Crew Exploration Vehicle), which consists of a capsule (LAV: Launch Abort Vehicle) and a rocket (SM: Service Module). By changing the relative position of the two components as well as the profile area of the rocket, their effects on the capsule/rocket aerodynamic interaction and characteristics (drag and pitching moment) are experimentally and numerically investigated at a supersonic speed (M∞ = 3.0). It is found from the results that the clearance have little effects on the flow field for the case of the baseline configuration. The capsule always showed a positive drag (CD = 0.34), which means that thrust is required to overcome the drag. Otherwise the capsule will recontact the rocket. However in the case where the rocket contact area is 2.2 times as large as the capsule profile, more favorable effects were obtained. Especially in the case of a certain clearance (h/D = 0.40), the drag coefficient of the capsule is CD = -0.35, which means that the capsule suffers a thrust force from the aerodynamic interaction. Under this condition, if capsule has a pitch angle with 5 degrees instantaneously, then pitching moment coefficient becomes CMp = -0.41 therefore capsule stabilize. However, in the case of a very small clearance (h/D ∝ 0.00), the flow becomes unsteady involving pulsating shock wave, leading to a potentially risky separation of the capsule.
Computing supersonic non-premixed turbulent combustion by an SMLD flamelet progress variable model
Coclite, A; Gurtner, M; De Palma, P; Haidnd, O J; Pascazio, G
2015-01-01
This paper describes the numerical simulation of the NASA Langley Research Center supersonic H2 -Air combustion chamber performed using two approaches to model the presumed probability density function (PDF) in the flamelet progress variable (FPV) framework. The first one is a standard FPV model, built presuming the functional shape of the PDFs of the mixture fraction, Z, and of the progress parameter, {\\Lambda}. In order to enhance the prediction capabilities of such a model in high-speed reacting flows, a second approach is proposed employing the statistically most likely distribution (SMLD) techcnique to presume the joint PDF of Z and {\\Lambda}, without any assumption about their behaviour. The standard and FPV-SMLD models have been developed using the low Mach number assumption. In both cases, the temperature is evaluated by solving the total-energy conservation equation, providing a more suitable approach for the simulation of supersonic combustion. By comparison with experimental data, the proposed SMLD...
Acoustic measurements of models of military style supersonic nozzle jets
Directory of Open Access Journals (Sweden)
Ching-Wen Kuo
2014-02-01
Full Text Available Modern military aircraft jet engines are designed with variable-geometry nozzles to provide optimal thrust in different operating conditions, depending on the flight envelope. However, acoustic measurements for such nozzles are scarce, due to the cost involved in making full-scale measurements and the lack of details about the exact geometries of these nozzles. Thus the present effort at Pennsylvania State University (PSU in partnership with GE Aviation and the NASA Glenn Research Center is aiming to study and characterize the acoustic field produced by supersonic jets issuing from converging-diverging military style nozzles, and to identify and test promising noise reduction techniques. An equally important objective is to develop methodology for using data obtained from small- and moderate-scale experiments to reliably predict the full-scale engine noise. The experimental results presented show reasonable agreement between small-scale and medium-scale jets, as well as between heated jets and heat-simulated ones.
Acoustic measurements of models of military style supersonic nozzle jets
Institute of Scientific and Technical Information of China (English)
Ching-Wen Kuo; Jérémy Veltin; Dennis K. McLaughlin
2014-01-01
Modern military aircraft jet engines are designed with variable-geometry nozzles to provide optimal thrust in different operating conditions, depending on the flight envelope. How-ever, acoustic measurements for such nozzles are scarce, due to the cost involved in making full-scale measurements and the lack of details about the exact geometries of these nozzles. Thus the present effort at Pennsylvania State University (PSU) in partnership with GE Aviation and the NASA Glenn Research Center is aiming to study and characterize the acoustic field produced by supersonic jets issuing from converging-diverging military style nozzles, and to identify and test promising noise reduction techniques. An equally important objective is to develop methodology for using data obtained from small-and moderate-scale experiments to reliably predict the full-scale engine noise. The experimental results presented show reasonable agreement between small-scale and medium-scale jets, as well as between heated jets and heat-simulated ones.
Energy Technology Data Exchange (ETDEWEB)
M. McGraw
2000-04-13
The UZ Colloid Transport model development plan states that the objective of this Analysis/Model Report (AMR) is to document the development of a model for simulating unsaturated colloid transport. This objective includes the following: (1) use of a process level model to evaluate the potential mechanisms for colloid transport at Yucca Mountain; (2) Provide ranges of parameters for significant colloid transport processes to Performance Assessment (PA) for the unsaturated zone (UZ); (3) Provide a basis for development of an abstracted model for use in PA calculations.
Kopasakis, George; Connolly, Joseph; Seidel, Jonathan
2014-01-01
A summary of the propulsion system modeling under NASA's High Speed Project (HSP) AeroPropulsoServoElasticity (APSE) task is provided with a focus on the propulsion system for the low-boom supersonic configuration developed by Lockheed Martin and referred to as the N+2 configuration. This summary includes details on the effort to date to develop computational models for the various propulsion system components. The objective of this paper is to summarize the model development effort in this task, while providing more detail in the modeling areas that have not been previously published. The purpose of the propulsion system modeling and the overall APSE effort is to develop an integrated dynamic vehicle model to conduct appropriate unsteady analysis of supersonic vehicle performance. This integrated APSE system model concept includes the propulsion system model, and the vehicle structural-aerodynamics model. The development to date of such a preliminary integrated model will also be summarized in this report.propulsion system dynamics, the structural dynamics, and aerodynamics.
CFD modelling of condensation process of water vapor in supersonic flows
DEFF Research Database (Denmark)
Wen, Chuang; Walther, Jens Honore; Yan, Yuying;
2016-01-01
-liquid phase change both in space and in time. The spontaneous condensation of water vapor will not appear immediately when the steam reaches the saturation state. Instead, it occurs further downstream the nozzle throat, where the steam is in the state of supersaturation.......The condensation phenomenon of vapor plays an important role in various industries, such as the steam flow in turbines and refrigeration system. A mathematical model is developed to predict the spontaneous condensing phenomenon in the supersonic conditions using the nucleation and droplet growth...
Modeling of turbulent supersonic H2-air combustion with a multivariate beta PDF
Baurle, R. A.; Hassan, H. A.
1993-01-01
Recent calculations of turbulent supersonic reacting shear flows using an assumed multivariate beta PDF (probability density function) resulted in reduced production rates and a delay in the onset of combustion. This result is not consistent with available measurements. The present research explores two possible reasons for this behavior: use of PDF's that do not yield Favre averaged quantities, and the gradient diffusion assumption. A new multivariate beta PDF involving species densities is introduced which makes it possible to compute Favre averaged mass fractions. However, using this PDF did not improve comparisons with experiment. A countergradient diffusion model is then introduced. Preliminary calculations suggest this to be the cause of the discrepancy.
LES Modeling of Supersonic Combustion at SCRAMJET Conditions
Vane, Zachary; Lacaze, Guilhem; Oefelein, Joseph
2016-11-01
Results from a series of large-eddy simulations (LES) of the Hypersonic International Flight Research Experiment (HIFiRE) are examined with emphasis placed on the coupled performance of the wall and combustion models. The test case of interest corresponds to the geometry and conditions found in the ground based experiments performed in the HIFiRE Direct Connect Rig (HDCR) in dual-mode operation. In these calculations, the turbulence and mixing characteristics of the high Reynolds number turbulent boundary layer with multi-species fuel injection are analyzed using a simplified chemical model and combustion closure to predict the heat release measured experimentally. These simulations are then used to identify different flame regimes in the combustor section. Concurrently, the performance of an equilibrium wall-model is evaluated in the vicinity of the fuel injectors and in the flame-holding cavity where regions of boundary layer and thermochemical non-equilibrium are present. Support for this research was provided by the Defense Advanced Research Projects Agency (DARPA).
Supersonic beams at high particle densities: model description beyond the ideal gas approximation.
Christen, Wolfgang; Rademann, Klaus; Even, Uzi
2010-10-28
Supersonic molecular beams constitute a very powerful technique in modern chemical physics. They offer several unique features such as a directed, collision-free flow of particles, very high luminosity, and an unsurpassed strong adiabatic cooling during the jet expansion. While it is generally recognized that their maximum flow velocity depends on the molecular weight and the temperature of the working fluid in the stagnation reservoir, not a lot is known on the effects of elevated particle densities. Frequently, the characteristics of supersonic beams are treated in diverse approximations of an ideal gas expansion. In these simplified model descriptions, the real gas character of fluid systems is ignored, although particle associations are responsible for fundamental processes such as the formation of clusters, both in the reservoir at increased densities and during the jet expansion. In this contribution, the various assumptions of ideal gas treatments of supersonic beams and their shortcomings are reviewed. It is shown in detail that a straightforward thermodynamic approach considering the initial and final enthalpy is capable of characterizing the terminal mean beam velocity, even at the liquid-vapor phase boundary and the critical point. Fluid properties are obtained using the most accurate equations of state available at present. This procedure provides the opportunity to naturally include the dramatic effects of nonideal gas behavior for a large variety of fluid systems. Besides the prediction of the terminal flow velocity, thermodynamic models of isentropic jet expansions permit an estimate of the upper limit of the beam temperature and the amount of condensation in the beam. These descriptions can even be extended to include spinodal decomposition processes, thus providing a generally applicable tool for investigating the two-phase region of high supersaturations not easily accessible otherwise.
Evolution of supersonic corner vortex in a hypersonic inlet/isolator model
Huang, He-Xia; Tan, Hui-Jun; Sun, Shu; Ling, Yu
2016-12-01
There are complex corner vortex flows in a rectangular hypersonic inlet/isolator. The corner vortex propagates downstream and interacts with the shocks and expansion waves in the isolator repeatedly. The supersonic corner vortex in a generic hypersonic inlet/isolator model is theoretically and numerically analyzed at a freestream Mach number of 4.92. The cross-flow topology of the corner vortex flow is found to obey Zhang's theory ["Analytical analysis of subsonic and supersonic vortex formation," Acta Aerodyn. Sin. 13, 259-264 (1995)] strictly, except for the short process with the vortex core situated in a subsonic flow which is surrounded by a supersonic flow. In general, the evolution history of the corner vortex under the influence of the background waves in the hypersonic inlet/isolator model can be classified into two types, namely, from the adverse pressure gradient region to the favorable pressure gradient region and the reversed one. For type 1, the corner vortex is a one-celled vortex with the cross-sectional streamlines spiraling inwards at first. Then the Hopf bifurcation occurs and the streamlines in the outer part of the limit cycle switch to spiraling outwards, yielding a two-celled vortex. The limit cycle shrinks gradually and finally vanishes with the streamlines of the entire corner vortex spiraling outwards. For type 2, the cross-sectional streamlines of the corner vortex spiral outwards first. Then a stable limit cycle is formed, yielding a two-celled vortex. The short-lived limit cycle forces the streamlines in the corner vortex to change the spiraling trends rapidly. Although it is found in this paper that there are some defects on the theoretical proof of the limit cycle, Zhang's theory is proven useful for the prediction and qualitative analysis of the complex corner vortex in a hypersonic inlet/isolator. In addition, three conservation laws inside the limit cycle are obtained.
Adamczyk, J. J.; Goldstein, M. E.; Hartmann, M. J.
1978-01-01
Recently two flutter analyses have been developed at NASA Lewis Research Center to predict the onset of supersonic unstalled flutter of a cascade of two-dimensional airfoils. The first of these analyzes the onset of supersonic flutter at low levels of aerodynamic loading (i.e., backpressure), while the second examines the occurrence of supersonic flutter at moderate levels of aerodynamic loading. Both of these analyses are based on the linearized unsteady inviscid equations of gas dynamics to model the flow field surrounding the cascade. The details of the development of the solution to each of these models have been published. The objective of the present paper is to utilize these analyses in a parametric study to show the effects of cascade geometry, inlet Mach number, and backpressure on the onset of single and multi degree of freedom unstalled supersonic flutter. Several of the results from this study are correlated against experimental qualitative observation to validate the models.
Application of Stereo PIV on a Supersonic Parachute Model
Wernet, Mark P.; Locke, Randy J.; Wroblewski, Adam; Sengupta, Anita
2009-01-01
The Mars Science Laboratory (MSL) is the next step in NASA's Mars Exploration Program, currently scheduled for 2011. The spacecraft's descent into the Martian atmosphere will be slowed from Mach 2 to subsonic speeds via a large parachute system with final landing under propulsive control. A Disk-Band-Gap (DBG) parachute will be used on MSL similar to the designs that have been used on previous missions, however; the DBG parachute used by MSL will be larger (21.5 m) than in any of the previous missions due to the weight of the payload and landing site requirements. The MSL parachute will also deploy at higher Mach number (M 2) than previous parachutes, which can lead to instabilities in canopy performance. Both the increased size of the DBG above previous demonstrated configurations and deployment at higher Mach numbers add uncertainty to the deployment, structural integrity and performance of the parachute. In order to verify the performance of the DBG on MSL, experimental testing, including acquisition of Stereo Particle Imaging Velocimetry (PIV) measurements were required for validating CFD predictions of the parachute performance. A rigid model of the DBG parachute was tested in the 10x10 foot wind tunnel at GRC. Prior to the MSL tests, a PIV system had never been used in the 10x10 wind tunnel. In this paper we discuss some of the technical challenges overcome in implementing a Stereo PIV system with a 750x400 mm field-of-view in the 10x10 wind tunnel facility and results from the MSL hardshell canopy tests.
Advanced transport systems analysis, modeling, and evaluation of performances
Janić, Milan
2014-01-01
This book provides a systematic analysis, modeling and evaluation of the performance of advanced transport systems. It offers an innovative approach by presenting a multidimensional examination of the performance of advanced transport systems and transport modes, useful for both theoretical and practical purposes. Advanced transport systems for the twenty-first century are characterized by the superiority of one or several of their infrastructural, technical/technological, operational, economic, environmental, social, and policy performances as compared to their conventional counterparts. The advanced transport systems considered include: Bus Rapid Transit (BRT) and Personal Rapid Transit (PRT) systems in urban area(s), electric and fuel cell passenger cars, high speed tilting trains, High Speed Rail (HSR), Trans Rapid Maglev (TRM), Evacuated Tube Transport system (ETT), advanced commercial subsonic and Supersonic Transport Aircraft (STA), conventionally- and Liquid Hydrogen (LH2)-fuelled commercial air trans...
Directory of Open Access Journals (Sweden)
Karthik Mummidisetti
2013-08-01
Full Text Available In the present work, investigation of various turbulence models has been carried out for predicting the efficient turbulence model for a two-dimensional nozzle designed for a supersonic cruise nozzle. Initially, a computational domain was created for a two-dimensional nozzle for a supersonic cruise, then, with an appropriate mesh size, various turbulence models has been used for simulations. The main objective of the present work is to determine the efficient turbulence model for nozzle designs. As till date, commercial software’s are implementing many advanced technique, the test of turbulence model is very much needed for today’s research. The results obtained from the computational approach were compared with experimental approach which was conducted in the Langley 16-Foot Transonic Tunnel at Mach numbers from 0.8 to 1.2 by NASA Langley Research Centre, Virginia. These supersonic cruise nozzles have a wide range of applications in designing Fighter jets and supersonic cruise aircraft's. The present work was conducted by using the commercial Computational Fluid Dynamics Software, STAR-CCM+. Initially, Nozzle at a free stream Mach number 0.9 was designed and all the initial and boundary conditions were calculated. From the results obtained in the present investigation, we can conclude that there was an excellent correlation between the experimental and computational data for K-Epsilon turbulence model.
Numerical and experimental investigations on supersonic ejectors
Energy Technology Data Exchange (ETDEWEB)
Bartosiewicz, Y.; Aidoun, Z. [CETC-Varennes, Natural Resources Canada (Canada); Desevaux, P. [CREST-UMR 6000, Belfort (France); Mercadier, Y. [Sherbrooke Univ. (Canada). THERMAUS
2005-02-01
Supersonic ejectors are widely used in a range of applications such as aerospace, propulsion and refrigeration. The primary interest of this study is to set up a reliable hydrodynamics model of a supersonic ejector, which may be extended to refrigeration applications. The first part of this work evaluated the performance of six well-known turbulence models for the study of supersonic ejectors. The validation concentrated on the shock location, shock strength and the average pressure recovery prediction. Axial pressure measurements with a capillary probe performed previously [Int. J. Turbo Jet Engines 19 (2002) 71; Conference Proc., 10th Int. Symp. Flow Visualization, Kyoto, Japan, 2002], were compared with numerical simulations while laser tomography pictures were used to evaluate the non-mixing length. The capillary probe has been included in the numerical model and the non-mixing length has been numerically evaluated by including an additional transport equation for a passive scalar, which acted as an ideal colorant in the flow. At this point, the results show that the k-omega-sst model agrees best with experiments. In the second part, the tested model was used to reproduce the different operation modes of a supersonic ejector, ranging from on-design point to off-design. In this respect, CFD turned out to be an efficient diagnosis tool of ejector analysis (mixing, flow separation), for design, and performance optimization (optimum entrainment and recompression ratios). (Author)
Community Sediment Transport Model
2007-01-01
are used to determine that model results are consistent across compilers, platforms, and computer architectures , and to ensure that changes in code do...Mississippi State University: Bhate During the early months of this project, the focus was on understanding ROMS-CSTM model, architecture , and...Marchesiello, J.C. McWilliams, & K.D. Stolzenbach, 2007: Sediment transport modeling on Southern Californian shelves: A ROMS case study. Continental
Use of advanced particle methods in modeling space propulsion and its supersonic expansions
Borner, Arnaud
This research discusses the use of advanced kinetic particle methods such as Molecular Dynamics (MD) and direct simulation Monte Carlo (DSMC) to model space propulsion systems such as electrospray thrusters and their supersonic expansions. MD simulations are performed to model an electrospray thruster for the ionic liquid (IL) EMIM--BF4 using coarse-grained (CG) potentials. The model is initially featuring a constant electric field applied in the longitudinal direction. Two coarse-grained potentials are compared, and the effective-force CG (EFCG) potential is found to predict the formation of the Taylor cone, the cone-jet, and other extrusion modes for similar electric fields and mass flow rates observed in experiments of a IL fed capillary-tip-extractor system better than the simple CG potential. Later, one-dimensional and fully transient three-dimensional electric fields, the latter solving Poisson's equation to take into account the electric field due to space charge at each timestep, are computed by coupling the MD model to a Poisson solver. It is found that the inhomogeneous electric field as well as that of the IL space-charge improve agreement between modeling and experiment. The boundary conditions (BCs) are found to have a substantial impact on the potential and electric field, and the tip BC is introduced and compared to the two previous BCs, named plate and needle, showing good improvement by reducing unrealistically high radial electric fields generated in the vicinity of the capillary tip. The influence of the different boundary condition models on charged species currents as a function of the mass flow rate is studied, and it is found that a constant electric field model gives similar agreement to the more rigorous and computationally expensive tip boundary condition at lower flow rates. However, at higher mass flow rates the MD simulations with the constant electric field produces extruded particles with higher Coulomb energy per ion, consistent with
Supersonic Retro-Propulsion Experimental Design for Computational Fluid Dynamics Model Validation
Berry, Scott A.; Laws, Christopher T.; Kleb, W. L.; Rhode, Matthew N.; Spells, Courtney; McCrea, Andrew C.; Truble, Kerry A.; Schauerhamer, Daniel G.; Oberkampf, William L.
2011-01-01
The development of supersonic retro-propulsion, an enabling technology for heavy payload exploration missions to Mars, is the primary focus for the present paper. A new experimental model, intended to provide computational fluid dynamics model validation data, was recently designed for the Langley Research Center Unitary Plan Wind Tunnel Test Section 2. Pre-test computations were instrumental for sizing and refining the model, over the Mach number range of 2.4 to 4.6, such that tunnel blockage and internal flow separation issues would be minimized. A 5-in diameter 70-deg sphere-cone forebody, which accommodates up to four 4:1 area ratio nozzles, followed by a 10-in long cylindrical aftbody was developed for this study based on the computational results. The model was designed to allow for a large number of surface pressure measurements on the forebody and aftbody. Supplemental data included high-speed Schlieren video and internal pressures and temperatures. The run matrix was developed to allow for the quantification of various sources of experimental uncertainty, such as random errors due to run-to-run variations and bias errors due to flow field or model misalignments. Some preliminary results and observations from the test are presented, although detailed analyses of the data and uncertainties are still on going.
Groupage Cargo Transportation Model
Directory of Open Access Journals (Sweden)
Aleksejevs Ruslans
2016-03-01
Full Text Available In this work we consider a specific problem of optimal planning of maritime transportation of multiproduct cargo by ships of one (corporate strategy or several (partially corporate strategy companies: the core of the problem consists of the existence of the network of intermediate seaports (i.e. transitional seaports, where for every ship arrived the cargo handling is done, and which are situated between the starting and the finishing seaports. In this work, there are mathematical models built from scratch in the form of multicriteria optimization problem; then the goal attainment method of Gembicki is used for reducing the built models to a one-criterion problem of linear programming.
Directory of Open Access Journals (Sweden)
L. Gulstad
2007-05-01
Full Text Available The demand for intercontinental transportation is increasing and people are requesting short travel times, which supersonic air transportation would enable. However, besides noise and sonic boom issues, which we are not referring to in this investigation, emissions from supersonic aircraft are known to alter the atmospheric composition, in particular the ozone layer, and hence affect climate significantly more than subsonic aircraft. Here, we suggest a metric to quantitatively assess different options for supersonic transport with regard to the potential destruction of the ozone layer and climate impacts. Options for fleet size, engine technology (nitrogen oxide emission level, cruising speed, range, and cruising altitude, are analyzed, based on SCENIC emissions scenarios for 2050, which underlay the requirements to be as realistic as possible in terms of e.g. economic markets and profitable market penetration. This methodology is based on a number of atmosphere-chemistry and climate models to reduce model dependencies. The model results differ significantly in terms of the response to a replacement of subsonic aircraft by supersonic aircraft. However, model differences are smaller when comparing the different options for a supersonic fleet. The base scenario, where supersonic aircraft get in service in 2015, a first fleet fully operational in 2025 and a second in 2050, lead in our simulations to a near surface temperature increase in 2050 of around 7 mK and with constant emissions afterwards to around 21 mK in 2100. The related total radiative forcing amounts to 22 mWm²in 2050, with an uncertainty between 9 and 29 mWm². A reduced supersonic cruise altitude or speed (from March 2 to Mach 1.6 reduces both, climate impact and ozone destruction, by around 40%. An increase in the range of the supersonic aircraft leads to more emissions at lower latitudes since more routes to SE Asia are taken into account, which increases ozone depletion, but
Despagne, Wilfried; Frenod, Emmanuel
2014-01-01
Purpose: The purpose of this paper is to investigate the road freight haulage activity. Using the physical and data flow information from a freight forwarder, we intend to model the flow of inbound and outbound goods in a freight transport hub. Approach: This paper presents the operation of a road haulage group. To deliver goods within two days to any location in France, a haulage contractor needs to be part of a network. This network handles the processing of both physical goods and data. We...
Roberts, II, William Byron; Lawlor, Shawn P.; Breidenthal, Robert E.
2016-04-12
A supersonic compressor including a rotor to deliver a gas at supersonic conditions to a diffuser. The diffuser includes a plurality of aerodynamic ducts that have converging and diverging portions, for deceleration of gas to subsonic conditions and then for expansion of subsonic gas, to change kinetic energy of the gas to static pressure. The aerodynamic ducts include vortex generating structures for controlling boundary layer, and structures for changing the effective contraction ratio to enable starting even when the aerodynamic ducts are designed for high pressure ratios, and structures for boundary layer control. In an embodiment, aerodynamic ducts are provided having an aspect ratio of in excess of two to one, when viewed in cross-section orthogonal to flow direction at an entrance to the aerodynamic duct.
Simulation of underexpanded supersonic jet flows with chemical reactions
Directory of Open Access Journals (Sweden)
Fu Debin
2014-06-01
Full Text Available To achieve a detailed understanding of underexpanded supersonic jet structures influenced by afterburning and other flow conditions, the underexpanded turbulent supersonic jet with and without combustions are investigated by computational fluid dynamics (CFD method. A program based on a total variation diminishing (TVD methodology capable of predicting complex shocks is created to solve the axisymmetric expanded Navier–Stokes equations containing transport equations of species. The finite-rate ratio model is employed to handle species sources in chemical reactions. CFD solutions indicate that the structure of underexpanded jet is typically influenced by the pressure ratio and afterburning. The shock reflection distance and maximum value of Mach number in the first shock cell increase with pressure ratio. Chemical reactions for the rocket exhaust mostly exist in the mixing layer of supersonic jet flows. This tends to reduce the intensity of shocks existing in the jet, responding to the variation of thermal parameters.
Simulation of underexpanded supersonic jet flows with chemical reactions
Institute of Scientific and Technical Information of China (English)
Fu Debin; Yu Yong; Niu Qinglin
2014-01-01
To achieve a detailed understanding of underexpanded supersonic jet structures influenced by afterburning and other flow conditions, the underexpanded turbulent supersonic jet with and without combustions are investigated by computational fluid dynamics (CFD) method. A program based on a total variation diminishing (TVD) methodology capable of predicting complex shocks is created to solve the axisymmetric expanded Navier-Stokes equations containing transport equations of species. The finite-rate ratio model is employed to handle species sources in chemical reactions. CFD solutions indicate that the structure of underexpanded jet is typically influenced by the pressure ratio and afterburning. The shock reflection distance and maximum value of Mach number in the first shock cell increase with pressure ratio. Chemical reactions for the rocket exhaust mostly exist in the mixing layer of supersonic jet flows. This tends to reduce the intensity of shocks existing in the jet, responding to the variation of thermal parameters.
CFD modeling of particle behavior in supersonic flows with strong swirls for gas separation
DEFF Research Database (Denmark)
Yang, Yan; Wen, Chuang
2017-01-01
flow from the dry gas outlet. The separation efficiency reached over 80%, when the droplet diameter was more than 1.5 μm. The optimum length of the cyclonic separation section was approximate 16–20 times of the nozzle throat diameter to obtain higher collection efficiency for the supersonic separator...
Stochastic models of intracellular transport
Bressloff, Paul C.
2013-01-09
The interior of a living cell is a crowded, heterogenuous, fluctuating environment. Hence, a major challenge in modeling intracellular transport is to analyze stochastic processes within complex environments. Broadly speaking, there are two basic mechanisms for intracellular transport: passive diffusion and motor-driven active transport. Diffusive transport can be formulated in terms of the motion of an overdamped Brownian particle. On the other hand, active transport requires chemical energy, usually in the form of adenosine triphosphate hydrolysis, and can be direction specific, allowing biomolecules to be transported long distances; this is particularly important in neurons due to their complex geometry. In this review a wide range of analytical methods and models of intracellular transport is presented. In the case of diffusive transport, narrow escape problems, diffusion to a small target, confined and single-file diffusion, homogenization theory, and fractional diffusion are considered. In the case of active transport, Brownian ratchets, random walk models, exclusion processes, random intermittent search processes, quasi-steady-state reduction methods, and mean-field approximations are considered. Applications include receptor trafficking, axonal transport, membrane diffusion, nuclear transport, protein-DNA interactions, virus trafficking, and the self-organization of subcellular structures. © 2013 American Physical Society.
Goods Transport Modelling, Vol 1
DEFF Research Database (Denmark)
Petersen, Morten Steen (red.); Kristiansen, Jørgen
The report is a study of data requirements and methodologies for goods transport. The study is intended to provide the basis for general discussion about the application of goods transport models in Denmark. The report provides an overview of different types of models and data availability....
Container Logistic Transport Planning Model
Directory of Open Access Journals (Sweden)
Xin Zhang
2013-05-01
Full Text Available The study proposed a stochastic method of container logistic transport in order to solve the unreasonable transportation’s problem and overcome the traditional models’ two shortcomings. Container transport has rapidly developed into a modern means of transportation because of their significant advantages. With the development, it also exacerbated the flaws of transport in the original. One of the most important problems was that the invalid transport had not still reduced due to the congenital imbalances of transportation. Container transport exacerbated the invalid transport for the empty containers. To solve the problem, people made many efforts, but they did not make much progress. There had two theoretical flaws by analyzing the previous management methods in container transport. The first one was the default empty containers inevitability. The second one was that they did not overall consider how to solve the problem of empty containers allocation. In order to solve the unreasonable transportation’s problem and overcome the traditional models’ two shortcomings, the study re-built the container transport planning model-gravity model. It gave the general algorithm and has analyzed the final result of model.
Energy Technology Data Exchange (ETDEWEB)
Rotman, D.A.; Tannahill, J.R.; Kinnison, D.E.; Connell, P.S.; Bergmann, D.; Proctor, D.; Rodriquez, J.M.; Lin, S.J.; Rood, R.B.; Prather, M.J.; Rasch, P.J.; Considine, D.B.; Ramaroson, R.; Kawa, S.R.
2000-04-25
We describe the three dimensional global stratospheric chemistry model developed under the NASA Global Modeling Initiative (GMI) to assess the possible environmental consequences from the emissions of a fleet of proposed high speed civil transport aircraft. This model was developed through a unique collaboration of the members of the GMI team. Team members provided computational modules representing various physical and chemical processes, and analysis of simulation results through extensive comparison to observation. The team members' modules were integrated within a computational framework that allowed transportability and simulations on massively parallel computers. A unique aspect of this model framework is the ability to interchange and intercompare different submodules to assess the sensitivity of numerical algorithms and model assumptions to simulation results. In this paper, we discuss the important attributes of the GMI effort, describe the GMI model computational framework and the numerical modules representing physical and chemical processes. As an application of the concept, we illustrate an analysis of the impact of advection algorithms on the dispersion of a NO{sub y}-like source in the stratosphere which mimics that of a fleet of commercial supersonic transports (High-Speed Civil Transport (HSCT)) flying between 17 and 20 kilometers.
Sun, Ming-bo; Zhong, Zhan; Liang, Jian-han; Wang, Hong-bo
2016-10-01
Supersonic combustion with cavity-strut injection of supercritical kerosene in a model scramjet engine was experimentally investigated in Mach 2.92 facility with the stagnation temperatures of approximately 1430 K. Static pressure distribution in the axial direction was determined using pressure transducers installed along the centerline of the model combustor top walls. High speed imaging camera was used to capture flame luminosity and combustion region distribution. Multi-cavities were used to and stabilize the combustion in the supersonic combustor. Intrusive injection by thin struts was used to enhance the fuel-air mixing. Supercritical kerosene at temperatures of approximately 780 K and various pressures was prepared using a heat exchanger driven by the hot gas from a pre-burner and injected at equivalence ratios of approximately 1.0. In the experiments, combustor performances with different strut injection schemes were investigated and compared to direct wall injection scheme based on the measured static pressure distributions, the specific thrust increments and the images obtained by high-speed imaging camera. The experimental results showed that the injection by thin struts could obtain an enhanced mixing in the field but could not acquire a steady flame when mixing field cannot well match cavity separation region. There is no significant difference on performance between different schemes since the unsteady intermittent and oscillating flame leads to no actual combustion efficiency improvement.
Johns, H. M.; Kline, J.; Lanier, N.; Perry, T.; Fontes, C.; Fryer, C.; Brown, C.; Morton, J.; Hager, J.
2016-10-01
The propagation of a heat front in an astrophysical or inertial confinement fusion plasma involves both the equation of state and the opacity of the plasma, and is therefore an important and challenging radiation transport problem. Past experiments have used absorption spectroscopy in chlorinated foams to measure the heat front. (D. Hoarty et al. PRL 82, 3070, 1999). Recent development of Ti-doped cylindrical aerogel foam targets (J. Hager et al. submitted to RSI) results in a more suitable platform for higher temperatures on NIF than Cl dopant. Ti K-shell absorption spectra can be modeled with PrismSPECT to obtain spatially resolved temperature profiles between 100-180eV. Sc dopant has been selected to characterize the heat front between 60-100eV. Improved understanding of non-planckian x-ray drives generated by hohlraums will advance characterization of the radiation transport. Prior work demonstrates PrismSPECT with OPLIB is more physically complete for Sc (H. Johns et al. submitted to RSI). We will present the first application of spectroscopic analysis of the Sc-doped aerogels utilizing this method. This work performed under the auspices of the U.S. Department of Energy by LANL under contract DE-AC52-06NA25396.
Turbulence models and Reynolds analogy for two-dimensional supersonic compression ramp flow
Wang, Chi R.; Bidek, Maleina C.
1994-01-01
Results of the application of turbulence models and the Reynolds analogy to the Navier-Stokes computations of Mach 2.9 two-dimensional compression ramp flows are presented. The Baldwin-Lomax eddy viscosity model and the kappa-epsilon turbulence transport equations for the turbulent momentum flux modeling in the Navier-Stokes equations are studied. The Reynolds analogy for the turbulent heat flux modeling in the energy equation was also studied. The Navier-Stokes equations and the energy equation were numerically solved for the flow properties. The Reynolds shear stress, the skin friction factor, and the surface heat transfer rate were calculated and compared with their measurements. It was concluded that with a hybrid kappa-epsilon turbulence model for turbulence modeling, the present computations predicted the skin friction factors of the 8 deg and 16 deg compression ramp flows and with the turbulent Prandtl number Pr(sub t) = 0.93 and the ratio of the turbulent thermal and momentum transport coefficients mu(sub q)/mu(sub t) = 2/Prt, the present computations also predicted the surface heat transfer rates beneath the boundary layer flow of the 16 compression ramp.
Evaluation of Industry Standard Turbulence Models on an Axisymmetric Supersonic Compression Corner
DeBonis, James R.
2015-01-01
Reynolds-averaged Navier-Stokes computations of a shock-wave/boundary-layer interaction (SWBLI) created by a Mach 2.85 flow over an axisymmetric 30-degree compression corner were carried out. The objectives were to evaluate four turbulence models commonly used in industry, for SWBLIs, and to evaluate the suitability of this test case for use in further turbulence model benchmarking. The Spalart-Allmaras model, Menter's Baseline and Shear Stress Transport models, and a low-Reynolds number k- model were evaluated. Results indicate that the models do not accurately predict the separation location; with the SST model predicting the separation onset too early and the other models predicting the onset too late. Overall the Spalart-Allmaras model did the best job in matching the experimental data. However there is significant room for improvement, most notably in the prediction of the turbulent shear stress. Density data showed that the simulations did not accurately predict the thermal boundary layer upstream of the SWBLI. The effect of turbulent Prandtl number and wall temperature were studied in an attempt to improve this prediction and understand their effects on the interaction. The data showed that both parameters can significantly affect the separation size and location, but did not improve the agreement with the experiment. This case proved challenging to compute and should provide a good test for future turbulence modeling work.
Welge, H. Robert; Bonet, John; Magee, Todd; Tompkins, Daniel; Britt, Terry R.; Nelson, Chet; Miller, Gregory; Stenson, Douglas; Staubach, J. Brent; Bala, Naushir;
2011-01-01
Boeing, with Pratt & Whitney, General Electric, Rolls-Royce, M4 Engineering, Wyle Laboratories and Georgia Institute of Technology, conducted a study of supersonic commercial aircraft concepts and enabling technologies for the year 2030-2035 timeframe. The work defined the market and environmental/regulatory conditions that could evolve by the 2030/35 time period, from which vehicle performance goals were derived. Relevant vehicle concepts and technologies are identified that are anticipated to meet these performance and environmental goals. A series of multidisciplinary analyses trade studies considering vehicle sizing, mission performance and environmental conformity determined the appropriate concepts. Combinations of enabling technologies and the required technology performance levels needed to meet the desired goals were identified. Several high priority technologies are described in detail, including roadmaps with risk assessments that outline objectives, key technology challenges, detailed tasks and schedules and demonstrations that need to be performed. A representative configuration is provided for reference purposes, along with associated performance estimates based on these key technologies.
Numerical simulations of transverse liquid jet to a supersonic crossflow using a pure two-fluid model
Directory of Open Access Journals (Sweden)
Haixu Liu
2016-01-01
Full Text Available A pure two-fluid model was used for investigating transverse liquid jet to a supersonic crossflow. The well-posedness problem of the droplet phase governing equations was solved by applying an equation of state in the kinetic theory. A k-ε-kp turbulence model was used to simulate the turbulent compressible multiphase flow. Separation of boundary layer in front of the liquid jet was predicted with a separation shock induced. A bow shock was found to interact with the separation shock in the simulation result, and the adjustment of shock structure caused by the interaction described the whipping phenomena. The predicted penetration height showed good agreement with the empirical correlations. In addition, the turbulent kinetic energies of both the gas and droplet phases were presented for comparison, and effects of the jet-to-air momentum flux ratio and droplet diameter on the penetration height were also examined in this work.
Energy Technology Data Exchange (ETDEWEB)
Kato, T.; Taguchi, H.; Omi, J.; Sakamoto, K. [Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan)
2000-01-01
IHI has been developing the SETF (Supersonic Engine Test Facility) to aim at the research and development of engines for the next generation commercial supersonic transport in the NAL (National Aerospace Laboratory in Japan). The SETF will supply the functions to test the supersonic engine performance in high altitude flight condition and supersonic intake-engine matching. The semi-free jet test mode was adopted for the supersonic intake-engine matching test, but this test configuration has not been conducted previously in Japan and there were a large number of unknown factors. IHI has developed a sub-scale test model in cooperation with NAL to identify the test conditions and a start sequence of the semi-free jet test mode. In addition, the designs of facility component were optimized and verified by using the CFD (Computational Fluid Dynamics) method. (author)
Modelling of Transport Projects Uncertainties
DEFF Research Database (Denmark)
Salling, Kim Bang; Leleur, Steen
2009-01-01
This paper proposes a new way of handling the uncertainties present in transport decision making based on infrastructure appraisals. The paper suggests to combine the principle of Optimism Bias, which depicts the historical tendency of overestimating transport related benefits and underestimating...... investment costs, with a quantitative risk analysis based on Monte Carlo simulation and to make use of a set of exploratory scenarios. The analysis is carried out by using the CBA-DK model representing the Danish standard approach to socio-economic cost-benefit analysis. Specifically, the paper proposes......-based graphs which function as risk-related decision support for the appraised transport infrastructure project....
Next Generation Transport Phenomenology Model
Strickland, Douglas J.; Knight, Harold; Evans, J. Scott
2004-01-01
This report describes the progress made in Quarter 3 of Contract Year 3 on the development of Aeronomy Phenomenology Modeling Tool (APMT), an open-source, component-based, client-server architecture for distributed modeling, analysis, and simulation activities focused on electron and photon transport for general atmospheres. In the past quarter, column emission rate computations were implemented in Java, preexisting Fortran programs for computing synthetic spectra were embedded into APMT through Java wrappers, and work began on a web-based user interface for setting input parameters and running the photoelectron and auroral electron transport models.
Ruhlin, C. L.; Doggett, R. V., Jr.; Gregory, R. A.
1976-01-01
An experimental and analytical study was made of the transonic flutter characteristics of a supersonic transport tail assembly model having an all-movable, horizontal tail with a geared elevator. Two model configurations, namely, one with a gear-elevator (2.8 to 1.0 gear ratio) and one with locked-elevator (1.0 to 1.0 gear ratio), were flutter tested in the Langley transonic dynamics tunnel with an empennage cantilever-mounted on a sting. The geared-elevator configuration fluttered experimentally at about 20% higher dynamic pressures than the locked-elevator configuration. The experimental flutter dynamic pressure boundaries for both configurations were nearly flat over a Mach number range from 0.9 to 1.1. Flutter calculations (mathematical models) were made for the geared-elevator configuration using three subsonic lifting-surface methods. In one method, the elevator was treated as a discrete surface, and in the other two methods, the stabilizer and elevator were treated as a single warped-surface with the primary difference between these two methods being in the mathematical implementation used. A comparison of the experimental and analytical results shows that the discrete-elevator method predicted best the experimental flutter dynamic pressure level. However, the single warped-surface methods predicts more closely the experimental flutter frequencies and Mach number trends.
An experimental investigation of a Mach 3.0 high-speed civil transport at supersonic speeds
Hernandez, Gloria; Covell, Peter F.; Mcgraw, Marvin E., Jr.
1993-01-01
An experimental study was conducted to determine the aerodynamic characteristics of a proposed high speed civil transport. This configuration was designed to cruise at Mach 3.0 and sized to carry 250 passengers for 6500 n.mi. The configuration consists of a highly blended wing body and features a blunt parabolic nose planform, a highly swept inboard wing panel, a moderately swept outboard wing panel, and a curved wingtip. Wind tunnel tests were conducted in the Langley Unitary Plan Wind Tunnel on a 0.0098-scale model. Force, moment, and pressure data were obtained for Mach numbers ranging from 1.6 to 3.6 and at angles of attack ranging from -4 to 10 deg. Extensive flow visualization studies (vapor screen and oil flow) were obtained in the experimental program. Both linear and advanced computational fluid dynamics (CFD) theoretical comparisons are shown to assess the ability to predict forces, moments, and pressures on configurations of this type. In addition, an extrapolation of the wind tunnel data, based on empirical principles, to full-scale conditions is compared with the theoretical aerodynamic predictions.
Heeg, Jennifer; Wieseman, Carol D.
2012-01-01
Orthogonal harmonic multisine excitations were utilized in a wind tunnel test and in simulation of the SemiSpan Supersonic Transport model to assess aeroservoelastic characteristics. Fundamental issues associated with analyzing sinusoidal signals were examined, including spectral leakage, excitation truncation, and uncertainties on frequency response functions and mean-square coherence. Simulation allowed for evaluation of these issues relative to a truth model, while wind tunnel data introduced real-world implementation issues.
Mathematical modeling of kidney transport.
Layton, Anita T
2013-01-01
In addition to metabolic waste and toxin excretion, the kidney also plays an indispensable role in regulating the balance of water, electrolytes, nitrogen, and acid-base. In this review, we describe representative mathematical models that have been developed to better understand kidney physiology and pathophysiology, including the regulation of glomerular filtration, the regulation of renal blood flow by means of the tubuloglomerular feedback mechanisms and of the myogenic mechanism, the urine concentrating mechanism, epithelial transport, and regulation of renal oxygen transport. We discuss the extent to which these modeling efforts have expanded our understanding of renal function in both health and disease.
Faizan-Ur-Rab, M.; Zahiri, S. H.; Masood, S. H.; Jahedi, M.; Nagarajah, R.
2017-06-01
This study presents the validation of a developed three-dimensional multicomponent model for cold spray process using two particle image velocimetry (PIV) experiments. The k- ɛ type 3D model developed for spherical titanium particles was validated with the measured titanium particle velocity within a nitrogen and helium supersonic jet. The 3D model predicted lower values of particle velocity than the PIV experimental study that used irregularly shaped titanium particles. The results of the 3D model were consistent with the PIV experiment that used spherical titanium powder. The 3D model simulation of particle velocity within the helium and nitrogen jet was coupled with an estimation of titanium particle temperature. This was achieved with the consideration of the fact that cold spray particle temperature is difficult and expensive to measure due to considerably lower temperature of particles than thermal spray. The model predicted an interesting pattern of particle size distribution with respect to the location of impact with a concentration of finer particles close to the jet center. It is believed that the 3D model outcomes for particle velocity, temperature and location could be a useful tool to optimize system design, deposition process and mechanical properties of the additively manufactured cold spray structures.
Grewe, V.; Stenke, A.; Ponater, M.; Sausen, R.; Pitari, G.; Iachetti, D.; Rogers, H.; Dessens, O.; Pyle, J.; Isaksen, I. S. A.; Gulstad, L.; Søvde, O. A.; Marizy, C.; Pascuillo, E.
2007-10-01
The demand for intercontinental transportation is increasing and people are requesting short travel times, which supersonic air transportation would enable. However, besides noise and sonic boom issues, which we are not referring to in this investigation, emissions from supersonic aircraft are known to alter the atmospheric composition, in particular the ozone layer, and hence affect climate significantly more than subsonic aircraft. Here, we suggest a metric to quantitatively assess different options for supersonic transport with regard to the potential destruction of the ozone layer and climate impacts. Options for fleet size, engine technology (nitrogen oxide emission level), cruising speed, range, and cruising altitude, are analyzed, based on SCENIC emission scenarios for 2050, which underlay the requirements to be as realistic as possible in terms of e.g., economic markets and profitable market penetration. This methodology is based on a number of atmosphere-chemistry and climate models to reduce model dependencies. The model results differ significantly in terms of the response to a replacement of subsonic aircraft by supersonic aircraft, e.g., concerning the ozone impact. However, model differences are smaller when comparing the different options for a supersonic fleet. Those uncertainties were taken into account to make sure that our findings are robust. The base case scenario, where supersonic aircraft get in service in 2015, a first fleet fully operational in 2025 and a second in 2050, leads in our simulations to a near surface temperature increase in 2050 of around 7 mK and with constant emissions afterwards to around 21 mK in 2100. The related total radiative forcing amounts to 22 mWm2 in 2050, with an uncertainty between 9 and 29 mWm2. A reduced supersonic cruise altitude or speed (from Mach 2 to Mach 1.6) reduces both, climate impact and ozone destruction, by around 40%. An increase in the range of the supersonic aircraft leads to more emissions at
Research of low boom and low drag supersonic aircraft design
Feng Xiaoqiang; Li Zhanke; Song Bifeng
2014-01-01
Sonic boom reduction will be an issue of utmost importance in future supersonic transport, due to strong regulations on acoustic nuisance. The paper describes a new multi-objective optimization method for supersonic aircraft design. The method is developed by coupling Seebass–George–Darden (SGD) inverse design method and multi-objective genetic algorithm. Based on the method, different codes are developed. Using a computational architecture, a conceptual supersonic aircraft design environment...
Modelling of Transport Projects Uncertainties
DEFF Research Database (Denmark)
Salling, Kim Bang; Leleur, Steen
2012-01-01
This paper proposes a new way of handling the uncertainties present in transport decision making based on infrastructure appraisals. The paper suggests to combine the principle of Optimism Bias, which depicts the historical tendency of overestimating transport related benefits and underestimating...... investment costs, with a quantitative risk analysis based on Monte Carlo simulation and to make use of a set of exploratory scenarios. The analysis is carried out by using the CBA-DK model representing the Danish standard approach to socio-economic cost-benefit analysis. Specifically, the paper proposes......-based graphs which functions as risk-related decision support for the appraised transport infrastructure project. The presentation of RSF is demonstrated by using an appraisal case concerning a new airfield in the capital of Greenland, Nuuk....
Development of Comprehensive Reduced Kinetic Models for Supersonic Reacting Shear Layer Simulations
Zambon, A. C.; Chelliah, H. K.; Drummond, J. P.
2006-01-01
Large-scale simulations of multi-dimensional unsteady turbulent reacting flows with detailed chemistry and transport can be computationally extremely intensive even on distributed computing architectures. With the development of suitable reduced chemical kinetic models, the number of scalar variables to be integrated can be decreased, leading to a significant reduction in the computational time required for the simulation with limited loss of accuracy in the results. A general MATLAB-based automated mechanism reduction procedure is presented to reduce any complex starting mechanism (detailed or skeletal) with minimal human intervention. Based on the application of the quasi steady-state (QSS) approximation for certain chemical species and on the elimination of the fast reaction rates in the mechanism, several comprehensive reduced models, capable of handling different fuels such as C2H4, CH4 and H2, have been developed and thoroughly tested for several combustion problems (ignition, propagation and extinction) and physical conditions (reactant compositions, temperatures, and pressures). A key feature of the present reduction procedure is the explicit solution of the concentrations of the QSS species, needed for the evaluation of the elementary reaction rates. In contrast, previous approaches relied on an implicit solution due to the strong coupling between QSS species, requiring computationally expensive inner iterations. A novel algorithm, based on the definition of a QSS species coupling matrix, is presented to (i) introduce appropriate truncations to the QSS algebraic relations and (ii) identify the optimal sequence for the explicit solution of the concentration of the QSS species. With the automatic generation of the relevant source code, the resulting reduced models can be readily implemented into numerical codes.
A Theoretic Model of Transport Logistics Demand
Directory of Open Access Journals (Sweden)
Natalija Jolić
2006-01-01
Full Text Available Concerning transport logistics as relation between transportand integrated approaches to logistics, some transport and logisticsspecialists consider the tenn tautological. However,transport is one of the components of logistics, along with inventories,resources, warehousing, infonnation and goods handling.Transport logistics considers wider commercial and operationalframeworks within which the flow of goods is plannedand managed. The demand for transport logistics services canbe valorised as highly qualitative, differentiated and derived.While researching transport phenomenon the implementationof models is inevitable and demand models highly desirable. Asa contribution to transport modelling this paper improves decisionmaking and planning in the transport logistics field.
Directory of Open Access Journals (Sweden)
V. E. Markevich
2017-01-01
Full Text Available A method of analytical synthesis of an optimal controller for the terminal control task of supersonic unmanned aerial vehicles based on synergetic approach to the design of control systems for nonlinear multidimensional dynamic objects is considered.The article provides analytical expressions describing the algorithm for control the velocity vector position of a supersonic UAV, the simulation results and the comparative analysis of the proposed control algorithm with the modified method of proportional navigation.
A multi-ion generalized transport model of the polar wind
Demars, H. G.; Schunk, R. W.
1994-01-01
The higher-order generalizations of the equations of standard hydrodynamics, known collectively as generalized transport theories, have been used since the early 1980s to describe the terrestrial polar wind. Inherent in the structure of generalized transport theories is the ability to describe not only interparticle collisions but also certain non-Maxwellian processes, such as heat flow and viscous stress, that are characteristic of any plasma flow that is not collision dominated. Because the polar wind exhibits a transition from collision-dominated to collisionless flow, generalized transport theories possess advantages for polar wind modeling not shared by either collision-dominated models (such as standard hydrodynamics) or collisionless models (such as those based on solving the collisionless Boltzmann equation). In general, previous polar wind models have used generalized transport equations to describe electrons and only one species of ion (H(+)). If other ion species were included in the models at all, it was in a simplified or semiempirical manner. The model described in this paper is the first polar wind model that uses a generalized transport theory (bi-Maxwellian-based 16-moment theory) to describe all of the species, both major and minor, in the polar wind plasma. In the model, electrons and three ion species (H(+), He(+), O(+)) are assumed to be major and several ion species are assumed to be minor (NO(+), Fe(+), O(++)). For all species, a complete 16-moment transport formulation is used, so that profiles of density, drift velocity, parallel and perpendicular temperatures, and the field-aligned parallel and perpendicular energy flows are obtained. In the results presented here, emphasis is placed on describing those constituents of the polar wind that have received little attention in past studies. In particular, characteristic solutions are presented for supersonic H(+) outflow and for both supersonic and subsonic outflows of the major ion He
Afsar, Mohammed; Sescu, Adrian; Sassanis, Vasileios; Bres, Guillaume; Towne, Aaron; Lele, Sanjiva
2016-11-01
The Goldstein-Sescu-Afsar asymptotic theory postulated that the appropriate distinguished limit in which non-parallel mean flow effects introduces a leading order change in the 'propagator' (which is related adjoint linearized Euler Green's function) within Goldstein's acoustic analogy must be when the jet spread rate is the same order as Strouhal number. We analyze the low frequency structure of the acoustic spectrum using Large-eddy simulations of two axi-symmetric jets (heated & unheated) at constant supersonic jet Mach number to obtain the mean flow for the asymptotic theory. This approach provides excellent quantitative agreement for the peak jet noise when the coefficients of the turbulence model are tuned for good agreement with the far-field acoustic data. Our aim in this talk, however, is to show the predictive capability of the asymptotics when the turbulence model in the acoustic analogy is 'exactly' re-constructed by numerically matching the length scale coefficients of an algebraic-exponential model for the 1212-component of the Reynolds stress auto-covariance tensor (1 is streamwise & 2 is radial direction) with LES data at any spatial location and temporal frequency. In this way, all information is obtained from local unsteady flow. We thank Professor Parviz Moin for supporting this work as part of the Center for Turbulence Research Summer Program 2016.
Supersonic Mass Flux Measurements via Tunable Diode Laser Absorption and Non-Uniform Flow Modeling
Chang, Leyen S.; Strand, Christopher L.; Jeffries, Jay B.; Hanson, Ronald K.; Diskin, Glenn S.; Gaffney, Richard L.; Capriotti, Diego P.
2011-01-01
Measurements of mass flux are obtained in a vitiated supersonic ground test facility using a sensor based on line-of-sight (LOS) diode laser absorption of water vapor. Mass flux is determined from the product of measured velocity and density. The relative Doppler shift of an absorption transition for beams directed upstream and downstream in the flow is used to measure velocity. Temperature is determined from the ratio of absorption signals of two transitions (lambda(sub 1)=1349 nm and lambda(sub 2)=1341.5 nm) and is coupled with a facility pressure measurement to obtain density. The sensor exploits wavelength-modulation spectroscopy with second-harmonic detection (WMS-2f) for large signal-to-noise ratios and normalization with the 1f signal for rejection of non-absorption related transmission fluctuations. The sensor line-of-sight is translated both vertically and horizontally across the test section for spatially-resolved measurements. Time-resolved measurements of mass flux are used to assess the stability of flow conditions produced by the facility. Measurements of mass flux are within 1.5% of the value obtained using a facility predictive code. The distortion of the WMS lineshape caused by boundary layers along the laser line-of-sight is examined and the subsequent effect on the measured velocity is discussed. A method for correcting measured velocities for flow non-uniformities is introduced and application of this correction brings measured velocities within 4 m/s of the predicted value in a 1630 m/s flow.
Modelling of Transport Projects Uncertainties
DEFF Research Database (Denmark)
Salling, Kim Bang; Leleur, Steen
2009-01-01
This paper proposes a new way of handling the uncertainties present in transport decision making based on infrastructure appraisals. The paper suggests to combine the principle of Optimism Bias, which depicts the historical tendency of overestimating transport related benefits and underestimating...... investment costs, with a quantitative risk analysis based on Monte Carlo simulation and to make use of a set of exploratory scenarios. The analysis is carried out by using the CBA-DK model representing the Danish standard approach to socio-economic cost-benefit analysis. Specifically, the paper proposes...... to supplement Optimism Bias and the associated Reference Class Forecasting (RCF) technique with a new technique that makes use of a scenario-grid. We tentatively introduce and refer to this as Reference Scenario Forecasting (RSF). The final RSF output from the CBA-DK model consists of a set of scenario...
Directory of Open Access Journals (Sweden)
Abdulkareem Shafiq Mahdi Al-Obaidi
2011-12-01
Full Text Available 0 0 1 328 1876 International Islamic University 15 4 2200 14.0 Normal 0 false false false EN-US JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Times New Roman";} This paper introduces an attempt to enhance the accuracy of panel methods. A low-order panel method is selected and coupled with semi-empirical methods to enhance the accuracy of drag prediction of flying bodies at supersonic speeds. The semi-empirical methods are used to improve the accuracy of drag prediction by mathematical modelling of viscosity, base drag, and drag due to wing-body interference. Both methods were implemented by a computer program and validated against experimental and analytical results. The comparisons show that a considerable improvement has been achieved for the selected panel method for prediction of drag coefficients. In general, accuracy within an average value of -4.4% was obtained for the enhanced panel method. Such accuracy could be considered acceptable for the preliminary design stages of supersonic flying bodies such as projectiles and missiles. The developed computer program gives satisfactory results as long as the considered configurations are slender and the angles of attack are small (below stall angle. ABSTRAK: Kertas kerja ini memperkenalkan percubaan untuk mempertingkatkan ketepatan kaedah panel. Kaedah panel tertib rendah telah dipilih dan digabungkan dengan kaedah separa empirik untuk mempertingkatkan ketepatan ramalan seret objek terbang pada kelajuan supersonik. Kaedah semi empirikal yang digunakan untuk meningkatkan ketepatan jangkaan seret menggunakan model matematik bagi kelikatan, seretan dasar, dan seretan disebabkan oleh
Khavaran, A.; Krejsa, E. A.; Kim, C. M.
1992-01-01
The turbulent mixing noise of a supersonic jet is calculated for a round convergent-divergent nozzle at the design pressure ratio. Aerodynamic computations are performed using the PARC code with a k-epsilon turbulence model. Lighthill's acoustic analogy combined with Ribner's assumption is adopted. The acoustics solution is based upon the methodology followed by GE in the MGB code. The source correlation function is expressed as a linear combination of second-order tensors. Assuming separable second-order correlations and incorporating Batchelor's isotropic turbulence model, the source term was calculated from the kinetic energy of turbulence. A Gaussian distribution for the time-delay of correlation was introduced. The computational fluid dynamics (CFD) solution was used to obtain the source strength as well as the characteristic time-delay of correlation. The effect of sound/flow interaction was incorporated using the high frequency asymptotic solution to Lilley's equation for axisymmetric geometries. Acoustic results include sound pressure level directivity and spectra at different polar angles. The aerodynamic and acoustic results demonstrate favorable agreement with experimental data.
Institute of Scientific and Technical Information of China (English)
袁生学
1999-01-01
Some basic concepts and features of supersonic combustion are explained from the view point of macroscopic aerodynamics. Two kinds of interpretations of supersonic combustion are proposed. The difference between supersonic combustion and subsonic combustion is discussed, and the mechanism of supersonic combustion propagation and the limitation of heat addition in supersonic flow are pointed out. The results of the calculation of deflagration in supersonic flow show that the entropy increment and the total pressure loss of the combustion products may decrease with the increase of combustion velocity. It is also demonstrated that the oblique detonation wave angle may not be controlled by the wedge angle under weak underdriven solution conditions and be determined only by combustion velocity. Therefore, the weak underdriven solution may become self-sustaining oblique detonation waves with a constant wave angle.
Pdf prediction of supersonic hydrogen flames
Eifler, P.; Kollmann, W.
1993-01-01
A hybrid method for the prediction of supersonic turbulent flows with combustion is developed consisting of a second order closure for the velocity field and a multi-scalar pdf method for the local thermodynamic state. It is shown that for non-premixed flames and chemical equilibrium mixture fraction, the logarithm of the (dimensionless) density, internal energy per unit mass and the divergence of the velocity have several advantages over other sets of scalars. The closure model is applied to a supersonic non-premixed flame burning hydrogen with air supplied by a supersonic coflow and the results are compared with a limited set of experimental data.
MODELING SUPERSONIC-JET DEFLECTION IN THE HERBIG–HARO 110-270 SYSTEM WITH HIGH-POWER LASERS
Energy Technology Data Exchange (ETDEWEB)
Yuan, Dawei; Li, Yutong; Lu, Xin; Yin, Chuanlei; Su, Luning; Liao, Guoqian; Zhang, Jie [National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Wu, Junfeng; Wang, Lifeng; He, Xiantu [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China); Zhong, Jiayong; Wei, Huigang; Zhang, Kai; Han, Bo; Zhao, Gang [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Jiang, Shaoen; Du, Kai; Ding, Yongkun [Research Center for Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Zhu, Jianqiang, E-mail: ytli@iphy.ac.cn, E-mail: jzhang@sjtu.edu.cn [National Laboratory on High Power Lasers and Physics, Shanghai, 201800 (China)
2015-12-10
Herbig–Haro (HH) objects associated with newly born stars are typically characterized by two high Mach number jets ejected in opposite directions. However, HH 110 appears to only have a single jet instead of two. Recently, Kajdi et al. measured the proper motions of knots in the whole system and noted that HH 110 is a continuation of the nearby HH 270. It has been proved that the HH 270 collides with the surrounding mediums and is deflected by 58°, reshaping itself as HH 110. Although the scales of the astrophysical objects are very different from the plasmas created in the laboratory, similarity criteria of physical processes allow us to simulate the jet deflection in the HH 110/270 system in the laboratory with high power lasers. A controllable and repeatable laboratory experiment could give us insight into the deflection behavior. Here we show a well downscaled experiment in which a laser-produced supersonic-jet is deflected by 55° when colliding with a nearby orthogonal side-flow. We also present a two-dimensional hydrodynamic simulation with the Euler program, LARED-S, to reproduce the deflection. Both are in good agreement. Our results show that the large deflection angle formed in the HH 110/270 system is probably due to the ram pressure from a flow–flow collision model.
Modelling of radon transport in porous media
van der Graaf, E.R.; de Meijer, R.J.; Katase, A; Shimo, M
1998-01-01
This paper aims to describe the state of the art of modelling radon transport in soil on basis of multiphase radon transport equations. Emphasis is given to methods to obtain a consistent set of input parameters needed For such models. Model-measurement comparisons with the KVI radon transport Facil
Modelling of radon transport in porous media
van der Graaf, E.R.; de Meijer, R.J.; Katase, A; Shimo, M
1998-01-01
This paper aims to describe the state of the art of modelling radon transport in soil on basis of multiphase radon transport equations. Emphasis is given to methods to obtain a consistent set of input parameters needed For such models. Model-measurement comparisons with the KVI radon transport Facil
Transport Properties for Combustion Modeling
Energy Technology Data Exchange (ETDEWEB)
Brown, N.J.; Bastein, L.; Price, P.N.
2010-02-19
This review examines current approximations and approaches that underlie the evaluation of transport properties for combustion modeling applications. Discussed in the review are: the intermolecular potential and its descriptive molecular parameters; various approaches to evaluating collision integrals; supporting data required for the evaluation of transport properties; commonly used computer programs for predicting transport properties; the quality of experimental measurements and their importance for validating or rejecting approximations to property estimation; the interpretation of corresponding states; combination rules that yield pair molecular potential parameters for unlike species from like species parameters; and mixture approximations. The insensitivity of transport properties to intermolecular forces is noted, especially the non-uniqueness of the supporting potential parameters. Viscosity experiments of pure substances and binary mixtures measured post 1970 are used to evaluate a number of approximations; the intermediate temperature range 1 < T* < 10, where T* is kT/{var_epsilon}, is emphasized since this is where rich data sets are available. When suitable potential parameters are used, errors in transport property predictions for pure substances and binary mixtures are less than 5 %, when they are calculated using the approaches of Kee et al.; Mason, Kestin, and Uribe; Paul and Warnatz; or Ern and Giovangigli. Recommendations stemming from the review include (1) revisiting the supporting data required by the various computational approaches, and updating the data sets with accurate potential parameters, dipole moments, and polarizabilities; (2) characterizing the range of parameter space over which the fit to experimental data is good, rather than the current practice of reporting only the parameter set that best fits the data; (3) looking for improved combining rules, since existing rules were found to under-predict the viscosity in most cases; (4
Directions in Radiation Transport Modelling
Directory of Open Access Journals (Sweden)
P Nicholas Smith
2016-12-01
More exciting advances are on the horizon to increase the power of simulation tools. The advent of high performance computers is allowing bigger, higher fidelity models to be created, if the challenges of parallelization and memory management can be met. 3D whole core transport modelling is becoming possible. Uncertainty quantification is improving with large benefits to be gained from more accurate, less pessimistic estimates of uncertainty. Advanced graphical displays allow the user to assimilate and make sense of the vast amounts of data produced by modern modelling tools. Numerical solvers are being developed that use goal-based adaptivity to adjust the nodalisation of the system to provide the optimum scheme to achieve the user requested accuracy on the results, thus removing the need to perform costly convergence studies in space and angle etc. More use is being made of multi-physics methods in which radiation transport is coupled with other phenomena, such as thermal-hydraulics, structural response, fuel performance and/or chemistry in order to better understand their interplay in reactor cores.
Up-gradient transport in a probabilistic transport model
DEFF Research Database (Denmark)
Gavnholt, J.; Juul Rasmussen, J.; Garcia, O.E.
2005-01-01
The transport of particles or heat against the driving gradient is studied by employing a probabilistic transport model with a characteristic particle step length that depends on the local concentration or heat gradient. When this gradient is larger than a prescribed critical value, the standard....... These results supplement recent works by van Milligen [Phys. Plasmas 11, 3787 (2004)], which applied Levy distributed step sizes in the case of supercritical gradients to obtain the up-gradient transport. (c) 2005 American Institute of Physics....
Multi-Fraction Bayesian Sediment Transport Model
Directory of Open Access Journals (Sweden)
Mark L. Schmelter
2015-09-01
Full Text Available A Bayesian approach to sediment transport modeling can provide a strong basis for evaluating and propagating model uncertainty, which can be useful in transport applications. Previous work in developing and applying Bayesian sediment transport models used a single grain size fraction or characterized the transport of mixed-size sediment with a single characteristic grain size. Although this approach is common in sediment transport modeling, it precludes the possibility of capturing processes that cause mixed-size sediments to sort and, thereby, alter the grain size available for transport and the transport rates themselves. This paper extends development of a Bayesian transport model from one to k fractional dimensions. The model uses an existing transport function as its deterministic core and is applied to the dataset used to originally develop the function. The Bayesian multi-fraction model is able to infer the posterior distributions for essential model parameters and replicates predictive distributions of both bulk and fractional transport. Further, the inferred posterior distributions are used to evaluate parametric and other sources of variability in relations representing mixed-size interactions in the original model. Successful OPEN ACCESS J. Mar. Sci. Eng. 2015, 3 1067 development of the model demonstrates that Bayesian methods can be used to provide a robust and rigorous basis for quantifying uncertainty in mixed-size sediment transport. Such a method has heretofore been unavailable and allows for the propagation of uncertainty in sediment transport applications.
Business Models For Transport eBusiness
Dragan Cisic; Ivan Franciskovic; Ana Peric
2003-01-01
In this paper authors are presenting expectations from electronic commerce and its connotations on transport logistics. Based on trends, the relations between the companies in the international transport have to be strengthened using Internet business models. In the paper authors are investigating e-business information models for usage in transport
Modeling energy transport in nanostructures
Pattamatta, Arvind
Heat transfer in nanostructures differ significantly from that in the bulk materials since the characteristic length scales associated with heat carriers, i.e., the mean free path and the wavelength, are comparable to the characteristic length of the nanostructures. Nanostructure materials hold the promise of novel phenomena, properties, and functions in the areas of thermal management and energy conversion. Example of thermal management in micro/nano electronic devices is the use of efficient nanostructured materials to alleviate 'hot spots' in integrated circuits. Examples in the manipulation of heat flow and energy conversion include nanostructures for thermoelectric energy conversion, thermophotovoltaic power generation, and data storage. One of the major challenges in Metal-Oxide Field Effect Transistor (MOSFET) devices is to study the 'hot spot' generation by accurately modeling the carrier-optical phonon-acoustic phonon interactions. Prediction of hotspot temperature and position in MOSFET devices is necessary for improving thermal design and reliability of micro/nano electronic devices. Thermoelectric properties are among the properties that may drastically change at nanoscale. The efficiency of thermoelectric energy conversion in a material is measured by a non-dimensional figure of merit (ZT) defined as, ZT = sigmaS2T/k where sigma is the electrical conductivity, S is the Seebeck coefficient, T is the temperature, and k is the thermal conductivity. During the last decade, advances have been made in increasing ZT using nanostructures. Three important topics are studied with respect to energy transport in nanostructure materials for micro/nano electronic and thermoelectric applications; (1) the role of nanocomposites in improving the thermal efficiency of thermoelectric devices, (2) the interfacial thermal resistance for the semiconductor/metal contacts in thermoelectric devices and for metallic interconnects in micro/nano electronic devices, (3) the
Modeling of turbulent supersonic H2-air combustion with an improved joint beta PDF
Baurle, R. A.; Hassan, H. A.
1991-01-01
Attempts at modeling recent experiments of Cheng et al. indicated that discrepancies between theory and experiment can be a result of the form of assumed probability density function (PDF) and/or the turbulence model employed. Improvements in both the form of the assumed PDF and the turbulence model are presented. The results are again used to compare with measurements. Initial comparisons are encouraging.
Sarimurat, Mehmet Nasir
Flow blowing/suction has multiple beneficial effects on the performance of axial flow compressors. In both low speed and high speed compressors a small amount of flow blowing and/or suction can be applied in the region of adverse pressure gradient to control the boundary layer separation and obtain high pressure ratio across the compressor. On the other hand in high speed compressors where a passage shock is present inside the passage, flow blowing/suction can also be used to manage the shock location inside the passage and increase the operating range of the compressor. In the first part of this study, an analytical model based on the integral method for boundary layer with flow blowing in incompressible flows is developed that shows the effect of mass, momentum, velocity magnitude and injection angle of the blowing flow on the behavior of the boundary layer. According to the model the change in the boundary layer momentum thickness across the blowing location is linear function of the momentum of the blowing flow and exponential function of the velocity of the blowing flow. Also if the size of the blowing slot and the velocity of the blown flow are kept constant, when the amount of the blown flow is increased by increasing the blowing angle, there is an "optimum" angle that maximizes the decrease in the momentum thickness across the blowing station. This angle is a function of the velocity ratio and it reaches an asymptotic value of around 40°. The model also shows that the change in the trailing-edge momentum thickness is an exponential function of the change in the momentum thickness across the blowing location. The developed modeled is confirmed for the NACA-65-410 low speed cascade using Computational Fluid Dynamics and a good agreement between the theory and CFD is obtained. In the second part of the thesis a quasi-1D inviscid and compressible flow theory in a converging/diverging flow passage is presented that can predict the amount of flow blowing or
Cholesterol transport in model membranes
Garg, Sumit; Porcar, Lionel; Butler, Paul; Perez-Salas, Ursula
2010-03-01
Physiological processes distribute cholesterol unevenly within the cell. The levels of cholesterol are maintained by intracellular transport and a disruption in the cell's ability to keep these normal levels will lead to disease. Exchange rates of cholesterol are generally studied in model systems using labeled lipid vesicles. Initially donor vesicles have all the cholesterol and acceptor vesicles are devoid of it. They are mixed and after some time the vesicles are separated and cholesterol is traced in each vesicle. The studies performed up to date have significant scatter indicating that the methodologies are not consistent. The present work shows in-situ Time-Resolved SANS studies of cholesterol exchange rates in unsaturated PC lipid vesicles. Molecular dynamics simulations were done to investigate the energetic and kinetic behavior of cholesterol in this system. This synergistic approach will provide insight into our efforts to understand cholesterol traffic.
Turbulence Model Effects on Cold-Gas Lateral Jet Interaction in a Supersonic Crossflow
2014-06-01
symmetry of the geometry . The computational domains were meshed with MIME from Metacomp Technologies (18). In both computational domains, the forward...van Leer-Contact (HLLC) Riemann solver and a multidimensional Total-Variation-Diminishing (TVD) continuous flux limiter (19). The choice of... Riemann 10 problem at the boundary. For the cases modeling the wind tunnel wall, the cylindrical section of the outer boundary was modeled as a no
SATURATED ZONE FLOW AND TRANSPORT MODEL ABSTRACTION
Energy Technology Data Exchange (ETDEWEB)
B.W. ARNOLD
2004-10-27
The purpose of the saturated zone (SZ) flow and transport model abstraction task is to provide radionuclide-transport simulation results for use in the total system performance assessment (TSPA) for license application (LA) calculations. This task includes assessment of uncertainty in parameters that pertain to both groundwater flow and radionuclide transport in the models used for this purpose. This model report documents the following: (1) The SZ transport abstraction model, which consists of a set of radionuclide breakthrough curves at the accessible environment for use in the TSPA-LA simulations of radionuclide releases into the biosphere. These radionuclide breakthrough curves contain information on radionuclide-transport times through the SZ. (2) The SZ one-dimensional (I-D) transport model, which is incorporated in the TSPA-LA model to simulate the transport, decay, and ingrowth of radionuclide decay chains in the SZ. (3) The analysis of uncertainty in groundwater-flow and radionuclide-transport input parameters for the SZ transport abstraction model and the SZ 1-D transport model. (4) The analysis of the background concentration of alpha-emitting species in the groundwater of the SZ.
Numerical modeling of a glow discharge through a supersonic bow shock in air
Rassou, S.; Packan, D.; Elias, P.-Q.; Tholin, F.; Chemartin, L.; Labaune, J.
2017-03-01
The interaction between a glow discharge and the bow shock of a Mach 3 air flow around a truncated conical model with a central spike is modeled, and comparison is made with prior experimental results. The KRONOS workflow for plasma modeling in flow fields, which has recently been developed at ONERA, was used for the modeling. Based on the quasi-neutral approximation, it couples hypersonic and reactive flow fields with electron chemistry, including the effect of non-Maxwellian electron energy distribution function. The model used for the discharge involves 12 species and 82 reactions, including ionization, electronic and vibrational excitation, and attachment. The simulations reproduce the main features of the discharge observed experimentally well, in particular, the very recognizable topology of the discharge. It was found from the simulations that behind the bow shock, in the afterglow, the negative ion flow ensures the electrical conduction and the establishment of the glow discharge. The influence of kinetic rates on the voltage-current characteristics is discussed.
Logistics and Transport - a conceptual model
DEFF Research Database (Denmark)
Jespersen, Per Homann; Drewes, Lise
2004-01-01
This paper describes how the freight transport sector is influenced by logistical principles of production and distribution. It introduces new ways of understanding freight transport as an integrated part of the changing trends of mobility. By introducing a conceptual model for understanding...... the interaction between logistics and transport, it points at ways to over-come inherent methodological difficulties when studying this relation...
Numerical Model of a Variable-Combined-Cycle Engine for Dual Subsonic and Supersonic Cruise
Directory of Open Access Journals (Sweden)
Victor Fernandez-Villace
2013-02-01
Full Text Available Efficient high speed propulsion requires exploiting the cooling capability of the cryogenic fuel in the propulsion cycle. This paper presents the numerical model of a combined cycle engine while in air turbo-rocket configuration. Specific models of the various heat exchanger modules and the turbomachinery elements were developed to represent the physical behavior at off-design operation. The dynamic nature of the model allows the introduction of the engine control logic that limits the operation of certain subcomponents and extends the overall engine operational envelope. The specific impulse and uninstalled thrust are detailed while flying a determined trajectory between Mach 2.5 and 5 for varying throttling levels throughout the operational envelope.
RADIONUCLIDE TRANSPORT MODELS UNDER AMBIENT CONDITIONS
Energy Technology Data Exchange (ETDEWEB)
S. Magnuson
2004-11-01
The purpose of this model report is to document the unsaturated zone (UZ) radionuclide transport model, which evaluates, by means of three-dimensional numerical models, the transport of radioactive solutes and colloids in the UZ, under ambient conditions, from the repository horizon to the water table at Yucca Mountain, Nevada.
Macroscopic Quantum Superposition States in a Model of Photon-Supersonic Phonon Interaction
Institute of Scientific and Technical Information of China (English)
CHAI Jin-Hua; WANG Yan-Bang; LU Yi-Qun
2000-01-01
A model of photon-hypersonic phonon interaction is proposed. The evolution of macroscopic quantum superpo sition states is analyzed, including the wave function and number distribution. It is shown that a superposition state of hypersonic phonon modes can be generated in the case of nondetuning and no losses.
Biological transportation networks: Modeling and simulation
Albi, Giacomo
2015-09-15
We present a model for biological network formation originally introduced by Cai and Hu [Adaptation and optimization of biological transport networks, Phys. Rev. Lett. 111 (2013) 138701]. The modeling of fluid transportation (e.g., leaf venation and angiogenesis) and ion transportation networks (e.g., neural networks) is explained in detail and basic analytical features like the gradient flow structure of the fluid transportation network model and the impact of the model parameters on the geometry and topology of network formation are analyzed. We also present a numerical finite-element based discretization scheme and discuss sample cases of network formation simulations.
A Sediment Transport Model for Sewers
DEFF Research Database (Denmark)
Mark, Ole; Larsson, Johan; Larsen, Torben
1993-01-01
This paper describes a mathematical model for transport processes in sewers. The model consists of three sub models, a surface model for the description of the buildup and the washoff of sediment particles from the surface area, a morphological model and an advection-dispersion model. The model...
Wolf, Stephen W. D.; Laub, James A.; King, Lyndell S.; Reda, Daniel C.
1992-01-01
A unique, low-disturbance supersonic wind tunnel is being developed at NASA-Ames to support supersonic laminar flow control research at cruise Mach numbers of the High Speed Civil Transport (HSCT). The distinctive design features of this new quiet tunnel are a low-disturbance settling chamber, laminar boundary layers along the nozzle/test section walls, and steady supersonic diffuser flow. This paper discusses these important aspects of our quiet tunnel design and the studies necessary to support this design. Experimental results from an 1/8th-scale pilot supersonic wind tunnel are presented and discussed in association with theoretical predictions. Natural laminar flow on the test section walls is demonstrated and both settling chamber and supersonic diffuser performance is examined. The full-scale wind tunnel should be commissioned by the end of 1993.
今村, 宰; 石川, 雄太; 鈴木, 俊介; 福本, 皓士郎; 西田, 俊介; 氏家, 康成; 津江, 光洋
Effect of kinds of one-component n-alkane liquid fuels on combustion characteristics was investigated experimentally using a model combustor of scramjet engine. The inlet condition of a model combustor is 2.0 of Mach number, up to 2400K of total temperature, and 0.38MPa of total pressure. Five kinds of n-alkane are tested, of which carbon numbers are 7, 8, 10, 13, and 16. They are more chemically active and less volatile with an increase of alkane carbon number. Fuels are injected to the combustor in the upstream of cavity with barbotage nitrogen gas and self-ignition performance was investigated. The result shows that self-ignition occurs with less equivalence ratio when alkane carbon number is smaller. This indicates that physical characteristic of fuel, namely volatile of fuel, is dominant for self-ignition behavior. Effect on flame-holding performance is also examined with adding pilot hydrogen and combustion is kept after cutting off pilot hydrogen with the least equivalence ratio where alkane carbon number is from 8 to 10. These points are discussed qualitatively from the conflict effect of chemical and physical properties on alkane carbon number.
Analysis of impact of general-purpose graphics processor units in supersonic flow modeling
Emelyanov, V. N.; Karpenko, A. G.; Kozelkov, A. S.; Teterina, I. V.; Volkov, K. N.; Yalozo, A. V.
2017-06-01
Computational methods are widely used in prediction of complex flowfields associated with off-normal situations in aerospace engineering. Modern graphics processing units (GPU) provide architectures and new programming models that enable to harness their large processing power and to design computational fluid dynamics (CFD) simulations at both high performance and low cost. Possibilities of the use of GPUs for the simulation of external and internal flows on unstructured meshes are discussed. The finite volume method is applied to solve three-dimensional unsteady compressible Euler and Navier-Stokes equations on unstructured meshes with high resolution numerical schemes. CUDA technology is used for programming implementation of parallel computational algorithms. Solutions of some benchmark test cases on GPUs are reported, and the results computed are compared with experimental and computational data. Approaches to optimization of the CFD code related to the use of different types of memory are considered. Speedup of solution on GPUs with respect to the solution on central processor unit (CPU) is compared. Performance measurements show that numerical schemes developed achieve 20-50 speedup on GPU hardware compared to CPU reference implementation. The results obtained provide promising perspective for designing a GPU-based software framework for applications in CFD.
Ko, Malcolm K. W.; Weisenstein, Debra K.; Sze, Nein Dak; Shia, Run-Lie; Rodriguez, Jose M.; Heisey, Curtis
1991-01-01
The AER two-dimensional chemistry-transport model is used to study the effect of supersonic and subsonic aircraft operation in the 2010 atmosphere on stratospheric ozone (O3). The results show that: (1) the calculated O3 response is smaller in the 2010 atmosphere compared to previous calculations performed in the 1980 atmosphere; (2) with the emissions provided, the calculated decrease in O3 column is less than 1 percent; and (3) the effect of model grid resolution on O3 response is small provided that the physics is not modified.
The european Trans-Tools transport model
Rooijen, T. van; Burgess, A.
2008-01-01
The paper presents the use of ArcGIS in the Transtools Transport Model, TRANS-TOOLS, created by an international consortium for the European Commission. The model describe passenger as well as freight transport in Europe with all medium and long distance modes (cars, vans, trucks, train, inland
The european Trans-Tools transport model
Rooijen, T. van; Burgess, A.
2008-01-01
The paper presents the use of ArcGIS in the Transtools Transport Model, TRANS-TOOLS, created by an international consortium for the European Commission. The model describe passenger as well as freight transport in Europe with all medium and long distance modes (cars, vans, trucks, train, inland wate
Optimal transportation networks models and theory
Bernot, Marc; Morel, Jean-Michel
2009-01-01
The transportation problem can be formalized as the problem of finding the optimal way to transport a given measure into another with the same mass. In contrast to the Monge-Kantorovitch problem, recent approaches model the branched structure of such supply networks as minima of an energy functional whose essential feature is to favour wide roads. Such a branched structure is observable in ground transportation networks, in draining and irrigation systems, in electrical power supply systems and in natural counterparts such as blood vessels or the branches of trees. These lectures provide mathematical proof of several existence, structure and regularity properties empirically observed in transportation networks. The link with previous discrete physical models of irrigation and erosion models in geomorphology and with discrete telecommunication and transportation models is discussed. It will be mathematically proven that the majority fit in the simple model sketched in this volume.
Borner, Arnaud; Li, Zheng; Levin, Deborah A
2013-02-14
Supersonic expansions to vacuum produce clusters of sufficiently small size that properties such as heat capacities and latent heat of evaporation cannot be described by bulk vapor thermodynamic values. In this work the Monte-Carlo Canonical-Ensemble (MCCE) method was used to provide potential energies and constant-volume heat capacities for small water clusters. The cluster structures obtained using the well-known simple point charge model were found to agree well with earlier simulations using more rigorous potentials. The MCCE results were used as the starting point for molecular dynamics simulations of the evaporation rate as a function of cluster temperature and size which were found to agree with unimolecular dissociation theory and classical nucleation theory. The heat capacities and latent heat obtained from the MCCE simulations were used in direct-simulation Monte-Carlo of two experiments that measured Rayleigh scattering and terminal dimer mole fraction of supersonic water-jet expansions. Water-cluster temperature and size were found to be influenced by the use of kinetic rather than thermodynamic heat-capacity and latent-heat values as well as the nucleation model.
Up-gradient transport in a probabilistic transport model
DEFF Research Database (Denmark)
Gavnholt, J.; Juul Rasmussen, J.; Garcia, O.E.
2005-01-01
The transport of particles or heat against the driving gradient is studied by employing a probabilistic transport model with a characteristic particle step length that depends on the local concentration or heat gradient. When this gradient is larger than a prescribed critical value, the standard...... deviation of the step size is large compared to its value when the gradient is below critical. For symmetric as well as asymmetric off-axis fueling, the model is capable of producing profiles peaking at the axis. Additionally, profile consistency is obtained over a broad range of source strengths....... These results supplement recent works by van Milligen [Phys. Plasmas 11, 3787 (2004)], which applied Levy distributed step sizes in the case of supercritical gradients to obtain the up-gradient transport. (c) 2005 American Institute of Physics....
Uncertainty in tsunami sediment transport modeling
Jaffe, Bruce E.; Goto, Kazuhisa; Sugawara, Daisuke; Gelfenbaum, Guy R.; La Selle, SeanPaul M.
2016-01-01
Erosion and deposition from tsunamis record information about tsunami hydrodynamics and size that can be interpreted to improve tsunami hazard assessment. We explore sources and methods for quantifying uncertainty in tsunami sediment transport modeling. Uncertainty varies with tsunami, study site, available input data, sediment grain size, and model. Although uncertainty has the potential to be large, published case studies indicate that both forward and inverse tsunami sediment transport models perform well enough to be useful for deciphering tsunami characteristics, including size, from deposits. New techniques for quantifying uncertainty, such as Ensemble Kalman Filtering inversion, and more rigorous reporting of uncertainties will advance the science of tsunami sediment transport modeling. Uncertainty may be decreased with additional laboratory studies that increase our understanding of the semi-empirical parameters and physics of tsunami sediment transport, standardized benchmark tests to assess model performance, and development of hybrid modeling approaches to exploit the strengths of forward and inverse models.
Modelling transport of graded sediment under partial transport conditions
Tuijnder, Arjan; Ribberink, Jan S.; Hulscher, Suzanne J.M.H.; Weerts, H.J.T.; Ritsema, I.L; van Os, A.G.
2006-01-01
Tentative plans are presented for research on the modelling of i) selective sediment transport in suspension and as bed-load, and ii) large-scale morphology in mixed sand-gravel bed rivers. Since the planning of the research is still in its early stages, the plans are flexible. Please feel free to
Charge-transport model for conducting polymers
Dongmin Kang, Stephen; Jeffrey Snyder, G.
2016-11-01
The growing technological importance of conducting polymers makes the fundamental understanding of their charge transport extremely important for materials and process design. Various hopping and mobility edge transport mechanisms have been proposed, but their experimental verification is limited to poor conductors. Now that advanced organic and polymer semiconductors have shown high conductivity approaching that of metals, the transport mechanism should be discernible by modelling the transport like a semiconductor with a transport edge and a transport parameter s. Here we analyse the electrical conductivity and Seebeck coefficient together and determine that most polymers (except possibly PEDOT:tosylate) have s = 3 and thermally activated conductivity, whereas s = 1 and itinerant conductivity is typically found in crystalline semiconductors and metals. The different transport in polymers may result from the percolation of charge carriers from conducting ordered regions through poorly conducting disordered regions, consistent with what has been expected from structural studies.
Simulating Supersonic Turbulence in Galaxy Outflows
Scannapieco, Evan
2010-01-01
We present three-dimensional, adaptive mesh simulations of dwarf galaxy out- flows driven by supersonic turbulence. Here we develop a subgrid model to track not only the thermal and bulk velocities of the gas, but also its turbulent velocities and length scales. This allows us to deposit energy from supernovae directly into supersonic turbulence, which acts on scales much larger than a particle mean free path, but much smaller than resolved large-scale flows. Unlike previous approaches, we are able to simulate a starbursting galaxy modeled after NGC 1569, with realistic radiative cooling throughout the simulation. Pockets of hot, diffuse gas around individual OB associations sweep up thick shells of material that persist for long times due to the cooling instability. The overlapping of high-pressure, rarefied regions leads to a collective central outflow that escapes the galaxy by eating away at the exterior gas through turbulent mixing, rather than gathering it into a thin, unstable shell. Supersonic, turbul...
Advanced Noise Abatement Procedures for a Supersonic Business Jet
Berton, Jeffrey J.; Jones, Scott M.; Seidel, Jonathan A.; Huff, Dennis L.
2017-01-01
Supersonic civil aircraft present a unique noise certification challenge. High specific thrust required for supersonic cruise results in high engine exhaust velocity and high levels of jet noise during takeoff. Aerodynamics of thin, low-aspect-ratio wings equipped with relatively simple flap systems deepen the challenge. Advanced noise abatement procedures have been proposed for supersonic aircraft. These procedures promise to reduce airport noise, but they may require departures from normal reference procedures defined in noise regulations. The subject of this report is a takeoff performance and noise assessment of a notional supersonic business jet. Analytical models of an airframe and a supersonic engine derived from a contemporary subsonic turbofan core are developed. These models are used to predict takeoff trajectories and noise. Results indicate advanced noise abatement takeoff procedures are helpful in reducing noise along lateral sidelines.
Polar auxin transport: models and mechanisms
Berkel, van K.; Boer, de R.J.; Scheres, B.; Tusscher, ten K.
2013-01-01
Spatial patterns of the hormone auxin are important drivers of plant development. The observed feedback between the active, directed transport that generates auxin patterns and the auxin distribution that influences transport orientation has rendered this a popular subject for modelling studies. Her
Review and prospect of supersonic business jet design
Sun, Yicheng; Smith, Howard
2017-04-01
This paper reviews the environmental issues and challenges appropriate to the design of supersonic business jets (SSBJs). There has been a renewed, worldwide interest in developing an environmentally friendly, economically viable and technologically feasible supersonic transport aircraft. A historical overview indicates that the SSBJ will be the pioneer for the next generation of supersonic airliners. As a high-end product itself, the SSBJ will likely take a market share in the future. The mission profile appropriate to this vehicle is explored considering the rigorous environmental constraints. Mitigation of the sonic boom and improvements aerodynamic efficiency in flight are the most challenging features of civil supersonic transport. Technical issues and challenges associated with this type of aircraft are identified, and methodologies for the SSBJ design are discussed. Due to the tightly coupled issues, a multidisciplinary design, analysis and optimization environment is regarded as the essential approach to the creation of a low-boom low-drag supersonic aircraft. Industrial and academic organizations have an interest in this type of vehicle are presented. Their investments in SSBJ design will hopefully get civil supersonic transport back soon.
Supersonic flows over cavities
Institute of Scientific and Technical Information of China (English)
Tianwen FANG; Meng DING; Jin ZHOU
2008-01-01
The characteristics of supersonic cold flows over cavities were investigated experimentally and numer-ically, and the effects of cavities of different sizes on super-sonic flow field were analyzed. The results indicate that the ratio of length to depth L/D within the range of 5-9 has little relevance to integral structures of cavity flow. The bevel angle of the rear wall does not alter the overall structure of the cavity flow within the range of 30°-60°, but it can exert obvious effect on the evolvement of shear layer and vortexes in cavities.
Concept Layout Model of Transportation Terminals
Directory of Open Access Journals (Sweden)
Li-ya Yao
2012-01-01
Full Text Available Transportation terminal is the key node in transport systems. Efficient terminals can improve operation of passenger transportation networks, adjust the layout of public transportation networks, provide a passenger guidance system, and regulate the development of commercial forms, as well as optimize the assembly and distribution of modern logistic modes, among others. This study aims to clarify the relationship between the function and the structure of transportation terminals and establish the function layout design. The mapping mechanism of demand, function, and structure was analyzed, and a quantitative relationship between function and structure was obtained from a design perspective. Passenger demand and terminal structure were decomposed into several demand units and structural elements following the principle of reverse engineering. The relationship maps between these two kinds of elements were then analyzed. Function-oriented concept layout model of transportation terminals was established using the previous method. Thus, a technique in planning and design of transportation structures was proposed. Meaningful results were obtained from the optimization of transportation terminal facilities, which guide the design of the functional layout of transportation terminals and improve the development of urban passenger transportation systems.
Structural concept trends for commercial supersonic cruise aircraft design
Sakat, I. F.; Davis, G. W.; Saelman, B.
1980-01-01
Structural concept trends for future commercial supersonic transport aircraft are considered. Highlights, including the more important design conditions and requirements, of two studies are discussed. Knowledge of these design parameters, as determined through studies involving the application of flexible mathematical models, enabled inclusion of aeroelastic considerations in the structural-material concepts evaluation. The design trends and weight data of the previous contractual study of Mach 2.7 cruise aircraft were used as the basis for incorporating advanced materials and manufacturing approaches to the airframe for reduced weight and cost. Structural studies of design concepts employing advanced aluminum alloys, advanced composites, and advanced titanium alloy and manufacturing techniques are compared for a Mach 2.0 arrow-wing configuration concept. Appraisals of the impact of these new materials and manufacturing concepts to the airframe design are shown and compared. The research and development to validate the potential sources of weight and cost reduction identified as necessary to attain a viable advanced commercial supersonic transport are discussed.
Supersonic combustion engine testbed, heat lightning
Hoying, D.; Kelble, C.; Langenbahn, A.; Stahl, M.; Tincher, M.; Walsh, M.; Wisler, S.
1990-01-01
The design of a supersonic combustion engine testbed (SCET) aircraft is presented. The hypersonic waverider will utilize both supersonic combustion ramjet (SCRAMjet) and turbofan-ramjet engines. The waverider concept, system integration, electrical power, weight analysis, cockpit, landing skids, and configuration modeling are addressed in the configuration considerations. The subsonic, supersonic and hypersonic aerodynamics are presented along with the aerodynamic stability and landing analysis of the aircraft. The propulsion design considerations include: engine selection, turbofan ramjet inlets, SCRAMjet inlets and the SCRAMjet diffuser. The cooling requirements and system are covered along with the topics of materials and the hydrogen fuel tanks and insulation system. A cost analysis is presented and the appendices include: information about the subsonic wind tunnel test, shock expansion calculations, and an aerodynamic heat flux program.
Supersonic Flutter of Laminated Curved Panels
Directory of Open Access Journals (Sweden)
M. Ganapathi
1995-04-01
Full Text Available Supersonic flutter analysis of laminated composite curved panels is investigated using doubly-curved, quadrilateral, shear flexible, shell element based on field-consistency approach. The formulation includes transverse shear deformation, in-plane and rotary inertias. The aerodynamic force is evaluated using two-dimensional static aerodynamic approximation for high supersonic flow. Initially, the model developed here is verified for the flutter analysis of flat plates. Numerical results are presented for isotropic, orthotropic and laminated anisotropic curved panels. A detailed parametric study is carried out to observe the effects of aspect and thickness ratios, number of layers, lamination scheme, and boundary conditions on flutter boundary.
Boltzmann Transport in Hybrid PIC HET Modeling
2015-07-01
Paper 3. DATES COVERED (From - To) July 2015-July 2015 4. TITLE AND SUBTITLE Boltzmann transport in hybrid PIC HET modeling 5a. CONTRACT NUMBER In...produced a variety of self-consistent electron swarm codes, such as the Magboltz code, focused on directly solving the steady Boltzmann trans-port...Std. 239.18 Boltzmann transport in hybrid PIC HET modeling IEPC-2015- /ISTS-2015-b- Presented at Joint Conference of 30th International
Conditions for supersonic bent Marshak waves
Xu, Qiang; Li, Jing; Dan, Jia-kun; Wang, Kun-lun; Zhou, Shao-tong
2014-01-01
Supersonic radiation diffusion approximation is a useful way to study the radiation transportation. Considering the bent Marshak wave theory in 2-dimensions, and an invariable source temperature, we get the supersonic radiation diffusion conditions which are about the Mach number $M>8(1+\\sqrt{\\ep})/3$, and the optical depth $\\tau>1$. A large Mach number requires a high temperature, while a large optical depth requires a low temperature. Only when the source temperature is in a proper region these conditions can be satisfied. Assuming the material opacity and the specific internal energy depend on the temperature and the density as a form of power law, for a given density, these conditions correspond to a region about source temperature and the length of the sample. This supersonic diffusion region involves both lower and upper limit of source temperature, while that in 1-dimension only gives a lower limit. Taking $\\rm SiO_2$ and the Au for example, we show the supersonic region numerically.
Hydrologic modeling of pathogen fate and transport.
Dorner, Sarah M; Anderson, William B; Slawson, Robin M; Kouwen, Nicholas; Huck, Peter M
2006-08-01
A watershed-scale fate and transport model has been developed for Escherichia coli and several waterborne pathogens: Cryptosporidiumspp., Giardiaspp., Campylobacter spp, and E. coli O157:H7. The objectives were to determine the primary sources of pathogenic contamination in a watershed used for drinking water supply and to gain a greater understanding of the factors that most influence their survival and transport. To predict the levels of indicator bacteria and pathogens in surface water, an existing hydrologic model, WATFLOOD, was augmented for pathogen transport and tested on a watershed in Southwestern Ontario, Canada. The pathogen model considered transport as a result of overland flow, subsurface flow to tile drainage systems, and in-stream routing. The model predicted that most microorganisms entering the stream from land-based sources enter the stream from tile drainage systems rather than overland transport. Although the model predicted overland transport to be rare, when it occurred, it corresponded to the highest observed and modeled microbial concentrations. Furthermore, rapid increases in measured E. coli concentrations during storm events suggested that the resuspension of microorganisms from stream sediments may be of equal or greater importance than land-based sources of pathogens.
Computational modelling flow and transport
Stelling, G.S.; Booij, N.
1999-01-01
Lecture notes CT wa4340. Derivation of equations using balance principles; numerical treatment of ordinary differential equations; time dependent partial differential equations; the strucure of a computer model:DUFLO; usage of numerical models.
Infinitesimal Conical Supersonic Flow
Busemann, Adolf
1947-01-01
The calculation of infinitesimal conical supersonic flow has been applied first to the simplest examples that have also been calculated in another way. Except for the discovery of a miscalculation in an older report, there was found the expected conformity. The new method of calculation is limited more definitely to the conical case.
Molecular model of the neural dopamine transporter
Ravna, Aina Westrheim; Sylte, Ingebrigt; Dahl, Svein G.
2003-05-01
The dopamine transporter (DAT) regulates the action of dopamine by reuptake of the neurotransmitter into presynaptic neurons, and is the main molecular target of amphetamines and cocaine. DAT and the Na+/H+ antiporter (NhaA) are secondary transporter proteins that carry small molecules across a cell membrane against a concentration gradient, using ion gradients as energy source. A 3-dimensional projection map of the E. coli NhaA has confirmed a topology of 12 membrane spanning domains, and was previously used to construct a 3-dimensional NhaA model with 12 trans-membrane α-helices (TMHs). The NhaA model, and site directed mutagenesis data on DAT, were used to construct a detailed 3-dimensional DAT model using interactive molecular graphics and empiric force field calculations. The model proposes a dopamine transport mechanism involving TMHs 1, 3, 4, 5, 7 and 11. Asp79, Tyr252 and Tyr274 were the primary cocaine binding residues. Binding of cocaine or its analogue, (-)-2β-carbomethoxy-3β-(4-fluorophenyl)tropane (CFT), seemed to lock the transporter in an inactive state, and thus inhibit dopamine transport. The present model may be used to design further experimental studies of the molecular structure and mechanisms of DAT and other secondary transporter proteins.
Uncertainty calculation in transport models and forecasts
DEFF Research Database (Denmark)
Manzo, Stefano; Prato, Carlo Giacomo
in a four-stage transport model related to different variable distributions (to be used in a Monte Carlo simulation procedure), assignment procedures and levels of congestion, at both the link and the network level. The analysis used as case study the Næstved model, referring to the Danish town of Næstved2...... the uncertainty propagation pattern over time specific for key model outputs becomes strategically important. 1 Manzo, S., Nielsen, O. A. & Prato, C. G. (2014). The Effects of uncertainty in speed-flow curve parameters on a large-scale model. Transportation Research Record, 1, 30-37. 2 Manzo, S., Nielsen, O. A...
Energy Technology Data Exchange (ETDEWEB)
Grossman, A.S.; Kinnison, D.E.; Penner, J.E.; Grant, K.E.; Tamaresis, J.; Connell, P.S. [Lawrence Livermore National Lab., CA (United States). Atmospheric Science Research Div.
1996-01-01
The tropospheric radiative forcing has been calculated for ozone and water vapor perturbations caused by a realistic High Speed Civil Transport (HSCT) aircraft emission scenario. Atmospheric profiles of water vapor and ozone were obtained using the LLNL 2-D chemical-radiative-transport model (CRT) of the global troposphere and stratosphere. IR radiative forcing calculations were made with the LLNL correlated k-distribution radiative transfer model. UV-Visible-Near IR radiative forcing calculations were made with the LLNL two stream solar radiation model. For the case of water vapor the IR and Near IR radiative forcing was determined at five different latitudes and then averaged using an appropriate latitudinal average to obtain the global average value. Global average values of radiative forcing were approximately 1.2--2.6 10{sup {minus}3} W/m{sup 2}, depending on the background atmospheric water vapor profile. This result is consistent with prior published values for a similar aircraft scenario and supports the conclusion that the water vapor climate forcing effect is very small. The radiative forcing in the IR and UV-Visible spectral ranges, due to the ozone perturbation, was calculated for the globally averaged atmosphere. Global average values of the radiative forcing were 0.034 W/m{sup 2} for the UV-Visible spectral range and 0.006 W/m{sup 2} for the IR spectral range (0.04 W/m{sup 2} total). This result is also consistent with the range of published values obtained for a similar HSCT scenario. As was the case for water vapor, the ozone forcing is too small to be of major consequence.
在超音速压缩角下的湍流模型数值比较%Comparison of Turbulent Models for Supersonic Compression Corner Flow
Institute of Scientific and Technical Information of China (English)
胡李鹏; 苏莫明; 孙正中; 李小平
2009-01-01
在超音速飞机进气道的湍流数值仿真中,选择合适的湍流模型可以比较准确的捕捉激波位置和流场分布,对飞机发动机的设计和控制都是很重要的.但是对湍流模型的选择,文献中并无记载.针对上述情况选择了进气道的简化结构.分别运用标准的高雷诺数k-epsilon模型,重整化群RNG模型,Realizable k-epsilon模型及ASM模型等进行了数值仿真和比较.基于SIMPLE算法,采用相同的分析壁面函数处理法,并且对流项都采用MINMOD格式.从比较发现:RNG模型比标准的k-epsilon模型和Realizable k-epsilon模型精度高,比ASM模型精度稍低,但是比ASM模型省时间,最后作者认为RNG模型在算例中是最经济实用的湍流模型.%A decent turbulence model in the numerical simulation of supersonic inlet can precisely capture the shock wave and predict the flow field, which is very important to the design and control of aircraft engine. However, no reference deals with the selection of turbulence model under this condition, so a comparison of turbulent models is performed on the supersonic compression corner which is a similar and simple configuration of inlet channel. The four turbulent models are standard k -epsilon model, RNG model , Realizable model and ASM model. They depend on the same SIMPLE algorithm ,analytical wall function and MINMOD scheme of convection. The paper concludes that the RNG turbulent model is more precise than the standard k -epsilon model and the Realizable k -epsilon model, and needs less time than ASM model . In the end , the it is concluded that the RNG model is the most economic and practical one.
Supersonic Jet Noise: Main Sources and Reduction Methodologies
Directory of Open Access Journals (Sweden)
Mohammadreza Azimi
2014-07-01
Full Text Available The large velocity ratio and the presence of Shocks in the exhaust plume from low bypass engines or supersonic jetliners cause jet noise to be dominant component of overall aircraft noise, and therefore is an important issue in design of the next generation of civil supersonic transport. Jet noise reduction technology also has application in the design of highperformance tactical aircraft. Jet noise is of particular concern on aircraft carriers where it is necessary for deck crew to be in relatively close proximity to the aircraft at takeoff and landing. In this paper, a brief discussion about supersonic jet noise sources and a review of the main passive technologies employed for the reduction of supersonic jet noise are presented.
Real time model for public transportation management
Directory of Open Access Journals (Sweden)
Ireneusz Celiński
2014-03-01
Full Text Available Background: The article outlines managing a public transportation fleet in the dynamic aspect. There are currently many technical possibilities of identifying demand in the transportation network. It is also possible to indicate legitimate basis of estimating and steering demand. The article describes a general public transportation fleet management concept based on balancing demand and supply. Material and methods: The presented method utilizes a matrix description of demand for transportation based on telemetric and telecommunication data. Emphasis was placed mainly on a general concept and not the manner in which data was collected by other researchers. Results: The above model gave results in the form of a system for managing a fleet in real-time. The objective of the system is also to optimally utilize means of transportation at the disposal of service providers. Conclusions: The presented concept enables a new perspective on managing public transportation fleets. In case of implementation, the project would facilitate, among others, designing dynamic timetables, updated based on observed demand, and even designing dynamic points of access to public transportation lines. Further research should encompass so-called rerouting based on dynamic measurements of the characteristics of the transportation system.
Radionuclide Transport Models Under Ambient Conditions
Energy Technology Data Exchange (ETDEWEB)
G. Moridis; Q. Hu
2001-12-20
The purpose of Revision 00 of this Analysis/Model Report (AMR) is to evaluate (by means of 2-D semianalytical and 3-D numerical models) the transport of radioactive solutes and colloids in the unsaturated zone (UZ) under ambient conditions from the potential repository horizon to the water table at Yucca Mountain (YM), Nevada.
Radionuclide Transport Models Under Ambient Conditions
Energy Technology Data Exchange (ETDEWEB)
G. Moridis; Q. Hu
2000-03-12
The purpose of this Analysis/Model Report (AMR) is to evaluate (by means of 2-D semianalytical and 3-D numerical models) the transport of radioactive solutes and colloids in the unsaturated zone (UZ) under ambient conditions from the potential repository horizon to the water table at Yucca Mountain (YM), Nevada. This is in accordance with the ''AMR Development Plan U0060, Radionuclide Transport Models Under Ambient Conditions'' (CRWMS M and O 1999a). This AMR supports the UZ Flow and Transport Process Model Report (PMR). This AMR documents the UZ Radionuclide Transport Model (RTM). This model considers: the transport of radionuclides through fractured tuffs; the effects of changes in the intensity and configuration of fracturing from hydrogeologic unit to unit; colloid transport; physical and retardation processes and the effects of perched water. In this AMR they document the capabilities of the UZ RTM, which can describe flow (saturated and/or unsaturated) and transport, and accounts for (a) advection, (b) molecular diffusion, (c) hydrodynamic dispersion (with full 3-D tensorial representation), (d) kinetic or equilibrium physical and/or chemical sorption (linear, Langmuir, Freundlich or combined), (e) first-order linear chemical reaction, (f) radioactive decay and tracking of daughters, (g) colloid filtration (equilibrium, kinetic or combined), and (h) colloid-assisted solute transport. Simulations of transport of radioactive solutes and colloids (incorporating the processes described above) from the repository horizon to the water table are performed to support model development and support studies for Performance Assessment (PA). The input files for these simulations include transport parameters obtained from other AMRs (i.e., CRWMS M and O 1999d, e, f, g, h; 2000a, b, c, d). When not available, the parameter values used are obtained from the literature. The results of the simulations are used to evaluate the transport of radioactive
Transport properties site descriptive model. Guidelines for evaluation and modelling
Energy Technology Data Exchange (ETDEWEB)
Berglund, Sten [WSP Environmental, Stockholm (Sweden); Selroos, Jan-Olof [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)
2004-04-01
This report describes a strategy for the development of Transport Properties Site Descriptive Models within the SKB Site Investigation programme. Similar reports have been produced for the other disciplines in the site descriptive modelling (Geology, Hydrogeology, Hydrogeochemistry, Rock mechanics, Thermal properties, and Surface ecosystems). These reports are intended to guide the site descriptive modelling, but also to provide the authorities with an overview of modelling work that will be performed. The site descriptive modelling of transport properties is presented in this report and in the associated 'Strategy for the use of laboratory methods in the site investigations programme for the transport properties of the rock', which describes laboratory measurements and data evaluations. Specifically, the objectives of the present report are to: Present a description that gives an overview of the strategy for developing Site Descriptive Models, and which sets the transport modelling into this general context. Provide a structure for developing Transport Properties Site Descriptive Models that facilitates efficient modelling and comparisons between different sites. Provide guidelines on specific modelling issues where methodological consistency is judged to be of special importance, or where there is no general consensus on the modelling approach. The objectives of the site descriptive modelling process and the resulting Transport Properties Site Descriptive Models are to: Provide transport parameters for Safety Assessment. Describe the geoscientific basis for the transport model, including the qualitative and quantitative data that are of importance for the assessment of uncertainties and confidence in the transport description, and for the understanding of the processes at the sites. Provide transport parameters for use within other discipline-specific programmes. Contribute to the integrated evaluation of the investigated sites. The site descriptive
System Convergence in Transport Modelling
DEFF Research Database (Denmark)
Rich, Jeppe; Nielsen, Otto Anker; Cantarella, Guilio E.
2010-01-01
-of-successive-averages (MSA) have been proposed. Convergence of the MSA under fairly weak regularity conditions was shown in Robbins and Monro (1951). The iteration between demand and assignment ? the external equilibrium ? are in many models either decoupled or follow a very simple iteration pattern. However, as demand...
Honda, Mitsuru
2005-10-01
In order to predict the performance of ITER plasma, it is important to validate the existing theory-based turbulent transport models by systematicallycomparing them with the experimental observations. Taking experimental data from the ITPA profile database, we have carried out transport simulations with the CDBM, GLF23 and Weiland models by the one-dimensional diffusive transport code TASK/TR. The results are evaluated by the six figures of merit as specified in ITER Physics Basis^1. From the simulation on 55 discharges, it is found that each model has unique dependence on devices and operation modes and the CDBM model gives the most satisfactory results. We have incorporated the dependence on the elongation on the CDBM model^2 and confirmed that the accuracy of the prediction is improved for H-mode discharges. Single-particle-species heat transport simulations have indicated that the CDBM model reproduces Ti profiles more accurately than Te profiles. We will also show the results of the predictive simulations coupling TASK/TR and TASK/EQ, two-dimensional equilibrium code, for high performance plasmas with internal transport barriers like the high βp and reversed shear plasmas. [1] ITER Physics Basis Expert Groups, Nucl. Fusion, 39, 2175 (1999) [2] M. Yagi et al., J. Phys. Soc. Japan, 66, 379 (1997)
LES of an inclined jet into a supersonic cross-flow
Ferrante, Antonino; Matheou, Georgios; Dimotakis, Paul E; Stephens, Mike; Adams, Paul; Walters, Richard; Hand, Randall
2008-01-01
This short article describes flow parameters, numerical method, and animations of the fluid dynamics video LES of an Inclined Jet into a Supersonic Cross-Flow (http://hdl.handle.net/1813/11480). Helium is injected through an inclined round jet into a supersonic air flow at Mach 3.6. The video shows 2D contours of Mach number and magnitude of density gradient, and 3D iso-surfaces of Helium mass-fraction and vortical structures. Large eddy simulation with the sub-grid scale (LES-SGS) stretched vortex model of turbulent and scalar transport captures the main flow features: bow shock, Mach disk, shear layers, counter-rotating vortices, and large-scale structures.
Supersonic Injection of Aerated Liquid Jet
Choudhari, Abhijit; Sallam, Khaled
2016-11-01
A computational study of the exit flow of an aerated two-dimensional jet from an under-expanded supersonic nozzle is presented. The liquid sheet is operating within the annular flow regime and the study is motivated by the application of supersonic nozzles in air-breathing propulsion systems, e.g. scramjet engines, ramjet engines and afterburners. The simulation was conducted using VOF model and SST k- ω turbulence model. The test conditions included: jet exit of 1 mm and mass flow rate of 1.8 kg/s. The results show that air reaches transonic condition at the injector exit due to the Fanno flow effects in the injector passage. The aerated liquid jet is alternately expanded by Prandtl-Meyer expansion fan and compressed by oblique shock waves due to the difference between the back (chamber) pressure and the flow pressure. The process then repeats itself and shock (Mach) diamonds are formed at downstream of injector exit similar to those typical of exhaust plumes of propulsion system. The present results, however, indicate that the flow field of supersonic aerated liquid jet is different from supersonic gas jets due to the effects of water evaporation from the liquid sheet. The contours of the Mach number, static pressure of both cases are compared to the theory of gas dynamics.
Development of A Stochastic Bedload Transport Model
Tsai, C. W.; Kuai, Z.
2009-12-01
Sediment particle transport can be viewed as a Markov chain process. In a non-equilibrium condition, the interchange of sediment particles occurs not only between the bedload layer and the bed surface, but also across the interface between bedload and suspended load. We can quantify the number of saltating particles by modeling the occupancy probabilities vector of particles staying in three states, namely, the bed surface, bedload layer, and suspended sediment layer. Most bedload transport models in the literature are formulated in terms of the mean bed shear stress or flow velocity. The proposed Markovian bedload model and the bedload transport rates are governed by various transition probabilities. These transition probabilities are all functions of the bed shear stress. The stochastic property of the bed shear stress can be incorporated into the above bedload transport model knowing the probability density function of the bed shear stress. This study presents a theoretical method to compute stochastic bedload transport rates considering the stochastic fluctuation of the bed shear stress.
Band transport model for discotic liquid crystals
Lever, L. J.; Kelsall, R. W.; Bushby, R. J.
2005-07-01
A theoretical model is presented for charge transport in discotic liquid crystals in which a charge is delocalized over more than one lattice site. As such, charge transport is via a banded conduction process in a narrow bandwidth system and takes place over coherent lengths of a few molecules. The coherent lengths are disrupted by the geometrical disorder of the system and are treated as being terminated by quantum tunnel barriers. The transmission probabilities at these barriers have been calculated as a function of the charge carrier energy. Phononic interactions are also considered and the charge carrier scattering rates are calculated for intermolecular and intramolecular vibrations. The results of the calculations have been used to develop a Monte Carlo simulation of the charge transport model. Simulated data are presented and used to discuss the nature of the tunnel barriers required to reproduce experimental data. We find that the model successfully reproduces experimental time of flight data including temperature dependence.
GEOS-5 Chemistry Transport Model User's Guide
Kouatchou, J.; Molod, A.; Nielsen, J. E.; Auer, B.; Putman, W.; Clune, T.
2015-01-01
The Goddard Earth Observing System version 5 (GEOS-5) General Circulation Model (GCM) makes use of the Earth System Modeling Framework (ESMF) to enable model configurations with many functions. One of the options of the GEOS-5 GCM is the GEOS-5 Chemistry Transport Model (GEOS-5 CTM), which is an offline simulation of chemistry and constituent transport driven by a specified meteorology and other model output fields. This document describes the basic components of the GEOS-5 CTM, and is a user's guide on to how to obtain and run simulations on the NCCS Discover platform. In addition, we provide information on how to change the model configuration input files to meet users' needs.
Bibliography of Supersonic Cruise Research (SCR) program from 1980 to 1983
Hoffman, S.
1984-01-01
A bibliography for the Supersonic Cruise Research (SCR) and Variable Cycle Engine (VCE) Programs is presented. An annotated bibliography for the last 123 formal reports and a listing of titles for 44 articles and presentations is included. The studies identifies technologies for producing efficient supersonic commercial jet transports for cruise Mach numbers from 2.0 to 2.7.
Modelling Transition Towards Sustainable Transportation Sector
DEFF Research Database (Denmark)
Dominkovic, Dominik Franjo; Bačeković, I.; Mýrdal, Jón Steinar Garðarsson
2016-01-01
In a transition towards 100% renewable energy system, transportation sector is rarely dealt withusing the holistic approach and measuring its impact on the whole energy system. Furthermore, assolutions for power and heat sectors are clearer, it is a tendency of the researchers to focus on thelatter...... two energy sectors. In order to deal with the raised issue, authors of this paper developed amethodology for calculation of the transition towards sustainable transport sector, focusing on thesolutions that are already available. Furthermore, as a part of the model, a detailed mapping ofresources...... needed has been carried out for each of the alternatives. It was shown that theelectrification of the transportation sector is a crucial point in transition, while for the transportmodes that cannot be electrified, or shifted to different transportation modes, four alternatives weredefined: synthetic...
Directory of Open Access Journals (Sweden)
Mosel Ulrich
2013-06-01
Full Text Available We give an overview over the hadronic transport model GiBUU as a simulation tool for hadronic and electroweak reactions on nuclei over a wide energy range [1]. The model is able to handle hadron-, photon- and lepton-induced reactions as well as nucleus nucleus collisions from sub-GeV energies up to hundreds of GeV. After a general introduction of the model, we discuss its possible application to cosmic ray air showers.
The chemical transport model Oslo CTM3
Directory of Open Access Journals (Sweden)
O. A. Søvde
2012-06-01
Full Text Available We present here the global chemical transport model Oslo CTM3, an update of the Oslo CTM2. The update comprises a faster transport scheme, an improved wet scavenging scheme for large scale rain, updated photolysis rates and a new lightning parameterization. Oslo CTM3 is better parallelized and allows for stable, large time steps for advection, enabling more complex or high resolution simulations. Thorough comparisons between the Oslo CTM3, Oslo CTM2 and measurements are performed, and in general the Oslo CTM3 is found to reproduce measurements well. Inclusion of tropospheric sulfur chemistry and nitrate aerosols in CTM3 is shown to be important to reproduce tropospheric O_{3}, OH and the CH_{4} lifetime well. Using the same meteorology to drive the two models, shows that some features related to transport are better resolved by the CTM3, such as polar cap transport, while features like transport close to the vortex edge are resolved better in the Oslo CTM2 due to its required shorter transport time step. The longer transport time steps in CTM3 result in larger errors e.g. near the jets, and when necessary, this can be remedied by using a shorter time step. An additional, more accurate and time consuming, treatment of polar cap transport is presented, however, both perform acceptably. A new treatment of the horizontal distribution of lightning is presented and found to compare well with measurements. Vertical distributions of lighting are updated, and tested against the old vertical distribution. The new profiles are found to produce more NO_{x} in the tropical middle troposphere, and less at the surface and at high altitudes.
An Introduction to the Supersonic Molecular Beam Injection
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
Recently a new fuelling method with supersonic molecular beam injection (MBI) has been developed and used in the tokamaks experiments successfully. It is economical to develop and maintain. The advantages of supersonic MBI compared with the conventional of gas-puffing method are as follows: deep deposition of fuel, better fuelling efficiency, reduced recycling and pure plasma. Particle and energy confinement can be improved and density limit extended. This review described the Laval nozzle molecular beam and a simple collective model for the injection of a supersonic MBI into the tokamak plasma.
Multi-compartment Aerosol Transport Model
Energy Technology Data Exchange (ETDEWEB)
Hubbard, Joshua Allen; Santarpia, Joshua; Brotherton, Christopher M.; Omana, Michael Alexis; Rivera, Danielle; Lucero, Gabriel Anthony
2017-06-01
A simple aerosol transport model was developed for a multi-compartmented cleanroom. Each compartment was treated as a well-mixed volume with ventilating supply and return air. Gravitational settling, intercompartment transport, and leakage of exterior air into the system were included in the model. A set of first order, coupled, ordinary differential equations was derived from the conservation equations of aerosol mass and air mass. The system of ODEs was then solved in MATLAB using pre-existing numerical methods. The model was verified against cases of (1) constant inlet-duct concentration, and (2) exponentially decaying inlet-duct concentration. Numerical methods resulted in normalized error of less than 10 -9 when model solutions were compared to analytical solutions. The model was validated against experimental measurements from a single field test and showed good agreement in the shape and magnitude of the aerosol concentration profile with time.
Hahne, David E.; Glaab, Louis J.
1999-01-01
An investigation was performed to evaluate leading-and trailing-edge flap deflections for optimal aerodynamic performance of a High-Speed Civil Transport concept during takeoff and approach-to-landing conditions. The configuration used for this study was designed by the Douglas Aircraft Company during the 1970's. A 0.1-scale model of this configuration was tested in the Langley 30- by 60-Foot Tunnel with both the original leading-edge flap system and a new leading-edge flap system, which was designed with modem computational flow analysis and optimization tools. Leading-and trailing-edge flap deflections were generated for the original and modified leading-edge flap systems with the computational flow analysis and optimization tools. Although wind tunnel data indicated improvements in aerodynamic performance for the analytically derived flap deflections for both leading-edge flap systems, perturbations of the analytically derived leading-edge flap deflections yielded significant additional improvements in aerodynamic performance. In addition to the aerodynamic performance optimization testing, stability and control data were also obtained. An evaluation of the crosswind landing capability of the aircraft configuration revealed that insufficient lateral control existed as a result of high levels of lateral stability. Deflection of the leading-and trailing-edge flaps improved the crosswind landing capability of the vehicle considerably; however, additional improvements are required.
Error estimation and adaptive chemical transport modeling
Directory of Open Access Journals (Sweden)
Malte Braack
2014-09-01
Full Text Available We present a numerical method to use several chemical transport models of increasing accuracy and complexity in an adaptive way. In largest parts of the domain, a simplified chemical model may be used, whereas in certain regions a more complex model is needed for accuracy reasons. A mathematically derived error estimator measures the modeling error and provides information where to use more accurate models. The error is measured in terms of output functionals. Therefore, one has to consider adjoint problems which carry sensitivity information. This concept is demonstrated by means of ozone formation and pollution emission.
A depth integrated model for suspended transport
Galappatti, R.
1983-01-01
A new depth averaged model for suspended sediment transport in open channels has been developed based on an asymptotic solution to the two dimensional convection-diffusion equation in the vertical plane. The solution for the depth averaged concentration is derived from the bed boundary condition and
Climate impact of transportation A model comparison
Girod, B.; Vuuren, D.P. van; Grahn, M.; Kitous, A.; Kim, S.H.; Kyle, P.
2013-01-01
Transportation contributes to a significant and rising share of global energy use and GHG emissions. Therefore modeling future travel demand, its fuel use, and resulting CO2 emission is highly relevant for climate change mitigation. In this study we compare the baseline projections for global
Transport properties of fully screened Kondo models
Hörig, Christoph B M; Mora, Christophe; Schuricht, Dirk
2014-01-01
We study the nonequilibrium transport properties of fully (exactly) screened Kondo quantum dots subject to a finite bias voltage or a finite temperature. First, we calculate the Fermi-liquid coefficients of the conductance for models with arbitrary spin, i.e., its leading behavior for small bias vol
Logistics Chains in Freight Transport Modelling
Davydenko, I.Y.
2015-01-01
The flow of trade is not equal to transport flows, mainly due to the fact that warehouses and distribution facilities are used as intermediary stops on the way from production locations to the points of consumption or further rework of goods. This thesis proposes a logistics chain model, which estim
Climate impact of transportation A model comparison
Girod, B.; Vuuren, D.P. van; Grahn, M.; Kitous, A.; Kim, S.H.; Kyle, P.
2013-01-01
Transportation contributes to a significant and rising share of global energy use and GHG emissions. Therefore modeling future travel demand, its fuel use, and resulting CO2 emission is highly relevant for climate change mitigation. In this study we compare the baseline projections for global servic
Logistics Chains in Freight Transport Modelling
Davydenko, I.Y.
2015-01-01
The flow of trade is not equal to transport flows, mainly due to the fact that warehouses and distribution facilities are used as intermediary stops on the way from production locations to the points of consumption or further rework of goods. This thesis proposes a logistics chain model, which
Equilibrium models in multimodal container transport systems
Corman, F.; Viti, F.; Negenborn, R.R.
2015-01-01
Optimizing the performance of multimodal freight transport networks involves adequately balancing the interplay between costs, volumes, times of departure and arrival, and times of travel. In order to study this interplay, we propose an assignment model that is able to efficiently determine flows an
Supersonic Turbulent Boundary Layer: DNS and RANS
Institute of Scientific and Technical Information of China (English)
XU Jing-Lei; MA Hui-Yang
2007-01-01
We assess the performance of a few turbulence models for Reynolds averaged Navier-Stokes (RANS) simulation of supersonic boundary layers, compared to the direct numerical simulations (DNS) of supersonic flat-plate turbulent boundary layers, carried out by Gao et al. [Chin. Phys. Lett. 22 (2005) 1709] and Huang et al. [Sci.Chin. 48 (2005) 614], as well as some available experimental data. The assessment is made for two test cases, with incoming Mach numbers and Reynolds numbers M = 2.25, Re = 365, 000/in, and M = 4.5, Re - 1.7 × 107/m,respectively. It is found that in the first case the prediction of RANS models agrees well with the DNS and the experimental data, while for the second case the agreement of the DNS models with experiment is less satisfactory.The compressibility effect on the RANS models is discussed.
Supersonic propagation of ionization waves in an under-dense, laser-produced plasma
Energy Technology Data Exchange (ETDEWEB)
Constantin, C; Back, C A; Fournier, K B; Gregori, G; Landen, O L; Glenzer, S H; Dewald, E L; Miller, M C
2004-10-22
We observe a laser-driven supersonic ionization wave heating a mm-scale plasma of sub-critical density up to 2-3 keV electron temperatures. Propagation velocities initially 10 times the sound speed were measured by means of time-resolved x-ray imaging diagnostics. The measured ionization wave trajectory is modeled analytically and by a 2D radiation-hydrodynamics code. The comparison to the modeling suggests that nonlocal heat transport effects may contribute to the attenuation of the heat wave propagation.
ACE-Asia Chemical Transport Modeling Overview
UNO, I.; Chin, M.; Collins, W.; Ginoux, P.; Rasch, P.; Carmichael, G. R.; Yienger, J. J.
2001-12-01
ACE-Asia (Asia Pacific Regional Aerosol Characterization Experiment) was designed to increase our understanding of how atmospheric aerosol particles affect the Earth?s climate system. The intensive observation period was carried out during March to May, 2001, and more than 100 researchers from several countries (United States, Japan, Korea, China, and many other Asian countries) participated using aircraft, a research vessel, surface stations and numerical models. Aerosol transport forecast activities played an important role during the ACE-Asia intensive observation period. Three independent modeling groups operated chemical transport models in forecast mode and participated in flight planning activities at the operations center. These models were: MATCH (Model of Atmospheric Transport and Chemistry; Rasch and Collins); GOCART (Georgia Tech/Goddard Global Ozone Chemistry Aerosol Radiation and Transport model; Chin and Ginour) and CFORS (Research Institute for Applied Mechanics, Kyushu University + University of Iowa - Chemical weather FORecast System; Uno, Carmichael and Yienger). The MATCH model used in ACE-Asia was a transport model applied for the Asia region, driven by NCEP forecast meteorology. A unique feature of this model was that it assimilated satellite derived optical depths into its forecast algorithm. The GOCART model provided global aerosol forecast using forecast meteorological fields provided by the Goddard Earth Observing System Data Assimilation System (GEOS DAS). The CFORS model provided regional forecasts using a limited area transport model coupled with Regional Meteorological Modeling System (RAMS), initialized by NCEP and JMA forecasts. All models produced 3-d aerosol forecast products consisting of aerosol mass distributions and optical depths for sulfate, black carbon, organic carbon, sea salt, and dust. In the field these model products were made available to all participating scientists via the Web, and were also presented during the
Numerical modelling of ion transport in flames
Han, Jie
2015-10-20
This paper presents a modelling framework to compute the diffusivity and mobility of ions in flames. The (n, 6, 4) interaction potential is adopted to model collisions between neutral and charged species. All required parameters in the potential are related to the polarizability of the species pair via semi-empirical formulas, which are derived using the most recently published data or best estimates. The resulting framework permits computation of the transport coefficients of any ion found in a hydrocarbon flame. The accuracy of the proposed method is evaluated by comparing its predictions with experimental data on the mobility of selected ions in single-component neutral gases. Based on this analysis, the value of a model constant available in the literature is modified in order to improve the model\\'s predictions. The newly determined ion transport coefficients are used as part of a previously developed numerical approach to compute the distribution of charged species in a freely propagating premixed lean CH4/O2 flame. Since a significant scatter of polarizability data exists in the literature, the effects of changes in polarizability on ion transport properties and the spatial distribution of ions in flames are explored. Our analysis shows that changes in polarizability propagate with decreasing effect from binary transport coefficients to species number densities. We conclude that the chosen polarizability value has a limited effect on the ion distribution in freely propagating flames. We expect that the modelling framework proposed here will benefit future efforts in modelling the effect of external voltages on flames. Supplemental data for this article can be accessed at http://dx.doi.org/10.1080/13647830.2015.1090018. © 2015 Taylor & Francis.
Delft Mass Transport model DMT-2
Ditmar, Pavel; Hashemi Farahani, Hassan; Inacio, Pedro; Klees, Roland; Zhao, Qile; Guo, Jing; Liu, Xianglin; Sun, Yu; Riva, Ricardo; Ran, Jiangjun
2013-04-01
Gravity Recovery And Climate Experiment (GRACE) satellite mission has enormously extended our knowledge of the Earth's system by allowing natural mass transport of various origin to be quantified. This concerns, in particular, the depletion and replenishment of continental water stocks; shrinking of polar ice sheets; deformation of the Earth's crust triggered by large earthquakes, and isostatic adjustment processes. A number of research centers compute models of temporal gravity field variations and mass transport, using GRACE data as input. One of such models - Delft Mass Transport model - is being produced at the Delft University of Technology in collaboration with the GNSS Research Center of Wuhan University. A new release of this model, DMT-2, has been produced on the basis of a new (second) release of GRACE level-1b data. This model consists of a time-series of monthly solutions spanning a time interval of more than 8 years, starting from Feb. 2003. Each solution consists of spherical harmonic coefficients up to degree 120. Both unconstrained and optimally filtered solutions are obtained. The most essential improvements of the DMT-2 model, as compared to its predecessors (DMT-1 and DMT-1b), are as follows: (i) improved estimation and elimination of low-frequency noise in GRACE data, so that strong mass transport signals are not damped; (ii) computation of accurate stochastic models of data noise for each month individually with a subsequent application of frequency-dependent data weighting, which allows statistically optimal solutions to be compiled even if data noise is colored and gradually changes in time; (iii) optimized estimation of accelerometer calibration parameters; (iv) incorporation of degree 1 coefficients estimated with independent techniques; (v) usage of state-of-the-art background models to de-alias GRACE data from rapid mass transport signals (this includes the EOT11a model of ocean tides and the latest release of the AOD1B product describing
Symposium on unsaturated flow and transport modeling
Energy Technology Data Exchange (ETDEWEB)
Arnold, E.M.; Gee, G.W.; Nelson, R.W. (eds.)
1982-09-01
This document records the proceedings of a symposium on flow and transport processes in partially saturated groundwater systems, conducted at the Battelle Seattle Research Center on March 22-24, 1982. The symposium was sponsored by the US Nuclear Regulatory Commission for the purpose of assessing the state-of-the-art of flow and transport modeling for use in licensing low-level nuclear waste repositories in partially saturated zones. The first day of the symposium centered around research in flow through partially saturated systems. Papers were presented with the opportunity for questions following each presentation. In addition, after all the talks, a formal panel discussion was held during which written questions were addressed to the panel of the days speakers. The second day of the Symposium was devoted to solute and contaminant transport in partially saturated media in an identical format. Individual papers are abstracted.
Continuous supersonic plasma wind tunnel
DEFF Research Database (Denmark)
Andersen, S.A.; Jensen, Vagn Orla; Nielsen, P.
1968-01-01
The B field configuration of a Q-device has been modified into a magnetic Laval nozzle. Continuous supersonic plasma flow is observed with M≈3......The B field configuration of a Q-device has been modified into a magnetic Laval nozzle. Continuous supersonic plasma flow is observed with M≈3...
Continuous supersonic plasma wind tunnel
DEFF Research Database (Denmark)
Andersen, S.A.; Jensen, Vagn Orla; Nielsen, P.
1969-01-01
The normal magnetic field configuration of a Q device has been modified to obtain a 'magnetic Laval nozzle'. Continuous supersonic plasma 'winds' are obtained with Mach numbers ~3. The magnetic nozzle appears well suited for the study of the interaction of supersonic plasma 'winds' with either...
Model prodrugs for the intestinal oligopeptide transporter
DEFF Research Database (Denmark)
Nielsen, C U; Andersen, R; Brodin, Birger
2001-01-01
(sigma*) may influence the acid, water or base catalyzed model drug release rates, when released from series of D-Glu-Ala and D-Asp-Ala pro-moieties. Release rates were investigated in both aqueous solutions with varying pH, ionic strength, and buffer concentrations as well as in in vitro biological...... as Taft (sigma*) values, has a significant influence on the release rate of the model drug.......The human intestinal di/tri-peptide carrier, hPepT1, has been suggested as a target for increasing intestinal transport of low permeability compounds by creating prodrugs designed for the transporter. Model ester prodrugs using the stabilized dipeptides D-Glu-Ala and D-Asp-Ala as pro...
A Radiative Transport Model for Blazars
Lewis, Tiffany; Justin, Finke; Becker, Peter A.
2017-01-01
Blazars are observed across the electromagnetic spectrum, often with strong variability throughout. The underlying electron distribution associated with the observed emission is typically not computed from first principles. We start from first-principles to build up a transport model, whose solution is the electron distribution, rather than assuming a convenient functional form. Our analytical transport model considers shock acceleration, adiabatic expansion, stochastic acceleration, Bohm diffusion, and synchrotron radiation. We use this solution to generate predictions for the X-ray spectrum and time lags, and compare the results with data products from BeppoSAX observations of X-ray flares from Mrk 421. This new self-consistent model provides an unprecedented view into the jet physics at play in this source, especially the strength of the shock and stochastic acceleration components and the size of the acceleration region.More recently, we augmented the transport model to incorporate Compton scattering, including Klein-Nishina effects. In this case, an analytical solution cannot be derived, and therefore we obtain the steady-state electron distribution computationally. We compare the resulting radiation spectrum with multi-wavelength data for 3C 279. We show that our new Compton + synchrotron blazar model is the first to successfully fit the FermiLAT gamma-ray data for this source based on a first-principles physical calculation.
Transperitoneal transport of creatinine. A comparison of kinetic models
DEFF Research Database (Denmark)
Fugleberg, S; Graff, J; Joffe, P;
1994-01-01
Six kinetic models of transperitoneal creatinine transport were formulated and validated on the basis of experimental results obtained from 23 non-diabetic patients undergoing peritoneal dialysis. The models were designed to elucidate the presence or absence of diffusive, non-lymphatic convective...... including all three forms of transport is superior to other models. We conclude that the best model of transperitoneal creatinine transport includes diffusion, non-lymphatic convective transport and lymphatic convective transport....
Energy Technology Data Exchange (ETDEWEB)
Rocha, Jussie Soares da, E-mail: jussie.soares@ifpi.edu.br [Instituto Federal de Educacao, Ciencia e Tecnologia do Piaui (IFPI), Valenca, PI (Brazil); Maciel, Edisson Savio de G., E-mail: edissonsavio@yahoo.com.br [Instituto Tecnologico de Aeronautica (ITA), Sao Paulo, SP (Brazil); Lira, Carlos A.B. de O., E-mail: cabol@ufpe.edu.br [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil)
2015-07-01
Very High Temperature Gas Cooled Reactors - VHTGRs are studied by several research groups for the development of advanced reactors that can meet the world's growing energy demand. The analysis of the flow of helium coolant around the various geometries at the core of these reactors through computational fluid dynamics techniques is an essential tool in the development of conceptual designs of nuclear power plants that provide added safety. This analysis suggests a close analogy with aeronautical cases widely studied using computational numerical techniques to solve systems of governing equations for the flow involved. The present work consists in solving the Navier-Stokes equations in a conservative form, in two-dimensional space employing a finite difference formulation for spatial discretization using the Euler method for explicit marching in time. The physical problem of supersonic laminar flow of helium gas along a ramp configuration is considered. For this, the Jameson and Mavriplis algorithm and the artificial dissipations models linear and nonlinear of Pulliam was implemented. A spatially variable time step is employed aiming to accelerate the convergence to the steady state solution. The main purpose of this work is to study the cited dissipation models and describe their characteristics in relation to the overall quality of the solution, aiming preliminary results for the development of computational tools of dynamic analysis of helium flow for the VHTGR core. (author)
Modelling an Ammonium Transporter with SCLS
Directory of Open Access Journals (Sweden)
Angelo Troina
2009-10-01
Full Text Available The Stochastic Calculus of Looping Sequences (SCLS is a recently proposed modelling language for the representation and simulation of biological systems behaviour. It has been designed with the aim of combining the simplicity of notation of rewrite systems with the advantage of compositionality. It also allows a rather simple and accurate description of biological membranes and their interactions with the environment.In this work we apply SCLS to model a newly discovered ammonium transporter. This transporter is believed to play a fundamental role for plant mineral acquisition, which takes place in the arbuscular mycorrhiza, the most wide-spread plant-fungus symbiosis on earth. Due to its potential application in agriculture this kind of symbiosis is one of the main focuses of the BioBITs project. In our experiments the passage of NH3 / NH4+ from the fungus to the plant has been dissected in known and hypothetical mechanisms; with the model so far we have been able to simulate the behaviour of the system under different conditions. Our simulations confirmed some of the latest experimental results about the LjAMT2;2 transporter. The initial simulation results of the modelling of the symbiosis process are promising and indicate new directions for biological investigations.
Chemical element transport in stellar evolution models
Cassisi, Santi
2017-01-01
Stellar evolution computations provide the foundation of several methods applied to study the evolutionary properties of stars and stellar populations, both Galactic and extragalactic. The accuracy of the results obtained with these techniques is linked to the accuracy of the stellar models, and in this context the correct treatment of the transport of chemical elements is crucial. Unfortunately, in many respects calculations of the evolution of the chemical abundance profiles in stars are still affected by sometimes sizable uncertainties. Here, we review the various mechanisms of element transport included in the current generation of stellar evolution calculations, how they are implemented, the free parameters and uncertainties involved, the impact on the models and the observational constraints.
Variational multiscale models for charge transport.
Wei, Guo-Wei; Zheng, Qiong; Chen, Zhan; Xia, Kelin
2012-01-01
This work presents a few variational multiscale models for charge transport in complex physical, chemical and biological systems and engineering devices, such as fuel cells, solar cells, battery cells, nanofluidics, transistors and ion channels. An essential ingredient of the present models, introduced in an earlier paper (Bulletin of Mathematical Biology, 72, 1562-1622, 2010), is the use of differential geometry theory of surfaces as a natural means to geometrically separate the macroscopic domain from the microscopic domain, meanwhile, dynamically couple discrete and continuum descriptions. Our main strategy is to construct the total energy functional of a charge transport system to encompass the polar and nonpolar free energies of solvation, and chemical potential related energy. By using the Euler-Lagrange variation, coupled Laplace-Beltrami and Poisson-Nernst-Planck (LB-PNP) equations are derived. The solution of the LB-PNP equations leads to the minimization of the total free energy, and explicit profiles of electrostatic potential and densities of charge species. To further reduce the computational complexity, the Boltzmann distribution obtained from the Poisson-Boltzmann (PB) equation is utilized to represent the densities of certain charge species so as to avoid the computationally expensive solution of some Nernst-Planck (NP) equations. Consequently, the coupled Laplace-Beltrami and Poisson-Boltzmann-Nernst-Planck (LB-PBNP) equations are proposed for charge transport in heterogeneous systems. A major emphasis of the present formulation is the consistency between equilibrium LB-PB theory and non-equilibrium LB-PNP theory at equilibrium. Another major emphasis is the capability of the reduced LB-PBNP model to fully recover the prediction of the LB-PNP model at non-equilibrium settings. To account for the fluid impact on the charge transport, we derive coupled Laplace-Beltrami, Poisson-Nernst-Planck and Navier-Stokes equations from the variational principle
Investigation of nonlinear turbulence models for separated supersonic flows%超声速分离流非线性湍流模式的研究
Institute of Scientific and Technical Information of China (English)
杨晓东; 马晖扬
2002-01-01
本文在低雷诺数k-ε两方程框架下,应用八个常见的非线性湍流模式,对两个激波/边界层相互作用诱导分离的超声速流动进行了研究.采用的非线性模式有:二阶模式(Wilcox & Rubesin (1980), Shih, Zhu & Lumley (1993), Shih, Zhu & Lumley (1995), Gatski & Speziale (1993))和三阶模式(Craft, Launder & Suga (1996), Lien & Leschziner (1996), Apsley & Leschziner (1998), Shih (1997)).两个超声速流动为:20°可压缩拐角绕流和轴对称尖顶拱-柱-裙组合体绕流.计算结果表明,对于激波边界层相互作用,在不做任何可压缩性修正的情况下,非线性模式并没有给出明显优于线性模式的结果.%Eight popular nonlinear turbulence models under low-Re k-ε framework have been tested and validated against experimental data of two supersonic flows with shock-wave/ boundary-layer interaction including separation. These models are: the nonlinear quadratic models ( Wilcox & Rubesin (1980), Shih, Zhu & Lumley (1993), Shih, Zhu & Lumley (1995), Gatski & Speziale (1993) ) and the nonlinear cubic models ( Craft, Launder & Suga (1996), Lien & Leschziner (1996), Apsley & Leschziner (1998), Shih (1997) ). The configurations consist of a 20°compression corner and an axisymmetric ogive-cylinder-flare. The computational results show that nonlinear models yield little improvement over linear models without any compressibility correction.
Mixing in Supersonic Turbulence
Pan, Liubin
2010-01-01
In many astrophysical environments, mixing of heavy elements occurs in the presence of a supersonic turbulent velocity field. Here we carry out the first systematic numerical study of such passive scalar mixing in isothermal supersonic turbulence. Our simulations show that the ratio of the scalar mixing timescale, $\\tau_{\\rm c}$, to the flow dynamical time, $\\tau_{\\rm dyn}$ (defined as the flow driving scale divided by the rms velocity), increases with the Mach number, $M$, for $M \\lsim3$, and becomes essentially constant for $M \\gsim3.$ This trend suggests that compressible modes are less efficient in enhancing mixing than solenoidal modes. However, since the majority of kinetic energy is contained in solenoidal modes at all Mach numbers, the overall change in $\\tau_{\\rm c}/\\tau_{\\rm dyn}$ is less than 20\\% over the range $1 \\lsim M \\lsim 6$. At all Mach numbers, if pollutants are injected at around the flow driving scale, $\\tau_{\\rm c}$ is close to $\\tau_{\\rm dyn}.$ This suggests that scalar mixing is drive...
Titanium honeycomb structure. [for supersonic aircraft wing structure
Davis, R. A.; Elrod, S. D.; Lovell, D. T.
1972-01-01
A brazed titanium honeycomb sandwich system for supersonic transport wing cover panels provides the most efficient structure spanwise, chordwise, and loadwise. Flutter testing shows that high wing stiffness is most efficient in a sandwich structure. This structure also provides good thermal insulation if liquid fuel is carried in direct contact with the wing structure in integral fuel tanks.
Radiative forcing from particle emissions by future supersonic aircraft
Directory of Open Access Journals (Sweden)
G. Pitari
2008-07-01
Full Text Available In this work we focus on the direct radiative forcing (RF of black carbon (BC and sulphuric acid particles emitted by future supersonic aircraft, as well as on the ozone RF due to changes produced by emissions of both gas species (NO_{x}, H_{2}O and aerosol particles capable of affecting stratospheric ozone chemistry. Heterogeneous chemical reactions on the surface of sulphuric acid stratospheric particles (SSA-SAD are the main link between ozone chemistry and supersonic aircraft emissions of sulphur precursors (SO_{2} and particles (H_{2}O–H_{2}SO_{4}. Photochemical O_{3} changes are compared from four independent 3-D atmosphere-chemistry models (ACMs, using as input the perturbation of SSA-SAD calculated in the University of L'Aquila model, which includes on-line a microphysics code for aerosol formation and growth. The ACMs in this study use aircraft emission scenarios for the year 2050 developed by AIRBUS as a part of the EU project SCENIC, assessing options for fleet size, engine technology (NO_{x} emission index, Mach number, range and cruising altitude. From our baseline modeling simulation, the impact of supersonic aircraft on sulphuric acid aerosol and BC mass burdens is 53 and 1.5 μg/m^{2}, respectively, with a direct RF of −11.4 and 4.6 mW/m^{2} (net RF=−6.8 mW/m^{2}. This paper discusses the similarities and differences amongst the participating models in terms of changes to O_{3} precursors due to aircraft emissions (NO_{x}, HO_{x},Cl_{x},Br_{x} and the stratospheric ozone sensitivity to them. In the baseline case, the calculated global ozone change is −0.4 ±0.3 DU, with a net radiative forcing (IR+UV of −2.5± 2 mW/m^{2}. The fraction of this O_{3}-RF attributable to SSA-SAD changes is, however, highly variable among the models, depending on the NO_{x} removal
Directory of Open Access Journals (Sweden)
Chen Jian
2015-01-01
Full Text Available The pressure matching performance of the constant area supersonic-supersonic ejector has been studied by varying the primary and secondary Mach numbers. The effect of the primary fluid injection configurations in ejector, namely peripheral and central, has been investigated as well. Schlieren pictures of flow structure in the former part of the mixing duct with different stagnation pressure ratio of the primary and secondary flows have been taken. Pressure ratios of the primary and secondary flows at the limiting condition have been obtained from the results of pressure and optical measurements. Additionally, a computational fluid dynamics analysis has been performed to clarify the physical meaning of the pressure matching performance diagram of the ejector. The obtained results show that the pressure matching performance of the constant area supersonic-supersonic ejector increases with the increase of the secondary Mach number, and the performance decreases slightly with the increase of the primary Mach number. The phenomenon of boundary layer separation induced by shock wave results in weaker pressure matching performance of the central ejector than that of the peripheral one. Furthermore, based on the observations of the experiment, a simplified analytical model has been proposed to predict the limiting pressure ratio, and the predicted values obtained by this model agree well with the experimental data.
Meeting in Turkey: WASP Transport Modeling and WASP Ecological Modeling
A combination of lectures, demonstrations, and hands-on excercises will be used to introduce pollutant transport modeling with the U.S. EPA's general water quality model, WASP (Water Quality Analysis Simulation Program). WASP features include a user-friendly Windows-based interfa...
Model for radionuclide transport in running waters
Energy Technology Data Exchange (ETDEWEB)
Jonsson, Karin; Elert, Mark [Kemakta Konsult AB, Stockholm (Sweden)
2005-11-15
Two sites in Sweden are currently under investigation by SKB for their suitability as places for deep repository of radioactive waste, the Forsmark and Simpevarp/Laxemar area. As a part of the safety assessment, SKB has formulated a biosphere model with different sub-models for different parts of the ecosystem in order to be able to predict the dose to humans following a possible radionuclide discharge from a future deep repository. In this report, a new model concept describing radionuclide transport in streams is presented. The main difference from the previous model for running water used by SKB, where only dilution of the inflow of radionuclides was considered, is that the new model includes parameterizations also of the exchange processes present along the stream. This is done in order to be able to investigate the effect of the retention on the transport and to be able to estimate the resulting concentrations in the different parts of the system. The concentrations determined with this new model could later be used for order of magnitude predictions of the dose to humans. The presented model concept is divided in two parts, one hydraulic and one radionuclide transport model. The hydraulic model is used to determine the flow conditions in the stream channel and is based on the assumption of uniform flow and quasi-stationary conditions. The results from the hydraulic model are used in the radionuclide transport model where the concentration is determined in the different parts of the stream ecosystem. The exchange processes considered are exchange with the sediments due to diffusion, advective transport and sedimentation/resuspension and uptake of radionuclides in biota. Transport of both dissolved radionuclides and sorbed onto particulates is considered. Sorption kinetics in the stream water phase is implemented as the time scale of the residence time in the stream water probably is short in comparison to the time scale of the kinetic sorption. In the sediment
Understanding transport in model water desalination membranes
Chan, Edwin
Polyamide based thin film composites represent the the state-of-the-art nanofiltration and reverse osmosis membranes used in water desalination. The performance of these membranes is enabled by the ultrathin (~100 nm) crosslinked polyamide film in facilitating the selective transport of water over salt ions. While these materials have been refined over the last several decades, understanding the relationships between polyamide structure and membrane performance remains a challenge because of the complex and heterogeneous nature of the polyamide film. In this contribution, we present our approach to addressing this challenge by studying the transport properties of model polyamide membranes synthesized via molecular layer-by-layer (mLbL) assembly. First, we demonstrate that mLbL can successfully construct polyamide membranes with well-defined nanoscale thickness and roughness using a variety of monomer formulations. Next, we present measurement tools for characterizing the network structure and transport of these model polyamide membranes. Specifically, we used X-ray and neutron scattering techniques to characterize their structure as well as a recently-developed indentation based poromechanics approach to extrapolate their water diffusion coefficient. Finally, we illustrate how these measurements can provide insight into the original problem by linking the key polyamide network properties, i.e. water-polyamide interaction parameter and characteristic network mesh size, to the membrane performance.
Transport model of underground sediment in soils.
Jichao, Sun; Guangqian, Wang
2013-01-01
Studies about sediment erosion were mainly concentrated on the river channel sediment, the terrestrial sediment, and the underground sediment. The transport process of underground sediment is studied in the paper. The concept of the flush potential sediment is founded. The transport equation with stable saturated seepage is set up, and the relations between the flush potential sediment and water sediment are discussed. Flushing of underground sediment begins with small particles, and large particles will be taken away later. The pore ratio of the soil increases gradually. The flow ultimately becomes direct water seepage, and the sediment concentration at the same position in the water decreases over time. The concentration of maximal flushing potential sediment decreases along the path. The underground sediment flushing model reflects the flushing mechanism of underground sediment.
Io Volcanism: Modeling Vapor And Heat Transport
Allen, Daniel R.; Howell, R. R.
2010-10-01
Loki is a large, active volcanic source on Jupiter's moon, Io, whose overall temperatures are well explained by current cooling models, but there are unexplainable subtleties. Using the SO2 atmospheric models of Ingersoll (1989) as a starting point, we are investigating how volatiles, specifically sulfur, are transported on the surface and how they modify the temperatures at Loki and other volcanoes. Voyager images reveal light colored deposits, colloquially called "sulfur bergs,” on Loki's dark patera floor that may be sulfur fumaroles. Galileo images show the presence of red short-chain sulfur deposits around the patera. We are investigating the mechanisms that lead to these features. The light deposits are a few kilometers across. Calculations of the mean free paths for day time conditions on Io indicate lengths on the order of 0.1 km while poorly constrained night time conditions indicate mean free paths about 100 times greater, on the order of what is needed to produce the deposits under ballistic conditions. Preliminary calculations reveal horizontal transport length scales for diffuse transport in a collisional atmosphere of approximately 30 km for sublimating S8 sulfur at 300 K. These length scales would be sufficient to move the sulfur from the warm patera floor to the locations of the red sulfur deposits. At a typical Loki temperature of 300 K, the sublimation/evaporation rate of S8 is a few tens of microns/day. It then requires just a few days to deposit an optically thick 100 µm layer of material. Preliminary length scales and sublimation rates are thus of sufficient scale to produce the deposits. Investigations into the sulfur transport and its effect on temperature are ongoing.
3 Lectures: "Lagrangian Models", "Numerical Transport Schemes", and "Chemical and Transport Models"
Douglass, A.
2005-01-01
The topics for the three lectures for the Canadian Summer School are Lagrangian Models, numerical transport schemes, and chemical and transport models. In the first lecture I will explain the basic components of the Lagrangian model (a trajectory code and a photochemical code), the difficulties in using such a model (initialization) and show some applications in interpretation of aircraft and satellite data. If time permits I will show some results concerning inverse modeling which is being used to evaluate sources of tropospheric pollutants. In the second lecture I will discuss one of the core components of any grid point model, the numerical transport scheme. I will explain the basics of shock capturing schemes, and performance criteria. I will include an example of the importance of horizontal resolution to polar processes. We have learned from NASA's global modeling initiative that horizontal resolution matters for predictions of the future evolution of the ozone hole. The numerical scheme will be evaluated using performance metrics based on satellite observations of long-lived tracers. The final lecture will discuss the evolution of chemical transport models over the last decade. Some of the problems with assimilated winds will be demonstrated, using satellite data to evaluate the simulations.
Hall, Albert W.; Harris, Jack E.
1961-01-01
A simulator study has been made to determine the effectiveness of a single instrument presentation as an aid to the pilot in controlling both rotation and climbout path in take-off. The instrument was basically an angle-of-attack indicator, biased with a total-pressure-rate input as a means of suppressing the phugoid oscillation. Linearized six-degree-of-freedom equations of motion were utilized in simulating a hypothetical supersonic transport as the test vehicle. Each of several experienced pilots performed a number of simulated take-offs, using conventional flight instruments and either an angle-of-attack instrument or the combined angle-of-attack and total-pressure-rate instrument. The pilots were able to rotate the airplane, with satisfactory precision, to the 15 deg. angle of attack required for lift-off when using either an angle-of-attack instrument or the instrument which combined total-pressure-rate with angle of attack. At least 4 to 6 second-S appeared to be required for rotation to prevent overshoot, particularly with the latter instrument. The flight paths resulting from take-offs with simulated engine failures were relatively smooth and repeatable within a reasonably narrow band when the combined angle-of-attack and total-pressure-rate instrument presentation was used. Some of the flight paths resulting from take-offs with the same engine-failure conditions were very oscillatory when conventional instruments and an angle-of-attack instrument were used. The pilots considered the combined angle-of-attack and total- pressure-rate instrument a very effective aid. Even though they could, with sufficient practice, perform satisfactory climbouts after simulated engine failure by monitoring the conventional instruments and making correction based on their readings, it was much easier to maintain a smooth flight path with the single combined angle-of-attack and total-pressure-rate instrument.
A disaggregate freight transport model of transport chain and shipment size choice
Windisch, E.; De Jong, G.C.; Van Nes, R.; Hoogendoorn, S.P.
2010-01-01
The field of freight transport modelling is relatively young compared to passenger transport modelling. However, some key issues in freight policy, like growing freight shares on the road, advanced logistics concepts or emerging strict freight transport regulations, have been creating increasing dem
A disaggregate freight transport model of transport chain and shipment size choice
Windisch, E.; De Jong, G.C.; Van Nes, R.; Hoogendoorn, S.P.
2010-01-01
The field of freight transport modelling is relatively young compared to passenger transport modelling. However, some key issues in freight policy, like growing freight shares on the road, advanced logistics concepts or emerging strict freight transport regulations, have been creating increasing
A disaggregate freight transport model of transport chain and shipment size choice
Windisch, E.; De Jong, G.C.; Van Nes, R.; Hoogendoorn, S.P.
2010-01-01
The field of freight transport modelling is relatively young compared to passenger transport modelling. However, some key issues in freight policy, like growing freight shares on the road, advanced logistics concepts or emerging strict freight transport regulations, have been creating increasing dem
Modeling charge transport in organic photovoltaic materials.
Nelson, Jenny; Kwiatkowski, Joe J; Kirkpatrick, James; Frost, Jarvist M
2009-11-17
The performance of an organic photovoltaic cell depends critically on the mobility of charge carriers within the constituent molecular semiconductor materials. However, a complex combination of phenomena that span a range of length and time scales control charge transport in disordered organic semiconductors. As a result, it is difficult to rationalize charge transport properties in terms of material parameters. Until now, efforts to improve charge mobilities in molecular semiconductors have proceeded largely by trial and error rather than through systematic design. However, recent developments have enabled the first predictive simulation studies of charge transport in disordered organic semiconductors. This Account describes a set of computational methods, specifically molecular modeling methods, to simulate molecular packing, quantum chemical calculations of charge transfer rates, and Monte Carlo simulations of charge transport. Using case studies, we show how this combination of methods can reproduce experimental mobilities with few or no fitting parameters. Although currently applied to material systems of high symmetry or well-defined structure, further developments of this approach could address more complex systems such anisotropic or multicomponent solids and conjugated polymers. Even with an approximate treatment of packing disorder, these computational methods simulate experimental mobilities within an order of magnitude at high electric fields. We can both reproduce the relative values of electron and hole mobility in a conjugated small molecule and rationalize those values based on the symmetry of frontier orbitals. Using fully atomistic molecular dynamics simulations of molecular packing, we can quantitatively replicate vertical charge transport along stacks of discotic liquid crystals which vary only in the structure of their side chains. We can reproduce the trends in mobility with molecular weight for self-organizing polymers using a cheap, coarse
Risk management model in road transport systems
Sakhapov, R. L.; Nikolaeva, R. V.; Gatiyatullin, M. H.; Makhmutov, M. M.
2016-08-01
The article presents the results of a study of road safety indicators that influence the development and operation of the transport system. Road safety is considered as a continuous process of risk management. Authors constructed a model that relates the social risks of a major road safety indicator - the level of motorization. The model gives a fairly accurate assessment of the level of social risk for any given level of motorization. Authors calculated the dependence of the level of socio-economic costs of accidents and injured people in them. The applicability of the concept of socio-economic damage is caused by the presence of a linear relationship between the natural and economic indicators damage from accidents. The optimization of social risk is reduced to finding the extremum of the objective function that characterizes the economic effect of the implementation of measures to improve safety. The calculations make it possible to maximize the net present value, depending on the costs of improving road safety, taking into account socio-economic damage caused by accidents. The proposed econometric models make it possible to quantify the efficiency of the transportation system, allow to simulate the change in road safety indicators.
Modeling in transport phenomena a conceptual approach
Tosun, Ismail
2007-01-01
Modeling in Transport Phenomena, Second Edition presents and clearly explains with example problems the basic concepts and their applications to fluid flow, heat transfer, mass transfer, chemical reaction engineering and thermodynamics. A balanced approach is presented between analysis and synthesis, students will understand how to use the solution in engineering analysis. Systematic derivations of the equations and the physical significance of each term are given in detail, for students to easily understand and follow up the material. There is a strong incentive in science and engineering to
Model of reversible vesicular transport with exclusion
Bressloff, Paul C.; Karamched, Bhargav R.
2016-08-01
A major question in neurobiology concerns the mechanics behind the motor-driven transport and delivery of vesicles to synaptic targets along the axon of a neuron. Experimental evidence suggests that the distribution of vesicles along the axon is relatively uniform and that vesicular delivery to synapses is reversible. A recent modeling study has made explicit the crucial role that reversibility in vesicular delivery to synapses plays in achieving uniformity in vesicle distribution, so called synaptic democracy (Bressloff et al 2015 Phys. Rev. Lett. 114 168101). In this paper we generalize the previous model by accounting for exclusion effects (hard-core repulsion) that may occur between molecular motor-cargo complexes (particles) moving along the same microtubule track. The resulting model takes the form of an exclusion process with four internal states, which distinguish between motile and stationary particles, and whether or not a particle is carrying vesicles. By applying a mean field approximation and an adiabatic approximation we reduce the system of ODEs describing the evolution of occupation numbers of the sites on a 1D lattice to a system of hydrodynamic equations in the continuum limit. We find that reversibility in vesicular delivery allows for synaptic democracy even in the presence of exclusion effects, although exclusion does exacerbate nonuniform distributions of vesicles in an axon when compared with a model without exclusion. We also uncover the relationship between our model and other models of exclusion processes with internal states.
Experimental & Numerical Modeling of Non-combusting Model Firebrands' Transport
Tohidi, Ali; Kaye, Nigel
2016-11-01
Fire spotting is one of the major mechanisms of wildfire spread. Three phases of this phenomenon are firebrand formation and break-off from burning vegetation, lofting and downwind transport of firebrands through the velocity field of the wildfire, and spot fire ignition upon landing. The lofting and downwind transport phase is modeled by conducting large-scale wind tunnel experiments. Non-combusting rod-like model firebrands with different aspect ratios are released within the velocity field of a jet in a boundary layer cross-flow that approximates the wildfire velocity field. Characteristics of the firebrand dispersion are quantified by capturing the full trajectory of the model firebrands using the developed image processing algorithm. The results show that the lofting height has a direct impact on the maximum travel distance of the model firebrands. Also, the experimental results are utilized for validation of a highly scalable coupled stochastic & parametric firebrand flight model that, couples the LES-resolved velocity field of a jet-in-nonuniform-cross-flow (JINCF) with a 3D fully deterministic 6-degrees-of-freedom debris transport model. The validation results show that the developed numerical model is capable of estimating average statistics of the firebrands' flight. Authors would like to thank support of the National Science Foundation under Grant No. 1200560. Also, the presenter (Ali Tohid) would like to thank Dr. Michael Gollner from the University of Maryland College Park for the conference participation support.
Documentation of TRU biological transport model (BIOTRAN)
Energy Technology Data Exchange (ETDEWEB)
Gallegos, A.F.; Garcia, B.J.; Sutton, C.M.
1980-01-01
Inclusive of Appendices, this document describes the purpose, rationale, construction, and operation of a biological transport model (BIOTRAN). This model is used to predict the flow of transuranic elements (TRU) through specified plant and animal environments using biomass as a vector. The appendices are: (A) Flows of moisture, biomass, and TRU; (B) Intermediate variables affecting flows; (C) Mnemonic equivalents (code) for variables; (D) Variable library (code); (E) BIOTRAN code (Fortran); (F) Plants simulated; (G) BIOTRAN code documentation; (H) Operating instructions for BIOTRAN code. The main text is presented with a specific format which uses a minimum of space, yet is adequate for tracking most relationships from their first appearance to their formulation in the code. Because relationships are treated individually in this manner, and rely heavily on Appendix material for understanding, it is advised that the reader familiarize himself with these materials before proceeding with the main text.
A Theoretic Model of Transport Logistics Demand
Natalija Jolić; Nikolina Brnjac; Ivica Oreb
2006-01-01
Concerning transport logistics as relation between transportand integrated approaches to logistics, some transport and logisticsspecialists consider the tenn tautological. However,transport is one of the components of logistics, along with inventories,resources, warehousing, infonnation and goods handling.Transport logistics considers wider commercial and operationalframeworks within which the flow of goods is plannedand managed. The demand for transport logistics services canbe valorised as ...
Modelling Emission of Pollutants from transportation using mobile sensing data
DEFF Research Database (Denmark)
Lehmann, Anders
2017-01-01
to use data acquired from smartphones to im- prove transportation related air quality models and models for climate gas emission from transportation. These models can be used for planning of transportation net- works, monitoring of air quality, and automate transport related green accounting. More...... accurate transportation models can be obtained by using observed travel routes, acquired from smartphone data, rather than indirectly computed routes, as input to a model of route choice in a transportation network. Smartphone data can also be used to gain detailed knowledge of the driving style...... database imple- mentations are a subfield of computer science. I have worked to bring these diverse research fields together to solve the challenge of improving modelling of transporta- tion related air quality emissions as well as modelling of transportation related climate gas emissions. The main...
A Numerical Comparison of Symmetric and Asymmetric Supersonic Wind Tunnels
Clark, Kylen D.
Supersonic wind tunnels are a vital aspect to the aerospace industry. Both the design and testing processes of different aerospace components often include and depend upon utilization of supersonic test facilities. Engine inlets, wing shapes, and body aerodynamics, to name a few, are aspects of aircraft that are frequently subjected to supersonic conditions in use, and thus often require supersonic wind tunnel testing. There is a need for reliable and repeatable supersonic test facilities in order to help create these vital components. The option of building and using asymmetric supersonic converging-diverging nozzles may be appealing due in part to lower construction costs. There is a need, however, to investigate the differences, if any, in the flow characteristics and performance of asymmetric type supersonic wind tunnels in comparison to symmetric due to the fact that asymmetric configurations of CD nozzle are not as common. A computational fluid dynamics (CFD) study has been conducted on an existing University of Michigan (UM) asymmetric supersonic wind tunnel geometry in order to study the effects of asymmetry on supersonic wind tunnel performance. Simulations were made on both the existing asymmetrical tunnel geometry and two axisymmetric reflections (of differing aspect ratio) of that original tunnel geometry. The Reynolds Averaged Navier Stokes equations are solved via NASAs OVERFLOW code to model flow through these configurations. In this way, information has been gleaned on the effects of asymmetry on supersonic wind tunnel performance. Shock boundary layer interactions are paid particular attention since the test section integrity is greatly dependent upon these interactions. Boundary layer and overall flow characteristics are studied. The RANS study presented in this document shows that the UM asymmetric wind tunnel/nozzle configuration is not as well suited to producing uniform test section flow as that of a symmetric configuration, specifically one
Design project: LONGBOW supersonic interceptor
Stoney, Robert; Baker, Matt; Capstaff, Joseph G.; Dishman, Robert; Fick, Gregory; Frick, Stephen N.; Kelly, Mark
1993-01-01
A recent white paper entitled 'From the Sea' has spotlighted the need for Naval Aviation to provide overland support to joint operations. The base for this support, the Aircraft Carrier (CVN), will frequently be unable to operate within close range of the battleground because of littoral land-based air and subsurface threats. A high speed, long range, carrier capable aircraft would allow the CVN to provide timely support to distant battleground operations. Such an aircraft, operating as a Deck-Launched Interceptor (DLI), would also be an excellent counter to Next Generation Russian Naval Aviation (NGRNA) threats consisting of supersonic bombers, such as the Backfire, equipped with the next generation of high-speed, long-range missiles. Additionally, it would serve as an excellent high speed Reconnaissance airplane, capable of providing Battle Force commanders with timely, accurate pre-mission targeting information and post-mission Bomb Damage Assessment (BDA). Recent advances in computational hypersonic airflow modeling has produced a method of defining aircraft shapes that fit a conical shock flow model to maximize the efficiency of the vehicle. This 'Waverider' concept provides one means of achieving long ranges at high speeds. A Request for Proposal (RFP) was issued by Professor Conrad Newberry that contained design requirements for an aircraft to accomplish the above stated missions, utilizing Waverider technology.
Anathpindika, S
2009-01-01
In this, second paper of the sequel of two papers, we present five SPH simulations of fast head-on cloud collisions and study the evolution of the ram pressure confined gas slab. Anathpindika (2008) (hereafter paper I) considered highly supersonic cloud collisions and examined the effect of bending and shearing instabilities on the shocked gas slab. The post-collision shock here, as in paper I, is also modelled by a simple barotropic equation of state (EOS). However, a much stiffer EOS is used to model the shock resulting from a low velocity cloud collision. We explore the parameter space by varying the pre-collision velocity and the impact parameter. We observe that pressure confined gas slabs become Jeans unstable if the sound crossing time, $t_{cr}$, is much larger than the freefall time, $t_{ff}$, of putative clumps condensing out of them. Self gravitating clumps may spawn multiple/larger $N$-body star clusters. We also suggest that warmer gas slabs are unlikely to fragment and may end up as diffuse gas c...
Numerical Modelling Approaches for Sediment Transport in Sewer Systems
DEFF Research Database (Denmark)
Mark, Ole
A study of the sediment transport processes in sewers has been carried out. Based on this study a mathematical modelling system has been developed to describe the transport processes of sediments and dissolved matter in sewer systems. The modelling system consists of three sub-models which...... constitute the basic modelling system necessary to give a discription of the most dominant physical transport processes concerning particles and dissolved matter in sewer systems: A surface model. An advection-dispersion model. A sediment transport model....
A new conceptual model for aeolian transport rates on beaches
De Vries, S.; Stive, M.J.F.; Van Rijn, L.; Ranasinghe, R.
2012-01-01
In this paper a new conceptual model for aeolian sediment transport rates is presented. Traditional sediment transport formulations have known limitations when applied to coastal beach situations. A linear model for sediment transport rates with respect to wind speed is proposed and supported by
Ecosystem element transport model for Lake Eckarfjaerden
Energy Technology Data Exchange (ETDEWEB)
Konovalenko, L.; Bradshaw, C. [The Department of Ecology, Environment and Plant Sciences, Stockholm University (Sweden); Andersson, E.; Kautsky, U. [Swedish Nuclear Fuel and Waste Management Co. - SKB (Sweden)
2014-07-01
The ecosystem transport model of elements was developed for Lake Eckarfjaerden located in the Forsmark area in Sweden. Forsmark has currently a low level repository (SFR) and a repository for spent fuel is planned. A large number of data collected during site-investigation program 2002-2009 for planning the repository were available for the creation of the compartment model based on carbon circulation, physical and biological processes (e.g. primary production, consumption, respiration). The model is site-specific in the sense that the food web model is adapted to the actual food web at the site, and most estimates of biomass and metabolic rates for the organisms and meteorological data originate from site data. The functional organism groups of Lake Eckarfjaerden were considered as separate compartments: bacterio-plankton, benthic bacteria, macro-algae, phytoplankton, zooplankton, fish, benthic fauna. Two functional groups of bacteria were taken into account for the reason that they have the highest biomass of all functional groups during the winter, comprising 36% of the total biomass. Effects of ecological parameters, such as bacteria and algae biomass, on redistribution of a hypothetical radionuclide release in the lake were examined. The ecosystem model was used to estimate the environmental transfer of several elements (U, Th, Ra) and their isotopes (U-238, U-234,Th-232, Ra-226) to various aquatic organisms in the lake, using element-specific distribution coefficients for suspended particle and sediment. Results of chemical analyses of the water, sediment and biota were used for model validation. The model gives estimates of concentration factors for fish based on modelling rather on in situ measurement, which reduces the uncertainties for many radionuclides with scarce of data. Document available in abstract form only. (authors)
Wang, Yunpeng; Ozawa, Hiroshi; Nakamura, Yoshiaki
The flow past a capsule-shaped space transportation system (STS) is numerically analyzed using computational fluid dynamics (CFD) for different free stream Mach numbers ranging from 1.2 to 5.0, where a capsule is modeled by a cone, and a rocket by a circular cylinder. The objective of this research is to study Mach number effects on phenomena of the supersonic aerodynamic interference with periodic flow oscillations at supersonic regime. So far we have considered two models: model A (without disk) and model B (with disk). It was found from experimental and computational results that the flow around model A becomes steady, where aerodynamic interaction is not observed, while in model B, flow becomes unsteady with periodic oscillations. This flow oscillation is considered to be a potentially high risk in separation of the capsule and rocket. Therefore, the present study focuses on the unsteady case of model B. Numerical results at M=3.0 compared well with experimental ones, which validates the present CFD. Time-averaged results are employed to see the whole trajectories of shock waves and the variation in amplitude of flow oscillation during one cycle. Moreover, a fence is proposed as a device to suppress the flow oscillation.
Measurement and modeling of oil slick transport
Jones, Cathleen E.; Dagestad, Knut-Frode; Breivik, Åyvind; Holt, Benjamin; Röhrs, Johannes; Christensen, Kai Hâkon; Espeseth, Martine; Brekke, Camilla; Skrunes, Stine
2016-10-01
Transport characteristics of oil slicks are reported from a controlled release experiment conducted in the North Sea in June 2015, during which mineral oil emulsions of different volumetric oil fractions and a look-alike biogenic oil were released and allowed to develop naturally. The experiment used the Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) to track slick location, size, and shape for ˜8 h following release. Wind conditions during the exercise were at the high end of the range considered suitable for radar-based slick detection, but the slicks were easily detectable in all images acquired by the low noise, L-band imaging radar. The measurements are used to constrain the entrainment length and representative droplet radii for oil elements in simulations generated using the OpenOil advanced oil drift model. Simultaneously released drifters provide near-surface current estimates for the single biogenic release and one emulsion release, and are used to test model sensitivity to upper ocean currents and mixing. Results of the modeling reveal a distinct difference between the transport of the biogenic oil and the mineral oil emulsion, in particular in the vertical direction, with faster and deeper entrainment of significantly smaller droplets of the biogenic oil. The difference in depth profiles for the two types of oils is substantial, with most of the biogenic oil residing below depths of 10 m, compared to the majority of the emulsion remaining above 10 m depth. This difference was key to fitting the observed evolution of the two different types of slicks.
Signal Processing Model for Radiation Transport
Energy Technology Data Exchange (ETDEWEB)
Chambers, D H
2008-07-28
This note describes the design of a simplified gamma ray transport model for use in designing a sequential Bayesian signal processor for low-count detection and classification. It uses a simple one-dimensional geometry to describe the emitting source, shield effects, and detector (see Fig. 1). At present, only Compton scattering and photoelectric absorption are implemented for the shield and the detector. Other effects may be incorporated in the future by revising the expressions for the probabilities of escape and absorption. Pair production would require a redesign of the simulator to incorporate photon correlation effects. The initial design incorporates the physical effects that were present in the previous event mode sequence simulator created by Alan Meyer. The main difference is that this simulator transports the rate distributions instead of single photons. Event mode sequences and other time-dependent photon flux sequences are assumed to be marked Poisson processes that are entirely described by their rate distributions. Individual realizations can be constructed from the rate distribution using a random Poisson point sequence generator.
Modeling sediment transport in river networks
Wang, Xu-Ming; Hao, Rui; Huo, Jie; Zhang, Jin-Feng
2008-11-01
A dynamical model is proposed to study sediment transport in river networks. A river can be divided into segments by the injection of branch streams of higher rank. The model is based on the fact that in a real river, the sediment-carrying capability of the stream in the ith segment may be modulated by the undergone state, which may be erosion or sedimentation, of the i-1th and ith segments, and also influenced by that of the ith injecting branch of higher rank. We select a database about the upper-middle reach of the Yellow River in the lower-water season to test the model. The result shows that the data, produced by averaging the erosion or sedimentation over the preceding transient process, are in good agreement with the observed average in a month. With this model, the steady state after transience can be predicted, and it indicates a scaling law that the quantity of erosion or sedimentation exponentially depends on the number of the segments along the reach of the channel. Our investigation suggests that fluctuation of the stream flow due to random rainfall will prevent this steady state from occurring. This is owing to the phenomenon that the varying trend of the quantity of erosion or sedimentation is opposite to that of sediment-carrying capability of the stream.
Modeling Transport of Flushed Reservoir Sediment
Dubinski, I. M.
2014-12-01
Drawdown flushing of a reservoir is often part of a reservoir sediment management program. Flushing can deliver higher than normal sediment loads to the river channel located downstream of a reservoir. The flushed sediment may contain a higher proportion of finer sediment than what was delivered to a channel prior to the presence of the reservoir. The extent of long-term impacts caused by the flushed sediment on the channel morphology and habitat will in part depend on the residence time of the sediment within the channel. In this study we used MIKE 21C to model the fate of flushed sediment through a river channel where the bed material consists of an armoring layer of gravels overlying finer sediment. MIKE 21C is a two-dimensional curvilinear morphological model for rivers developed by DHI. Curvilinear means that the model grid may curve to better follow the channel and flow direction, for example in a meandering channel. Multiple bed material layers are included in the model to represent the armoring and underlying layers existing in the bed separately from the overlying flushed sediment. These layers may also mix. The nature of the interactions between these two layers helps regulate transport and deposition of the flushed sediment, thus are critical to assessing the fate of the flushed sediment and associated potential impacts.
2015-07-01
and is shown in Fig. 2. Only one-half of the domain was modeled, taking advantage of the symmetry of the geometry . The computational domains were...Harten-Lax-van Leer-Contact Riemann solver and a multidimensional Total-Variation-Diminishing continuous flux limiter.17 The compressible, perfect...and radial boundaries were modeled using a characteristics-based inflow/outflow boundary condition, which is based on solving a Riemann problem at the
Numerical Modelling of Sediment Transport in Combined Sewer Systems
DEFF Research Database (Denmark)
Schlütter, Flemming
A conceptual sediment transport model has been developed. Through a case study a comparison with other numerical models is performed.......A conceptual sediment transport model has been developed. Through a case study a comparison with other numerical models is performed....
A new conceptual model for aeolian transport rates on beaches
de Vries, S.; Stive, M.J.F.; van Rijn, L.; Ranasinghe, R.
2012-01-01
In this paper a new conceptual model for aeolian sediment transport rates is presented. Traditional sediment transport formulations have known limitations when applied to coastal beach situations. A linear model for sediment transport rates with respect to wind speed is proposed and supported by both data and numerical model simulations. The presented model does not solve complex wind fields and is therefore very easily applicable. Physical principles such as the presence of a threshold veloc...
Institute of Scientific and Technical Information of China (English)
Guang-sheng WEI; Rong ZHU; Ting CHENG; Fei ZHAO
2016-01-01
As a novel supersonic j et technology,preheating shrouded supersonic j et was developed to deliver oxygen into molten bath efficiently and affordably.However,there has been limited research on the jet behavior and im-pingement characteristics of preheating shrouded supersonic j ets.Computational fluid dynamics (CFD)models were established to investigate the effects of main and shrouding gas temperatures on the characteristics of flow field and impingement of shrouded supersonic j et.The preheating shrouded supersonic j et behavior was simulated and meas-ured by numerical simulation and j et measurement experiment respectively.The influence of preheating shrouded su-personic j et on gas j et penetration and fluid flow in liquid bath was calculated by the CFD model which was validated against water model experiments.The results show that the uptrend of the potential core length of shrouded super-sonic j et would be accelerated with increasing the main and shrouding gas temperatures.Also,preheating supersonic j ets demonstrated significant advantages in penetrating and stirring the liquid bath.
The modelling of an SF6 arc in a supersonic nozzle: II. Current zero behaviour of the nozzle arc
Zhang, Q.; Liu, J.; Yan, J. D.; Fang, M. T. C.
2016-08-01
The present work (part II) forms the second part of an investigation into the behaviour of SF6 nozzle arc. It is concerned with the aerodynamic and electrical behaviour of a transient nozzle arc under a current ramp specified by a rate of current decay (di/dt) before current zero and a voltage ramp (dV/dt) after current zero. The five flow models used in part I [1] for cold gas flow and DC nozzle arcs have been applied to study the transient arc at three stagnation pressures (P 0) and two values of di/dt for the current ramp, representing a wide range of arcing conditions. An analysis of the physical mechanisms encompassed in each flow model is given with an emphasis on the adequacy of a particular model in describing the rapidly varying arc around current zero. The critical rate of rise of recovery voltage (RRRV) is found computationally and compared with test results of Benenson et al [2]. For transient nozzle arcs, the RRRV is proportional to the square of P 0, rather than to the square root of P 0 for DC nozzle arcs. The physical mechanisms responsible for the strong dependence of RRRV on P 0 have been investigated. The relative merits of the flow models employed are discussed.
Modeling Oxygen Transport in the Human Placenta
Serov, Alexander; Filoche, Marcel; Salafia, Carolyn; Grebenkov, Denis
Efficient functioning of the human placenta is crucial for the favorable pregnancy outcome. We construct a 3D model of oxygen transport in the placenta based on its histological cross-sections. The model accounts for both diffusion and convention of oxygen in the intervillous space and allows one to estimate oxygen uptake of a placentone. We demonstrate the existence of an optimal villi density maximizing the uptake and explain it as a trade-off between the incoming oxygen flow and the absorbing villous surface. Calculations performed for arbitrary shapes of fetal villi show that only two geometrical characteristics - villi density and the effective villi radius - are required to predict fetal oxygen uptake. Two combinations of physiological parameters that determine oxygen uptake are also identified: maximal oxygen inflow of a placentone and the Damköhler number. An automatic image analysis method is developed and applied to 22 healthy placental cross-sections demonstrating that villi density of a healthy human placenta lies within 10% of the optimal value, while overall geometry efficiency is rather low (around 30-40%). In a perspective, the model can constitute the base of a reliable tool of post partum oxygen exchange efficiency assessment in the human placenta. Also affiliated with Department of Chemistry and Biochemistry, UCLA, Los Angeles, CA 90095, USA.
Wornom, Dewey E.
1960-01-01
Force tests of a model of a proposed six-engine hull-type seaplane were performed in the Langley 8-foot transonic pressure tunnel. The results of these tests have indicated that the model had a subsonic zero-lift drag coefficient of 0.0240 with the highest zero-lift drag coefficient slightly greater than twice the subsonic drag level. Pitchup tendencies were noted for subsonic Mach numbers at relatively high lift coefficients. Wing leading-edge droop increased the maximum lift-drag ratio approximately 8 percent at a Mach number of 0.80 but this effect was negligible at a Mach number of 0.90 and above. The configuration exhibited stable lateral characteristics over the test Mach number range.
Modeling Biodegradation and Reactive Transport: Analytical and Numerical Models
Energy Technology Data Exchange (ETDEWEB)
Sun, Y; Glascoe, L
2005-06-09
The computational modeling of the biodegradation of contaminated groundwater systems accounting for biochemical reactions coupled to contaminant transport is a valuable tool for both the field engineer/planner with limited computational resources and the expert computational researcher less constrained by time and computer power. There exists several analytical and numerical computer models that have been and are being developed to cover the practical needs put forth by users to fulfill this spectrum of computational demands. Generally, analytical models provide rapid and convenient screening tools running on very limited computational power, while numerical models can provide more detailed information with consequent requirements of greater computational time and effort. While these analytical and numerical computer models can provide accurate and adequate information to produce defensible remediation strategies, decisions based on inadequate modeling output or on over-analysis can have costly and risky consequences. In this chapter we consider both analytical and numerical modeling approaches to biodegradation and reactive transport. Both approaches are discussed and analyzed in terms of achieving bioremediation goals, recognizing that there is always a tradeoff between computational cost and the resolution of simulated systems.
DEFF Research Database (Denmark)
Liu, W.; Lund, H.; Mathiesen, B.V.
2013-01-01
in China. With this purpose in mind, a Chinese transport model has been created and three current transport strategies which are high speed railway (HSR), urban rail transit (URT) and electric vehicle (EV) were evaluated together with a reference transport system in 2020. As conservative results, 13......Transport is one of the most challenge sectors when addressing energy security and climate change due to its high reliance on oil products and lack of the alternative fuels. This paper explores the ability of three transport strategies to contribute to the development of a sustainable transport......% of the energy saving and 12% of the CO2 emission reduction can be attained by accomplishing three strategies compared with the reference transport system. However, the energy demand of transport in 2020 with the implementation of three strategies will be about 1.7 times as much as today. The three strategies...
Supersonic Dislocation Bursts in Silicon
Hahn, E. N.; Zhao, S.; Bringa, E. M.; Meyers, M. A.
2016-06-01
Dislocations are the primary agents of permanent deformation in crystalline solids. Since the theoretical prediction of supersonic dislocations over half a century ago, there is a dearth of experimental evidence supporting their existence. Here we use non-equilibrium molecular dynamics simulations of shocked silicon to reveal transient supersonic partial dislocation motion at approximately 15 km/s, faster than any previous in-silico observation. Homogeneous dislocation nucleation occurs near the shock front and supersonic dislocation motion lasts just fractions of picoseconds before the dislocations catch the shock front and decelerate back to the elastic wave speed. Applying a modified analytical equation for dislocation evolution we successfully predict a dislocation density of 1.5 × 1012 cm-2 within the shocked volume, in agreement with the present simulations and realistic in regards to prior and on-going recovery experiments in silicon.
Properties of Supersonic Evershed Downflows
Pozuelo, S. Esteban; Bellot Rubio, L. R.; de la Cruz Rodríguez, J.
2016-12-01
We study supersonic Evershed downflows in a sunspot penumbra by means of high spatial resolution spectropolarimetric data acquired in the Fe i 617.3 nm line with the CRISP instrument at the Swedish 1 m Solar Telescope. Physical observables, such as Dopplergrams calculated from line bisectors and Stokes V zero-crossing wavelengths, and Stokes V maps in the far red-wing, are used to find regions where supersonic Evershed downflows may exist. We retrieve the line-of-sight velocity and the magnetic field vector in these regions using two-component inversions of the observed Stokes profiles with the help of the SIR code. We follow these regions during their lifetime to study their temporal behavior. Finally, we carry out a statistical analysis of the detected supersonic downflows to characterize their physical properties. Supersonic downflows are contained in compact patches moving outward, which are located in the mid- and outer penumbra. They are observed as bright, roundish structures at the outer end of penumbral filaments that resemble penumbral grains. The patches may undergo fragmentations and mergings during their lifetime; some of them are recurrent. Supersonic downflows are associated with strong and rather vertical magnetic fields with a reversed polarity compared to that of the sunspot. Our results suggest that downflows returning back to the solar surface with supersonic velocities are abruptly stopped in dense deep layers and produce a shock. Consequently, this shock enhances the temperature and is detected as a bright grain in the continuum filtergrams, which could explain the existence of outward-moving grains in the mid- and outer penumbra.
Ureña, A. González; Caceres, J. O.; Morato, M.
2006-09-01
In previous experimental works from this laboratory two unexpected phenomena were reported: (i) a depletion of ca. 40% in the total intensity of a pulsed He seeded NO beam when these molecules passed a homogeneous and a resonant oscillating RF electric field and (ii) a beam splitting of ca. 0.5° when the transverse beam profile is measured, under the same experimental conditions. In this work a model based on molecular beam interferences is introduced which satisfactorily accounts for these two observations. It is shown how the experimental set-up a simple device used as C-field in early molecular beam electric resonance experiments, can be employed as molecular interferometer to investigate matter-wave interferences in beams of polar molecules.
Modeling sheet-flow sand transport under progressive surface waves
Kranenburg, W.M.
2013-01-01
In the near-shore zone, energetic sea waves generate sheet-flow sand transport. In present day coastal models, wave-induced sheet-flow sand transport rates are usually predicted with semi-empirical transport formulas, based on extensive research on this phenomenon in oscillatory flow tunnels. Howeve
DEFF Research Database (Denmark)
Sonnenborg, Torben Obel; Engesgaard, Peter Knudegaard; Rosbjerg, Dan
1996-01-01
and transport simulation model is combined with nonlinear least squares multiple regression. The U.S. Geological Survey method of characteristics model is used to simulate flow and transport, and the optimization part is solved using a Levenberg-Marquardt algorithm. The sensitivity of the optimization approach...
Comparison of global passenger transport models and available literature
Breugem RMH; Vuuren DP van; Wee B van; MNV
2002-01-01
Over the last decade transport has been strongest growing sector in terms of worldwide energy demand. As a result, proper modelling of transport has become more important in models describing global climate change. RIVM has developed the energy model TIMER as part of the global integrated assessmen
Comparison of global passenger transport models and available literature
Breugem RMH; Vuuren DP van; Wee B van; MNV
2002-01-01
Over the last decade transport has been strongest growing sector in terms of worldwide energy demand. As a result, proper modelling of transport has become more important in models describing global climate change. RIVM has developed the energy model TIMER as part of the global integrated
The Turbulent Dynamo in Highly Compressible Supersonic Plasmas
Federrath, Christoph; Bovino, Stefano; Schleicher, Dominik R G
2014-01-01
The turbulent dynamo may explain the origin of cosmic magnetism. While the exponential amplification of magnetic fields has been studied for incompressible gases, little is known about dynamo action in highly-compressible, supersonic plasmas, such as the interstellar medium of galaxies and the early Universe. Here we perform the first quantitative comparison of theoretical models of the dynamo growth rate and saturation level with three-dimensional magnetohydrodynamical simulations of supersonic turbulence with grid resolutions of up to 1024^3 cells. We obtain numerical convergence and find that dynamo action occurs for both low and high magnetic Prandtl numbers Pm = nu/eta = 0.1-10 (the ratio of viscous to magnetic dissipation), which had so far only been seen for Pm >= 1 in supersonic turbulence. We measure the critical magnetic Reynolds number, Rm_crit = 129 (+43, -31), showing that the compressible dynamo is almost as efficient as in incompressible gas. Considering the physical conditions of the present a...
Supersonic stall flutter of high-speed fans
Adamczyk, J. J.; Stevans, W.; Jutras, R.
1981-01-01
An analytical model is proposed for predicting the onset of supersonic stall bending flutter in high-speed rotors. The analysis is based on a modified two-dimensional, compressible, unsteady actuator disk theory. The stability boundary predicted by the analysis is shown to be in good agreement with the measured boundary of a high speed fan. The prediction that the flutter mode would be a forward traveling wave sensitive to wheel speed and aerodynamic loading is confirmed by experimental measurements. In addition, the analysis shows that reduced frequency and dynamic head also play a significant role in establishing the supersonic stall bending flutter boundary of an unshrouded fan.
Coupling dynamic of twin supersonic jets
Kuo, Ching-Wen; Cluts, Jordan; Samimy, Mo
2015-11-01
In a supersonic shock-containing jet, the interaction of large-scale structures in the jet's shear layer with the shock waves generates acoustic waves. The waves propagate upstream, excite the jet initial shear layer instability, establish a feedback loop at certain conditions, and generate screech noise. The screech normally contains different modes of various strengths. Similarly, twin-jet plumes contain screech tones. If the dynamics of the two jet plumes are synchronized, the screech amplitude could be significantly amplified. There is a proposed analytical model in the literature for screech synchronization in twin rectangular jets. This model shows that with no phase difference in acoustic waves arriving at neighboring nozzle lips, twin-jet plumes feature a strong coupling with a significant level of screech tones. In this work the maximum nozzle separation distance for sustained screech synchronization and strong coupling is analytically derived. This model is used with our round twin-jet experiments and the predicted coupling level agrees well with the experimental results. Near-field microphone measurements and schlieren visualization along with the analytical model are used to investigate the coupling mechanisms of twin supersonic jets. Supported by ONR.
A study on iron ore transportation model with penalty value of transportation equipment waiting
Directory of Open Access Journals (Sweden)
Kailing Pan
2017-03-01
Full Text Available As some steel enterprises are at a disadvantage in the choice of the mode of transportation, this paper made further studies of the characteristics of the iron ore logistics, taking comprehensive consideration of optimizing the waiting time under the conditions with limited loading capacity and setting up a procedural model of the iron ore logistics system with minimum cost of transportation, storage, loading, unloading, and transportation equipment waiting. Finally, taking the iron ore transport system of one steel enterprise as example, the solution and the validity of the model were analyzed and verified in this paper.
Research of low boom and low drag supersonic aircraft design
Institute of Scientific and Technical Information of China (English)
Feng Xiaoqiang; Li Zhanke; Song Bifeng
2014-01-01
Sonic boom reduction will be an issue of utmost importance in future supersonic trans-port, due to strong regulations on acoustic nuisance. The paper describes a new multi-objective optimization method for supersonic aircraft design. The method is developed by coupling Seebass-George-Darden (SGD) inverse design method and multi-objective genetic algorithm. Based on the method, different codes are developed. Using a computational architecture, a concep-tual supersonic aircraft design environment (CSADE) is constructed. The architecture of CSADE includes inner optimization level and out optimization level. The low boom configuration is gener-ated in inner optimization level by matching the target equivalent area distribution and actual equivalent area distribution. And low boom/low drag configuration is generated in outer optimiza-tion level by using NSGA-II multi-objective genetic algorithm to optimize the control parameters of SGD method and aircraft shape. Two objective functions, low sonic boom and low wave drag, are considered in CSADE. Physically reasonable Pareto solutions are obtained from the present optimization. Some supersonic aircraft configurations are selected from Pareto front and the optimization results indicate that the swept forward wing configuration has benefits in both sonic boom reduction and wave drag reduction. The results are validated by using computational fluid dynamics (CFD) analysis.
NASA F-16XL supersonic laminar flow control program overview
Fischer, Michael C.
1992-01-01
The viewgraphs and discussion of the NASA supersonic laminar flow control program are provided. Successful application of laminar flow control to a High Speed Civil Transport (HSCT) offers significant benefits in reductions of take-off gross weight, mission fuel burn, cruise drag, structural temperatures, engine size, emissions, and sonic boom. The ultimate economic success of the proposed HSCT may depend on the successful adaption of laminar flow control, which offers the single most significant potential improvements in lift drag ratio (L/D) of all the aerodynamic technologies under consideration. The F-16XL Supersonic Laminar Flow Control (SLFC) Experiment was conceived based on the encouraging results of in-house and NASA supported industry studies to determine if laminar flow control is feasible for the HSCT. The primary objective is to achieve extensive laminar flow (50-60 percent chord) on a highly swept supersonic wing. Data obtained from the flight test will be used to validate existing Euler and Navier Stokes aerodynamic codes and transition prediction boundary layer stability codes. These validated codes and developed design methodology will be delivered to industry for their use in designing supersonic laminar flow control wings. Results from this experiment will establish preliminary suction system design criteria enabling industry to better size the suction system and develop improved estimates of system weight, fuel volume loss due to wing ducting, turbocompressor power requirements, etc. so that benefits and penalties can be more accurately assessed.
Research of low boom and low drag supersonic aircraft design
Directory of Open Access Journals (Sweden)
Feng Xiaoqiang
2014-06-01
Full Text Available Sonic boom reduction will be an issue of utmost importance in future supersonic transport, due to strong regulations on acoustic nuisance. The paper describes a new multi-objective optimization method for supersonic aircraft design. The method is developed by coupling Seebass–George–Darden (SGD inverse design method and multi-objective genetic algorithm. Based on the method, different codes are developed. Using a computational architecture, a conceptual supersonic aircraft design environment (CSADE is constructed. The architecture of CSADE includes inner optimization level and out optimization level. The low boom configuration is generated in inner optimization level by matching the target equivalent area distribution and actual equivalent area distribution. And low boom/low drag configuration is generated in outer optimization level by using NSGA-II multi-objective genetic algorithm to optimize the control parameters of SGD method and aircraft shape. Two objective functions, low sonic boom and low wave drag, are considered in CSADE. Physically reasonable Pareto solutions are obtained from the present optimization. Some supersonic aircraft configurations are selected from Pareto front and the optimization results indicate that the swept forward wing configuration has benefits in both sonic boom reduction and wave drag reduction. The results are validated by using computational fluid dynamics (CFD analysis.
Modelling multicomponent solute transport in structured soils
Beinum, van G.W.
2007-01-01
The mobility of contaminants in soil is an important factor in determining their ability to spread into the wider environment. For non-volatile substances, transport within the soil is generally dominated by transport of dissolved fractions in the soil water phase, via either diffusion or convection
European initiatives for modeling emissions from transport
DEFF Research Database (Denmark)
Joumard, Robert; Hickman, A. John; Samaras, Zissis
1998-01-01
In Europe there have been many cooperative studies into transport emission inventories since the late 80s. These cover the scope of CORINAIR program involving experts from seven European Community laboratories addressing only road transport emissions at national level. These also include the late...
Modelling global container freight transport demand
Tavasszy, L.A.; Ivanova, O.; Halim, R.A.
2015-01-01
The objective of this chapter is to discuss methods and techniques for a quantitative and descriptive analysis of future container transport demand at a global level. Information on future container transport flows is useful for various purposes. It is instrumental for the assessment of returns of i
Directory of Open Access Journals (Sweden)
Tafireyi eNemaura
2015-06-01
Full Text Available Understanding drug transportation mechanisms in the human body is of paramount importance in modelling Pharmacokinetic-Pharmacodynamic relationships. This work gives a novel general model of efavirenz transportation projections based on concentrations simulated from patients on a dose of 600mg. The work puts forward a proposition that transportation can wholly be modeled by concentration and time in a uniform volumetric space. Furthermore, movement entities are used to inform the state of kinetic solubility of a solution. There is use of Ricker’s model, and forms of the Hill’s equation in modelling transportation. Characterization on the movement rates of solution particle are suggested in relation to advection rate of solution particle. At turning points on the transportation rate of solution particle vs concentration curve, a suggestion of possibly change of dominance in the mode of transportation and saturation is made. There are four movement rates postulated at primary micro-level transportation, that are attributed to convection, diffusion (passive transportation ( EI and energy dependent system transportation ( ED in relation to advection. Furthermore, a new parameter is introduced which is defined as an advection rate constant of solution particle. It is postulated to be dependent on two rate constants of solution particle, that is a convection rate constant of solution particle and a saturable transportation rate constant of solution particle. At secondary micro-level transportation, the results show convection as sum of advection and saturable transportation. The kinetics of dissolution of efavirenz in the solution space is postulated. Relatively, a good level of kinetics of dissolution is projected in the concentration region 0−32.82μg/ml.
Combinatorial model of solute transport in porous media
Institute of Scientific and Technical Information of China (English)
张妙仙; 张丽萍
2004-01-01
Modeling of solute transport is a key issue in the area of soil physics and hydrogeology. The most common approach (the convection-dispersion equation) considers an average convection flow rate and Fickian-like dispersion. Here,we propose a solute transport model in porous media of continuously expanding scale, according to the combinatorics principle. The model supposed actual porous media as a combinative body of many basic segments. First, we studied the solute transport process in each basic segment body, and then deduced the distribution of pore velocity in each basic segment body by difference approximation, finally assembled the solute transport process of each basic segment body into one of the combinative body. The simulation result coincided with the solute transport process observed in test. The model provides useful insight into the solute transport process of the non-Fickian dispersion in continuously expanding scale.
Modeling of Anomalous Transport in Tokamaks with FACETS code
Pankin, A. Y.; Batemann, G.; Kritz, A.; Rafiq, T.; Vadlamani, S.; Hakim, A.; Kruger, S.; Miah, M.; Rognlien, T.
2009-05-01
The FACETS code, a whole-device integrated modeling code that self-consistently computes plasma profiles for the plasma core and edge in tokamaks, has been recently developed as a part of the SciDAC project for core-edge simulations. A choice of transport models is available in FACETS through the FMCFM interface [1]. Transport models included in FMCFM have specific ranges of applicability, which can limit their use to parts of the plasma. In particular, the GLF23 transport model does not include the resistive ballooning effects that can be important in the tokamak pedestal region and GLF23 typically under-predicts the anomalous fluxes near the magnetic axis [2]. The TGLF and GYRO transport models have similar limitations [3]. A combination of transport models that covers the entire discharge domain is studied using FACETS in a realistic tokamak geometry. Effective diffusivities computed with the FMCFM transport models are extended to the region near the separatrix to be used in the UEDGE code within FACETS. 1. S. Vadlamani et al. (2009) %First time-dependent transport simulations using GYRO and NCLASS within FACETS (this meeting).2. T. Rafiq et al. (2009) %Simulation of electron thermal transport in H-mode discharges Submitted to Phys. Plasmas.3. C. Holland et al. (2008) %Validation of gyrokinetic transport simulations using %DIII-D core turbulence measurements Proc. of IAEA FEC (Switzerland, 2008)
Properties of Supersonic Evershed Downflows
Pozuelo, Sara Esteban; Rodriguez, Jaime de la Cruz
2016-01-01
We study supersonic Evershed downflows in a sunspot penumbra by means of high spatial resolution spectropolarimetric data acquired in the Fe I 617.3 nm line with the CRISP instrument at the Swedish 1-m Solar Telescope. Physical observables, such as Dopplergrams calculated from line bisectors and Stokes V zero-crossing wavelengths, and Stokes V maps in the far red wing, are used to find regions where supersonic Evershed downflows may exist. We retrieve the LOS velocity and the magnetic field vector in these regions using two-component inversions of the observed Stokes profiles with the help of the SIR code. We follow these regions during their lifetime to study their temporal behavior. Finally, we carry out a statistical analysis of the detected supersonic downflows to characterize their physical properties. Supersonic downflows are contained in compact patches moving outward, which are located in the mid and outer penumbra. They are observed as bright, roundish structures at the outer end of penumbral filamen...
Numerical Analysis of Supersonic Film Cooling in Supersonic Flow in Hypersonic Inlet with Isolator
Directory of Open Access Journals (Sweden)
Silong Zhang
2014-02-01
Full Text Available Supersonic film cooling is an efficient method to cool the engine with extremely high heat load. In order to study supersonic film cooling in a real advanced engine, a two-dimensional model of the hypersonic inlet in a scramjet engine with supersonic film cooling in the isolator is built and validated through experimental data. The simulation results show that the cooling effect under different coolant injection angles does not show clear differences; a small injection angle can ensure both the cooling effect and good aerodynamic performances (e.g., flow coefficient of the hypersonic inlet. Under selected coolant injection angle and inlet Mach number, the cooling efficiency increases along with the injection Mach number of the coolant flow, only causing a little total pressure loss in the isolator. Along with the increase of the inlet Mach number of the hypersonic inlet, the cooling efficiency does not present a monotonic change because of the complex shock waves. However, the wall temperature shows a monotonic increase when the inlet Mach number increases. The mass flow rate of coolant flow should be increased to cool the engine more efficiently according to the mass flow rate of the main stream when the inlet Mach number increases.
Mathematical model of transportation flow dynamics on a multilane highway
Mazurin, D. S.
2013-01-01
We present a microscopic model for the dynamics of a transportation flow based on cellular automata with improved lane changing rules. With this model, we study the influence of crossing transportation flows on the throughput of a multilane highway. For a two-lane highway with an exit, we obtain spa
SIMULATION OF THE LASER DISCHARGE IN A SUPERSONIC GAS FLOW
Directory of Open Access Journals (Sweden)
Tropina, A. A.
2013-06-01
Full Text Available A heat model of the laser discharge in a supersonic turbulent gas flow has been developed. A numerical investigation of the error of the method of velocity measurements, which is based on the nitrogen molecules excitation, has been carried out. It is shown that fast gas heating by the discharge causes the velocity profiles deformation.
Efficiency of a statistical transport model for turbulent particle dispersion
Litchford, Ron J.; Jeng, San-Mou
1992-01-01
In developing its theory for turbulent dispersion transport, the Litchford and Jeng (1991) statistical transport model for turbulent particle dispersion took a generalized approach in which the perturbing influence of each turbulent eddy on consequent interactions was transported through all subsequent eddies. Nevertheless, examinations of this transport relation shows it to be able to decay rapidly: this implies that additional computational efficiency may be obtained via truncation of unneccessary transport terms. Attention is here given to the criterion for truncation, as well as to expected efficiency gains.
Runkel, Robert L.
2010-01-01
OTEQ is a mathematical simulation model used to characterize the fate and transport of waterborne solutes in streams and rivers. The model is formed by coupling a solute transport model with a chemical equilibrium submodel. The solute transport model is based on OTIS, a model that considers the physical processes of advection, dispersion, lateral inflow, and transient storage. The equilibrium submodel is based on MINTEQ, a model that considers the speciation and complexation of aqueous species, acid-base reactions, precipitation/dissolution, and sorption. Within OTEQ, reactions in the water column may result in the formation of solid phases (precipitates and sorbed species) that are subject to downstream transport and settling processes. Solid phases on the streambed may also interact with the water column through dissolution and sorption/desorption reactions. Consideration of both mobile (waterborne) and immobile (streambed) solid phases requires a unique set of governing differential equations and solution techniques that are developed herein. The partial differential equations describing physical transport and the algebraic equations describing chemical equilibria are coupled using the sequential iteration approach. The model's ability to simulate pH, precipitation/dissolution, and pH-dependent sorption provides a means of evaluating the complex interactions between instream chemistry and hydrologic transport at the field scale. This report details the development and application of OTEQ. Sections of the report describe model theory, input/output specifications, model applications, and installation instructions. OTEQ may be obtained over the Internet at http://water.usgs.gov/software/OTEQ.
Symmetrization of mathematical model of charge transport in semiconductors
Directory of Open Access Journals (Sweden)
Alexander M. Blokhin
2002-11-01
Full Text Available A mathematical model of charge transport in semiconductors is considered. The model is a quasilinear system of differential equations. A problem of finding an additional entropy conservation law and system symmetrization are solved.
Advances in dynamic network modeling in complex transportation systems
Ukkusuri, Satish V
2013-01-01
This book focuses on the latest in dynamic network modeling, including route guidance and traffic control in transportation systems and other complex infrastructure networks. Covers dynamic traffic assignment, flow modeling, mobile sensor deployment and more.
Smyshlyaev, Sergei P.; Geller, Marvin A.; Yudin, Valery A.
1999-11-01
Lightning NOx production is one of the most important and most uncertain sources of reactive nitrogen in the atmosphere. To examine the role of NOx lightning production uncertainties in supersonic aircraft assessment studies, we have done a number of numerical calculations with the State University of New York at Stony Brook-Russian State Hydrometeorological Institute of Saint-Petersburg two-dimensional model. The amount of nitrogen oxides produced by lightning discharges was varied within its quoted uncertainty from 2 to 12 Tg N/yr. Different latitudinal, altitudinal, and seasonal distributions of lightning NOx production were considered. Results of these model calculations show that the assessment of supersonic aircraft impacts on the ozone layer is very sensitive to the strength of NOx production from lightning. The high-speed civil transport produced NOx leads to positive column ozone changes for lightning NOx production less than 4 Tg N/yr, and to total ozone decrease for lightning NOx production more than 5 Tg N/yr for the same NOx emission scenario. For large lightning production the ozone response is mostly decreasing with increasing emission index, while for low lightning production the ozone response is mostly increasing with increasing emission index. Uncertainties in the global lightning NOx production strength may lead to uncertainties in column ozone up to 4%. The uncertainties due to neglecting the seasonal variations of the lightning NOx production and its simplified latitude distribution are about 2 times less (1.5-2%). The type of altitude distribution for the lightning NOx production does not significally impact the column ozone, but is very important for the assessment studies of aircraft perturbations of atmospheric ozone. Increased global lightning NOx production causes increased total ozone, but for assessment of the column ozone response to supersonic aircraft emissions, the increase of lightning NOx production leads to column ozone
A mesoscale chemical transport model (MEDIUM) nested in a global chemical transport model (MEDIANTE)
Energy Technology Data Exchange (ETDEWEB)
Claveau, J.; Ramaroson, R. [Office National d`Etudes et de Recherches Aerospatiales (ONERA), 92 - Chatillon (France)
1997-12-31
The lower stratosphere and upper troposphere (UT-LS) are frequently subject to mesoscale or local scale exchange of air masses occurring along discontinuities. This exchange (e.g. downward) can constitute one of the most important source of ozone from the stratosphere down to the middle troposphere where strong mixing dilutes the air mass and competing the non-linear chemistry. The distribution of the chemical species in the troposphere and the lower stratosphere depends upon various source emissions, e.g. from polluted boundary layer or from aircraft emissions. Global models, as well as chemical transport models describe the climatological state of the atmosphere and are not able to describe correctly the stratosphere and troposphere exchange. Mesoscale models go further in the description of smaller scales and can reasonably include a rather detailed chemistry. They can be used to assess the budget of NO{sub x} from aircraft emissions in a mesoscale domain. (author) 4 refs.
Implementation of Gravity Model to Estimation of Transportation Market Shares
Krata, Przemysław
2010-03-01
The theoretical consideration presented in the paper is inspired by market gravity models, as an interesting attitude towards operations research on a market. The transportation market issues are emphasized. The mathematical model of relations, taking place between transportation companies and their customers on the market, which is applied in the course of the research is based on continuous functions characteristics. This attitude enables the use of the field theory notions. The resultant vector-type utility function facilitates obtaining of competitive advantage areas for all transportation companies located on the considered transportation market.
Mathematical Modelling of Cation Transport and Regulation in Yeast.
Kahm, Matthiasé; Kschischo, Maik
2016-01-01
Mathematical modelling of ion transport is a strategy to understand the complex interplay between various ionic species and their transporters. Such models should provide new insights and suggest new interesting experiments. Two essential variables in models for ion transport and control are the membrane potential and the intracellular pH, which generates an additional layer of complexity absent from many other models of biochemical reaction pathways. The aim of this text is to introduce the reader to the basic principles and assumptions of modelling in this field. A simplified model of potassium transport will be used as an example and will be derived in a step by step manner. This forms the basis for understanding the advantages and limitations of more complex models. These are briefly reviewed at the end of this chapter.
Particle Tracking Model and Abstraction of Transport Processes
Energy Technology Data Exchange (ETDEWEB)
B. Robinson
2000-04-07
The purpose of the transport methodology and component analysis is to provide the numerical methods for simulating radionuclide transport and model setup for transport in the unsaturated zone (UZ) site-scale model. The particle-tracking method of simulating radionuclide transport is incorporated into the FEHM computer code and the resulting changes in the FEHM code are to be submitted to the software configuration management system. This Analysis and Model Report (AMR) outlines the assumptions, design, and testing of a model for calculating radionuclide transport in the unsaturated zone at Yucca Mountain. In addition, methods for determining colloid-facilitated transport parameters are outlined for use in the Total System Performance Assessment (TSPA) analyses. Concurrently, process-level flow model calculations are being carrier out in a PMR for the unsaturated zone. The computer code TOUGH2 is being used to generate three-dimensional, dual-permeability flow fields, that are supplied to the Performance Assessment group for subsequent transport simulations. These flow fields are converted to input files compatible with the FEHM code, which for this application simulates radionuclide transport using the particle-tracking algorithm outlined in this AMR. Therefore, this AMR establishes the numerical method and demonstrates the use of the model, but the specific breakthrough curves presented do not necessarily represent the behavior of the Yucca Mountain unsaturated zone.
A transport-rate model of wind-blown sand
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
Sand transport by wind plays an important role in environmental problems.Formulating the sand-transport rate model has been of continuing significance,because the majority of the existing models relate sand-transport rate to the wind-shear velocity.However,the wind-shear velocity readapted to blown sand is difficult to determine from the measured wind profiles when sand movement occurs,especially at high wind velocity.Detailed wind tunnel tests were carried out to reformulate the sand-transport rate model,followed by attempts to relate sand-transport rate to parameters of wind velocity,threshold shear-velocity,and grain size.Finally,we validated the model based on the data from field observations.
Reduced Fast Ion Transport Model For The Tokamak Transport Code TRANSP
Energy Technology Data Exchange (ETDEWEB)
Podesta,, Mario; Gorelenkova, Marina; White, Roscoe
2014-02-28
Fast ion transport models presently implemented in the tokamak transport code TRANSP [R. J. Hawryluk, in Physics of Plasmas Close to Thermonuclear Conditions, CEC Brussels, 1 , 19 (1980)] are not capturing important aspects of the physics associated with resonant transport caused by instabilities such as Toroidal Alfv en Eigenmodes (TAEs). This work describes the implementation of a fast ion transport model consistent with the basic mechanisms of resonant mode-particle interaction. The model is formulated in terms of a probability distribution function for the particle's steps in phase space, which is consistent with the MonteCarlo approach used in TRANSP. The proposed model is based on the analysis of fast ion response to TAE modes through the ORBIT code [R. B. White et al., Phys. Fluids 27 , 2455 (1984)], but it can be generalized to higher frequency modes (e.g. Compressional and Global Alfv en Eigenmodes) and to other numerical codes or theories.
Capone, Francis J.; Bare, E. Ann
1987-01-01
The aeropropulsive characteristics of an advanced twin-engine fighter aircraft designed for supersonic cruise have been studied in the Langley 16-Foot Tansonic Tunnel and the Lewis 10- by 10-Foot Supersonic Tunnel. The objective was to determine multiaxis control-power characteristics from thrust vectoring. A two-dimensional convergent-divergent nozzle was designed to provide yaw vector angles of 0, -10, and -20 deg combined with geometric pitch vector angles of 0 and 15 deg. Yaw thrust vectoring was provided by yaw flaps located in the nozzle sidewalls. Roll control was obtained from differential pitch vectoring. This investigation was conducted at Mach numbers from 0.20 to 2.47. Angle of attack was varied from 0 to about 19 deg, and nozzle pressure ratio was varied from about 1 (jet off) to 28, depending on Mach number. Increments in force or moment coefficient that result from pitch or yaw thrust vectoring remain essentially constant over the entire angle-of-attack range of all Mach numbers tested. There was no effect of pitch vectoring on the lateral aerodynamic forces and moments and only very small effects of yaw vectoring on the longitudinal aerodynamic forces and moments. This result indicates little cross-coupling of control forces and moments for combined pitch-yaw vectoring.
Model for Estimation Urban Transportation Supply-Demand Ratio
Directory of Open Access Journals (Sweden)
Chaoqun Wu
2015-01-01
Full Text Available The paper establishes an estimation model of urban transportation supply-demand ratio (TSDR to quantitatively describe the conditions of an urban transport system and to support a theoretical basis for transport policy-making. This TSDR estimation model is supported by the system dynamic principle and the VENSIM (an application that simulates the real system. It was accomplished by long-term observation of eight cities’ transport conditions and by analyzing the estimated results of TSDR from fifteen sets of refined data. The estimated results indicate that an urban TSDR can be classified into four grades representing four transport conditions: “scarce supply,” “short supply,” “supply-demand balance,” and “excess supply.” These results imply that transport policies or measures can be quantified to facilitate the process of ordering and screening them.
Kulasiri, Don
2002-01-01
Most of the natural and biological phenomena such as solute transport in porous media exhibit variability which can not be modeled by using deterministic approaches. There is evidence in natural phenomena to suggest that some of the observations can not be explained by using the models which give deterministic solutions. Stochastic processes have a rich repository of objects which can be used to express the randomness inherent in the system and the evolution of the system over time. The attractiveness of the stochastic differential equations (SDE) and stochastic partial differential equations (SPDE) come from the fact that we can integrate the variability of the system along with the scientific knowledge pertaining to the system. One of the aims of this book is to explaim some useufl concepts in stochastic dynamics so that the scientists and engineers with a background in undergraduate differential calculus could appreciate the applicability and appropriateness of these developments in mathematics. The ideas ...
Particle Tracking Model and Abstraction of Transport Processes
Energy Technology Data Exchange (ETDEWEB)
B. Robinson
2004-10-21
The purpose of this report is to document the abstraction model being used in total system performance assessment (TSPA) model calculations for radionuclide transport in the unsaturated zone (UZ). The UZ transport abstraction model uses the particle-tracking method that is incorporated into the finite element heat and mass model (FEHM) computer code (Zyvoloski et al. 1997 [DIRS 100615]) to simulate radionuclide transport in the UZ. This report outlines the assumptions, design, and testing of a model for calculating radionuclide transport in the UZ at Yucca Mountain. In addition, methods for determining and inputting transport parameters are outlined for use in the TSPA for license application (LA) analyses. Process-level transport model calculations are documented in another report for the UZ (BSC 2004 [DIRS 164500]). Three-dimensional, dual-permeability flow fields generated to characterize UZ flow (documented by BSC 2004 [DIRS 169861]; DTN: LB03023DSSCP9I.001 [DIRS 163044]) are converted to make them compatible with the FEHM code for use in this abstraction model. This report establishes the numerical method and demonstrates the use of the model that is intended to represent UZ transport in the TSPA-LA. Capability of the UZ barrier for retarding the transport is demonstrated in this report, and by the underlying process model (BSC 2004 [DIRS 164500]). The technical scope, content, and management of this report are described in the planning document ''Technical Work Plan for: Unsaturated Zone Transport Model Report Integration'' (BSC 2004 [DIRS 171282]). Deviations from the technical work plan (TWP) are noted within the text of this report, as appropriate. The latest version of this document is being prepared principally to correct parameter values found to be in error due to transcription errors, changes in source data that were not captured in the report, calculation errors, and errors in interpretation of source data.
A consistent transported PDF model for treating differential molecular diffusion
Wang, Haifeng; Zhang, Pei
2016-11-01
Differential molecular diffusion is a fundamentally significant phenomenon in all multi-component turbulent reacting or non-reacting flows caused by the different rates of molecular diffusion of energy and species concentrations. In the transported probability density function (PDF) method, the differential molecular diffusion can be treated by using a mean drift model developed by McDermott and Pope. This model correctly accounts for the differential molecular diffusion in the scalar mean transport and yields a correct DNS limit of the scalar variance production. The model, however, misses the molecular diffusion term in the scalar variance transport equation, which yields an inconsistent prediction of the scalar variance in the transported PDF method. In this work, a new model is introduced to remedy this problem that can yield a consistent scalar variance prediction. The model formulation along with its numerical implementation is discussed, and the model validation is conducted in a turbulent mixing layer problem.
Modelling the full trip costs of urban intermodal passenger transport
Yeh, Chao-Fu; Papon, Francis
2011-01-01
To face the competition of private motorized vehicles, intermodal transport becomes a successful condition to encourage public transport and non-motorized modes and to reasonably control the continual growth of individual motorized vehicles in the city area. Therefore, the objective of this research intends to develop a comparable calculating model combining the private, public and external costs of passenger urban transport networks. Private costs consist in the operational-private costs bor...
Mathematical modeling of sediment transport jn estuaries and coastal regions
Institute of Scientific and Technical Information of China (English)
窦国仁; 董凤舞; 窦希萍; 李禔来
1995-01-01
Based on the suspended sediment transport equation and transport capacity formula under the action of tidal currents and wind waves, a horizontal 2-D mathematical model of suspended sediment transport for estuaries and coastal regions is established. The verification of calculations shows that the sediment concentration distribution and sea bed deformation in the estuaries and coastal regions can be successfully simulated. Therefore, a new method for studying and solving the sediment problems in the estuarine and coastal engineering is presented.
Modelling passenger flows in public transport facilities
Daamen, W.
2004-01-01
This thesis describes the developement of a new type of simulation tool for the assessment of designs of public transport facilities (stations, airports) and other public spaces with intensive pedestrian flows. Since the available space for such facilities is increasingly under pressure, the space
Logistics chains in freight transport modelling
Davydenko, I.
2015-01-01
The research presented in this PhD thesis has been motivated by the fact that the Netherlands, and the Randstad region in particular, are affected by the large transport flows and extensive operations of the logistics sector. These operations create welfare for those people who work in the sector, w
Logistics chains in freight transport modelling
Davydenko, I.
2015-01-01
The research presented in this PhD thesis has been motivated by the fact that the Netherlands, and the Randstad region in particular, are affected by the large transport flows and extensive operations of the logistics sector. These operations create welfare for those people who work in the sector,
Paving the road from transport models to “new mobilities” models
DEFF Research Database (Denmark)
Wind, Simon; Jensen, Ole B.; Kaplan, Sigal
2012-01-01
For half a century, tremendous efforts have been invested in developing transport models as a decision aid for policy makers in designing effective policy interventions and deciding among costly public projects for the benefit of the population. Transport and activity-based models are often...... the traditional transport modeling approach and “new mobilities” research by suggesting a model framework that considers non-instrumental transport rationales, personal latent traits and intra-household decision dynamics....
Sting Supported Bell XS-2 in the 9 Inch Supersonic Tunnel
1947-01-01
A sting supported model of the Bell XS-2 was tested in the 9 Inch Supersonic Tunnel. Photograph published in Engineer in Charge: A History of the Langley Aeronautical Laboratory, 1917-1958 by James R. Hansen. Page 316.
Backcasting in freight transport demand modelling – chances and challenges
Lange, Peter; Huber, Stefan
2015-01-01
Freight transport demand models are important tools to support policy decision-making by enabling decision makers to evaluate transport policies and correlated effects. This significance puts high pressure on freight models regarding their accuracy. In order to ensure model accuracy there are different methods within the wide area of quality assurance that can be applied. Although backcasting is such a method it is, however, often neglected or implemented insufficiently. The paper presents ma...
Structural Design of Oligopeptides for Intestinal Transport Model.
Hong, Seong-Min; Tanaka, Mitsuru; Koyanagi, Riho; Shen, Weilin; Matsui, Toshiro
2016-03-16
Glycyl-sarcosine (Gly-Sar) is a well-known model substrate for the intestinal uptake of dipeptides through peptide transporter 1 (PepT1). However, there are no other model peptides larger than tripeptides to evaluate their intestinal transport ability. In this study, we designed new oligopeptides based on the Gly-Sar structure in terms of protease resistance. Gly-Sar-Sar was found to be an appropriate transport model for tripeptides because it does not degrade during the transport across the rat intestinal membrane, while Gly-Gly-Sar was degraded to Gly-Sar during the 60 min transport. Caco-2 cell transport experiments revealed that the designed oligopeptides based on Gly-Sar-Sar showed a significantly (p transport ability by factors of 1/10-, 1/25-, and 1/40-fold for Gly-Sar-Sar, Gly-Sar-Sar-Sar, and Gly-Sar-Sar-Sar-Sar, respectively, compared to Gly-Sar (apparent permeability coefficient: 38.6 ± 11.4 cm/s). Cell experiments also showed that the designed tripeptide and Gly-Sar were transported across Caco-2 cell via PepT1, whereas the tetra- and pentapeptides were transported through the paracellular tight-junction pathway.
IOT technology application model research of transportation industry in China
Institute of Scientific and Technical Information of China (English)
Lai Mingyong; Zhou Tang; Liu Zhengchi
2013-01-01
The paper studied the connection between intemet of things (IOT) technology and transportation industry.Meanwhile,the definition of IOT in transportation was given.Concerning that many problems occurred during the process of traditional intelligent transportation system,the paper proposed a promising model of IOT in transportation.The advantage of the information utilization model from information to function was confirmed through comparative study.Finally,the model presented that a real interconnection of transportation would be achieved based on the unified information collection.It can greatly save cost on technology transfer,exploit potential value of information,and promote the emergence of a sustainable information service market and the industrial upgrade.
Synchronizing production and air transportation scheduling using mathematical programming models
Zandieh, M.; Molla-Alizadeh-Zavardehi, S.
2009-08-01
Traditional scheduling problems assume that there are always infinitely many resources for delivering finished jobs to their destinations, and no time is needed for their transportation, so that finished products can be transported to customers without delay. So, for coordination of these two different activities in the implementation of a supply chain solution, we studied the problem of synchronizing production and air transportation scheduling using mathematical programming models. The overall problem is decomposed into two sub-problems, which consists of air transportation allocation problem and a single machine scheduling problem which they are considered together. We have taken into consideration different constraints and assumptions in our modeling such as special flights, delivery tardiness and no delivery tardiness. For these purposes, a variety of models have been proposed to minimize supply chain total cost which encompass transportation, makespan, delivery earliness tardiness and departure time earliness tardiness costs.
Tsai, C. H.; Yeh, G. T.
2015-12-01
In this investigation, a coupled model of multiphase flow, reactive biogeochemical transport, thermal transport and geo-mechanics in subsurface media is presented. It iteratively solves the mass conservation equation for fluid flow, thermal transport equation for temperature, reactive biogeochemical transport equations for concentration distributions, and solid momentum equation for displacement with successive linearization algorithm. With species-based equations of state, density of a phase in the system is obtained by summing up concentrations of all species. This circumvents the problem of having to use empirical functions. Moreover, reaction rates of all species are incorporated in mass conservation equation for fluid flow. Formation enthalpy of all species is included in the law of energy conservation as a source-sink term. Finite element methods are used to discretize the governing equations. Numerical experiments are presented to examine the accuracy and robustness of the proposed model. The results demonstrate the feasibility and capability of present model in subsurface media.
Supersonic Plasma Flow Control Experiments
2005-12-01
to liquid metals , for example, the conductivities of typical plasma and electrolyte flows are relatively low. Ref. 14 cites the conductivity of...heating is the dominant effect. 15. SUBJECT TERMS Supersonic, plasma , MHD , boundary-layer 16. SECURITY CLASSIFICATION OF: 19a. NAME OF RESPONSIBLE...horns in operation on Mach 5 wind tunnel with a plasma discharge. 31 Figure 17 Front view of a 100 mA DC discharge generated with upstream pointing
Supersonic Chordwise Bending Flutter in Cascades
1975-05-31
such a flutter boundary can be made by utilizing the trend lines predicted from a supersonic analysis based on supersonic cascade theory (Appendix I...bonding agent was injected via hypodermic needles after the blade tabs were properly inserted, The integrity and repeatability of the mounting of the indi...in conjunction with NASTRAN predictions and supersonic cascade aerodynamic computa- tions. Comparisons between theory and experiment are discussed. DD
Studies of the unsteady supersonic base flows around three afterbodies
Institute of Scientific and Technical Information of China (English)
Zhixiang Xiao; Song Fu
2009-01-01
Unsteady supersonic base flows around three afterbodies, cylindrical (Cy), boattailed (BT) and three-step (MS), are investigated in this paper. Reynolds-averaged Navier-Stokes (RANS) and two RANS/LES (large-eddy simulation) hybrid methods, detached eddy simulation (DES) and delayed-DES (DDES), are used to predict the base flow characteristics around the baseline Cy afterbody. All the RANS and hybrid methods are based on the two-equation SST (shear-stress transport) model with compressible corrections (CC). According to the comparison of measurements, both DES and DDES can produce more satisfactory results than RANS. RANS can only present the "stable" flow patterns, while the hybrid methods can demonstrate unsteady flow structures. DDES and DES results are little different from one another although the latter exhibits better agreement with the experiment. DES is taken to investigate the 5 BT and three-step afterbodies. The mean flow data and the instantaneous turbulent coherent structures are compared against available measurements.
Fast Cherenkov model of optical photons generation and transportation
The ATLAS collaboration
2017-01-01
This note describes the technical details of Fast Cherenkov model of optical photons generation and transportation: in particular, the mechanism of Cherenkov photons transportation through the straight bar geometry. As an example of usage, the implemetation of the method inside Quartic detector simulation in GEANT4 will be presented and compared to the nominal results.
Modeling Quantum Transport in Nanoscale Vertical SOI nMOSFET
Institute of Scientific and Technical Information of China (English)
TONG Jian-nong; ZOU Xue-chang; SHEN Xu-bang
2004-01-01
The electron transports in micro-architecture semiconductor are simulated using vertical SOI nMOSFET with different models. Some details in transport can be presented by changing channel length, channel thickness and drain voltage. An interesting phenomenon similar to collimation effect in mesoscopic system is observed. This may suggest the quite intriguing possibility that scattering may open new channel in sufficiently narrow devices.
Finite difference methods for coupled flow interaction transport models
Directory of Open Access Journals (Sweden)
Shelly McGee
2009-04-01
Full Text Available Understanding chemical transport in blood flow involves coupling the chemical transport process with flow equations describing the blood and plasma in the membrane wall. In this work, we consider a coupled two-dimensional model with transient Navier-Stokes equation to model the blood flow in the vessel and Darcy's flow to model the plasma flow through the vessel wall. The advection-diffusion equation is coupled with the velocities from the flows in the vessel and wall, respectively to model the transport of the chemical. The coupled chemical transport equations are discretized by the finite difference method and the resulting system is solved using the additive Schwarz method. Development of the model and related analytical and numerical results are presented in this work.
Supersonic Wing Optimization Using SpaRibs
Locatelli, David; Mulani, Sameer B.; Liu, Qiang; Tamijani, Ali Y.; Kapania, Rakesh K.
2014-01-01
This research investigates the advantages of using curvilinear spars and ribs, termed SpaRibs, to design a supersonic aircraft wing-box in comparison to the use of classic design concepts that employ straight spars and ribs. The objective is to achieve a more efficient load-bearing mechanism and to passively control the deformation of the structure under the flight loads. Moreover, the use of SpaRibs broadens the design space and allows for natural frequencies and natural mode shape tailoring. The SpaRibs concept is implemented in a new optimization MATLAB-based framework referred to as EBF3SSWingOpt. This optimization scheme performs both the sizing and the shaping of the internal structural elements, connecting the optimizer with the analysis software. The shape of the SpaRibs is parametrically defined using the so called Linked Shape method. Each set of SpaRibs is placed in a one by one square domain of the natural space. The set of curves is subsequently transformed in the physical space for creating the wing structure geometry layout. The shape of each curve of each set is unique; however, mathematical relations link the curvature in an effort to reduce the number of design variables. The internal structure of a High Speed Commercial Transport aircraft concept developed by Boeing is optimized subjected to stress, subsonic flutter and supersonic flutter constraints. The results show that the use of the SpaRibs allows for the reduction of the aircraft's primary structure weight without violating the constraints. A weight reduction of about 15 percent is observed.
Supersonic flow imaging via nanoparticles
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
Due to influence of compressibility,shock wave,instabilities,and turbulence on supersonic flows, current flow visualization and imaging techniques encounter some problems in high spatiotemporal resolution and high signal-to-noise ratio(SNR)measurements.Therefore,nanoparticle based planar laser scattering method(NPLS)is developed here.The nanoparticles are used as tracer,and pulse planar laser is used as light source in NPLS;by recording images of particles in flow field with CCD, high spatiotemporal resolution supersonic flow imaging is realized.The flow-following ability of nanoparticles in supersonic flows is studied according to multiphase flow theory and calibrating experiment of oblique shock wave.The laser scattering characteristics of nanoparticles are analyzed with light scattering theory.The results of theoretical and experimental studies show that the dynamic behavior and light scattering characteristics of nanoparticles highly enhance the spatiotemporal resolution and SNR of NPLS,with which the flow field involving shock wave,expansion,Mach disk,boundary layer,sliding-line,and mixing layer can be imaged clearly at high spatiotemporal resolution.
Using Transport Diagnostics to Understand Chemistry Climate Model Ozone Simulations
Strahan, S. E.; Douglass, A. R.; Stolarski, R. S.; Akiyoshi, H.; Bekki, S.; Braesicke, P.; Butchart, N.; Chipperfield, M. P.; Cugnet, D.; Dhomse, S.; Frith, S. M.; Gettleman, A.; Hardiman, S. C.; Kinnison, D. E.; Lamarque, J.-F.; Mancini, E.; Marchand, M.; Michou, M.; Morgenstern, O.; Nakamura, T.; Olivie, D.; Pawson, S.; Pitari, G.; Plummer, D. A.; Pyle, J. A.
2010-01-01
We demonstrate how observations of N2O and mean age in the tropical and midlatitude lower stratosphere (LS) can be used to identify realistic transport in models. The results are applied to 15 Chemistry Climate Models (CCMs) participating in the 2010 WMO assessment. Comparison of the observed and simulated N2O/mean age relationship identifies models with fast or slow circulations and reveals details of model ascent and tropical isolation. The use of this process-oriented N2O/mean age diagnostic identifies models with compensating transport deficiencies that produce fortuitous agreement with mean age. We compare the diagnosed model transport behavior with a model's ability to produce realistic LS O3 profiles in the tropics and midlatitudes. Models with the greatest tropical transport problems show the poorest agreement with observations. Models with the most realistic LS transport agree more closely with LS observations and each other. We incorporate the results of the chemistry evaluations in the SPARC CCMVal Report (2010) to explain the range of CCM predictions for the return-to-1980 dates for global (60 S-60 N) and Antarctic column ozone. Later (earlier) Antarctic return dates are generally correlated to higher (lower) vortex Cl(sub y) levels in the LS, and vortex Cl(sub y) is generally correlated with the model's circulation although model Cl(sub y) chemistry or Cl(sub y) conservation can have a significant effect. In both regions, models that have good LS transport produce a smaller range of predictions for the return-to-1980 ozone values. This study suggests that the current range of predicted return dates is unnecessarily large due to identifiable model transport deficiencies.
Modelling heat transport through completely positive maps
Wichterich, H; Gemmer, J; Henrich, M J; Michel, M; Breuer, Heinz-Peter; Gemmer, Jochen; Henrich, Markus J.; Michel, Mathias; Wichterich, Hannu
2007-01-01
We investigate heat transport in a spin-1/2 Heisenberg chain, coupled locally to independent thermal baths of different temperature. The analysis is carried out within the framework of the theory of open systems by means of appropriate quantum master equations. The standard microscopic derivation of the weak-coupling Lindblad equation in the secular approximation is considered, and shown to be inadequate for the description of stationary nonequilibrium properties like a non-vanishing energy current. Furthermore, we derive an alternative master equation that is capable to describe a stationary energy current and, at the same time, leads to a completely positive dynamical map. This paves the way for efficient numerical investigations of heat transport in larger systems based on Monte Carlo wave function techniques.
Modeling of titration experiments by a reactive transport model
Institute of Scientific and Technical Information of China (English)
Ma Hongyun; Samper Javier; Xin Xin
2011-01-01
Acid mine drainage (AMD) is commonly treated by neutralization with alkaline substances. This treatment is supported by titration experiments that illustrate the buffering mechanisms and estimate the base neutralization capacity (BNC) of the AMD. Detailed explanation of titration curves requires modeling with a hydro-chemical model. In this study the titration curves of water samples from the drainage of the As Pontes mine and the corresponding dumps have been investigated and six buffers are selected by analyzing those curves. Titration curves have been simulated by a reactive transport model to discover the detailed buffering mechanisms. These simulations show seven regions involving different buffering mechanism. The BNC is primarily from buffers of dissolved Fe, Al and hydrogen sulfate. The BNC can be approximated by: BNC = 3(CFe + CAl) + 0.05Csulfate, where the units are mol/L. The BNC of the sample from the mine is 9.25 × 10-3 mol/L and that of the dumps sample is 1.28 × 10-2 mol/L.
Modelling aeolian sand transport using a dynamic mass balancing approach
Mayaud, Jerome R.; Bailey, Richard M.; Wiggs, Giles F. S.; Weaver, Corinne M.
2017-03-01
Knowledge of the changing rate of sediment flux in space and time is essential for quantifying surface erosion and deposition in desert landscapes. Whilst many aeolian studies have relied on time-averaged parameters such as wind velocity (U) and wind shear velocity (u*) to determine sediment flux, there is increasing field evidence that high-frequency turbulence is an important driving force behind the entrainment and transport of sand. At this scale of analysis, inertia in the saltation system causes changes in sediment transport to lag behind de/accelerations in flow. However, saltation inertia has yet to be incorporated into a functional sand transport model that can be used for predictive purposes. In this study, we present a new transport model that dynamically balances the sand mass being transported in the wind flow. The 'dynamic mass balance' (DMB) model we present accounts for high-frequency variations in the horizontal (u) component of wind flow, as saltation is most strongly associated with the positive u component of the wind. The performance of the DMB model is tested by fitting it to two field-derived (Namibia's Skeleton Coast) datasets of wind velocity and sediment transport: (i) a 10-min (10 Hz measurement resolution) dataset; (ii) a 2-h (1 Hz measurement resolution) dataset. The DMB model is shown to outperform two existing models that rely on time-averaged wind velocity data (e.g. Radok, 1977; Dong et al., 2003), when predicting sand transport over the two experiments. For all measurement averaging intervals presented in this study (10 Hz-10 min), the DMB model predicted total saltation count to within at least 0.48%, whereas the Radok and Dong models over- or underestimated total count by up to 5.50% and 20.53% respectively. The DMB model also produced more realistic (less 'peaky') time series of sand flux than the other two models, and a more accurate distribution of sand flux data. The best predictions of total sand transport are achieved using
DEFF Research Database (Denmark)
Larsen, Erik Hviid; Møbjerg, N.; Sørensen, J. N.
2006-01-01
Aim: By mathematical modelling, we analyse conditions for near-isotonic and isotonic transport by mammalian kidney proximal tubule. Methods: The model comprises compliant lateral intercellular space (lis) and cells, and infinitely large luminal and peritubular compartments with diffusible species......: Na+, K+, Cl- and an intracellular non-diffusible anion. Unknown model variables are solute concentrations, electrical potentials, volumes and hydrostatic pressures in cell and lis, and transepithelial potential. We used data mainly from rat proximal tubule to model epithelial cells and interspace...... transport similar to rat proximal tubule. Na+ recirculation is required for truly isotonic transport. The tonicity of the absorbate and the recirculation flux depend critically on ion permeabilities of interspace basement membrane. Conclusion: Our model based on solute-solvent coupling in lateral space...
DEFF Research Database (Denmark)
Larsen, E.H.; Møbjerg, N.; Sørensen, Jens Nørkær
2006-01-01
Aim: By mathematical modelling, we analyse conditions for near-isotonic and isotonic transport by mammalian kidney proximal tubule. Methods: The model comprises compliant lateral intercellular space (lis) and cells, and infinitely large luminal and peritubular compartments with diffusible species......: Na+, K+, Cl and an intracellular non-diffusible anion. Unknown model variables are solute concentrations, electrical potentials, volumes and hydrostatic pressures in cell and lis, and transepithelial potential. We used data mainly from rat proximal tubule to model epithelial cells and interspace...... transport similar to rat proximal tubule. Na+ recirculation is required for truly isotonic transport. The tonicity of the absorbate and the recirculation flux depend critically on ion permeabilities of interspace basement membrane. Conclusion: Our model based on solute-solvent coupling in lateral space...
Feedback network models for quantum transport.
Gough, John
2014-12-01
Quantum feedback networks have been introduced in quantum optics as a framework for constructing arbitrary networks of quantum mechanical systems connected by unidirectional quantum optical fields, and has allowed for a system theoretic approach to open quantum optics systems. Our aim here is to establish a network theory for quantum transport systems where typically the mediating fields between systems are bidirectional. Mathematically, this leads us to study quantum feedback networks where fields arrive at ports in input-output pairs, making it a special case of the unidirectional theory where inputs and outputs are paired. However, it is conceptually important to develop this theory in the context of quantum transport theory-the resulting theory extends traditional approaches which tend to view the components in quantum transport as scatterers for the various fields, in the process allowing us to consider emission and absorption of field quanta by these components. The quantum feedback network theory is applicable to both Bose and Fermi fields, moreover, it applies to nonlinear dynamics for the component systems. We advance the general theory, but study the case of linear passive quantum components in some detail.
The flow feature of transverse hydrogen jet in presence of micro air jets in supersonic flow
Barzegar Gerdroodbary, M.; Amini, Younes; Ganji, D. D.; Takam, M. Rahimi
2017-03-01
Scramjet is found to be the efficient method for the space shuttle. In this paper, numerical simulation is performed to investigate the fundamental flow physics of the interaction between an array of fuel jets and multi air jets in a supersonic transverse flow. Hydrogen as a fuel is released with a global equivalence ratio of 0.5 in presence of micro air jets on a flat plate into a Mach 4 crossflow. The fuel and air are injected through streamwise-aligned flush circular portholes. The hydrogen is injected through 4 holes with 7dj space when the air is injected in the interval of the hydrogen jets. The numerical simulation is performed by using the Reynolds-averaged Navier-Stokes equations with Menter's Shear Stress Transport (SST) turbulence model. Both the number of air jets and jet-to-freestream total pressure ratio are varied in a parametric study. The interaction of the fuel and air jet in the supersonic flow present extremely complex feature of fuel and air jet. The results present various flow features depending upon the number and mass flow rate of micro air jets. These flow features were found to have significant effects on the penetration of hydrogen jets. A variation of the number of air jets, along with the jet-to-freestream total pressure ratio, induced a variety of flow structure in the downstream of the fuel jets.
Metal transport across biomembranes: emerging models for a distinct chemistry.
Argüello, José M; Raimunda, Daniel; González-Guerrero, Manuel
2012-04-20
Transition metals are essential components of important biomolecules, and their homeostasis is central to many life processes. Transmembrane transporters are key elements controlling the distribution of metals in various compartments. However, due to their chemical properties, transition elements require transporters with different structural-functional characteristics from those of alkali and alkali earth ions. Emerging structural information and functional studies have revealed distinctive features of metal transport. Among these are the relevance of multifaceted events involving metal transfer among participating proteins, the importance of coordination geometry at transmembrane transport sites, and the presence of the largely irreversible steps associated with vectorial transport. Here, we discuss how these characteristics shape novel transition metal ion transport models.
Energy Technology Data Exchange (ETDEWEB)
NONE
2003-07-01
COPERT III (computer programme to calculate emissions from road transport) is the third version of an MS Windows software programme aiming at the calculation of air pollutant emissions from road transport. COPERT estimates emissions of all regulated air pollutants (CO, NO{sub x}, VOC, PM) produced by different vehicle categories as well as CO{sub 2} emissions on the basis of fuel consumption. This research seminar was organized by the French agency of environment and energy mastery (Ademe) around the following topics: the uncertainties and sensitiveness analysis of the COPERT III model, the presentation of case studies that use COPERT III for the estimation of road transport emissions, and the future of the modeling of road transport emissions: from COPERT III to ARTEMIS (assessment and reliability of transport emission models and inventory systems). This document is a compilation of 8 contributions to this seminar and dealing with: the uncertainty and sensitiveness analysis of the COPERT III model; the road mode emissions of the ESCOMPTE program: sensitivity study; the sensitivity analysis of the spatialized traffic at the time-aggregation level: application in the framework of the INTERREG project (Alsace); the road transport aspect of the regional air quality plan of Bourgogne region: exhaustive consideration of the road network; intercomparison of tools and methods for the inventory of emissions of road transport origin; evolution of the French park of vehicles by 2025: new projections; application of COPERT III to the French context: a new version of IMPACT-ADEME; the European ARTEMIS project: new structural considerations for the modeling of road transport emissions. (J.S.)
Modeling Reactive Transport in Coupled Groundwater-Conduit Systems
Spiessl, S. M.; Sauter, M.; Zheng, C.; Viswanathan, H. S.
2002-05-01
Modeling reactive transport in coupled groundwater-conduit systems requires consideration of two transport time scales in the flow and transport models. Consider for example a subsurface mine consisting of a network of highly conductive shafts, drifts or ventilation raises (i.e., conduits) within the considerably less permeable ore material (i.e., matrix). In the conduits, potential contaminants can travel much more rapidly than in the background aquifer (matrix). Since conduits cannot necessarily be regarded as a continuum, double continuum models are only of limited use for simulation of contaminant transport in such coupled groundwater-conduit systems. This study utilizes a "hybrid" flow and transport model in which contaminants can in essence be transported at a slower time scale in the matrix and at a faster time scale in the conduits. The hybrid flow model uses an approach developed by Clemens et al. (1996), which is based on the modelling of flow in a discrete pipe network, coupled to a continuum representing the low-permeability inter-conduit matrix blocks. Laminar or turbulent flow can be simulated in the different pipes depending on the flow conditions in the model domain. The three-dimensional finite-difference groundwater flow model MODFLOW (Harbaugh and McDonald, 1996) is used to simulate flow in the continuum. Contaminant transport within the matrix is simulated with a continuum approach using the three-dimensional multi-species solute transport model MT3DMS (Zheng and Wang, 1999), while that in the conduit system is simulated with a one-dimensional advective transport model. As a first step for reactive transport modeling in such systems, only equilibrium reactions among multiple species are considered by coupling the hybrid transport model to a geochemical speciation package. An idealized mine network developed by Viswanathan and Sauter (2001) is used as a test problem in this study. The numerical experiment is based on reference date collected from
Electronic transport in VO{sub 2}—Experimentally calibrated Boltzmann transport modeling
Energy Technology Data Exchange (ETDEWEB)
Kinaci, Alper; Rosenmann, Daniel; Chan, Maria K. Y., E-mail: debasish.banerjee@toyota.com, E-mail: mchan@anl.gov [Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Kado, Motohisa [Higashifuji Technical Center, Toyota Motor Corporation, Susono, Shizuoka 410-1193 (Japan); Ling, Chen; Zhu, Gaohua; Banerjee, Debasish, E-mail: debasish.banerjee@toyota.com, E-mail: mchan@anl.gov [Materials Research Department, Toyota Motor Engineering and Manufacturing North America, Inc., Ann Arbor, Michigan 48105 (United States)
2015-12-28
Materials that undergo metal-insulator transitions (MITs) are under intense study, because the transition is scientifically fascinating and technologically promising for various applications. Among these materials, VO{sub 2} has served as a prototype due to its favorable transition temperature. While the physical underpinnings of the transition have been heavily investigated experimentally and computationally, quantitative modeling of electronic transport in the two phases has yet to be undertaken. In this work, we establish a density-functional-theory (DFT)-based approach with Hubbard U correction (DFT + U) to model electronic transport properties in VO{sub 2} in the semiconducting and metallic regimes, focusing on band transport using the Boltzmann transport equations. We synthesized high quality VO{sub 2} films and measured the transport quantities across the transition, in order to calibrate the free parameters in the model. We find that the experimental calibration of the Hubbard correction term can efficiently and adequately model the metallic and semiconducting phases, allowing for further computational design of MIT materials for desirable transport properties.
Plasma transport simulation modeling for helical confinement systems
Energy Technology Data Exchange (ETDEWEB)
Yamazaki, K.; Amano, T.
1991-08-01
New empirical and theoretical transport models for helical confinement systems are developed based on the neoclassical transport theory including the effect of radial electric field and multi-helicity magnetic components, and the drift wave turbulence transport for electrostatic and electromagnetic modes, or the anomalous semi-empirical transport. These electron thermal diffusivities are compared with CHS (Compact Helical System) experimental data, which indicates that the central transport coefficient of the ECH plasma agrees with the neoclassical axi-symmetric value and the transport outside the half radius is anomalous. On the other hand, the transport of NBI-heated plasmas is anomalous in the whole plasma region. This anomaly is not explained by the electrostatic drift wave turbulence models in these flat-density-profile discharges. For the detailed prediction of plasma parameters in LHD (Large Helical Device), 3-D(dimensional) equilibrium/1-D transport simulations including empirical or drift wave turbulence models are carried out, which suggests that the global confinement time of LHD is determined mainly by the electron anomalous transport near the plasma edge region rather than the helical ripple transport in the core region. Even if the ripple loss can be eliminated, the increase of the global confinement is 10%. However, the rise in the central ion temperature is more than 20%. If the anomalous loss can be reduced to the half level of the present scaling, like so-called `H-mode` of the tokamak discharge, the neoclassical ripple loss through the ion channel becomes important even in the plasma core. The 5% radial inward shift of the plasma column with respect to the major radius is effective for improving plasma confinement and raising more than 50% of the fusion product by reducing this neoclassical asymmetric ion transport loss and increasing 10% in the plasma radius. (author).
Modelling sediment transport processes in macro-tidal estuary
Institute of Scientific and Technical Information of China (English)
Rauen; William; B.
2009-01-01
This paper outlines a numerical modeling study to predict the sediment transport processes in a macro-tidal estuary, namely the Mersey Estuary, UK. An integrated numerical model study is conducted to investigate the interaction between the hydrodynamic, morphological and sediment transport processes occurring in the estuary. The numerical model widely used in environmental sediment transport studies worldwide, namely ECOMSED is used to simulate flow and sediment transport in estuary. A wetting and drying scheme is proposed and applied to the model, which defines "dry" cells as regions with a thin film of fluid O (cm). The primitive equations are solved in the thin film as well as in other regular wet cells. A model for the bed load transport is included in the code to account for the dynamics of the mobile bed boundary. The bed evolution due to bed load transport which is calculated according to van Rijn (1984a) is obtained by solving the sediment mass-balance equation. An estuary-related laboratory flume experiment is used to verify the model. Six sets of field measured hydrodynamic data are used to verify the corresponding predictions of the model, with the model-predicted water elevations and salinity levels generally agreeing well with the field measurements. The numerical model results show that in the Mersey Estuary both the tidal level and river discharge affect significantly the sediment transport. Reasonable agreement between the model results and field data has been obtained, indicating that the model can be used as computer-based tool for the environment management of estuarine system.
Sánchez, R.; van Milligen, B. Ph.; Carreras, B. A.
2005-05-01
It is argued that the modeling of plasma transport in tokamaks may benefit greatly from extending the usual local paradigm to accommodate scale-free transport mechanisms. This can be done by combining Lévy distributions and a nonlinear threshold condition within the continuous time random walk concept. The advantages of this nonlocal, nonlinear extension are illustrated by constructing a simple particle density transport model that, as a result of these ideas, spontaneously exhibits much of nondiffusive phenomenology routinely observed in tokamaks. The fluid limit of the system shows that the kind of equations that are appropriate to capture these dynamics are based on fractional differential operators. In them, effective diffusivities and pinch velocities are found that are dynamically set by the system in response to the specific characteristics of the fueling source and external perturbations. This fact suggests some dramatic consequences for the extrapolation of these transport properties to larger size systems.
The thermoballistic transport model a novel approach to charge carrier transport in semiconductors
Lipperheide, Reinhard
2014-01-01
The book presents a comprehensive survey of the thermoballistic approach to charge carrier transport in semiconductors. This semi-classical approach, which the authors have developed over the past decade, bridges the gap between the opposing drift-diffusion and ballistic models of carrier transport. While incorporating basic features of the latter two models, the physical concept underlying the thermoballistic approach constitutes a novel, unifying scheme. It is based on the introduction of "ballistic configurations" arising from a random partitioning of the length of a semiconducting sample into ballistic transport intervals. Stochastic averaging of the ballistic carrier currents over the ballistic configurations results in a position-dependent thermoballistic current, which is the key element of the thermoballistic concept and forms the point of departure for the calculation of all relevant transport properties. In the book, the thermoballistic concept and its implementation are developed in great detai...
Kinetic modelling of coupled transport across biological membranes.
Korla, Kalyani; Mitra, Chanchal K
2014-04-01
In this report, we have modelled a secondary active co-transporter (symport and antiport), based on the classical kinetics model. Michaelis-Menten model of enzyme kinetics for a single substrate, single intermediate enzyme catalyzed reaction was proposed more than a hundred years ago. However, no single model for the kinetics of co-transport of molecules across a membrane is available in the literature We have made several simplifying assumptions and have followed the basic Michaelis-Menten approach. The results have been simulated using GNU Octave. The results will be useful in general kinetic simulations and modelling.
Quantum Model of Energy Transport in Collagen Molecules
Institute of Scientific and Technical Information of China (English)
XIAO Yi; LIN Xian-Zhe
2001-01-01
A semi-quantum model for energy transport in collagen molecules is presented. Soliton-like dynamics of this model is investigated numerically without and with the temperature effect taking into account. It is found that in both the cases energy can transport for a long distance along the collagen chain. This indicates that collagen molecules can be taken as a candidate for the acupuncture channel.
Transport properties of stochastic Lorentz models
Beijeren, H. van
1982-01-01
Diffusion processes are considered for one-dimensional stochastic Lorentz models, consisting of randomly distributed fixed scatterers and one moving light particle. In waiting time Lorentz models the light particle makes instantaneous jumps between scatterers after a stochastically distributed waiti
Transport modelling in coastal waters using stochastic differential equations
Charles, W.M.
2007-01-01
In this thesis, the particle model that takes into account the short term correlation behaviour of pollutants dispersion has been developed. An efficient particle model for sediment transport has been developed. We have modified the existing particle model by adding extra equations for the suspensio
Setting up a freight transportation model for Java in Indonesia
De Baat, M.J.; Den Hertog, V.; De Jong, S.; De Regt, K.; Wijgergangs, K.
2015-01-01
The project consisted of the development of a freight transportation model for the island Java in Indonesia. A literature study concerning freight modelling has been performed to formulate an appropriate framework of such a model for the given situation. Different data sources have been identified,
Analysing Models as a Knowledge Technology in Transport Planning
DEFF Research Database (Denmark)
Gudmundsson, Henrik
2011-01-01
Models belong to a wider family of knowledge technologies, applied in the transport area. Models sometimes share with other such technologies the fate of not being used as intended, or not at all. The result may be ill-conceived plans as well as wasted resources. Frequently, the blame for such a ......Models belong to a wider family of knowledge technologies, applied in the transport area. Models sometimes share with other such technologies the fate of not being used as intended, or not at all. The result may be ill-conceived plans as well as wasted resources. Frequently, the blame...... critical analytic literature on knowledge utilization and policy influence. A simple scheme based in this literature is drawn up to provide a framework for discussing the interface between urban transport planning and model use. A successful example of model use in Stockholm, Sweden is used as a heuristic...
Gowrishankar, T R; Stewart, Donald A; Martin, Gregory T; Weaver, James C
2004-11-17
Investigation of bioheat transfer problems requires the evaluation of temporal and spatial distributions of temperature. This class of problems has been traditionally addressed using the Pennes bioheat equation. Transport of heat by conduction, and by temperature-dependent, spatially heterogeneous blood perfusion is modeled here using a transport lattice approach. We represent heat transport processes by using a lattice that represents the Pennes bioheat equation in perfused tissues, and diffusion in nonperfused regions. The three layer skin model has a nonperfused viable epidermis, and deeper regions of dermis and subcutaneous tissue with perfusion that is constant or temperature-dependent. Two cases are considered: (1) surface contact heating and (2) spatially distributed heating. The model is relevant to the prediction of the transient and steady state temperature rise for different methods of power deposition within the skin. Accumulated thermal damage is estimated by using an Arrhenius type rate equation at locations where viable tissue temperature exceeds 42 degrees C. Prediction of spatial temperature distributions is also illustrated with a two-dimensional model of skin created from a histological image. The transport lattice approach was validated by comparison with an analytical solution for a slab with homogeneous thermal properties and spatially distributed uniform sink held at constant temperatures at the ends. For typical transcutaneous blood gas sensing conditions the estimated damage is small, even with prolonged skin contact to a 45 degrees C surface. Spatial heterogeneity in skin thermal properties leads to a non-uniform temperature distribution during a 10 GHz electromagnetic field exposure. A realistic two-dimensional model of the skin shows that tissue heterogeneity does not lead to a significant local temperature increase when heated by a hot wire tip. The heat transport system model of the skin was solved by exploiting the mathematical
Directory of Open Access Journals (Sweden)
Martin Gregory T
2004-11-01
Full Text Available Abstract Background Investigation of bioheat transfer problems requires the evaluation of temporal and spatial distributions of temperature. This class of problems has been traditionally addressed using the Pennes bioheat equation. Transport of heat by conduction, and by temperature-dependent, spatially heterogeneous blood perfusion is modeled here using a transport lattice approach. Methods We represent heat transport processes by using a lattice that represents the Pennes bioheat equation in perfused tissues, and diffusion in nonperfused regions. The three layer skin model has a nonperfused viable epidermis, and deeper regions of dermis and subcutaneous tissue with perfusion that is constant or temperature-dependent. Two cases are considered: (1 surface contact heating and (2 spatially distributed heating. The model is relevant to the prediction of the transient and steady state temperature rise for different methods of power deposition within the skin. Accumulated thermal damage is estimated by using an Arrhenius type rate equation at locations where viable tissue temperature exceeds 42°C. Prediction of spatial temperature distributions is also illustrated with a two-dimensional model of skin created from a histological image. Results The transport lattice approach was validated by comparison with an analytical solution for a slab with homogeneous thermal properties and spatially distributed uniform sink held at constant temperatures at the ends. For typical transcutaneous blood gas sensing conditions the estimated damage is small, even with prolonged skin contact to a 45°C surface. Spatial heterogeneity in skin thermal properties leads to a non-uniform temperature distribution during a 10 GHz electromagnetic field exposure. A realistic two-dimensional model of the skin shows that tissue heterogeneity does not lead to a significant local temperature increase when heated by a hot wire tip. Conclusions The heat transport system model of the
Supersonic unstalled flutter. [aerodynamic loading of thin airfoils induced by cascade motion
Adamczyk, J. J.; Goldstein, M. E.; Hartmann, M. J.
1978-01-01
Flutter analyses were developed to predict the onset of supersonic unstalled flutter of a cascade of two-dimensional airfoils. The first of these analyzes the onset of supersonic flutter at low levels of aerodynamic loading (i.e., backpressure), while the second examines the occurrence of supersonic flutter at moderate levels of aerodynamic loading. Both of these analyses are based on the linearized unsteady inviscid equations of gas dynamics to model the flow field surrounding the cascade. These analyses are utilized in a parametric study to show the effects of cascade geometry, inlet Mach number, and backpressure on the onset of single and multi degree of freedom unstalled supersonic flutter. Several of the results are correlated against experimental qualitative observation to validate the models.
Influences of friction drag on spontaneous condensation in water vapor supersonic flows
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
A mathematical model was developed to investigate the water vapor spontaneous condensation under supersonic flow conditions. A numerical simulation was performed for the water vapor condensable supersonic flows through Laval nozzles under different flow friction conditions. The comparison between numerical and experimental results shows that the model is accurate enough to investigate the supersonic spontaneous condensation flow of water vapor inside Laval nozzles. The influences of flow friction drag on supersonic spontaneous condensation flow of water vapor inside Laval nozzles were investigated. It was found that the flow friction has a direct effect on the spontaneous condensation process and therefore it is important for an accurate friction prediction in designing this kind of Laval nozzles.
Influences of friction drag on spontaneous condensation in water vapor supersonic flows
Institute of Scientific and Technical Information of China (English)
JIANG WenMing; LIU ZhongLiang; LIU HengWei; PANG HuiZhong; BAO LingLing
2009-01-01
A mathematical model was developed to investigate the water vapor spontaneous condensation under supersonic flow conditions. A numerical simulation was performed for the water vapor condensable supersonic flows through Laval nozzles under different flow friction conditions. The comparison be-tween numerical and experimental results shows that the model is accurate enough to investigate the supersonic spontaneous condensation flow of water vapor inside Laval nozzles. The influences of flow friction drag on supersonic spontaneous condensation flow of water vapor inside Laval nozzles were investigated, It was found that the flow friction has a direct effect on the spontaneous condensation process and therefore it is important for an accurate friction prediction in designing this kind of Laval nozzles.
Comparing Numerical Methods for Isothermal Magnetized Supersonic Turbulence
Kritsuk, Alexei G.; Nordlund, Åke; Collins, David; Padoan, Paolo; Norman, Michael L.; Abel, Tom; Banerjee, Robi; Federrath, Christoph; Flock, Mario; Lee, Dongwook; Li, Pak Shing; Müller, Wolf-Christian; Teyssier, Romain; Ustyugov, Sergey D.; Vogel, Christian; Xu, Hao
2011-08-01
Many astrophysical applications involve magnetized turbulent flows with shock waves. Ab initio star formation simulations require a robust representation of supersonic turbulence in molecular clouds on a wide range of scales imposing stringent demands on the quality of numerical algorithms. We employ simulations of supersonic super-Alfvénic turbulence decay as a benchmark test problem to assess and compare the performance of nine popular astrophysical MHD methods actively used to model star formation. The set of nine codes includes: ENZO, FLASH, KT-MHD, LL-MHD, PLUTO, PPML, RAMSES, STAGGER, and ZEUS. These applications employ a variety of numerical approaches, including both split and unsplit, finite difference and finite volume, divergence preserving and divergence cleaning, a variety of Riemann solvers, and a range of spatial reconstruction and time integration techniques. We present a comprehensive set of statistical measures designed to quantify the effects of numerical dissipation in these MHD solvers. We compare power spectra for basic fields to determine the effective spectral bandwidth of the methods and rank them based on their relative effective Reynolds numbers. We also compare numerical dissipation for solenoidal and dilatational velocity components to check for possible impacts of the numerics on small-scale density statistics. Finally, we discuss the convergence of various characteristics for the turbulence decay test and the impact of various components of numerical schemes on the accuracy of solutions. The nine codes gave qualitatively the same results, implying that they are all performing reasonably well and are useful for scientific applications. We show that the best performing codes employ a consistently high order of accuracy for spatial reconstruction of the evolved fields, transverse gradient interpolation, conservation law update step, and Lorentz force computation. The best results are achieved with divergence-free evolution of the
ATTILA - Atmospheric Tracer Transport In a Langrangian Model
Energy Technology Data Exchange (ETDEWEB)
Reithmeier, C.; Sausen, R.
2000-07-01
The Lagrangian model ATTILA (atmospheric tracer transport in a Lagrangian model) has been developed to treat the global-scale transport of passive trace species in the atmosphere within the framework of a general circulation model (GCM). ATTILA runs online within the GCM ECHAM4 and uses the GCM produced wind field to advect the centrois of 80.000 to 180.000 constant mass air parcels into which the model atmosphere is divided. Each trace constituent is thereby represented by a mass mixing ratio in each parcel. ATTILA contains state-of-the-art parameterizations of convection, turbulent boundary layer mixing, and interparcel transport and provides an algorithm to map the tracer concentrations from the trajectories to the ECHAM model grid. We use two experiments to evaluate the transport characteristics of ATTILA against observations and the standard semiLagrangian transport scheme of ECHAM. In the first experiment we simulate the distribution of the short-lived tracer Radon ({sup 222}Rn) in order to examine fast vertical transport over continents, and long-range transport from the continents to remote areas. In the second experiment, we simulate the distribution of radiocarbon ({sup 14}C) that was injected into the northern stratosphere during the nuclear weapon tests in the early 60ties, in order to examine upper tropospheric and stratospheric transport characteristics. ATTILA compares well to the observations and in many respects to the semiLagrangian scheme. However, contrary to the semiLagrangian scheme, ATTILA shows a greatly reduced meridional transport in the upper troposphere and lower stratosphere, and a reduced downward flux from the stratosphere to the troposphere, especially in midlatitudes. Since both transport schemes use the same model meteorology, we conclude that the often cited enhanced meridional transport and overestimated downward flux in ECHAM as described above is rather due to the numerical properties of the semiLagrangian scheme than due to an
ATTILA - Atmospheric Tracer Transport In a Langrangian Model
Energy Technology Data Exchange (ETDEWEB)
Reithmeier, C.; Sausen, R.
2000-07-01
The Lagrangian model ATTILA (atmospheric tracer transport in a Lagrangian model) has been developed to treat the global-scale transport of passive trace species in the atmosphere within the framework of a general circulation model (GCM). ATTILA runs online within the GCM ECHAM4 and uses the GCM produced wind field to advect the centrois of 80.000 to 180.000 constant mass air parcels into which the model atmosphere is divided. Each trace constituent is thereby represented by a mass mixing ratio in each parcel. ATTILA contains state-of-the-art parameterizations of convection, turbulent boundary layer mixing, and interparcel transport and provides an algorithm to map the tracer concentrations from the trajectories to the ECHAM model grid. We use two experiments to evaluate the transport characteristics of ATTILA against observations and the standard semiLagrangian transport scheme of ECHAM. In the first experiment we simulate the distribution of the short-lived tracer Radon ({sup 222}Rn) in order to examine fast vertical transport over continents, and long-range transport from the continents to remote areas. In the second experiment, we simulate the distribution of radiocarbon ({sup 14}C) that was injected into the northern stratosphere during the nuclear weapon tests in the early 60ties, in order to examine upper tropospheric and stratospheric transport characteristics. ATTILA compares well to the observations and in many respects to the semiLagrangian scheme. However, contrary to the semiLagrangian scheme, ATTILA shows a greatly reduced meridional transport in the upper troposphere and lower stratosphere, and a reduced downward flux from the stratosphere to the troposphere, especially in midlatitudes. Since both transport schemes use the same model meteorology, we conclude that the often cited enhanced meridional transport and overestimated downward flux in ECHAM as described above is rather due to the numerical properties of the semiLagrangian scheme than due to an
Collisional broadening of angular correlations in a multiphase transport model
Edmonds, Terrence; Wang, Fuqiang
2016-01-01
Systematic comparisons of jetlike correlation data to radiative and collisional energy loss model calculations are essential to extract transport properties of the quark-gluon medium created in relativistic heavy ion collisions. This paper presents a transport study of collisional broadening of jetlike correlations, by following parton-parton collision history in a multiphase transport (AMPT) model. The correlation shape is studied as a function of the number of parton-parton collisions suffered by a high transverse momentum probe parton ($N_{\\rm coll}$) and the azimuth of the probe relative to the reaction plane ($\\phi_{\\rm fin.}^{\\rm probe}$). Correlation is found to broaden with increasing $N_{\\rm coll}$ and $\\phi_{\\rm fin.}^{\\rm probe}$ from in- to out-of-plane direction. This study provides a transport model benchmark for future jet-medium interaction studies.
Economic model of pipeline transportation systems
Energy Technology Data Exchange (ETDEWEB)
Banks, W. F.
1977-07-29
The objective of the work reported here was to develop a model which could be used to assess the economic effects of energy-conservative technological innovations upon the pipeline industry. The model is a dynamic simulator which accepts inputs of two classes: the physical description (design parameters, fluid properties, and financial structures) of the system to be studied, and the postulated market (throughput and price) projection. The model consists of time-independent submodels: the fluidics model which simulates the physical behavior of the system, and the financial model which operates upon the output of the fluidics model to calculate the economics outputs. Any of a number of existing fluidics models can be used in addition to that developed as a part of this study. The financial model, known as the Systems, Science and Software (S/sup 3/) Financial Projection Model, contains user options whereby pipeline-peculiar characteristics can be removed and/or modified, so that the model can be applied to virtually any kind of business enterprise. The several dozen outputs are of two classes: the energetics and the economics. The energetics outputs of primary interest are the energy intensity, also called unit energy consumption, and the total energy consumed. The primary economics outputs are the long-run average cost, profit, cash flow, and return on investment.
Interfacial and Wall Transport Models for SPACE-CAP Code
Energy Technology Data Exchange (ETDEWEB)
Hong, Soon Joon; Choo, Yeon Joon; Han, Tae Young; Hwang, Su Hyun; Lee, Byung Chul [FNC Tech., Seoul (Korea, Republic of); Choi, Hoon; Ha, Sang Jun [Korea Electric Power Research Institute, Daejeon (Korea, Republic of)
2009-10-15
The development project for the domestic design code was launched to be used for the safety and performance analysis of pressurized light water reactors. And CAP (Containment Analysis Package) code has been also developed for the containment safety and performance analysis side by side with SPACE. The CAP code treats three fields (gas, continuous liquid, and dispersed drop) for the assessment of containment specific phenomena, and is featured by its multidimensional assessment capabilities. Thermal hydraulics solver was already developed and now under testing of its stability and soundness. As a next step, interfacial and wall transport models was setup. In order to develop the best model and correlation package for the CAP code, various models currently used in major containment analysis codes, which are GOTHIC, CONTAIN2.0, and CONTEMPT-LT, have been reviewed. The origins of the selected models used in these codes have also been examined to find out if the models have not conflict with a proprietary right. In addition, a literature survey of the recent studies has been performed in order to incorporate the better models for the CAP code. The models and correlations of SPACE were also reviewed. CAP models and correlations are composed of interfacial heat/mass, and momentum transport models, and wall heat/mass, and momentum transport models. This paper discusses on those transport models in the CAP code.
Biogeochemical Transport and Reaction Model (BeTR) v1
Energy Technology Data Exchange (ETDEWEB)
2016-04-18
The Biogeochemical Transport and Reaction Model (BeTR) is a F90 code that enables reactive transport modeling in land modules of earth system models (e.g. CESM, ACME). The code adopts the Objective-Oriented-Design, and allows users to plug in their own biogeochemical (BGC) formulations/codes, and compare them to other existing BGC codes in those ESMs. The code takes information of soil physics variables, such as variables, such as temperature, moisture, soil density profile; water flow, etc., from a land model to track the movement of different chemicals in presence of biogeochemical reactions.
Chemical Kinetic Modeling of Advanced Transportation Fuels
Energy Technology Data Exchange (ETDEWEB)
PItz, W J; Westbrook, C K; Herbinet, O
2009-01-20
Development of detailed chemical kinetic models for advanced petroleum-based and nonpetroleum based fuels is a difficult challenge because of the hundreds to thousands of different components in these fuels and because some of these fuels contain components that have not been considered in the past. It is important to develop detailed chemical kinetic models for these fuels since the models can be put into engine simulation codes used for optimizing engine design for maximum efficiency and minimal pollutant emissions. For example, these chemistry-enabled engine codes can be used to optimize combustion chamber shape and fuel injection timing. They also allow insight into how the composition of advanced petroleum-based and non-petroleum based fuels affect engine performance characteristics. Additionally, chemical kinetic models can be used separately to interpret important in-cylinder experimental data and gain insight into advanced engine combustion processes such as HCCI and lean burn engines. The objectives are: (1) Develop detailed chemical kinetic reaction models for components of advanced petroleum-based and non-petroleum based fuels. These fuels models include components from vegetable-oil-derived biodiesel, oil-sand derived fuel, alcohol fuels and other advanced bio-based and alternative fuels. (2) Develop detailed chemical kinetic reaction models for mixtures of non-petroleum and petroleum-based components to represent real fuels and lead to efficient reduced combustion models needed for engine modeling codes. (3) Characterize the role of fuel composition on efficiency and pollutant emissions from practical automotive engines.
Analysis regarding the transport network models. Case study on finding the optimal transport route
Stîngă, V.-G.
2017-08-01
Transport networks are studied most of the time from a graph theory perspective, mostly studied in a static way, in order to emphasize their characteristics like: topology, morphology, costs, traffic flows etc. There are many methods used to describe these characteristics at local and global level. Usually when analysing the transport network models, the aim is to achieve minimum capacity transit or minimum cost of operating or investment. Throughout this paper we will get an insight into the many models of the transport network that were presented over the years and we will try to make a short analysis regarding the most important ones. We will make a case study on finding the optimal route by using one of the models presented within this paper.
UNCERTAINTY SUPPLY CHAIN MODEL AND TRANSPORT IN ITS DEPLOYMENTS
Directory of Open Access Journals (Sweden)
Fabiana Lucena Oliveira
2014-05-01
Full Text Available This article discusses the Model Uncertainty of Supply Chain, and proposes a matrix with their transportation modes best suited to their chains. From the detailed analysis of the matrix of uncertainty, it is suggested transportation modes best suited to the management of these chains, so that transport is the most appropriate optimization of the gains previously proposed by the original model, particularly when supply chains are distant from suppliers of raw materials and / or supplies.Here we analyze in detail Agile Supply Chains, which is a result of Uncertainty Supply Chain Model, with special attention to Manaus Industrial Center. This research was done at Manaus Industrial Pole, which is a model of industrial agglomerations, based in Manaus, State of Amazonas (Brazil, which contemplates different supply chains and strategies sharing same infrastructure of transport, handling and storage and clearance process and uses inbound for suppliers of raw material. The state of art contemplates supply chain management, uncertainty supply chain model, agile supply chains, Manaus Industrial Center (MIC and Brazilian legislation, as a business case, and presents concepts and features, of each one. The main goal is to present and discuss how transport is able to support Uncertainty Supply Chain Model, in order to complete management model. The results obtained confirms the hypothesis of integrated logistics processes are able to guarantee attractivity for industrial agglomerations, and open discussions when the suppliers are far from the manufacturer center, in a logistics management.
A quasi-linear gyrokinetic transport model for tokamak plasmas
Casati, Alessandro
2012-01-01
The development of a quasi-linear gyrokinetic transport model for tokamak plasmas, ultimately designed to provide physically comprehensive predictions of the time evolution of the thermodynamic relevant quantities, is a task that requires tight links among theoretical, experimental and numerical studies. The framework of the model here proposed, which operates a reduction of complexity on the nonlinear self-organizing plasma dynamics, allows in fact multiple validations of the current understanding of the tokamak micro-turbulence. The main outcomes of this work stem from the fundamental steps involved by the formulation of such a reduced transport model, namely: (1) the verification of the quasi-linear plasma response against the nonlinearly computed solution, (2) the improvement of the turbulent saturation model through an accurate validation of the nonlinear codes against the turbulence measurements, (3) the integration of the quasi-linear model within an integrated transport solver.
Guidelines for Homology Modeling of Dopamine, Norepinephrine, and Serotonin Transporters.
Haddad, Yazan; Heger, Zbynek; Adam, Vojtech
2016-11-16
The human dopamine, norepinephrine, and serotonin transporters (hDAT, hNET, and hSERT) are carriers of neurotransmitters and targets for many drugs. Pioneering works in the past three years to elucidate experimental models of the Drosophila dDAT and human hSERT structures will rapidly impact the field of neuroscience. Here, we evaluated automated homology-based human models of these transporters, employing systematic physics-based, knowledge-based, and empirical-based check. Modeling guidelines were conveyed with attention to the central binding site (S1), secondary binding site (S2), and the extracellular loops EL2 and EL4. Application of new experimental models (dDAT and hSERT) will improve the accuracy of homology models, previously utilizing prokaryotic leucine transporter (LeuT) structure, and provide better predictions of ligand interactions, which is required for understanding of cellular mechanisms and for development of novel therapeutics.
Kopp, Andreas; Wiengarten, Tobias; Fichtner, Horst; Effenberger, Frederic; Kühl, Patrick; Heber, Bernd; Raath, Jan-Louis; Potgieter, Marius S.
2017-03-01
The transport of cosmic rays (CRs) in the heliosphere is determined by the properties of the solar wind plasma. The heliospheric plasma environment has been probed by spacecraft for decades and provides a unique opportunity for testing transport theories. Of particular interest for the three-dimensional (3D) heliospheric CR transport are structures such as corotating interaction regions (CIRs), which, due to the enhancement of the magnetic field strength and magnetic fluctuations within and due to the associated shocks as well as stream interfaces, do influence the CR diffusion and drift. In a three-fold series of papers, we investigate these effects by modeling inner-heliospheric solar wind conditions with the numerical magnetohydrodynamic (MHD) framework Cronos (Wiengarten et al., referred as Paper I), and the results serve as input to a transport code employing a stochastic differential equation approach (this paper). While, in Paper I, we presented results from 3D simulations with Cronos, the MHD output is now taken as an input to the CR transport modeling. We discuss the diffusion and drift behavior of Galactic cosmic rays using the example of different theories, and study the effects of CIRs on these transport processes. In particular, we point out the wide range of possible particle fluxes at a given point in space resulting from these different theories. The restriction of this variety by fitting the numerical results to spacecraft data will be the subject of the third paper of this series.
Application of the New Weiland Model for Studying Transport Barriers
Kritz, Arnold; Fan, Xiang; Rafiq, Tariq; Tangri, Varun; Pankin, Alexei; Weiland, Jan
2012-10-01
Recent advances in the Weiland drift wave model include new correlation length and new kink (peeling) terms as well as collisions on free electrons. The new model also includes electromagnetic effects on toroidal and poloidal momentum transport. These advances make the model suitable for simulating anomalous effects in transport barriers. A description of the Weiland model content is included in the adjacent poster by T. Rafiq et al. In this study, particle, thermal, and momentum transport coefficients are computed in systematic scans over electron and ion temperature gradients, temperature ratio, density gradient, magnetic q, collision frequency, trapped particle fraction, magnetic shear, Larmor radius, plasma β and elongation. Special consideration is given to the plasma parameter scans that correspond to the plasma edge region such as large temperature and density gradients, large magnetic shear and large magnetic q. The transport results yielded by the new Weiland drift wave model are contrasted with the earlier version of the model. Combined with high fidelity models for neoclassical effects such as NEO and XGC0 models, it is anticipated that the new Weiland model can be used to model H-mode pedestal buildup and recovery between ELM crashes.
Transportation Sector Model of the National Energy Modeling System. Volume 2 -- Appendices: Part 1
Energy Technology Data Exchange (ETDEWEB)
NONE
1998-01-01
This volume contains input data and parameters used in the model of the transportation sector of the National Energy Modeling System. The list of Transportation Sector Model variables includes parameters for the following: Light duty vehicle modules (fuel economy, regional sales, alternative fuel vehicles); Light duty vehicle stock modules; Light duty vehicle fleet module; Air travel module (demand model and fleet efficiency model); Freight transport module; Miscellaneous energy demand module; and Transportation emissions module. Also included in these appendices are: Light duty vehicle market classes; Maximum light duty vehicle market penetration parameters; Aircraft fleet efficiency model adjustment factors; and List of expected aircraft technology improvements.
Computer modeling of electron and proton transport in chloroplasts.
Tikhonov, Alexander N; Vershubskii, Alexey V
2014-07-01
Photosynthesis is one of the most important biological processes in biosphere, which provides production of organic substances from atmospheric CO2 and water at expense of solar energy. In this review, we contemplate computer models of oxygenic photosynthesis in the context of feedback regulation of photosynthetic electron transport in chloroplasts, the energy-transducing organelles of the plant cell. We start with a brief overview of electron and proton transport processes in chloroplasts coupled to ATP synthesis and consider basic regulatory mechanisms of oxygenic photosynthesis. General approaches to computer simulation of photosynthetic processes are considered, including the random walk models of plastoquinone diffusion in thylakoid membranes and deterministic approach to modeling electron transport in chloroplasts based on the mass action law. Then we focus on a kinetic model of oxygenic photosynthesis that includes key stages of the linear electron transport, alternative pathways of electron transfer around photosystem I (PSI), transmembrane proton transport and ATP synthesis in chloroplasts. This model includes different regulatory processes: pH-dependent control of the intersystem electron transport, down-regulation of photosystem II (PSII) activity (non-photochemical quenching), the light-induced activation of the Bassham-Benson-Calvin (BBC) cycle. The model correctly describes pH-dependent feedback control of electron transport in chloroplasts and adequately reproduces a variety of experimental data on induction events observed under different experimental conditions in intact chloroplasts (variations of CO2 and O2 concentrations in atmosphere), including a complex kinetics of P700 (primary electron donor in PSI) photooxidation, CO2 consumption in the BBC cycle, and photorespiration. Finally, we describe diffusion-controlled photosynthetic processes in chloroplasts within the framework of the model that takes into account complex architecture of
The effects of profiles on supersonic jet noise
Tiwari, S. N.; Bhat, T. R. S.
1994-01-01
The effect of velocity profiles on supersonic jet noise are studied by using stability calculations made for a shock-free coannular jet, with both the inner and outer flows supersonic. The Mach wave emission process is modeled as the noise generated by the large scale turbulent structures or the instability waves in the mixing region. Both the vortex-sheet and the realistic finite thickness shear layer models are considered. The stability calculations were performed for both inverted and normal velocity profiles. Comparisons are made with the results for an equivalent single jet, based on equal thrust, mass flow rate and exit area to that of the coannular jet. The advantages and disadvantages of these velocity profiles as far as noise radiation is concerned are discussed. It is shown that the Rayleigh's model prediction of the merits and demerits of different velocity profiles are in good agreement with the experimental data.
Detonation in supersonic radial outflow
Kasimov, Aslan R.
2014-11-07
We report on the structure and dynamics of gaseous detonation stabilized in a supersonic flow emanating radially from a central source. The steady-state solutions are computed and their range of existence is investigated. Two-dimensional simulations are carried out in order to explore the stability of the steady-state solutions. It is found that both collapsing and expanding two-dimensional cellular detonations exist. The latter can be stabilized by putting several rigid obstacles in the flow downstream of the steady-state sonic locus. The problem of initiation of standing detonation stabilized in the radial flow is also investigated numerically. © 2014 Cambridge University Press.
Examining an important urban transportation management tool: subarea modeling
Directory of Open Access Journals (Sweden)
Xueming CHEN
2009-12-01
Full Text Available At present, customized subarea models have been widely used in local transportation planning throughout the United States. The biggest strengths of a subarea model lie in its more detailed and accurate modeling outputs which better meet local planning requirements. In addition, a subarea model can substantially reduce database size and model running time. In spite of these advantages, subarea models remain quite weak in maintaining consistency with a regional model, modeling transit projects, smart growth measures, air quality conformity, and other areas. Both opportunities and threats exist for subarea modeling. In addition to examining subarea models, this paper introduces the decision-making process in choosing a proper subarea modeling approach (windowing versus focusing and software package. This study concludes that subarea modeling will become more popular in the future. More GIS applications, travel surveys, transit modeling, microsimulation software utilization, and other modeling improvements are expected to be incorporated into the subarea modeling process.
Biophysical Modeling of Cross-Shore Plankton Transport
Fujimura, A.; Reniers, A.; Paris, C. B.; Shanks, A.; MacMahan, J.; Morgan, S.
2016-02-01
Coastal ecosystems are influenced by cross-shore flows. Processes that create coastal plankton distributions are not well understood, even though possible mechanisms of plankton transport in the surf zone have been investigated. Our data from a rip-channeled beach show that concentrations of zooplankton and phytoplankton are higher in the surf zone than offshore. To examine how plankton are transported toward the shore, we used a coupled biophysical model, comprised of Delft3D wave/flow simulations and an individual-based model for tracking plankton. Model results indicate that onshore delivery of zooplankton is enhanced by Stokes drift, wave-driven bottom boundary streaming, alongshore topographic variability, and turbulence-dependent sinking behavior of zooplankton. Phytoplankton sinking may also be accelerated by turbulence, but the mechanism differs from that which affects zooplankton. Turbulence has the potential to increase phytoplankton growth rates. Therefore, the phytoplankton transport model includes turbulence-induced sinking velocity and growth rate, although the latter appears to have little influence on phytoplankton distributions. Modeled phytoplankton concentrations in the surf zone are much lower than expected, although the zooplankton transport model qualitatively reproduced our observations. Thus, there must be other possible factors influencing phytoplankton transport, some of which will be discussed.
Aeolian Sediment Transport Integration in General Stratigraphic Forward Modeling
Directory of Open Access Journals (Sweden)
T. Salles
2011-01-01
Full Text Available A large number of numerical models have been developed to simulate the physical processes involved in saltation, and, recently to investigate the interaction between soil vegetation cover and aeolian transport. These models are generally constrained to saltation of monodisperse particles while natural saltation occurs over mixed soils. We present a three-dimensional numerical model of steady-state saltation that can simulate aeolian erosion, transport and deposition for unvegetated mixed soils. Our model simulates the motion of saltating particles using a cellular automata algorithm. A simple set of rules is used and takes into account an erosion formula, a transport model, a wind exposition function, and an avalanching process. The model is coupled to the stratigraphic forward model Sedsim that accounts for a larger number of geological processes. The numerical model predicts a wide range of typical dune shapes, which have qualitative correspondence to real systems. The model reproduces the internal structure and composition of the resulting aeolian deposits. It shows the complex formation of dune systems with cross-bedding strata development, bounding surfaces overlaid by fine sediment and inverse grading deposits. We aim to use it to simulate the complex interactions between different sediment transport processes and their resulting geological morphologies.
Evaluation of cloud convection and tracer transport in a three-dimensional chemical transport model
Directory of Open Access Journals (Sweden)
W. Feng
2011-06-01
Full Text Available We investigate the performance of cloud convection and tracer transport in a global off-line 3-D chemical transport model. Various model simulations are performed using different meteorological (reanalyses (ERA-40, ECMWF operational and ECMWF Interim to diagnose the updraft mass flux, convective precipitation and cloud top height.
The diagnosed upward mass flux distribution from TOMCAT agrees quite well with the ECMWF reanalysis data (ERA-40 and ERA-Interim below 200 hPa. Inclusion of midlevel convection improves the agreement at mid-high latitudes. However, the reanalyses show strong convective transport up to 100 hPa, well into the tropical tropopause layer (TTL, which is not captured by TOMCAT. Similarly, the model captures the spatial and seasonal variation of convective cloud top height although the mean modelled value is about 2 km lower than observed.
The ERA-Interim reanalyses have smaller archived upward convective mass fluxes than ERA-40, and smaller convective precipitation, which is in better agreement with satellite-based data. TOMCAT captures these relative differences when diagnosing convection from the large-scale fields. The model also shows differences in diagnosed convection with the version of the operational analyses used, which cautions against using results of the model from one specific time period as a general evaluation.
We have tested the effect of resolution on the diagnosed modelled convection with simulations ranging from 5.6° × 5.6° to 1° × 1°. Overall, in the off-line model, the higher model resolution gives stronger vertical tracer transport, however, it does not make a large change to the diagnosed convective updraft mass flux (i.e., the model results using the convection scheme fail to capture the strong convection transport up to 100 hPa as seen in the archived convective mass fluxes. Similarly, the resolution of the forcing winds in the higher resolution CTM does not make a
Modeling passenger flows in public transport stations
Directory of Open Access Journals (Sweden)
Cem Kırlangıçoğlu
2015-06-01
Full Text Available There are many architectural design parameters for public transport stations which include urban and station level studies. Each station must be designed in accordance with the basic passenger requirements such as accessibility, safety, comfort, satisfaction and etc. Circulation spaces must be formed and sized to meet the minimum movement needs of passengers. For an underground station; main entrance region, position of gates, location and number of turnstiles, escalators, stairs, ramps, passageways, intermediate concourses and platforms must be arranged to minimize walking distances and to prevent congestion. In this study, circulation of passengers is simulated in a quantitatively verifiable manner, taking into account how individuals interact with each other and with the physical obstacles in their environment in a metro station. Virtual experiments are performed to see the continuity and density of pedestrian flow at different levels of Haram Area East Metro Station of the first metro line of Madinah Al-Munawwarah, Saudi Arabia. According to the predictions, more than 40.000 passengers are expected to use this station in one hour after a Friday prayer during Ramadan period in the year of 2040. That means a critically high travel demand and it is really significant to design the most convenient underground station for these passengers to fulfil the necessary requirements.
Development of interfacial area transport equation - modeling and experimental benchmark
Energy Technology Data Exchange (ETDEWEB)
Ishii, M. [Purdue Univ., West Lafayette, Indiana (United States)
2011-07-01
A dynamic treatment of interfacial area concentration has been studied over the last decade by employing the interfacial area transport equation. When coupled with the two-fluid model, the interfacial area transport equation replaces the flow regime dependent correlations for interfacial area concentration and eliminates potential artificial bifurcation or numerical oscillations stemming from these static correlations. An extensive database has been established to evaluate the model under various two-phase flow conditions. These include adiabatic and heated conditions, vertical and horizontal flow orientations, round, rectangular, annulus and 8×8 rod bundle channel geometries, and normal-gravity and simulated reduced-gravity conditions. This paper reviews the current state-of-the-art in the development of the interfacial area transport equation, available experimental databases and 1D and 3D benchmarking work of the interfacial area transport equation. (author)
Hawk, C. W.; Landrum, D. B.; Muller, S.; Turner, M.; Parkinson, D.
1998-01-01
The Strutjet approach to Rocket Based Combined Cycle (RBCC) propulsion depends upon fuel-rich flows from the rocket nozzles and turbine exhaust products mixing with the ingested air for successful operation in the ramjet and scramjet modes. It is desirable to delay this mixing process in the air-augmented mode of operation present during low speed flight. A model of the Strutjet device has been built and is undergoing test to investigate the mixing of the streams as a function of distance from the Strutjet exit plane during simulated low speed flight conditions. Cold flow testing of a 1/6 scale Strutjet model is underway and nearing completion. Planar Laser Induced Fluorescence (PLIF) diagnostic methods are being employed to observe the mixing of the turbine exhaust gas with the gases from both the primary rockets and the ingested air simulating low speed, air augmented operation of the RBCC. The ratio of the pressure in the turbine exhaust duct to that in the rocket nozzle wall at the point of their intersection is the independent variable in these experiments. Tests were accomplished at values of 1.0, 1.5 and 2.0 for this parameter. Qualitative results illustrate the development of the mixing zone from the exit plane of the model to a distance of about 10 rocket nozzle exit diameters downstream. These data show the mixing to be confined in the vertical plane for all cases, The lateral expansion is more pronounced at a pressure ratio of 1.0 and suggests that mixing with the ingested flow would be likely beginning at a distance of 7 nozzle exit diameters downstream of the nozzle exit plane.
Lithium ion transport in a model of amorphous polyethylene oxide.
Energy Technology Data Exchange (ETDEWEB)
Boinske, P. T.; Curtiss, L.; Halley, J. W.; Lin, B.; Sutjianto, A.; Chemical Engineering; Univ. of Minnesota
1996-01-01
We have made a molecular dynamics study of transport of a single lithium ion in a previously reported model of amorphous polyethylene oxide. New ab initio calculations of the interaction of the lithium ion with 1,2-dimethoxyethane and with dimethyl ether are reported which are used to determine force fields for the simulation. We report preliminary calculations of solvation energies and hopping barriers and a calculation of the ionic conductivity which is independent of any assumptions about the mechanism of ion transport. We also report some details of a study of transport of the trapped lithium ion on intermediate time and length scales.
Mathematical modeling/problem solving in global oxygen transport.
Farrell, Kevin; Hill, Andrew; Dent, Leon; Nguyen, Minh Ly
2009-08-01
A simplified approach to mathematical modeling/problem solving in global oxygen transport is presented. In addition to standard oxygen transport formulae, it uses the S-Factor and a mathematical relationship relating SvO(2) to the ratio DO(2)/VO(2). This method allows the determination or specification of SvO(2), PvO(2), P(50), and systemic shunting in the context of this simplified approach. Heretofore this has not been possible. With this approach, essentially all clinical problems in global oxygen transport can be dealt with. This is illustrated by the broad scope of the five problems presented.
Numerical simulation of carbon dioxide removal from natural gas using supersonic nozzles
Sun, Wenjuan; Cao, Xuewen; Yang, Wen; Jin, Xuetang
2017-03-01
Supersonic separation is a technology potentially applicable to natural gas decarbonation process. Preliminary research on the performance of supersonic nozzle in the removal of carbon dioxide from natural gas is presented in this study. Computational Fluid Dynamics (CFD) technique is used to simulate the flow behavior inside the supersonic nozzle. The CFD model is validated successfully by comparing its results to the data borrowed from the literature. The results indicate that the liquefaction of carbon dioxide can be achieved in the properly designed nozzle. Shock wave occurs in the divergent section of the nozzle with the increase of the back pressure, destroying the liquefaction process. In the supersonic separator, the shock wave should be kept outside of the nozzle.
Numerical Modelling of Arctic Coastal Hydrodynamics and Sediment Transport
Borgersen, Benedicte T
2016-01-01
Coastal areas are experiencing an increase in human population and activities, both in temperate and in Arctic areas. This change in the coastal areas requires that the areas are safe and reliable in order to not put human lives and economical values in danger. To be about to protect the coastal areas it is important to know the hydrodynamics and sediment transport and their effect on coastal areas. Numerical modeling of coastal hydrodynamics and sediment transport is a normal approach to...
MODELS FOR THE COUNTER-GRADIENT TRANSPORT PHENOMENA
Institute of Scientific and Technical Information of China (English)
蒋剑波; 卢志明; 刘晓明; 刘宇陆
2001-01-01
The counter gradient transport phenomena on momentum, energy and passive scalar in turbulent flows were studied by use of the single response function for TSDIA. As a result, models that can describe qualitatively the phenomena are obtained. Then the results are simplified by use of the inertial range theory, and the results for lower degrees agree with results of predecessor. Finally the counter gradient-transport phenomena in channel flow and circular wake flow are analyzed.
Coupling of Groundwater Transport and Plant Uptake Models
DEFF Research Database (Denmark)
Rein, Arno; Bauer-Gottwein, Peter; Trapp, Stefan
2010-01-01
Plants significantly influence contaminant transport and fate. Important processes are uptake of soil and groundwater contaminants, as well as biodegradation in plants and their root zones. Models for the prediction of chemical uptake into plants are required for the setup of mass balances...... to groundwater transport simulation tools. Exemplary simulations of plant uptake were carried out, in order to estimate concentrations in the soilplant- air system and the influence of plants on contaminant mass fluxes from soil to groundwater....
A Fluid Mud Transport Model in Multi-Dimensions
2007-01-01
A Fluid Mud Transport Model in Multi-dimensions Tian-Jian Hsu Civil and Coastal Engineering, University of Florida, Gainesville, FL 32608 phone...NAME(S) AND ADDRESS(ES) University of Florida, Civil and Coastal Engineering,Gainesville,FL,32608 8. PERFORMING ORGANIZATION REPORT NUMBER 9...sediment transport processes are carried out in several directions: Extend to 2D and incorporate Bingham rheology : The previous 1DV fluid mud
Model inter-comparison on transport and chemistry
Energy Technology Data Exchange (ETDEWEB)
Bergamaschi, P. [European Commission, DG Joint Research Centre, Institute for Environment and Sustainability, Ispra (Italy); Meirink, J.F. [Royal Netherlands Meteorological Institute KNMI, De Bilt (Netherlands); Mueller, J.F. [Belgian Institute for Space Aeronomy, Brussels (Belgium); Koerner, S.; Heimann, M. [Max Planck Institute for Biogeochemie, Jena (Germany); Bousquet, P.; Ramonet, M. [Laboratoire des Sciences du Climat et de l' Environment LSCE, Gif sur Yvette (France); Dlugokencky, E.J. [NOAA Earth Science Research Laboratory, Global Monitoring Division, Boulder, CO (United States); Kaminski, U. [Deutscher Wetterdienst, Meteorologisches Observatorium Hohenpeissenberg (Germany); Vecchi, R.; Marcazzan, G. [Istituto di Fisica Generale Applicata, Universita' degli Studi di Milano, Milan (Italy); Meinhardt, F. [Umweltbundesamt, Messstelle Schauinsland, Kirchzarten (Germany); Sartorius, H. [Bundesamt fuer Strahlenschutz, Freiburg (Germany); Zahorowski, W. [Australian Nuclear Science and Technology Organisation, Menai (Australia)
2006-07-01
A comprehensive inter-comparison of 5 atmospheric chemistry transport models (TM5, TM4, TM3, IMAGES, and LMDZ) has been performed. The main objective was to analyze differences in model transport, in particular vertical mixing (boundary layer and convective transport), synoptic variations, and large scale global circulation (including inter-hemispheric exchange and stratospheric tropospheric exchange (STE)). For this purpose simulations of various tracers with very different atmospheric lifetimes {tau} have been carried out: 222Rn ({tau} = 3.8 days), SF6 ({tau} {approx}3000 years), and CH4 ({tau} = {approx}9 years), using prescribed boundary conditions for all models. Furthermore, OH fields from various model simulations with full chemistry have been compared.
Transport modeling of sorbing tracers in artificial fractures
Energy Technology Data Exchange (ETDEWEB)
Keum, Dong Kwon; Baik, Min Hoon; Park, Chung Kyun; Cho, Young Hwan; Hahn, Phil Soo
1998-02-01
This study was performed as part of a fifty-man year attachment program between AECL (Atomic Energy Canada Limited) and KAERI. Three kinds of computer code, HDD, POMKAP and VAMKAP, were developed to predict transport of contaminants in fractured rock. MDDM was to calculate the mass transport of contaminants in a single fracture using a simple hydrodynamic dispersion diffusion model. POMKAP was to predict the mass transport of contaminants by a two-dimensional variable aperture model. In parallel with modeling, the validation of models was also performed through the analysis of the migration experimental data obtained in acrylic plastic and granite artificial fracture system at the Whiteshell laboratories, AECL, Canada. (author). 34 refs., 11 tabs., 76 figs.
A MILP-Model for the Optimization of Transports
Björk, Kaj-Mikael
2010-09-01
This paper presents a work in developing a mathematical model for the optimization of transports. The decisions to be made are routing decisions, truck assignment and the determination of the pickup order for a set of loads and available trucks. The model presented takes these aspects into account simultaneously. The MILP model is implemented in the Microsoft Excel environment, utilizing the LP-solve freeware as the optimization engine and Visual Basic for Applications as the modeling interface.
Langevin model for reactive transport in porous media
Tartakovsky, Alexandre M.
2010-08-01
Existing continuum models for reactive transport in porous media tend to overestimate the extent of solute mixing and mixing-controlled reactions because the continuum models treat both the mechanical and diffusive mixings as an effective Fickian process. Recently, we have proposed a phenomenological Langevin model for flow and transport in porous media [A. M. Tartakovsky, D. M. Tartakovsky, and P. Meakin, Phys. Rev. Lett. 101, 044502 (2008)10.1103/PhysRevLett.101.044502]. In the Langevin model, the fluid flow in a porous continuum is governed by a combination of a Langevin equation and a continuity equation. Pore-scale velocity fluctuations, the source of mechanical dispersion, are represented by the white noise. The advective velocity (the solution of the Langevin flow equation) causes the mechanical dispersion of a solute. Molecular diffusion and sub-pore-scale Taylor-type dispersion are modeled by an effective stochastic advection-diffusion equation. Here, we propose a method for parameterization of the model for a synthetic porous medium, and we use the model to simulate multicomponent reactive transport in the porous medium. The detailed comparison of the results of the Langevin model with pore-scale and continuum (Darcy) simulations shows that: (1) for a wide range of Peclet numbers the Langevin model predicts the mass of reaction product more accurately than the Darcy model; (2) for small Peclet numbers predictions of both the Langevin and the Darcy models agree well with a prediction of the pore-scale model; and (3) the accuracy of the Langevin and Darcy model deteriorates with the increasing Peclet number but the accuracy of the Langevin model decreases more slowly than the accuracy of the Darcy model. These results show that the separate treatment of advective and diffusive mixing in the stochastic transport model is more accurate than the classical advection-dispersion theory, which uses a single effective diffusion coefficient (the dispersion
Water Transport Models of Moisture Absorption and Sweat Discharge Yarns
Institute of Scientific and Technical Information of China (English)
WANG Fa-ming; ZHOU Xiao-hong; WANG Shan-yuan
2008-01-01
An important property of moisture absorption and sweat discharge yams is their water transport property. In the paper, two water transport models of moisture absorption and sweat discharge yams were developed to investigate the influence factors on their wicking rate. In parallel Column Pores Model, wicking rate is determined by the equivalent capillary radius R and length of the capillary tube L. In Pellets Accumulation Model, wicking rate is decided by the capillary radius r and length of the fiber unit assemble L0.
GIS model to evaluate the accessibility to major transport ways
Directory of Open Access Journals (Sweden)
Antonio Tache
2015-03-01
Full Text Available In order to ensure a balanced accessibility to major transport ways, supporting spatial development and economic growth, a GIS model to assess accessibility it was proposed. The model is measuring the average cost of travel (by car, usually from a point to a predetermined number of destinations measured in units of time (minutes. Using the ARCGIS Spatial Analyst module, accessibility territorial indicators were calculated and presented as cartograms and maps that are outlining the accessibility to major transportation routes and to major cities. The proposed model to assess accessibility was tested for Tulcea county (NUTS III level and for the South East region (NUTS II level.
Genetics of traffic assignment models for strategic transport planning
Bliemer, M.C.J.; Raadsen, M.P.H.; Brederode, L.J.N.; Bell, M.G.H.; Wismans, Luc Johannes Josephus; Smith, M.J.
2016-01-01
This paper presents a review and classification of traffic assignment models for strategic transport planning purposes by using concepts analogous to genetics in biology. Traffic assignment models share the same theoretical framework (DNA), but differ in capability (genes). We argue that all traffic
Genetics of traffic assignment models for strategic transport planning
Bliemer, M.C.J.; Raadsen, M.; Brederode, L.; Bell, M.; Wismans, L.J.J.; Smith, M.
2016-01-01
This paper presents a review and classification of traffic assignment models for strategic transport planning purposes by using concepts analogous to genetics in biology. Traffic assignment models share the same theoretical framework (DNA), but differ in capability (genes). We argue that all traffic
Evaluation of 10 cross-shore sediment transport morphological models
CSIR Research Space (South Africa)
Schoonees, JS
1995-05-01
Full Text Available Cross-shore sediment transport models are used to model beach profile changes in order to determine, for example, coastal set-back lines, behaviour of beach fill and beach profile variations adjacent to coastal structures. A study was undertaken...
Modelling of human transplacental transport as performed in Copenhagen, Denmark
DEFF Research Database (Denmark)
Mathiesen, Line; Mørck, Thit Aarøe; Zuri, Giuseppina
2014-01-01
Placenta perfusion models are very effective when studying the placental mechanisms in order to extrapolate to real-life situations. The models are most often used to investigate the transport of substances between mother and foetus, including the potential metabolism of these. We have studied th...
On the Economic Order Quantity Model With Transportation Costs
S.I. Birbil (Ilker); K. Bulbul; J.B.G. Frenk (Hans); H.M. Mulder (Henry)
2009-01-01
textabstractWe consider an economic order quantity type model with unit out-of-pocket holding costs, unit opportunity costs of holding, fixed ordering costs and general transportation costs. For these models, we analyze the associated optimization problem and derive an easy procedure for determining
A transport model for prediction of wildfire behavior
Energy Technology Data Exchange (ETDEWEB)
Linn, R.R.
1997-07-01
Wildfires are a threat to human life and property, yet they are an unavoidable part of nature. In the past people have tried to predict wildfire behavior through the use of point functional models but have been unsuccessful at adequately predicting the gross behavior of the broad spectrum of fires that occur in nature. The majority of previous models do not have self-determining propagation rates. The author uses a transport approach to represent this complicated problem and produce a model that utilizes a self-determining propagation rate. The transport approach allows one to represent a large number of environments including transition regions such as those with nonhomogeneous vegetation and terrain. Some of the most difficult features to treat are the imperfectly known boundary conditions and the fine scale structure that is unresolvable, such as the specific location of the fuel or the precise incoming winds. The author accounts for the microscopic details of a fire with macroscopic resolution by dividing quantities into mean and fluctuating parts similar to what is done in traditional turbulence modelling. The author develops a complicated model that includes the transport of multiple gas species, such as oxygen and volatile hydrocarbons, and tracks the depletion of various fuels and other stationary solids and liquids. From this model the author also forms a simplified local burning model with which he performs a number of simulations for the purpose of demonstrating the properties of a self-determining transport-based wildfire model.
Modeling of far SOL plasma transport in NSTX
Energy Technology Data Exchange (ETDEWEB)
Sergei Krasheninnikov; Alexander Pigarov
2005-11-02
For better understanding and characterization of non-diffusive transport occurring in the NSTX tokamak edge plasma, we performed extensive simulations of NSTX edge plasmas with the multi-fluid two-dimensional UEDGE code by using realistic model for impurity sputtering sources and hybrid model for anomalous cross-field transport. Our cross-field transport model incorporates the effects of non-diffusive intermittent transport by introducing anomalous convective velocities whose spatial profile is adjusted for each ion charge state to match available experimental data. The research in 2002-2005 financial years was focused on the following areas: (i) development of capabilities for UEDGE simulation of NSTX spectroscopy data (i.e., the 3D real-geometry postprocessor UEDGE tools for comparison between UEDGE and experimental data), (ii) simulation of multi-diagnostic data from NSTX with UEDGE, (iii) study of anomalous cross-field convective transport of impurity ions, (iv) analysis of divertor plasma opacity to resonance radiation, and (v) study the effects of ballooning-like anomalous cross-field transport and spherical-torus magnetic configuration on parallel plasma flows in the SOL.
Assessment of the impact of advanced air-transport technology
Maxwell, R. L.; Dickinson, L. V., Jr.
1981-01-01
The long term prospects for commercial supersonic transportation appear attractive enough to keep supersonic research active and reasonably healthy. On the other hand, the uncertainties surrounding an advanced supersonic transport, (AST) specifically fuel price, fuel availability and noise, are too significant to warrant an accelerated research and development program until they are better resolved. It is estimated that an AST could capture about $50 billion (1979 dollars) of the potential $150 billion in sales up to the year 2010.
Morales-Casique, E.; Lezama-Campos, J. L.; Guadagnini, A.; Neuman, S. P.
2013-05-01
Modeling tracer transport in geologic porous media suffers from the corrupt characterization of the spatial distribution of hydrogeologic properties of the system and the incomplete knowledge of processes governing transport at multiple scales. Representations of transport dynamics based on a Fickian model of the kind considered in the advection-dispersion equation (ADE) fail to capture (a) the temporal variation associated with the rate of spreading of a tracer, and (b) the distribution of early and late arrival times which are often observed in field and/or laboratory scenarios and are considered as the signature of anomalous transport. Elsewhere we have presented exact stochastic moment equations to model tracer transport in randomly heterogeneous aquifers. We have also developed a closure scheme which enables one to provide numerical solutions of such moment equations at different orders of approximations. The resulting (ensemble) average and variance of concentration fields were found to display a good agreement against Monte Carlo - based simulation results for mildly heterogeneous (or well-conditioned strongly heterogeneous) media. Here we explore the ability of the moment equations approach to describe the distribution of early arrival times and late time tailing effects which can be observed in Monte-Carlo based breakthrough curves (BTCs) of the (ensemble) mean concentration. We show that BTCs of mean resident concentration calculated at a fixed space location through higher-order approximations of moment equations display long tailing features of the kind which is typically associated with anomalous transport behavior and are not represented by an ADE model with constant dispersive parameter, such as the zero-order approximation.
Spatial Economics Model Predicting Transport Volume
Directory of Open Access Journals (Sweden)
Lu Bo
2016-10-01
Full Text Available It is extremely important to predict the logistics requirements in a scientific and rational way. However, in recent years, the improvement effect on the prediction method is not very significant and the traditional statistical prediction method has the defects of low precision and poor interpretation of the prediction model, which cannot only guarantee the generalization ability of the prediction model theoretically, but also cannot explain the models effectively. Therefore, in combination with the theories of the spatial economics, industrial economics, and neo-classical economics, taking city of Zhuanghe as the research object, the study identifies the leading industry that can produce a large number of cargoes, and further predicts the static logistics generation of the Zhuanghe and hinterlands. By integrating various factors that can affect the regional logistics requirements, this study established a logistics requirements potential model from the aspect of spatial economic principles, and expanded the way of logistics requirements prediction from the single statistical principles to an new area of special and regional economics.
Computer-Supported Modelling of Multi modal Transportation Networks Rationalization
Directory of Open Access Journals (Sweden)
Ratko Zelenika
2007-09-01
Full Text Available This paper deals with issues of shaping and functioning ofcomputer programs in the modelling and solving of multimoda Itransportation network problems. A methodology of an integrateduse of a programming language for mathematical modellingis defined, as well as spreadsheets for the solving of complexmultimodal transportation network problems. The papercontains a comparison of the partial and integral methods ofsolving multimodal transportation networks. The basic hypothesisset forth in this paper is that the integral method results inbetter multimodal transportation network rationalization effects,whereas a multimodal transportation network modelbased on the integral method, once built, can be used as the basisfor all kinds of transportation problems within multimodaltransport. As opposed to linear transport problems, multimodaltransport network can assume very complex shapes. This papercontains a comparison of the partial and integral approach totransp01tation network solving. In the partial approach, astraightforward model of a transp01tation network, which canbe solved through the use of the Solver computer tool within theExcel spreadsheet inteiface, is quite sufficient. In the solving ofa multimodal transportation problem through the integralmethod, it is necessmy to apply sophisticated mathematicalmodelling programming languages which supp01t the use ofcomplex matrix functions and the processing of a vast amountof variables and limitations. The LINGO programming languageis more abstract than the Excel spreadsheet, and it requiresa certain programming knowledge. The definition andpresentation of a problem logic within Excel, in a manner whichis acceptable to computer software, is an ideal basis for modellingin the LINGO programming language, as well as a fasterand more effective implementation of the mathematical model.This paper provides proof for the fact that it is more rational tosolve the problem of multimodal transportation networks by
Assessment of parametric uncertainty for groundwater reactive transport modeling,
Shi, Xiaoqing; Ye, Ming; Curtis, Gary P.; Miller, Geoffery L.; Meyer, Philip D.; Kohler, Matthias; Yabusaki, Steve; Wu, Jichun
2014-01-01
The validity of using Gaussian assumptions for model residuals in uncertainty quantification of a groundwater reactive transport model was evaluated in this study. Least squares regression methods explicitly assume Gaussian residuals, and the assumption leads to Gaussian likelihood functions, model parameters, and model predictions. While the Bayesian methods do not explicitly require the Gaussian assumption, Gaussian residuals are widely used. This paper shows that the residuals of the reactive transport model are non-Gaussian, heteroscedastic, and correlated in time; characterizing them requires using a generalized likelihood function such as the formal generalized likelihood function developed by Schoups and Vrugt (2010). For the surface complexation model considered in this study for simulating uranium reactive transport in groundwater, parametric uncertainty is quantified using the least squares regression methods and Bayesian methods with both Gaussian and formal generalized likelihood functions. While the least squares methods and Bayesian methods with Gaussian likelihood function produce similar Gaussian parameter distributions, the parameter distributions of Bayesian uncertainty quantification using the formal generalized likelihood function are non-Gaussian. In addition, predictive performance of formal generalized likelihood function is superior to that of least squares regression and Bayesian methods with Gaussian likelihood function. The Bayesian uncertainty quantification is conducted using the differential evolution adaptive metropolis (DREAM(zs)) algorithm; as a Markov chain Monte Carlo (MCMC) method, it is a robust tool for quantifying uncertainty in groundwater reactive transport models. For the surface complexation model, the regression-based local sensitivity analysis and Morris- and DREAM(ZS)-based global sensitivity analysis yield almost identical ranking of parameter importance. The uncertainty analysis may help select appropriate likelihood
Modeling transport and aggregation of volcanic ash particles
Costa, Antonio; Folch, Arnau; Macedonio, Giovanni; Durant, Adam
2010-05-01
A complete description of ash aggregation processes in volcanic clouds is an very arduous task and the full coupling of ash transport and ash aggregation models is still computationally prohibitive. A large fraction of fine ash injected in the atmosphere during explosive eruptions aggregate because of complex interactions of surface liquid layers, electrostatic forces, and differences in settling velocities. The formation of aggregates of size and density different from those of the primary particles dramatically changes the sedimentation dynamics and results in lower atmospheric residence times of ash particles and in the formation of secondary maxima of tephra deposit. Volcanic ash transport models should include a full aggregation model accounting for all particle class interaction. However this approach would require prohibitive computational times. Here we present a simplified model for wet aggregation that accounts for both atmospheric and volcanic water transport. The aggregation model assumes a fractal relationship for the number of primary particles in aggregates, average efficiencies factors, and collision frequency functions accounting for Brownian motion, laminar and turbulent fluid shear, and differential settling velocity. We implemented the aggregation model in the WRF+FALL3D coupled modelling system and applied it to different eruptions where aggregation has been recognized to play an important role, such as the August and September 1992 Crater Peak eruptions and the 1980 Mt St Helens eruption. Moreover, understanding aggregation processes in volcanic clouds will contribute to mitigate the risks related with volcanic ash transport and sedimentation.
Modeling of patient's blood pressure variation during ambulance transportation
Sakatani, Kenji; Ono, Takahiko; Kobayasi, Yasuhide; Hikita, Shinichi; Saito, Mitsuyuki
2007-12-01
In an emergency transportation by ambulance, a patient is transported in a supine position. In this position, a patient's blood pressure (BP) variation depending on an inertial force which occurs when an ambulance accelerates or decelerates. This BP variation causes a critical damage for a patent with brain disorder. In order to keep a patient stable during transportation, it is required to maintain small BP variation. To analyze the BP variation during transportation, a model of the BP variation has so far been made. But, it can estimate the BP variation only in braking. The purpose of this paper is to make a dynamical model of the BP variation which can simulate it in both braking and accelerating. First, to obtain the data to construct the model, we used a tilting bed to measure a head-to-foot acceleration and BP of fingertip. Based on this data, we build a mathematical model whose input is the head-to-foot acceleration and output is the Mean BP variation. It is a switched model which switches two models depending on the jerk. We add baroreceptor reflex to the model as a offset value.
Radiative Transport Modelling of Thermal Barrier Coatings
2017-03-24
traveled by signal and reference beam photons) is the result of signal photons travelling a distance L through the sample . Since this distance L is related...performed in both tasks together for convenience . First, we briefly discuss the random walk model, since it is relevant in the discussion on both the...Figure 7, whereby a collinear low coherence beam (shown as a red arrow) is considered to be incident onto the sample at normal incidence to the surface
Directory of Open Access Journals (Sweden)
Simone Becker Lopes
2014-04-01
Full Text Available Considering the importance of spatial issues in transport planning, the main objective of this study was to analyze the results obtained from different approaches of spatial regression models. In the case of spatial autocorrelation, spatial dependence patterns should be incorporated in the models, since that dependence may affect the predictive power of these models. The results obtained with the spatial regression models were also compared with the results of a multiple linear regression model that is typically used in trips generation estimations. The findings support the hypothesis that the inclusion of spatial effects in regression models is important, since the best results were obtained with alternative models (spatial regression models or the ones with spatial variables included. This was observed in a case study carried out in the city of Porto Alegre, in the state of Rio Grande do Sul, Brazil, in the stages of specification and calibration of the models, with two distinct datasets.
Quantum transport in RTD and atomistic modeling of nanostructures
Jiang, Zhengping
As devices are scaled down to nanometer scale, new materials and device structures are introduced to extend Moore's law beyond Si devices. In this length scale, carrier transport moves from classical transport to quantum transport; material granularity has more and more impacts on performance. Computer Aided Design (CAD) becomes essential for both industrial and educational purposes. First part focuses on physical models and numerical issues in nano-scale devices modeling. Resonance Tunneling Diode (RTD) is simulated and used to illustrate phenomena in carrier transport. Non-Equilibrium Green's Function (NEGF) formulism is employed in quantum transport simulation. Inhomogeneous energy grid is used in energy integration, which is critical to capture essential physics in RTD simulation. All simulation results could be reproduced by developed simulators RTDNEGF and NEMO5. In nanostructures, device length becomes comparable to material granularity; it is not proper to consider materials as continuous in many situations. Second part of this work resolves this problem by introducing atomistic modeling method. Valley degeneracy in Si (110) QW is investigated. Inconsistency of experimental observations is resolved by introducing miscut in surface. Impacts of strain and electric field on electronic bandstructure are studied. Research of SiGe barrier disorder effects on valley splitting in Si (100) QW is then conducted. Behaviors of valley splitting in different well widths under electric field are predicted by atomistic simulation. Nearest neighbor empirical tight-binding method is used in electronic calculation and VFF Keating model is used in strain relaxation.
Stochastic Modeling of Non-equilibrium Bedload Transport
Kuai, Z.; Tsai, C. W.
2009-05-01
Traditional stochastic bed load models aimed to solve for the equilibrium bedload transport rate by matching the rate of bed erosion with the rate of deposition. Bedload transport can be in nonequilibrium even under the steady flow condition, as the quantity of moving particles in the bedload layer may vary. In a nonequilibrium condition, the interchange of sediment particles occurs not only between the bedload layer and the bed surface, but also across the interface between bedload and suspended load. The proposed approach attempts to add a new bedload-suspended load interchange layer to a stochastic bedlod transport model based on the Markov chain. The bedload transport rate is the product of the total particle volume in saltation and the average saltating velocity. We can quantify the number of saltating particles by modeling the occupancy probabilities vector of particles staying in three states (i.e., bed surface, bedload layer, and the interchange layer between the bedload and the suspended load.). The new stochastic bedload relation is validated against existing bedload model. The sudden change of flow and/or sediment condition leads to changes in the transition probabilities. The influence of sudden changes in flow-sediment properties on the bedload transport rate is investigated in this preliminary study. It is found that the neglecting the exchange process between the bedload layer and the suspended layer may lead to non-negligible errors in bedload calculation when the flow and/or sediment conditions change.
3D contaminant migration model with consolidation dependent transport coefficients
Institute of Scientific and Technical Information of China (English)
Lu Huang; Cheng-Gang Zhao; Yan Liu; Guo-Qing Cai
2012-01-01
Soil consolidation would induce variations of its transport coefficients such as hydraulic conductivity and diffusion coefficient. This paper presents a study of the influence of barrier consolidation on transport coefficients,and a 3D transport model based on mixture theory is proposed for describing the liners that involve circular defects in the geomembrane.The elastoplastic ALPHA model is revised by using the spatially mobilized plane (SMP) criterion for simulating the deformation of the soils.Then,the 3D model coupling the nonlinear consolidation and contaminant advection-diffusion is solved using the finite element software ABAQUS.The results show that the importance of reducing the defect size in the geomembrane and the liner porosity to control the contaminant concentration increase.
Catalog of selected heavy duty transport energy management models
Colello, R. G.; Boghani, A. B.; Gardella, N. C.; Gott, P. G.; Lee, W. D.; Pollak, E. C.; Teagan, W. P.; Thomas, R. G.; Snyder, C. M.; Wilson, R. P., Jr.
1983-01-01
A catalog of energy management models for heavy duty transport systems powered by diesel engines is presented. The catalog results from a literature survey, supplemented by telephone interviews and mailed questionnaires to discover the major computer models currently used in the transportation industry in the following categories: heavy duty transport systems, which consist of highway (vehicle simulation), marine (ship simulation), rail (locomotive simulation), and pipeline (pumping station simulation); and heavy duty diesel engines, which involve models that match the intake/exhaust system to the engine, fuel efficiency, emissions, combustion chamber shape, fuel injection system, heat transfer, intake/exhaust system, operating performance, and waste heat utilization devices, i.e., turbocharger, bottoming cycle.
Modelling vapour transport in Surtseyan bombs
McGuinness, Mark J.; Greenbank, Emma; Schipper, C. Ian
2016-05-01
We address questions that arise if a slurry containing liquid water is enclosed in a ball of hot viscous vesicular magma ejected as a bomb in the context of a Surtseyan eruption. We derive a mathematical model for transient changes in temperature and pressure due to flashing of liquid water to vapour inside the bomb. The magnitude of the transient pressure changes that are typically generated are calculated together with their dependence on material properties. A single criterion to determine whether the bomb will fragment as a result of the pressure changes is derived. Timescales for ejection of water vapour from a bomb that remains intact are also revealed.
Tavasszy, L.A.; Duijnisveld, M; Hofman, F.; Pronk van Hoogeveen, S.; Schmorak, N.; Van de Berg, M.; Francke, J.; Van de Riet, O.; Van der Waard, J.; Poot, H.; Reiding, E.
2010-01-01
The basic use of transport models is that they help to increase our understanding of the mobility system. In more operational terms, they can be a basis for developing quantitative insights in the past and current state of the system or scenarios about the future. Models are also useful as impact as
Tavasszy, L.A.; Duijnisveld, M; Hofman, F.; Pronk van Hoogeveen, S.; Schmorak, N.; Van de Berg, M.; Francke, J.; Van de Riet, O.; Van der Waard, J.; Poot, H.; Reiding, E.
2010-01-01
The basic use of transport models is that they help to increase our understanding of the mobility system. In more operational terms, they can be a basis for developing quantitative insights in the past and current state of the system or scenarios about the future. Models are also useful as impact
Groundwater transport modeling with nonlinear sorption and intraparticle diffusion
Singh, Anshuman; Allen-King, Richelle M.; Rabideau, Alan J.
2014-08-01
Despite recent advances in the mechanistic understanding of sorption in groundwater systems, most contaminant transport models provide limited support for nonideal sorption processes such as nonlinear isotherms and/or diffusion-limited sorption. However, recent developments in the conceptualization of "dual mode" sorption for hydrophobic organic contaminants have provided more realistic and mechanistically sound alternatives to the commonly used Langmuir and Freundlich models. To support the inclusion of both nonlinear and diffusion-limited sorption processes in groundwater transport models, this paper presents two numerical algorithms based on the split operator approach. For the nonlinear equilibrium scenario, the commonly used two-step split operator algorithm has been modified to provide a more robust treatment of complex multi-parameter isotherms such as the Polanyi-partitioning model. For diffusion-limited sorption, a flexible three step split-operator procedure is presented to simulate intraparticle diffusion in multiple spherical particles with different sizes and nonlinear isotherms. Numerical experiments confirmed the accuracy of both algorithms for several candidate isotherms. However, the primary advantages of the algorithms are: (1) flexibility to accommodate any isotherm equation including "dual mode" and similar expressions, and (2) ease of adapting existing grid-based transport models of any dimensionality to include nonlinear sorption and/or intraparticle diffusion. Comparisons are developed for one-dimensional transport scenarios with different isotherms and particle configurations. Illustrative results highlight (1) the potential influence of isotherm model selection on solute transport predictions, and (2) the combined effects of intraparticle diffusion and nonlinear sorption on the plume transport and flushing for both single-particle and multi-particle scenarios.
Multiscale modeling for fluid transport in nanosystems.
Energy Technology Data Exchange (ETDEWEB)
Lee, Jonathan W.; Jones, Reese E.; Mandadapu, Kranthi Kiran; Templeton, Jeremy Alan; Zimmerman, Jonathan A.
2013-09-01
Atomistic-scale behavior drives performance in many micro- and nano-fluidic systems, such as mircrofludic mixers and electrical energy storage devices. Bringing this information into the traditionally continuum models used for engineering analysis has proved challenging. This work describes one such approach to address this issue by developing atomistic-to-continuum multi scale and multi physics methods to enable molecular dynamics (MD) representations of atoms to incorporated into continuum simulations. Coupling is achieved by imposing constraints based on fluxes of conserved quantities between the two regions described by one of these models. The impact of electric fields and surface charges are also critical, hence, methodologies to extend finite-element (FE) MD electric field solvers have been derived to account for these effects. Finally, the continuum description can have inconsistencies with the coarse-grained MD dynamics, so FE equations based on MD statistics were derived to facilitate the multi scale coupling. Examples are shown relevant to nanofluidic systems, such as pore flow, Couette flow, and electric double layer.
Vertical shear instability in accretion disc models with radiation transport
Stoll, Moritz H R
2014-01-01
The origin of turbulence in accretion discs is still not fully understood. While the magneto-rotational instability is considered to operate in sufficiently ionized discs, its role in the poorly ionized protoplanetary disc is questionable. Recently, the vertical shear instability (VSI) has been suggested as a possible alternative. Our goal is to study the characteristics of this instability and the efficiency of angular momentum transport, in extended discs, under the influence of radiative transport and irradiation from the central star. We use multi-dimensional hydrodynamic simulations to model a larger section of an accretion disc. First we study inviscid and weakly viscous discs using a fixed radial temperature profile in two and three spatial dimensions. The simulations are then extended to include radiative transport and irradiation from the central star. In agreement with previous studies we find for the isothermal disc a sustained unstable state with a weak positive angular momentum transport of the o...
Simulation model for the WIPP transportation and delivery system
Energy Technology Data Exchange (ETDEWEB)
Sharif, F. [Westinghouse Electric Corp., Carlsbad, NM (United States); Lippis, J. [USDOE Albuquerque Operations Office, Carlsbad, NM (United States). Waste Isolation Pilot Plant Project Office; Quinn, D. [Systems Modeling Corp., Sewickley, PA (United States)
1992-12-31
The United States Department of Energy`s (DOE`s) Waste Isolation Pilot Plant (WIPP) is a first of its kind repository designed to demonstrate safe disposal of transuranic (TRU) waste in bedded salt 2150 feet underground. Contact-handled (CH) TRU waste, waste with low beta or gamma emitting radionuclides that can be handled without protective clothing or additional shielding, will be transported to WIPP in Nuclear Regulatory Commission (NRC) certified containers known as TRUPACT-IIs. The TRUPACT-II is the cornerstone of a transportation system designed for extraordinarily safe transport of TRU waste from ten DOE production and research sites to WIPP. This paper describes the complexities of the transportation system and discusses how a simulation model can be utilized as a tool to develop economical operating parameters for the system.
Computer-based modelling and optimization in transportation
Rossi, Riccardo
2014-01-01
This volume brings together works resulting from research carried out by members of the EURO Working Group on Transportation (EWGT) and presented during meetings and workshops organized by the Group under the patronage of the Association of European Operational Research Societies in 2012 and 2013. The main targets of the EWGT include providing a forum to share research information and experience, encouraging joint research and the development of both theoretical methods and applications, and promoting cooperation among the many institutions and organizations which are leaders at national level in the field of transportation and logistics. The primary fields of interest concern operational research methods, mathematical models and computation algorithms, to solve and sustain solutions to problems mainly faced by public administrations, city authorities, public transport companies, service providers and logistic operators. Related areas of interest are: land use and transportation planning, traffic control and ...
A coupled energy transport and hydrological model for urban canopies
Wang, Z.; Bou-Zeid, E.; Smith, J. A.
2011-12-01
Urban land-atmosphere interaction has been attracting more research efforts in order to understand the complex physics of flow and mass and heat transport in urban surfaces and the lower urban atmosphere. In this work, we developed and implemented a new physically-based single-layer urban canopy model, coupling the surface exchange of energy and the subsurface transport of water/soil moisture. The new model incorporates sub-facet heterogeneity for each urban surface (roof, wall or ground). This better simulates the energy transport in urban canopy layers, especially over low-intensity built (suburban type) terrains that include a significant fraction of vegetated surfaces. We implemented detailed urban hydrological models for both natural terrains (bare soil and vegetation) and porous engineered materials with water-holding capacity (concrete, gravel, etc). The skill of the new scheme was tested against experimental data collected through a wireless sensor network deployed over the campus of Princeton University. The model performance was found to be robust and insensitive to changes in weather conditions or seasonal variability. Predictions of the volumetric soil water content were also in good agreement with field measurements, highlighting the model capability of capturing subsurface water transport for urban lawns. The new model was also applied to a case study assessing different strategies, i.e. white versus green roofs, in the mitigation of urban heat island effect.
Radon transport in fractured soil. Laboratory experiments and modelling
Energy Technology Data Exchange (ETDEWEB)
Hoff, A.
1997-10-01
Radon (Rn-222) transport in fractured soil has been investigated by laboratory experiments and by modelling. Radon transport experiments have been performed with two sand columns (homogeneous and inhomogeneous) and one undisturbed clayey till column containing a net of preferential flow paths (root holes). A numerical model (the finite-element model FRACTRAN) and an analytic model (a pinhole model) have been applied in simulations if soil gas and radon transport in fractured soil. Experiments and model calculations are included in a discussion of radon entry rates into houses placed on fractured soil. The main conclusion is, that fractures does not in general alter transport of internally generated radon out of soil, when the pressure and flow conditions in the soil is comparable to the conditions prevailing under a house. This indicates the important result, that fractures in soil have no impact on radon entry into a house beyond that of an increased gas permeability, but a more thorough investigation of this subject is needed. Only in the case where the soil is exposed to large pressure gradients, relative to gradients induced by a house, may it be possible to observe effects of radon exchange between fractures and matrix. (au) 52 tabs., 60 ill., 5 refs.
A transport model for computer simulation of wildfires
Energy Technology Data Exchange (ETDEWEB)
Linn, R. [Los Alamos National Lab., NM (United States)
1997-12-31
Realistic self-determining simulation of wildfires is a difficult task because of a large variety of important length scales (including scales on the size of twigs or grass and the size of large trees), imperfect data, complex fluid mechanics and heat transfer, and very complicated chemical reactions. The author uses a transport approach to produce a model that exhibits a self-determining propagation rate. The transport approach allows him to represent a large number of environments such as those with nonhomogeneous vegetation and terrain. He accounts for the microscopic details of a fire with macroscopic resolution by dividing quantities into mean and fluctuating parts similar to what is done in traditional turbulence modeling. These divided quantities include fuel, wind, gas concentrations, and temperature. Reaction rates are limited by the mixing process and not the chemical kinetics. The author has developed a model that includes the transport of multiple gas species, such as oxygen and volatile hydrocarbons, and tracks the depletion of various fuels and other stationary solids and liquids. From this model he develops a simplified local burning model with which he performs a number of simulations that demonstrate that he is able to capture the important physics with the transport approach. With this simplified model he is able to pick up the essence of wildfire propagation, including such features as acceleration when transitioning to upsloping terrain, deceleration of fire fronts when they reach downslopes, and crowning in the presence of high winds.
Continuous Modeling of Calcium Transport Through Biological Membranes
Jasielec, J. J.; Filipek, R.; Szyszkiewicz, K.; Sokalski, T.; Lewenstam, A.
2016-08-01
In this work an approach to the modeling of the biological membranes where a membrane is treated as a continuous medium is presented. The Nernst-Planck-Poisson model including Poisson equation for electric potential is used to describe transport of ions in the mitochondrial membrane—the interface which joins mitochondrial matrix with cellular cytosis. The transport of calcium ions is considered. Concentration of calcium inside the mitochondrion is not known accurately because different analytical methods give dramatically different results. We explain mathematically these differences assuming the complexing reaction inside mitochondrion and the existence of the calcium set-point (concentration of calcium in cytosis below which calcium stops entering the mitochondrion).
Introduction to stochastic models of transportation flows. Part I
Malyshev, V A
2011-01-01
We consider here probabilistic models of transportation flows. The main goal of this introduction is rather not to present various techniques for problem solving but to present some intuition to invent adequate and natural models having visual simplicity and simple (but rigorous) formulation, the main objects being cars not abstract flows. The papers consists of three parts. First part considers mainly linear flows on short time scale - dynamics of the flow due to changing driver behavior. Second part studies linear flow on longer time scales - individual car trajectory from entry to exit from the road. Part three considers collective car movement in complex transport networks.
Cuttings Transport Models and Experimental Visualization of Underbalanced Horizontal Drilling
Directory of Open Access Journals (Sweden)
Na Wei
2013-01-01
Full Text Available Aerated underbalanced horizontal drilling technology has become the focus of the drilling industry at home and abroad, and one of the engineering core issues is the horizontal borehole cleaning. Therefore, calculating the minimum injection volume of gas and liquid accurately is essential for the construction in aerated underbalanced horizontal drilling. This paper establishes a physical model of carrying cuttings and borehole cleaning in wellbore of horizontal well and a critical transport mathematical model according to gas-liquid-solid flow mechanism and large plane dunes particle transport theory.
Stollenwerk, K.G.
1998-01-01
A natural-gradient tracer test was conducted in an unconfined sand and gravel aquifer on Cape Cod, Massachusetts. Molybdate was included in the injectate to study the effects of variable groundwater chemistry on its aqueous distribution and to evaluate the reliability of laboratory experiments for identifying and quantifying reactions that control the transport of reactive solutes in groundwater. Transport of molybdate in this aquifer was controlled by adsorption. The amount adsorbed varied with aqueous chemistry that changed with depth as freshwater recharge mixed with a plume of sewage-contaminated groundwater. Molybdate adsorption was strongest near the water table where pH (5.7) and the concentration of the competing solutes phosphate (2.3 micromolar) and sulfate (86 micromolar) were low. Adsorption of molybdate decreased with depth as pH increased to 6.5, phosphate increased to 40 micromolar, and sulfate increased to 340 micromolar. A one-site diffuse-layer surface-complexation model and a two-site diffuse-layer surface-complexation model were used to simulate adsorption. Reactions and equilibrium constants for both models were determined in laboratory experiments and used in the reactive-transport model PHAST to simulate the two-dimensional transport of molybdate during the tracer test. No geochemical parameters were adjusted in the simulation to improve the fit between model and field data. Both models simulated the travel distance of the molybdate cloud to within 10% during the 2-year tracer test; however, the two-site diffuse-layer model more accurately simulated the molybdate concentration distribution within the cloud.
Directory of Open Access Journals (Sweden)
Yi Wen
2014-08-01
Full Text Available Transportation system disruption due to a disaster results in "ripple effects" throughout the entire transportation system of a metropolitan region. Many researchers have focused on the economic costs of transportation system disruptions in transportation-related industries, specifïcally within commerce and logistics, in the assessment of the regional economic costs. However, the foundation of an assessment of the regional economic costs of a disaster needs to include the evaluation of consumer surplus in addition to the direct cost for reconstruction of the regional transportation system. The objective of this study is to propose a method to estimate the regional consumer surplus based on indirect economic costs of a disaster on intermodal transportation systems in the context of diverting vehicles and trains. The computational methods used to assess the regional indirect economic costs sustained by the highway and railroad system can utilize readily available state departments of transportation (DOTs and metropolitan planning organizations (MPOs traffic models allowing prioritization of regional recovery plans after a disaster and strengthening of infrastructure before a disaster. Hurricane Katrina is one of the most devastating hurricanes in the history of the United States. Due to the significance of Hurricane Katrina, a case study is presented to evaluate consumer surplus in the Gulf Coast Region of Mississippi. Results from the case study indicate the costs of rerouting and congestion delays in the regional highway system and the rent costs of right-of-way in the regional railroad system are major factors of the indirect costs in the consumer surplus.
Green Transport Balanced Scorecard Model with Analytic Network Process Support
Directory of Open Access Journals (Sweden)
David Staš
2015-11-01
Full Text Available In recent decades, the performance of economic and non-economic activities has required them to be friendly with the environment. Transport is one of the areas having considerable potential within the scope. The main assumption to achieve ambitious green goals is an effective green transport evaluation system. However, these systems are researched from the industrial company and supply chain perspective only sporadically. The aim of the paper is to design a conceptual framework for creating the Green Transport (GT Balanced Scorecard (BSC models from the viewpoint of industrial companies and supply chains using an appropriate multi-criteria decision making method. The models should allow green transport performance evaluation and support of an effective implementation of green transport strategies. Since performance measures used in Balanced Scorecard models are interdependent, the Analytic Network Process (ANP was used as the appropriate multi-criteria decision making method. The verification of the designed conceptual framework was performed on a real supply chain of the European automotive industry.
Ratner, Vadim; Gao, Yi; Lee, Hedok; Elkin, Rena; Nedergaard, Maiken; Benveniste, Helene; Tannenbaum, Allen
2017-01-01
The glymphatic pathway is a system which facilitates continuous cerebrospinal fluid (CSF) and interstitial fluid (ISF) exchange and plays a key role in removing waste products from the rodent brain. Dysfunction of the glymphatic pathway may be implicated in the pathophysiology of Alzheimer's disease. Intriguingly, the glymphatic system is most active during deep wave sleep general anesthesia. By using paramagnetic tracers administered into CSF of rodents, we previously showed the utility of MRI in characterizing a macroscopic whole brain view of glymphatic transport but we have yet to define and visualize the specific flow patterns. Here we have applied an alternative mathematical analysis approach to a dynamic time series of MRI images acquired every 4 min over ∼3 hrs in anesthetized rats, following administration of a small molecular weight paramagnetic tracer into the CSF reservoir of the cisterna magna. We use Optimal Mass Transport (OMT) to model the glymphatic flow vector field, and then analyze the flow to find the network of CSF-ISF flow channels. We use 3D visualization computational tools to visualize the OMT defined network of CSF-ISF flow channels in relation to anatomical and vascular key landmarks from the live rodent brain. The resulting OMT model of the glymphatic transport network agrees largely with the current understanding of the glymphatic transport patterns defined by dynamic contrast-enhanced MRI revealing key CSF transport pathways along the ventral surface of the brain with a trajectory towards the pineal gland, cerebellum, hypothalamus and olfactory bulb. In addition, the OMT analysis also revealed some interesting previously unnoticed behaviors regarding CSF transport involving parenchymal streamlines moving from ventral reservoirs towards the surface of the brain, olfactory bulb and large central veins. PMID:28323163
Intelligent Transportation and Evacuation Planning A Modeling-Based Approach
Naser, Arab
2012-01-01
Intelligent Transportation and Evacuation Planning: A Modeling-Based Approach provides a new paradigm for evacuation planning strategies and techniques. Recently, evacuation planning and modeling have increasingly attracted interest among researchers as well as government officials. This interest stems from the recent catastrophic hurricanes and weather-related events that occurred in the southeastern United States (Hurricane Katrina and Rita). The evacuation methods that were in place before and during the hurricanes did not work well and resulted in thousands of deaths. This book offers insights into the methods and techniques that allow for implementing mathematical-based, simulation-based, and integrated optimization and simulation-based engineering approaches for evacuation planning. This book also: Comprehensively discusses the application of mathematical models for evacuation and intelligent transportation modeling Covers advanced methodologies in evacuation modeling and planning Discusses principles a...
Passive Acoustic Radar for Detecting Supersonic Cruise Missile
Institute of Scientific and Technical Information of China (English)
XIAO Feng; XIAO Hui
2005-01-01
A Passive Acoustic Radar is presented as a necessary complement to electromagnetic wave radar, which will be expected to be an effective means for detecting cruise missiles. Acoustic characteristics of supersonic flying projectiles with diverse shapes are expounded via experiment. It is pointed out that simulation experiment could be implemented using bullet or shell instead of cruise missile. Based on theoretical analysis and experiment, the "acoustic fingerprint" character of cruise missile is illustrated to identify it in a strong noise environment. After establishing a locating mathematical model,the technique of acoustic embattling is utilized to resolve a problem of confirming the time of early-warning, considering the fact that velocity of sound is much slower than that of light. Thereby, a whole system of passive acoustic radar for detecting supersonic cruise missile is formed.
Measurements and models of reactive transport in geological media
Berkowitz, Brian; Dror, Ishai; Hansen, Scott K.; Scher, Harvey
2016-12-01
Reactive chemical transport plays a key role in geological media across scales, from pore scale to aquifer scale. Systems can be altered by changes in solution chemistry and a wide variety of chemical transformations, including precipitation/dissolution reactions that cause feedbacks that directly affect the flow and transport regime. The combination of these processes with advective-dispersive-diffusive transport in heterogeneous media leads to a rich spectrum of complex dynamics. The principal challenge in modeling reactive transport is to account for the subtle effects of fluctuations in the flow field and species concentrations; spatial or temporal averaging generally suppresses these effects. Moreover, it is critical to ground model conceptualizations and test model outputs against laboratory experiments and field measurements. This review emphasizes the integration of these aspects, considering carefully designed and controlled experiments at both laboratory and field scales, in the context of development and solution of reactive transport models based on continuum-scale and particle tracking approaches. We first discuss laboratory experiments and field measurements that define the scope of the phenomena and provide data for model comparison. We continue by surveying models involving advection-dispersion-reaction equation and continuous time random walk formulations. The integration of measurements and models is then examined, considering a series of case studies in different frameworks. We delineate the underlying assumptions, and strengths and weaknesses, of these analyses, and the role of probabilistic effects. We also show the key importance of quantifying the spreading and mixing of reactive species, recognizing the role of small-scale physical and chemical fluctuations that control the initiation of reactions.
Dissipative particle dynamics model for colloid transport in porous media
Energy Technology Data Exchange (ETDEWEB)
Pan, W.; Tartakovsky, A. M.
2013-08-01
We present that the transport of colloidal particles in porous media can be effectively modeled with a new formulation of dissipative particle dynamics, which augments standard DPD with non-central dissipative shear forces between particles while preserving angular momentum. Our previous studies have demonstrated that the new formulation is able to capture accurately the drag forces as well as the drag torques on colloidal particles that result from the hydrodynamic retardation effect. In the present work, we use the new formulation to study the contact efficiency in colloid filtration in saturated porous media. Note that the present model include all transport mechanisms simultaneously, including gravitational sedimentation, interception and Brownian diffusion. Our results of contact efficiency show a good agreement with the predictions of the correlation equation proposed by Tufenkji and EliMelech, which also incorporate all transport mechanisms simultaneously without the additivity assumption.
Review of modeling and control during transport airdrop process
Directory of Open Access Journals (Sweden)
Bin Xu
2016-12-01
Full Text Available This article presents the review of modeling and control during the airdrop process of transport aircraft. According to the airdrop height, technology can be classified into high and low altitude airdrop and in this article, the research is reviewed based on the two scenarios. While high altitude airdrop is mainly focusing on the precise landing control of cargo, the low altitude flight airdrop is on the control of transport aircraft dynamics to ensure flight safety. The history of high precision airdrop system is introduced first, and then the modeling and control problem of the ultra low altitude airdrop in transport aircraft is presented. Finally, the potential problems and future direction of low altitude airdrop are discussed.
A new turbulence-based model for sand transport
Mayaud, Jerome; Wiggs, Giles; Bailey, Richard
2016-04-01
Knowledge of the changing rate of sediment flux in space and time is essential for quantifying surface erosion and deposition in desert landscapes. While many aeolian studies have relied on time-averaged parameters such as wind velocity (U) and wind shear velocity (u*) to determine sediment flux, there is increasing evidence that high-frequency turbulence is an important driving force behind the entrainment and transport of sand. However, turbulence has yet to be incorporated into a functional sand transport model that can be used for predictive purposes. In this study we present a new transport model (the 'turbulence model') that accounts for high-frequency variations in the horizontal (u) and vertical (w) components of wind flow. The turbulence model is fitted to wind velocity and sediment transport data from a field experiment undertaken in Namibia's Skeleton Coast National Park, and its performance at three temporal resolutions (10 Hz, 1 Hz, 1 min) is compared to two existing models that rely on time-averaged wind velocity data (Radok, 1977; Dong et al., 2003). The validity of the three models is analysed under a variety of saltation conditions, using a 2-hour (1 Hz measurement resolution) dataset from the Skeleton Coast and a 5-hour (1 min measurement resolution) dataset from the southwestern Kalahari Desert. The turbulence model is shown to outperform the Radok and Dong models when predicting total saltation count over the three experimental periods. For all temporal resolutions presented in this study (10 Hz-10 min), the turbulence model predicted total saltation count to within at least 0.34%, whereas the Radok and Dong models over- or underestimated total count by up to 5.50% and 20.53% respectively. The strong performance of the turbulence model can be attributed to a lag in mass flux response built into its formulation, which can be adapted depending on the temporal resolution of investigation. This accounts for the inherent lag within the physical
A quasilinear model for solute transport under unsaturated flow
Energy Technology Data Exchange (ETDEWEB)
Houseworth, J.E.; Leem, J.
2009-05-15
We developed an analytical solution for solute transport under steady-state, two-dimensional, unsaturated flow and transport conditions for the investigation of high-level radioactive waste disposal. The two-dimensional, unsaturated flow problem is treated using the quasilinear flow method for a system with homogeneous material properties. Dispersion is modeled as isotropic and is proportional to the effective hydraulic conductivity. This leads to a quasilinear form for the transport problem in terms of a scalar potential that is analogous to the Kirchhoff potential for quasilinear flow. The solutions for both flow and transport scalar potentials take the form of Fourier series. The particular solution given here is for two sources of flow, with one source containing a dissolved solute. The solution method may easily be extended, however, for any combination of flow and solute sources under steady-state conditions. The analytical results for multidimensional solute transport problems, which previously could only be solved numerically, also offer an additional way to benchmark numerical solutions. An analytical solution for two-dimensional, steady-state solute transport under unsaturated flow conditions is presented. A specific case with two sources is solved but may be generalized to any combination of sources. The analytical results complement numerical solutions, which were previously required to solve this class of problems.
Modeling marine surface microplastic transport to assess optimal removal locations
Sherman, Peter; Van Sebille, Erik
2016-01-01
Marine plastic pollution is an ever-increasing problem that demands immediate mitigation and reduction plans. Here, a model based on satellite-tracked buoy observations and scaled to a large data set of observations on microplastic from surface trawls was used to simulate the transport of plastics f
Modelling two-phase transport of 3H/3He
Visser, A.; Schaap, J.D.; Leijnse, T.; Broers, H.P.; Bierkens, M.F.P.
2008-01-01
Degassing of groundwater by excess denitrification of agricultural pollution complicates the interpretation of 3H/3He data and hinders the estimation of travel times in nitrate pollution studies. In this study we used a two-phase flow and transport model (STOMP) to evaluate the method presented by
Development of numerical Grids for UZ Flow and Transport Modeling
Energy Technology Data Exchange (ETDEWEB)
P. Dobson
2004-08-31
This report describes the methods used to develop numerical grids of the unsaturated hydrogeologic system beneath Yucca Mountain, Nevada. Numerical grid generation is an integral part of the development of the unsaturated zone (UZ) flow and transport model, a complex, three-dimensional (3-D) model of Yucca Mountain. This revision contains changes made to improve the clarity of the description of grid generation. The numerical grids, developed using current geologic, hydrogeologic, and mineralogic data, provide the necessary framework to: (1) develop calibrated hydrogeologic property sets and flow fields, (2) test conceptual hypotheses of flow and transport, and (3) predict flow and transport behavior under a variety of climatic and thermal-loading conditions. The technical scope, content, and management for the current revision of this report are described in the planning document ''Technical Work Plan for: Unsaturated Zone Flow Analysis and Model Report Integration'' (BSC 2004 [DIRS 169654], Section 2). Grids generated and documented in this report supersede those documented in Revision 00 of this report, ''Development of Numerical Grids for UZ Flow and Transport Modeling'' (BSC 2001 [DIRS 159356]). The grids presented in this report are the same as those developed in Revision 01 (BSC 2003 [DIRS 160109]); however, the documentation of the development of the grids in Revision 02 has been updated to address technical inconsistencies and achieve greater transparency, readability, and traceability. The constraints, assumptions, and limitations associated with this report are discussed in the appropriate sections that follow.
Transport of Pathogen Surrogates in Soil Treatment Units: Numerical Modeling
Directory of Open Access Journals (Sweden)
Ivan Morales
2014-04-01
Full Text Available Segmented mesocosms (n = 3 packed with sand, sandy loam or clay loam soil were used to determine the effect of soil texture and depth on transport of two septic tank effluent (STE-borne microbial pathogen surrogates—green fluorescent protein-labeled E. coli (GFPE and MS-2 coliphage—in soil treatment units. HYDRUS 2D/3D software was used to model the transport of these microbes from the infiltrative surface. Mesocosms were spiked with GFPE and MS-2 coliphage at 105 cfu/mL STE and 105–106 pfu/mL STE, respectively. In all soils, removal rates were >99.99% at 25 cm. The transport simulation compared (1 optimization; and (2 trial-and-error modeling approaches. Only slight differences between the transport parameters were observed between these approaches. Treating both the die-off rates and attachment/detachment rates as variables resulted in an overall better model fit, particularly for the tailing phase of the experiments. Independent of the fitting procedure, attachment rates computed by the model were higher in sandy and sandy loam soils than clay, which was attributed to unsaturated flow conditions at lower water content in the coarser-textured soils. Early breakthrough of the bacteria and virus indicated the presence of preferential flow in the system in the structured clay loam soil, resulting in faster movement of water and microbes through the soil relative to a conservative tracer (bromide.
Electron thermal transport barriers in RTP: experiment and modelling
Schilham, A.M.R.; Hogeweij, G. M. D.; Cardozo, N. J. L.
2001-01-01
Experiments in which very localized electron cyclotron heating (ECH) is scanned through the RTP plasma show sharp transitions, in which the electron temperature profile abruptly changes shape. The phenomenology-the profiles shapes, the sharp transitions-can be reproduced with a transport model which
Modelling two-phase transport of 3H/3He
Visser, A.; Schaap, J.D.; Leijnse, T.; Broers, H.P.; Bierkens, M.F.P.
2008-01-01
Degassing of groundwater by excess denitrification of agricultural pollution complicates the interpretation of 3H/3He data and hinders the estimation of travel times in nitrate pollution studies. In this study we used a two-phase flow and transport model (STOMP) to evaluate the method presented by V
Tracking cellular telephones as an input for developing transport models
CSIR Research Space (South Africa)
Cooper, Antony K
2010-08-01
Full Text Available of tracking cellular telephones and using the data to populate transport and other models. We report here on one of the pilots, known as DYNATRACK (Dynamic Daily Path Tracking), a larger experiment conducted in 2007 with a more heterogeneous group of commuters...
Modeling marine surface microplastic transport to assess optimal removal locations
Sherman, Peter; Van Sebille, Erik|info:eu-repo/dai/nl/304831921
2016-01-01
Marine plastic pollution is an ever-increasing problem that demands immediate mitigation and reduction plans. Here, a model based on satellite-tracked buoy observations and scaled to a large data set of observations on microplastic from surface trawls was used to simulate the transport of plastics
Mathematical modeling of BTX: biotransformation and transport in the subsurface.
Abriola, L M; Chen, Y M
1995-06-01
A two-dimensional compositional model is presented; this model describes the transport and biotransformation of organic contaminants in a variably saturated subsurface environment. Modeled processes included mass exchange between constituent phases (water, air, soil, and organisms), advective and dispersive fluxes in the water phase, diffusive flux in the air phase, and biotransformation and biomass production in the biophase. In this model, solute transfer across air/water and water/solid interfaces is modeled using equilibrium relationships. Rate-limited mass transfer between the water and biophases is described with a linear driving force expression. Microbial degradation and biomass net growth are modeled by Monod-type kinetics. Solute transport and microbial growth equations are solved using an iterative Galerkin finite element method with a variable time-weighting scheme. Coupled biophase mass balance equations for each component are solved with a Newton-Raphson iterative scheme. Model capabilities are illustrated with two-dimensional, cross-sectional simulations of natural bioattenuation. The influence of biotransformation processes on the transport and extent of a toluene plume is examined.
Tests of the improved Weiland ion temperature gradient transport model
Energy Technology Data Exchange (ETDEWEB)
Kinsey, J.E.; Bateman, G.; Kritz, A.H. [Lehigh Univ., Bethlehem, PA (United States)] [and others
1996-12-31
The Weiland theoretically derived transport model for ion temperature gradient and trapped electron modes has been improved to include the effects of parallel ion motion, finite beta, and collisionality. The model also includes the effects of impurities, fast ions, unequal ion and electron temperatures, and finite Larmor radius. This new model has been implemented in our time-dependent transport code and is used in conjunction with pressure-driven modes and neoclassical theory to predict the radial particle and thermal transport in tokamak plasmas. Simulations of TFTR, DIII-D, and JET L-mode plasmas have been conducted to test how the new effects change the predicted density and temperature profiles. Comparisons are made with results obtained using the previous version of the model which was successful in reproducing experimental data from a wide variety of tokamak plasmas. Specifically, the older model has been benchmarked against over 50 discharges from at least 7 different tokamaks including L-mode scans in current, heating power, density, and dimensionless scans in normalized gyro-radius, collisionality, and beta. We have also investigated the non-diffusive elements included in the Weiland model, particularly the particle pinch in order to characterize its behavior. This is partly motivated by recent simulations of ITER. In those simulations, the older Weiland model predicted a particle pinch and ignition was more easily obtained.
Kinetic models for nucleocytoplasmic transport of messenger RNA.
Schröder, H C; Müller, W E; Agutter, P S
1995-05-21
Much is known about the mechanism by which mRNAs cross the nuclear envelope (the translocation stage of nucleocytoplasmic transport), but far less is known about the preceding (intranuclear migration/release) and succeeding (cytoplasmic binding) stages. Therefore, existing information suffices for articulating detailed kinetic models of translocation, but not models for the overall mRNA transport process. In this paper, we show that simple kinetic models of translocation can (i) accommodate data about nucleocytoplasmic distributions of endogenous transcripts; (ii) predict the overall effects on these distributions of effectors such as insulin and epidermal growth factor; (iii) throw some light on the mechanism(s) of action of the HIV-1 protein Rev and produce experimentally testable predictions about this mechanism; and (iv) account for the action of influenza virus NS1 protein. However, the simplest forms of translocation models apparently fail to account for some properties of viral regulators such as HIV Rev and adenovirus E1B-E4 complex. To elucidate these topics, less narrowly focused models of mRNA transport are required, describing intranuclear binding/release as well as translocation. On the basis of our examination of translocation models, we suggest some criteria that the requisite broadly based models must satisfy.
Percolation models of turbulent transport and scaling estimates
Energy Technology Data Exchange (ETDEWEB)
Bakunin, O.G. [FOM Instituut voor Plasmafysica ' Rijnhuizen' , Associate Euroatom-FOM, 3430 BE Nieuwegein (Netherlands) and Kurchatov Institute, Nuclear Fusion Institute, Kurchatov sq. 1, 123182 Moscow (Russian Federation)]. E-mail: oleg_bakunin@yahoo.com
2005-03-01
The variety of forms of turbulent transport requires not only special description methods, but also an analysis of general mechanisms. One such mechanism is the percolation transport. The percolation approach is based on fractality and scaling ideas. It is possible to explain the anomalous transport in two-dimensional random flow in terms of the percolation threshold. The percolation approach looks very attractive because it gives simple and, at same time, universal model of the behavior related to the strong correlation effects. In the present paper we concentrate our attention on scaling arguments that play the very important role in estimation of transport effects. We discuss the united approach to obtain the renormalization condition of the small parameter, which is responsible for the analytical description of the system near the percolation threshold. Both monoscale and multiscale models are treated. We consider the steady case, time-dependent perturbations, the influence of drift effects, the percolation transport in a stochastic magnetic field, and compressibility effects.
Modeling subsurface contaminant reactions and transport at the watershed scale
Energy Technology Data Exchange (ETDEWEB)
Gwo, J.P.; Jardine, P.M.; D`Azevedo, E.F. [Oak Ridge National Lab., TN (United States); Wilson, G.V. [Desert Research Inst., Las Vegas, NV (United States). Water Resources Center
1997-12-01
The objectives of this research are: (1) to numerically examine the multiscale effects of physical and chemical mass transfer processes on watershed scale, variably saturated subsurface contaminant transport, and (2) to conduct numerical simulations on watershed scale reactive solute transport and evaluate their implications to uncertainty characterization and cost benefit analysis. Concurrent physical and chemical nonequilibrium caused by inter aggregate gradients of pressure head and solute concentration and intra-aggregate geochemical and microbiological processes, respectively, may arise at various scales and flowpaths. To this date, experimental investigations of these complex processes at watershed scale remain a challenge and numerical studies are often needed for guidance of water resources management and decision making. This research integrates the knowledge bases developed during previous experimental and numerical investigations at a proposed waste disposal site at the Oak Ridge National Laboratory to study the concurrent effects of physical and chemical nonequilibrium. Comparison of numerical results with field data indicates that: (1) multiregion, preferential flow and solute transport exist under partially saturated condition and can be confirmed theoretically, and that (2) mass transfer between pore regions is an important process influencing contaminant movement in the subsurface. Simulations of watershed scale, multi species reactive solute transport suggest that dominance of geochemistry and hydrodynamics may occur simultaneously at different locales and influence the movement of one species relative to another. Execution times on the simulations of the reactive solute transport model also indicate that the model is ready to assist the selection of important parameters for site characterization.
Analytical model for flux saturation in sediment transport.
Pähtz, Thomas; Parteli, Eric J R; Kok, Jasper F; Herrmann, Hans J
2014-05-01
The transport of sediment by a fluid along the surface is responsible for dune formation, dust entrainment, and a rich diversity of patterns on the bottom of oceans, rivers, and planetary surfaces. Most previous models of sediment transport have focused on the equilibrium (or saturated) particle flux. However, the morphodynamics of sediment landscapes emerging due to surface transport of sediment is controlled by situations out of equilibrium. In particular, it is controlled by the saturation length characterizing the distance it takes for the particle flux to reach a new equilibrium after a change in flow conditions. The saturation of mass density of particles entrained into transport and the relaxation of particle and fluid velocities constitute the main relevant relaxation mechanisms leading to saturation of the sediment flux. Here we present a theoretical model for sediment transport which, for the first time, accounts for both these relaxation mechanisms and for the different types of sediment entrainment prevailing under different environmental conditions. Our analytical treatment allows us to derive a closed expression for the saturation length of sediment flux, which is general and thus can be applied under different physical conditions.
Modeling subsurface contaminant reactions and transport at the watershed scale
Energy Technology Data Exchange (ETDEWEB)
Gwo, J.P.; Jardine, P.M.; D`Azevedo, E.F. [Oak Ridge National Lab., TN (United States); Wilson, G.V. [Desert Research Inst., Las Vegas, NV (United States). Water Resources Center
1997-12-01
The objectives of this research are: (1) to numerically examine the multiscale effects of physical and chemical mass transfer processes on watershed scale, variably saturated subsurface contaminant transport, and (2) to conduct numerical simulations on watershed scale reactive solute transport and evaluate their implications to uncertainty characterization and cost benefit analysis. Concurrent physical and chemical nonequilibrium caused by inter aggregate gradients of pressure head and solute concentration and intra-aggregate geochemical and microbiological processes, respectively, may arise at various scales and flowpaths. To this date, experimental investigations of these complex processes at watershed scale remain a challenge and numerical studies are often needed for guidance of water resources management and decision making. This research integrates the knowledge bases developed during previous experimental and numerical investigations at a proposed waste disposal site at the Oak Ridge National Laboratory to study the concurrent effects of physical and chemical nonequilibrium. Comparison of numerical results with field data indicates that: (1) multiregion, preferential flow and solute transport exist under partially saturated condition and can be confirmed theoretically, and that (2) mass transfer between pore regions is an important process influencing contaminant movement in the subsurface. Simulations of watershed scale, multi species reactive solute transport suggest that dominance of geochemistry and hydrodynamics may occur simultaneously at different locales and influence the movement of one species relative to another. Execution times on the simulations of the reactive solute transport model also indicate that the model is ready to assist the selection of important parameters for site characterization.
Reconciling transport models across scales: The role of volume exclusion
Taylor, P. R.; Yates, C. A.; Simpson, M. J.; Baker, R. E.
2015-10-01
Diffusive transport is a universal phenomenon, throughout both biological and physical sciences, and models of diffusion are routinely used to interrogate diffusion-driven processes. However, most models neglect to take into account the role of volume exclusion, which can significantly alter diffusive transport, particularly within biological systems where the diffusing particles might occupy a significant fraction of the available space. In this work we use a random walk approach to provide a means to reconcile models that incorporate crowding effects on different spatial scales. Our work demonstrates that coarse-grained models incorporating simplified descriptions of excluded volume can be used in many circumstances, but that care must be taken in pushing the coarse-graining process too far.
A Coupled Chemical and Mass Transport Model for Concrete Durability
DEFF Research Database (Denmark)
Jensen, Mads Mønster; Johannesson, Björn; Geiker, Mette Rica
2012-01-01
curves which is established from a set of mathematical criteria. The chemical degradation is modelled with the geochemical code iphreeqc, which provides a general tool for evaluating different paste compositions. The governing system of equations is solved by the finite element method with a Newton......-Raphson iteration scheme arising from the non-linearity. The overall model is a transient problem, solved using a single parameter formulation. The sorption hysteresis and chemical equilibrium is included as source or sink terms. The advantages with this formulation is that each node in the discrete system has......In this paper a general continuum theory is used to evaluate the service life of cement based materials, in terms of mass transport processes and chemical degradation of the solid matrix. The model established is a reactive mass transport model, based on an extended version of the Poisson...
Transport Processes from Mechanics: Minimal and Simplest Models
Bunimovich, Leonid A.; Grigo, Alexander
2017-02-01
We review the current state of a fundamental problem of rigorous derivation of transport processes in classical statistical mechanics from classical mechanics. Such derivations for diffusion and momentum transport (viscosities) were obtained for minimal models of these processes involving one and two particles respectively. However, a minimal model which demonstrates heat conductivity contains three particles. Its rigorous analysis is currently out of reach for existing mathematical techniques. The gas of localized balls is widely accepted as a basis for a simplest model for derivation of Fourier's law. We suggest a modification of the localized balls gas and argue that this gas of localized activated balls is a good candidate to rigorously prove Fourier's law. In particular, hyperbolicity is derived for a reduced version of this model.
Transport Processes from Mechanics: Minimal and Simplest Models
Bunimovich, Leonid A.; Grigo, Alexander
2016-12-01
We review the current state of a fundamental problem of rigorous derivation of transport processes in classical statistical mechanics from classical mechanics. Such derivations for diffusion and momentum transport (viscosities) were obtained for minimal models of these processes involving one and two particles respectively. However, a minimal model which demonstrates heat conductivity contains three particles. Its rigorous analysis is currently out of reach for existing mathematical techniques. The gas of localized balls is widely accepted as a basis for a simplest model for derivation of Fourier's law. We suggest a modification of the localized balls gas and argue that this gas of localized activated balls is a good candidate to rigorously prove Fourier's law. In particular, hyperbolicity is derived for a reduced version of this model.
Groundwater and contaminant transport modelling at the Sydney Tar Ponds
Energy Technology Data Exchange (ETDEWEB)
King, M. [Groundwater Insight Inc., Halifax, NS (Canada); Check, G. [Jacques Whitford Environment Ltd., Halifax, NS (Canada); Carey, G. [Environmental Inst. for Continuing Education, Waterloo, ON (Canada); Abbey, D. [Waterloo Hydrogeologic, Waterloo, ON (Canada); Baechler, F. [ADI Ltd., Sydney, NS (Canada)
2003-07-01
The Muggah Creek Watershed, a tidal estuary located in Sydney, Nova Scotia, is known locally as the Tar Ponds. Over the past century, the Tar Ponds have accumulated contaminants in the contributing watershed from the iron, steel and coke manufacturing. There are sediments contaminated with polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). A groundwater modelling program was developed to estimate current contaminant fluxes to the estuary and site streams, through groundwater. Attempts were made to incorporate a complex stratigraphic profile, where groundwater flow and contaminant transport is strongly controlled by shallow fractured bedrock, into the conceptual model developed for the site. This conceptual model for groundwater flow and contaminant transport at the Sydney Tar Ponds site was presented. The complex flow patterns between bedrock and overburden, and between the bedrock units and surface water bodies were illustrated with model simulations. It was found that groundwater flow was dominated by discharge to the streams and the estuary. 6 refs., 2 tabs., 11 figs.
O'Brien, Ricky; Fowkes, Nev; Bassom, Andrew P
2010-11-01
Gibberellins are growth hormones produced in the embryo of grain released during germination. They promote growth through the production of enzymes in the aleurone layer surrounding the endosperm. These enzymes then diffuse into the endosperm and produce the sugars required by the growing acrospire. Here we model the transport of gibberellins into and along the aleurone layer, the consequent production of enzymes, and their transport into the endosperm. Simple approximate solutions of the governing equations are obtained which suggest that the enzymes are released immediately behind a gibberellin front which travels with almost constant speed along the aleurone layer. The model also suggests that this propagation speed is determined primarily by conditions near the scutellum-aleurone junction, which may enable the embryo to actively control the germination process.
Combined physical and chemical nonequilibrium transport model for solution conduits.
Field, Malcolm S; Leij, Feike J
2014-02-01
Solute transport in karst aquifers is primarily constrained to relatively complex and inaccessible solution conduits where transport is often rapid, turbulent, and at times constrictive. Breakthrough curves generated from tracer tests in solution conduits are typically positively-skewed with long tails evident. Physical nonequilibrium models to fit breakthrough curves for tracer tests in solution conduits are now routinely employed. Chemical nonequilibrium processes are likely important interactions, however. In addition to partitioning between different flow domains, there may also be equilibrium and nonequilibrium partitioning between the aqueous and solid phases. A combined physical and chemical nonequilibrium (PCNE) model was developed for an instantaneous release similar to that developed by Leij and Bradford (2009) for a pulse release. The PCNE model allows for partitioning open space in solution conduits into mobile and immobile flow regions with first-order mass transfer between the two regions to represent physical nonequilibrium in the conduit. Partitioning between the aqueous and solid phases proceeds either as an equilibrium process or as a first-order process and represents chemical nonequilibrium for both the mobile and immobile regions. Application of the model to three example breakthrough curves demonstrates the applicability of the combined physical and chemical nonequilibrium model to tracer tests conducted in karst aquifers, with exceptionally good model fits to the data. The three models, each from a different state in the United States, exhibit very different velocities, dispersions, and other transport properties with most of the transport occurring via the fraction of mobile water. Fitting the model suggests the potentially important interaction of physical and chemical nonequilibrium processes.
Validation of transport models using additive flux minimization technique
Energy Technology Data Exchange (ETDEWEB)
Pankin, A. Y.; Kruger, S. E. [Tech-X Corporation, 5621 Arapahoe Ave., Boulder, Colorado 80303 (United States); Groebner, R. J. [General Atomics, San Diego, California 92121 (United States); Hakim, A. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543-0451 (United States); Kritz, A. H.; Rafiq, T. [Department of Physics, Lehigh University, Bethlehem, Pennsylvania 18015 (United States)
2013-10-15
A new additive flux minimization technique is proposed for carrying out the verification and validation (V and V) of anomalous transport models. In this approach, the plasma profiles are computed in time dependent predictive simulations in which an additional effective diffusivity is varied. The goal is to obtain an optimal match between the computed and experimental profile. This new technique has several advantages over traditional V and V methods for transport models in tokamaks and takes advantage of uncertainty quantification methods developed by the applied math community. As a demonstration of its efficiency, the technique is applied to the hypothesis that the paleoclassical density transport dominates in the plasma edge region in DIII-D tokamak discharges. A simplified version of the paleoclassical model that utilizes the Spitzer resistivity for the parallel neoclassical resistivity and neglects the trapped particle effects is tested in this paper. It is shown that a contribution to density transport, in addition to the paleoclassical density transport, is needed in order to describe the experimental profiles. It is found that more additional diffusivity is needed at the top of the H-mode pedestal, and almost no additional diffusivity is needed at the pedestal bottom. The implementation of this V and V technique uses the FACETS::Core transport solver and the DAKOTA toolkit for design optimization and uncertainty quantification. The FACETS::Core solver is used for advancing the plasma density profiles. The DAKOTA toolkit is used for the optimization of plasma profiles and the computation of the additional diffusivity that is required for the predicted density profile to match the experimental profile.
Energy Technology Data Exchange (ETDEWEB)
Onishi, Y.; Yabusaki, S.B.; Kincaid, C.T.; Skaggs, R.L.; Walters, W.H.
1982-12-01
SERATRA, a transient, two-dimensional (laterally-averaged) computer model of sediment-contaminant transport in rivers, satisfactorily resolved the distribution of sediment and radionuclide concentrations in the Cattaraugus Creek stream system in New York. By modeling the physical processes of advection, diffusion, erosion, deposition, and bed armoring, SERATRA routed three sediment size fractions, including cohesive soils, to simulate three dynamic flow events. In conjunction with the sediment transport, SERATRA computed radionuclide levels in dissolved, suspended sediment, and bed sediment forms for four radionuclides (/sup 137/Cs, /sup 90/Sr, /sup 239/ /sup 240/Pu, and /sup 3/H). By accounting for time-dependent sediment-radionuclide interaction in the water column and bed, SERATA is a physically explicit model of radionuclide fate and migration. Sediment and radionuclide concentrations calculated by SERATA in the Cattaraugus Creek stream system are in reasonable agreement with measured values. SERATRA is in the field performance phase of an extensive testing program designed to establish the utility of the model as a site assessment tool. The model handles not only radionuclides but other contaminants such as pesticides, heavy metals and other toxic chemicals. Now that the model has been applied to four field sites, including the latest study of the Cattaraugus Creek stream system, it is recommended that a final model be validated through comparison of predicted results with field data from a carefully controlled tracer test at a field site. It is also recommended that a detailed laboratory flume be tested to study cohesive sediment transport, deposition, and erosion characteristics. The lack of current understanding of these characteristics is one of the weakest areas hindering the accurate assessment of the migration of radionuclides sorbed by fine sediments of silt and clay.
Directory of Open Access Journals (Sweden)
J. Brandt
2002-06-01
Full Text Available A tracer model, DREAM (the Danish Rimpuff and Eulerian Accidental release Model, has been developed for modelling transport, dispersion and deposition (wet and dry of radioactive material from accidental releases, as the Chernobyl accident. The model is a combination of a Lagrangian model, that includes the near source dispersion, and an Eulerian model describing the long-range transport. The performance of the transport model has previously been tested within the European Tracer Experiment, ETEX, which included transport and dispersion of an inert, non-depositing tracer from a controlled release. The focus of this paper is the model performance with respect to the deposition of ^{137}Cs, ^{134}Cs and ^{131}I from the Chernobyl accident, using different relatively simple and comprehensive parameterizations. The performance, compared to measurements, of different combinations of parameterizations of wet and dry deposition schemes has been evaluated, using different statistical tests.
Markov-Tree model of intrinsic transport in Hamiltonian systems
Meiss, J. D.; Ott, E.
1985-01-01
A particle in a chaotic region of phase space can spend a long time near the boundary of a regular region since transport there is slow. This 'stickiness' of regular regions is thought to be responsible for previous observations in numerical experiments of a long-time algebraic decay of the particle survival probability, i.e., survival probability approximately t to the (-z) power for large t. This paper presents a global model for transport in such systems and demonstrates the essential role of the infinite hierarchy of small islands interspersed in the chaotic region. Results for z are discussed.
Complexities in coastal sediment transport studies by numerical modelling
Digital Repository Service at National Institute of Oceanography (India)
Ilangovan, D.; ManiMurali, R.
stream_size 10748 stream_content_type text/plain stream_name Proc_Int_Conf_APAC_2013_364.pdf.txt stream_source_info Proc_Int_Conf_APAC_2013_364.pdf.txt Content-Encoding UTF-8 Content-Type text/plain; charset=UTF-8 Procee... could under estimate or over estimate the quantity of sediment transport and the result may not help to predict either erosion or accrction over a coastal region. CONCLUSIONS The authors conclude that sediment transport modelers need a thorough and long...
In vitro placental model optimization for nanoparticle transport studies
Directory of Open Access Journals (Sweden)
Cartwright L
2012-01-01
Full Text Available Laura Cartwright1, Marie Sønnegaard Poulsen2, Hanne Mørck Nielsen3, Giulio Pojana4, Lisbeth E Knudsen2, Margaret Saunders1, Erik Rytting2,51Bristol Initiative for Research of Child Health (BIRCH, Biophysics Research Unit, St Michael's Hospital, UH Bristol NHS Foundation Trust, Bristol, UK; 2University of Copenhagen, Faculty of Health Sciences, Department of Public Health, 3University of Copenhagen, Faculty of Pharmaceutical Sciences, Department of Pharmaceutics and Analytical Chemistry, Copenhagen, Denmark; 4Department of Environmental Sciences, Informatics and Statistics, University Ca' Foscari Venice, Venice, Italy; 5Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas, USABackground: Advances in biomedical nanotechnology raise hopes in patient populations but may also raise questions regarding biodistribution and biocompatibility, especially during pregnancy. Special consideration must be given to the placenta as a biological barrier because a pregnant woman's exposure to nanoparticles could have significant effects on the fetus developing in the womb. Therefore, the purpose of this study is to optimize an in vitro model for characterizing the transport of nanoparticles across human placental trophoblast cells.Methods: The growth of BeWo (clone b30 human placental choriocarcinoma cells for nanoparticle transport studies was characterized in terms of optimized Transwell® insert type and pore size, the investigation of barrier properties by transmission electron microscopy, tight junction staining, transepithelial electrical resistance, and fluorescein sodium transport. Following the determination of nontoxic concentrations of fluorescent polystyrene nanoparticles, the cellular uptake and transport of 50 nm and 100 nm diameter particles was measured using the in vitro BeWo cell model.Results: Particle size measurements, fluorescence readings, and confocal microscopy indicated both cellular uptake of
A mathematical model of inter-terminal transportation
DEFF Research Database (Denmark)
Tierney, Kevin; Voß, Stefan; Stahlbock, Robert
2014-01-01
, which costs ports money and affects a port’s reputation. Our model assists ports in analyzing the impact of new infrastructure, the placement of terminals, and ITT vehicle investments. We provide analysis of ITT at two ports, the port of Hamburg, Germany and the Maasvlakte 1 & 2 area of the port...... contains special structures to model the long term loading and unloading of vehicles, and our model is general enough to model a number of important real-world aspects of ITT, such as traffic congestion, penalized late container delivery, multiple ITT transportation modes, and port infrastructure...
Transport of Solar Wind Fluctuations: A Two-Component Model
Oughton, S.; Matthaeus, W. H.; Smith, C. W.; Breech, B.; Isenberg, P. A.
2011-01-01
We present a new model for the transport of solar wind fluctuations which treats them as two interacting incompressible components: quasi-two-dimensional turbulence and a wave-like piece. Quantities solved for include the energy, cross helicity, and characteristic transverse length scale of each component, plus the proton temperature. The development of the model is outlined and numerical solutions are compared with spacecraft observations. Compared to previous single-component models, this new model incorporates a more physically realistic treatment of fluctuations induced by pickup ions and yields improved agreement with observed values of the correlation length, while maintaining good observational accord with the energy, cross helicity, and temperature.
Experiments on free and impinging supersonic microjets
Energy Technology Data Exchange (ETDEWEB)
Phalnikar, K.A.; Kumar, R.; Alvi, F.S. [Florida A and M University and Florida State University, Department of Mechanical Engineering, Tallahassee, FL (United States)
2008-05-15
The fluid dynamics of microflows has recently commanded considerable attention because of their potential applications. Until now, with a few exceptions, most of the studies have been limited to low speed flows. This experimental study examines supersonic microjets of 100-1,000 {mu}m in size with exit velocities in the range of 300-500 m/s. Such microjets are presently being used to actively control larger supersonic impinging jets, which occur in STOVL (short takeoff and vertical landing) aircraft, cavity flows, and flow separation. Flow properties of free as well as impinging supersonic microjets have been experimentally investigated over a range of geometric and flow parameters. The flowfield is visualized using a micro-schlieren system with a high magnification. These schlieren images clearly show the characteristic shock cell structure typically observed in larger supersonic jets. Quantitative measurements of the jet decay and spreading rates as well as shock cell spacing are obtained using micro-pitot probe surveys. In general, the mean flow features of free microjets are similar to larger supersonic jets operating at higher Reynolds numbers. However, some differences are also observed, most likely due to pronounced viscous effects associated with jets at these small scales. Limited studies of impinging microjets were also conducted. They reveal that, similar to the behavior of free microjets, the flow structure of impinging microjets strongly resembles that of larger supersonic impinging jets. (orig.)
Experiments on free and impinging supersonic microjets
Phalnikar, K. A.; Kumar, R.; Alvi, F. S.
2008-05-01
The fluid dynamics of microflows has recently commanded considerable attention because of their potential applications. Until now, with a few exceptions, most of the studies have been limited to low speed flows. This experimental study examines supersonic microjets of 100-1,000 μm in size with exit velocities in the range of 300-500 m/s. Such microjets are presently being used to actively control larger supersonic impinging jets, which occur in STOVL (short takeoff and vertical landing) aircraft, cavity flows, and flow separation. Flow properties of free as well as impinging supersonic microjets have been experimentally investigated over a range of geometric and flow parameters. The flowfield is visualized using a micro-schlieren system with a high magnification. These schlieren images clearly show the characteristic shock cell structure typically observed in larger supersonic jets. Quantitative measurements of the jet decay and spreading rates as well as shock cell spacing are obtained using micro-pitot probe surveys. In general, the mean flow features of free microjets are similar to larger supersonic jets operating at higher Reynolds numbers. However, some differences are also observed, most likely due to pronounced viscous effects associated with jets at these small scales. Limited studies of impinging microjets were also conducted. They reveal that, similar to the behavior of free microjets, the flow structure of impinging microjets strongly resembles that of larger supersonic impinging jets.
Modelling animal waste pathogen transport from agricultural land to streams
Pandey, Pramod K.; Soupir, Michelle L.; Ikenberry, Charles
2014-03-01
The transport of animal waste pathogens from crop land to streams can potentially elevate pathogen levels in stream water. Applying animal manure into crop land as fertilizers is a common practice in developing as well as in developed countries. Manure application into the crop land, however, can cause potential human health. To control pathogen levels in ambient water bodies such as streams, improving our understanding of pathogen transport at farm scale as well as at watershed scale is required. To understand the impacts of crop land receiving animal waste as fertilizers on stream's pathogen levels, here we investigate pathogen indicator transport at watershed scale. We exploited watershed scale hydrological model to estimate the transport of pathogens from the crop land to streams. Pathogen indicator levels (i.e., E. coli levels) in the stream water were predicted. With certain assumptions, model results are reasonable. This study can be used as guidelines for developing the models for calculating the impacts of crop land's animal manure on stream water.
Stability properties of elementary dynamic models of membrane transport.
Hernández, Julio A
2003-01-01
Living cells are characterized by their capacity to maintain a stable steady state. For instance, cells are able to conserve their volume, internal ionic composition and electrical potential difference across the plasma membrane within values compatible with the overall cell functions. The dynamics of these cellular variables is described by complex integrated models of membrane transport. Some clues for the understanding of the processes involved in global cellular homeostasis may be obtained by the study of the local stability properties of some partial cellular processes. As an example of this approach, I perform, in this study, the neighborhood stability analysis of some elementary integrated models of membrane transport. In essence, the models describe the rate of change of the intracellular concentration of a ligand subject to active and passive transport across the plasma membrane of an ideal cell. The ligand can be ionic or nonionic, and it can affect the cell volume or the plasma membrane potential. The fundamental finding of this study is that, within the physiological range, the steady states are asymptotically stable. This basic property is a necessary consequence of the general forms of the expressions employed to describe the active and passive fluxes of the transported ligand.
Study on the Characteristics of Supersonic Coanda Jet
Institute of Scientific and Technical Information of China (English)
ShigeruMatsuo; ShenYu; 等
1998-01-01
Techniques using coanda effect have been applied to the fluid control devices.In this field,experimental studies were so far performed for the spiral jet obtained by the Coanda jet issuing from a conical cylinder with an annular slit ,thrust vectoring of supersonic Coanda jets and so on,It is important from the viewpoints of effective applications to investigate the characteristics of the supersonic coanda jet in detail,In the present study,The effects of pressure rations and nozzle configurations on the characteristics of the supersonic COanda jet have been investigated.experimentally by a schlieren optical method and pressure measurements.Furthermore.Navier-Stokes equations were solved numerically using a 2nd-order TVD finite-volume scheme with a 3rd-order three stage Runge-Kutta method for time integration,κ-ε model was used in the computations.The effects of initial conditions on Coanda flow were investigated numerically.As a result,the simulated flow fields were compared with experimental data in good agreement qualitatively.
THE TURBULENT DYNAMO IN HIGHLY COMPRESSIBLE SUPERSONIC PLASMAS
Energy Technology Data Exchange (ETDEWEB)
Federrath, Christoph [Research School of Astronomy and Astrophysics, The Australian National University, Canberra, ACT 2611 (Australia); Schober, Jennifer [Universität Heidelberg, Zentrum für Astronomie, Institut für Theoretische Astrophysik, Albert-Ueberle-Strasse 2, D-69120 Heidelberg (Germany); Bovino, Stefano; Schleicher, Dominik R. G., E-mail: christoph.federrath@anu.edu.au [Institut für Astrophysik, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen (Germany)
2014-12-20
The turbulent dynamo may explain the origin of cosmic magnetism. While the exponential amplification of magnetic fields has been studied for incompressible gases, little is known about dynamo action in highly compressible, supersonic plasmas, such as the interstellar medium of galaxies and the early universe. Here we perform the first quantitative comparison of theoretical models of the dynamo growth rate and saturation level with three-dimensional magnetohydrodynamical simulations of supersonic turbulence with grid resolutions of up to 1024{sup 3} cells. We obtain numerical convergence and find that dynamo action occurs for both low and high magnetic Prandtl numbers Pm = ν/η = 0.1-10 (the ratio of viscous to magnetic dissipation), which had so far only been seen for Pm ≥ 1 in supersonic turbulence. We measure the critical magnetic Reynolds number, Rm{sub crit}=129{sub −31}{sup +43}, showing that the compressible dynamo is almost as efficient as in incompressible gas. Considering the physical conditions of the present and early universe, we conclude that magnetic fields need to be taken into account during structure formation from the early to the present cosmic ages, because they suppress gas fragmentation and drive powerful jets and outflows, both greatly affecting the initial mass function of stars.
Assessing uncertainties in solute transport models: Upper Narew case study
Osuch, M.; Romanowicz, R.; Napiórkowski, J. J.
2009-04-01
This paper evaluates uncertainties in two solute transport models based on tracer experiment data from the Upper River Narew. Data Based Mechanistic and transient storage models were applied to Rhodamine WT tracer observations. We focus on the analysis of uncertainty and the sensitivity of model predictions to varying physical parameters, such as dispersion and channel geometry. An advection-dispersion model with dead zones (Transient Storage model) adequately describes the transport of pollutants in a single channel river with multiple storage. The applied transient storage model is deterministic; it assumes that observations are free of errors and the model structure perfectly describes the process of transport of conservative pollutants. In order to take into account the model and observation errors, an uncertainty analysis is required. In this study we used a combination of the Generalized Likelihood Uncertainty Estimation technique (GLUE) and the variance based Global Sensitivity Analysis (GSA). The combination is straightforward as the same samples (Sobol samples) were generated for GLUE analysis and for sensitivity assessment. Additionally, the results of the sensitivity analysis were used to specify the best parameter ranges and their prior distributions for the evaluation of predictive model uncertainty using the GLUE methodology. Apart from predictions of pollutant transport trajectories, two ecological indicators were also studied (time over the threshold concentration and maximum concentration). In particular, a sensitivity analysis of the length of "over the threshold" period shows an interesting multi-modal dependence on model parameters. This behavior is a result of the direct influence of parameters on different parts of the dynamic response of the system. As an alternative to the transient storage model, a Data Based Mechanistic approach was tested. Here, the model is identified and the parameters are estimated from available time series data using
Mathematical Model of Oxygen Transport in Tuberculosis Granulomas
Datta, Meenal; Via, Laura E.; Chen, Wei; Baish, James W.; Xu, Lei; Barry, Clifton E.; Jain, Rakesh K.
2016-01-01
Pulmonary granulomas—the hallmark of Mycobacterium tuberculosis (MTB) infection—are dense cellular lesions that often feature regions of hypoxia and necrosis, partially due to limited transport of oxygen. Low oxygen in granulomas can impair the host immune response, while MTB are able to adapt and persist in hypoxic environments. Here, we used a physiologically based mathematical model of oxygen diffusion and consumption to calculate oxygen profiles within the granuloma, assuming Michaelis–Menten kinetics. An approximate analytical solution—using a priori and newly estimated parameters from experimental data in a rabbit model of tuberculosis—was able to predict the size of hypoxic and necrotic regions in agreement with experimental results from the animal model. Such quantitative understanding of transport limitations can inform future tuberculosis therapeutic strategies that may include adjunct host-directed therapies that facilitate oxygen and drug delivery for more effective treatment. PMID:26253038
Numerical modelling of flow and transport in rough fractures
Institute of Scientific and Technical Information of China (English)
Scott Briggs; Bryan W. Karney; Brent E. Sleep
2014-01-01
Simulation of flow and transport through rough walled rock fractures is investigated using the lattice Boltzmann method (LBM) and random walk (RW), respectively. The numerical implementation is developed and validated on general purpose graphic processing units (GPGPUs). Both the LBM and RW method are well suited to parallel implementation on GPGPUs because they require only next-neighbour communication and thus can reduce expenses. The LBM model is an order of magnitude faster on GPGPUs than published results for LBM simulations run on modern CPUs. The fluid model is verified for parallel plate flow, backward facing step and single fracture flow;and the RW model is verified for point-source diffusion, Taylor-Aris dispersion and breakthrough behaviour in a single fracture. Both algorithms place limitations on the discrete displacement of fluid or particle transport per time step to minimise the numerical error that must be considered during implementation.
Directory of Open Access Journals (Sweden)
R. Locatelli
2013-04-01
Full Text Available A modelling experiment has been conceived to assess the impact of transport model errors on the methane emissions estimated by an atmospheric inversion system. Synthetic methane observations, given by 10 different model outputs from the international TransCom-CH4 model exercise, are combined with a prior scenario of methane emissions and sinks, and integrated into the PYVAR-LMDZ-SACS inverse system to produce 10 different methane emission estimates at the global scale for the year 2005. The same set-up has been used to produce the synthetic observations and to compute flux estimates by inverse modelling, which means that only differences in the modelling of atmospheric transport may cause differences in the estimated fluxes. In our framework, we show that transport model errors lead to a discrepancy of 27 Tg CH4 per year at the global scale, representing 5% of the total methane emissions. At continental and yearly scales, transport model errors have bigger impacts depending on the region, ranging from 36 Tg CH4 in north America to 7 Tg CH4 in Boreal Eurasian (from 23% to 48%. At the model gridbox scale, the spread of inverse estimates can even reach 150% of the prior flux. Thus, transport model errors contribute to significant uncertainties on the methane estimates by inverse modelling, especially when small spatial scales are invoked. Sensitivity tests have been carried out to estimate the impact of the measurement network and the advantage of higher resolution models. The analysis of methane estimated fluxes in these different configurations questions the consistency of transport model errors in current inverse systems. For future methane inversions, an improvement in the modelling of the atmospheric transport would make the estimations more accurate. Likewise, errors of the observation covariance matrix should be more consistently prescribed in future inversions in order to limit the impact of transport model errors on estimated methane
Model documentation report: Transportation sector model of the National Energy Modeling System
Energy Technology Data Exchange (ETDEWEB)
1994-03-01
This report documents the objectives, analytical approach and development of the National Energy Modeling System (NEMS) Transportation Model (TRAN). The report catalogues and describes the model assumptions, computational methodology, parameter estimation techniques, model source code, and forecast results generated by the model. This document serves three purposes. First, it is a reference document providing a detailed description of TRAN for model analysts, users, and the public. Second, this report meets the legal requirements of the Energy Information Administration (EIA) to provide adequate documentation in support of its statistical and forecast reports (Public Law 93-275, 57(b)(1)). Third, it permits continuity in model development by providing documentation from which energy analysts can undertake model enhancements, data updates, and parameter refinements.
Collette, J. G. R.
1984-01-01
A test was conducted in the NASA/Ames Research Center 9x7-foot Supersonic Wind Tunnel to help resolve an anomaly that developed during the STS-6 orbiter flight wherein sections of the Advanced Flexible Reusable Surface Insulation (AFRSI) covering the OMS pods suffered some damage. A one-third scale two-dimensional shell structure model of an OMS pod cross-section was employed to support the test articles. These consisted of 15 AFRSI blanket panels form-fitted over the shell structures for exposure to simulated flight conditions. Of six baseline blankets, two were treated with special surface coatings. Two other panels were configured with AFRSI sections removed from the OV099 orbiter vehicle after the STS-6 flight. Seven additional specimens incorporated alternative designs and repairs. Following a series of surface pressure calibration runs, the specimens were exposed to simulated ascent and entry dynamic pressure profiles. Entry conditions included the use of a vortex generator to evaluate the effect of shed vortices on the AFRSI located in the area of concern.
Modelling of electron transport and of sawtooth activity in tokamaks
Energy Technology Data Exchange (ETDEWEB)
Angioni, C
2001-10-01
Transport phenomena in tokamak plasmas strongly limit the particle and energy confinement and represent a crucial obstacle to controlled thermonuclear fusion. Within the vast framework of transport studies, three topics have been tackled in the present thesis: first, the computation of neoclassical transport coefficients for general axisymmetric equilibria and arbitrary collisionality regime; second, the analysis of the electron temperature behaviour and transport modelling of plasma discharges in the Tokamak a configuration Variable (TCV); third, the modelling and simulation of the sawtooth activity with different plasma heating conditions. The work dedicated to neoclassical theory has been undertaken in order to first analytically identify a set of equations suited for implementation in existing Fokker-Planck codes. Modifications of these codes enabled us to compute the neoclassical transport coefficients considering different realistic magnetic equilibrium configurations and covering a large range of variation of three key parameters: aspect ratio, collisionality, and effective charge number. A comparison of the numerical results with an analytical limit has permitted the identification of two expressions for the trapped particle fraction, capable of encapsulating the geometrical effects and thus enabling each transport coefficient to be fitted with a single analytical function. This has allowed us to provide simple analytical formulae for all the neoclassical transport coefficients valid for arbitrary aspect ratio and collisionality in general realistic geometry. This work is particularly useful for a correct evaluation of the neoclassical contribution in tokamak scenarios with large bootstrap cur- rent fraction, or improved confinement regimes with low anomalous transport and for the determination of the plasma current density profile, since the plasma conductivity is usually assumed neoclassical. These results have been included in the plasma transport code
Charge transport model to predict intrinsic reliability for dielectric materials
Energy Technology Data Exchange (ETDEWEB)
Ogden, Sean P. [Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); GLOBALFOUNDRIES, 400 Stonebreak Rd. Ext., Malta, New York 12020 (United States); Borja, Juan; Plawsky, Joel L., E-mail: plawsky@rpi.edu; Gill, William N. [Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Lu, T.-M. [Department of Physics, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Yeap, Kong Boon [GLOBALFOUNDRIES, 400 Stonebreak Rd. Ext., Malta, New York 12020 (United States)
2015-09-28
Several lifetime models, mostly empirical in nature, are used to predict reliability for low-k dielectrics used in integrated circuits. There is a dispute over which model provides the most accurate prediction for device lifetime at operating conditions. As a result, there is a need to transition from the use of these largely empirical models to one built entirely on theory. Therefore, a charge transport model was developed to predict the device lifetime of low-k interconnect systems. The model is based on electron transport and donor-type defect formation. Breakdown occurs when a critical defect concentration accumulates, resulting in electron tunneling and the emptying of positively charged traps. The enhanced local electric field lowers the barrier for electron injection into the dielectric, causing a positive feedforward failure. The charge transport model is able to replicate experimental I-V and I-t curves, capturing the current decay at early stress times and the rapid current increase at failure. The model is based on field-driven and current-driven failure mechanisms and uses a minimal number of parameters. All the parameters have some theoretical basis or have been measured experimentally and are not directly used to fit the slope of the time-to-failure versus applied field curve. Despite this simplicity, the model is able to accurately predict device lifetime for three different sources of experimental data. The simulation's predictions at low fields and very long lifetimes show that the use of a single empirical model can lead to inaccuracies in device reliability.
Farr, Rebecca A.; Chang, Chau-Lyan.; Jones, Jess H.; Dougherty, N. Sam
2015-01-01
The authors provide a brief overview of the classic tonal screech noise problem created by underexpanded supersonic jets, briefly describing the fluid dynamic-acoustics feedback mechanism that has been long established as the basis for this well-known aeroacoustics problem. This is followed by a description of the Long Penetration Mode (LPM) supersonic underexpanded counterflowing jet phenomenon which has been demonstrated in several wind tunnel tests and modeled in several computational fluid dynamics (CFD) simulations. The authors provide evidence from test and CFD analysis of LPM that indicates that acoustics feedback and fluid interaction seen in LPM are analogous to the aeroacoustics interactions seen in screech jets. Finally, the authors propose applying certain methodologies to LPM which have been developed and successfully demonstrated in the study of screech jets and mechanically induced excitation in fluid oscillators for decades. The authors conclude that the large body of work done on jet screech, other aeroacoustic phenomena, and fluid oscillators can have direct application to the study and applications of LPM counterflowing supersonic cold flow jets.
COMPARISON OF RF CAVITY TRANSPORT MODELS FOR BBU SIMULATIONS
Energy Technology Data Exchange (ETDEWEB)
Ilkyoung Shin,Byung Yunn,Todd Satogata,Shahid Ahmed
2011-03-01
The transverse focusing effect in RF cavities plays a considerable role in beam dynamics for low-energy beamline sections and can contribute to beam breakup (BBU) instability. The purpose of this analysis is to examine RF cavity models in simulation codes which will be used for BBU experiments at Jefferson Lab and improve BBU simulation results. We review two RF cavity models in the simulation codes elegant and TDBBU (a BBU simulation code developed at Jefferson Lab). elegant can include the Rosenzweig-Serafini (R-S) model for the RF focusing effect. Whereas TDBBU uses a model from the code TRANSPORT which considers the adiabatic damping effect, but not the RF focusing effect. Quantitative comparisons are discussed for the CEBAF beamline. We also compare the R-S model with the results from numerical simulations for a CEBAF-type 5-cell superconducting cavity to validate the use of the R-S model as an improved low-energy RF cavity transport model in TDBBU. We have implemented the R-S model in TDBBU. It will improve BBU simulation results to be more matched with analytic calculations and experimental results.
Representing Microbial Processes in Environmental Reactive Transport Models
van Cappellen, P.
2009-04-01
Microorganisms play a key role in the biogeochemical functioning of the earth's surface and shallow subsurface. In the context of reactive transport modeling, a major challenge is to derive, parameterize, calibrate and verify mathematical expressions for microbially-mediated reactions in the environmental. This is best achieved by combining field observations, laboratory experiments, theoretical principles and modeling. Here, I will illustrate such an integrated approach for the case of microbial respiration processes in aquatic sediments. Important issues that will be covered include experimental design, model consistency and performance, as well as the bioenergetics and transient behavior of geomicrobial reaction systems.
le Roux, J. A.; Zank, G. P.; Webb, G. M.
2014-12-01
3D and 2D MHD turbulence simulations with a strong large-scale magnetic field show that the turbulence is filled with quasi-2D inertial-scale flux ropes that intermittently reconnect, while test particle simulations stress how suprathermal particles can be efficiently accelerated to produce power law spectra (kappa distributions) when traversing multiple flux ropes. Solar wind observations indicate that the statistical properties of the turbulence agree well with the MHD turbulence simulation. In addition, recent observations show the presence of different size inertial-scale magnetic islands in the slow solar wind near the heliospheric current sheet, evidence of island merging, and of heating of ions and electrons in their vicinity. At the same time, observations in the supersonic solar wind suggest the existence of suprathermal ion spectra in the solar wind frame where the distribution function is a power law in momentum with a -5 exponent. We present a new statistical transport theory to model the acceleration of superthermal ions traversing multiple contracting and reconnecting inertial-scale quasi-2D flux ropes in the supersonic solar wind. Steady-state analytical solutions for the accelerated suprathermal particle spectrum in a radially expanding solar wind will be explored to show under what conditions one can reproduce the observed superthermal power-law slope.
Glider observations and modeling of sediment transport in Hurricane Sandy
Miles, Travis; Seroka, Greg; Kohut, Josh; Schofield, Oscar; Glenn, Scott
2015-03-01
Regional sediment resuspension and transport are examined as Hurricane Sandy made landfall on the Mid-Atlantic Bight (MAB) in October 2012. A Teledyne-Webb Slocum glider, equipped with a Nortek Aquadopp current profiler, was deployed on the continental shelf ahead of the storm, and is used to validate sediment transport routines coupled to the Regional Ocean Modeling System (ROMS). The glider was deployed on 25 October, 5 days before Sandy made landfall in southern New Jersey (NJ) and flew along the 40 m isobath south of the Hudson Shelf Valley. We used optical and acoustic backscatter to compare with two modeled size classes along the glider track, 0.1 and 0.4 mm sand, respectively. Observations and modeling revealed full water column resuspension for both size classes for over 24 h during peak waves and currents, with transport oriented along-shelf toward the southwest. Regional model predictions showed over 3 cm of sediment eroded on the northern portion of the NJ shelf where waves and currents were the highest. As the storm passed and winds reversed from onshore to offshore on the southern portion of the domain waves and subsequently orbital velocities necessary for resuspension were reduced leading to over 3 cm of deposition across the entire shelf, just north of Delaware Bay. This study highlights the utility of gliders as a new asset in support of the development and verification of regional sediment resuspension and transport models, particularly during large tropical and extratropical cyclones when in situ data sets are not readily available.
Curtis, Gary P.; Lu, Dan; Ye, Ming
2015-01-01
While Bayesian model averaging (BMA) has been widely used in groundwater modeling, it is infrequently applied to groundwater reactive transport modeling because of multiple sources of uncertainty in the coupled hydrogeochemical processes and because of the long execution time of each model run. To resolve these problems, this study analyzed different levels of uncertainty in a hierarchical way, and used the maximum likelihood version of BMA, i.e., MLBMA, to improve the computational efficiency. This study demonstrates the applicability of MLBMA to groundwater reactive transport modeling in a synthetic case in which twenty-seven reactive transport models were designed to predict the reactive transport of hexavalent uranium (U(VI)) based on observations at a former uranium mill site near Naturita, CO. These reactive transport models contain three uncertain model components, i.e., parameterization of hydraulic conductivity, configuration of model boundary, and surface complexation reactions that simulate U(VI) adsorption. These uncertain model components were aggregated into the alternative models by integrating a hierarchical structure into MLBMA. The modeling results of the individual models and MLBMA were analyzed to investigate their predictive performance. The predictive logscore results show that MLBMA generally outperforms the best model, suggesting that using MLBMA is a sound strategy to achieve more robust model predictions relative to a single model. MLBMA works best when the alternative models are structurally distinct and have diverse model predictions. When correlation in model structure exists, two strategies were used to improve predictive performance by retaining structurally distinct models or assigning smaller prior model probabilities to correlated models. Since the synthetic models were designed using data from the Naturita site, the results of this study are expected to provide guidance for real-world modeling. Limitations of applying MLBMA to the
Analysis of supersonic stall bending flutter in axial-flow compressor by actuator disk theory
Adamczyk, J. J.
1978-01-01
An analytical model was developed for predicting the onset of supersonic stall bending flutter in axial-flow compressors. The analysis is based on two-dimensional, compressible, unsteady actuator disk theory. It is applied to a rotor blade row by considering a cascade of airfoils. The effects of shock waves and flow separation are included in the model. Calculations show that the model predicts the onset, in an unshrouded rotor, of a bending flutter mode that exhibits many of the characteristics of supersonic stall bending flutter. The validity of the analysis for predicting this flutter mode is demonstrated.
Oscillations and multiple steady states in active membrane transport models.
Vieira, F M; Bisch, P M
1994-01-01
The dynamic behavior of some non-linear extensions of the six-state alternating access model for active membrane transport is investigated. We use stoichio-metric network analysis to study the stability of steady states. The bifurcation analysis has been done through standard numerical methods. For the usual six-state model we have proved that there is only one steady state, which is globally asymptotically stable. When we added an autocatalytic step we found self-oscillations. For the competition between a monomer cycle and a dimer cycle, with steps of dimer formation, we have also found self-oscillations. We have also studied models involving the formation of a complex with other molecules. The addition of two steps for formation of a complex of the monomer with another molecule does not alter either the number or the stability of steady states of the basic six-state model. The model which combines the formation of a complex with an autocatalytic step shows both self-oscillations and multiple steady states. The results lead us to conclude that oscillations could be produced by active membrane transport systems if the transport cycle contains a sufficiently large number of steps (six in the present case) and is coupled to at least one autocatalytic reaction,. Oscillations are also predicted when the monomer cycle is coupled to a dimer cycle. In fact, the autocatalytic reaction can be seen as a simplification of the model involving competition between monomer and dimer cycles, which seems to be a more realistic description of biological systems. A self-regulation mechanism of the pumps, related to the multiple stationary states, is expected only for a combined effect of autocatalysis and formation of complexes with other molecules. Within the six-state model this model also leads to oscillation.
Laat, A.T.J.de; Landgraf, J.; Aben, I.; Hasekamp, O.; Bregman, B.
2007-01-01
This paper presents a validation of Global Ozone Monitoring Experiment (GOME) ozone (O3) profiles which are used to evaluate stratospheric transport in the chemistry transport model (CTM) Tracer Model version 5 (TM5) using a linearized stratospheric O3 chemistry scheme. A comparison of GOME O3 profi
Preliminary identification of buffet problems in high speed civil transport
Ravindra, Krishnaswamy
1994-01-01
In the present study, some effort is made to identify whether empennage buffet is a relevant factor in the design and operation of the High Speed Civil Transport (HSCT). Based on some results of the only operational supersonic transport, Concorde and the innumerable studies that exist on the tail buffet of high performance airplanes, CFD analyses on the HSCT as well as low speed wind tunnel tests on models, it appears as though buffet will be a factor that needs attention in the proper design of empennage structure. Utilizing the existing empirical relation between the reduced frequency of the leading edge vortices and the geometric parameters, it is estimated that the characteristic frequencies of the vortices from the wing cranks are in the range of certain fundamental frequencies of the wing-fuselage-empennage structure. Buffet is believed to be critical during take-off, climb, descent and landing. Computational and experimental data available in open literature indicate coherent vortex flow structure in the empennage region at supersonic cruise speeds. This raises further concern on the fatigue life of the empennage structure. Three second generation supersonic transport designs taken from open literature are briefly compared with the 'empennage buffet' in mind. Future research efforts relating to buffet studies on the HSCT are summarized. A bibliography pertaining to the present research, including relevant studies on the first generation supersonic transport is presented. The effect of rounded wing leading edges on the present frequency estimates needs further study. The effect of engine exhaust on the flow field in the empennage region also needs further study.
Electron transport and dielectric breakdown in silicon nitride using a charge transport model
Ogden, Sean P.; Lu, Toh-Ming; Plawsky, Joel L.
2016-10-01
Silicon nitride is an important material used in the electronics industry. As such, the electronic transport and reliability of these materials are important to study and understand. We report on a charge transport model to predict leakage current and failure trends based on previously published data for a stoichiometric silicon nitride dielectric. Failure occurs when the defect density increases to a critical value of approximately 6 × 1025 traps/m3. The model's parameters are determined using voltage ramp data only, and yet, the model is also able to predict constant voltage stress failure over a time scale ranging from minutes to months. The successful fit of the model to the experimental data validates our assumption that the dominant defect in the dielectric is the Si dangling bond, located approximately 2.2 eV below the conduction band. A comparison with previous SiCOH simulations shows SiN and SiCOH have similar defect-related material properties. It is also speculated that, based on the estimated parameter values of 2.75 eV for the defect formation activation energy, the materials' TDDB wear-out are caused by broken Si-H bonds, resulting in Si dangling bond defects.
Multiscale model reduction for shale gas transport in fractured media
Akkutlu, I Y; Vasilyeva, Maria
2015-01-01
In this paper, we develop a multiscale model reduction technique that describes shale gas transport in fractured media. Due to the pore-scale heterogeneities and processes, we use upscaled models to describe the matrix. We follow our previous work \\cite{aes14}, where we derived an upscaled model in the form of generalized nonlinear diffusion model to describe the effects of kerogen. To model the interaction between the matrix and the fractures, we use Generalized Multiscale Finite Element Method. In this approach, the matrix and the fracture interaction is modeled via local multiscale basis functions. We developed the GMsFEM and applied for linear flows with horizontal or vertical fracture orientations on a Cartesian fine grid. In this paper, we consider arbitrary fracture orientations and use triangular fine grid and developed GMsFEM for nonlinear flows. Moreover, we develop online basis function strategies to adaptively improve the convergence. The number of multiscale basis functions in each coarse region ...
Simple predictive electron transport models applied to sawtoothing plasmas
Kim, D.; Merle, A.; Sauter, O.; Goodman, T. P.
2016-05-01
In this work, we introduce two simple transport models to evaluate the time evolution of electron temperature and density profiles during sawtooth cycles (i.e. over a sawtooth period time-scale). Since the aim of these simulations is to estimate reliable profiles within a short calculation time, two simplified ad-hoc models have been developed. The goal for these models is to rely on a few easy-to-check free parameters, such as the confinement time scaling factor and the profiles’ averaged scale-lengths. Due to the simplicity and short calculation time of the models, it is expected that these models can also be applied to real-time transport simulations. We show that it works well for Ohmic and EC heated L- and H-mode plasmas. The differences between these models are discussed and we show that their predictive capabilities are similar. Thus only one model is used to reproduce with simulations the results of sawtooth control experiments on the TCV tokamak. For the sawtooth pacing, the calculated time delays between the EC power off and sawtooth crash time agree well with the experimental results. The map of possible locking range is also well reproduced by the simulation.
Macroscopic Modeling of Transport Phenomena in Direct Methanol Fuel Cells
DEFF Research Database (Denmark)
Olesen, Anders Christian
An increasing need for energy efficiency and high energy density has sparked a growing interest in direct methanol fuel cells for portable power applications. This type of fuel cell directly generates electricity from a fuel mixture consisting of methanol and water. Although this technology...... for studying their transport. In this PhD dissertation the macroscopic transport phenomena governing direct methanol fuel cell operation are analyzed, discussed and modeled using the two-fluid approach in the computational fluid dynamics framework of CFX 14. The overall objective of this work is to extend...... the present fundamental understanding of direct methanol fuel cell operation by developing a three-dimensional, two-phase, multi-component, non-isotherm mathematical model including detailed non-ideal thermodynamics, non-equilibrium phase change and non-equilibrium sorption-desorption of methanol and water...
Modeling transport properties of inhomogeneous superconductor-metal composites
Energy Technology Data Exchange (ETDEWEB)
Borroto, A.; Altshuler, E., E-mail: ealtshuler@fisica.uh.cu [Superconductivity Laboratory and “Henri Poincarè” Group of Complex Systems, Physics Faculty-IMRE, University of Havana, 10400 Havana (Cuba); Del Río, L. [Superconductivity Laboratory and “Henri Poincarè” Group of Complex Systems, Physics Faculty-IMRE, University of Havana, 10400 Havana (Cuba); Physics Department, McGill University, Montreal, Quebec H3A 2T8 (Canada); Arronte, M. [BRALAX, S. de RL., Tampico, Tamaulipas (Mexico); Technological Laser Laboratory, IMRE, University of Havana, 10400 Havana (Cuba); Johansen, T. H. [Department of Physics, University of Oslo, P.O. Box 1048 Blindern, 0316 Oslo (Norway); Institute for Superconducting and Electronic Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia)
2014-11-17
We propose a model for a superconductor-metal composite that allows to derive intrinsic transport properties of the superconducting phase based on 2D images of its cross section, and a minimal set of parameters. The method is tested experimentally by using, as model composite, a “transversal bridge” made on a Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10+x} (BSCCO)-Ag multi-filamentary tape. It is shown that the approach allows to predict the measured I−〈E〉 curves of the filaments. In addition, one can determine the critical current anisotropy between the longitudinal and transverse directions of the Ag-BSCCO tape, and also of its superconducting filaments separately, which emphasizes the role of the morphology of the composite in the transport properties.
Ergodicity-breaking bifurcations and tunneling in hyperbolic transport models
Giona, M.; Brasiello, A.; Crescitelli, S.
2015-11-01
One of the main differences between parabolic transport, associated with Langevin equations driven by Wiener processes, and hyperbolic models related to generalized Kac equations driven by Poisson processes, is the occurrence in the latter of multiple stable invariant densities (Frobenius multiplicity) in certain regions of the parameter space. This phenomenon is associated with the occurrence in linear hyperbolic balance equations of a typical bifurcation, referred to as the ergodicity-breaking bifurcation, the properties of which are thoroughly analyzed.
Multiphysical modelling of fluid transport through osteo-articular media
Directory of Open Access Journals (Sweden)
Thibault Lemaire
2010-03-01
Full Text Available In this study, a multiphysical description of fluid transport through osteo-articular porous media is presented. Adapted from the model of Moyne and Murad, which is intended to describe clayey materials behaviour, this multiscale modelling allows for the derivation of the macroscopic response of the tissue from microscopical information. First the model is described. At the pore scale, electrohydrodynamics equations governing the electrolyte movement are coupled with local electrostatics (Gauss-Poisson equation, and ionic transport equations. Using a change of variables and an asymptotic expansion method, the macroscopic description is carried out. Results of this model are used to show the importance of couplings effects on the mechanotransduction of compact bone remodelling.Neste estudo uma descrição multifísica do transporte de fluidos em meios porosos osteo articulares é apresentada. Adaptado a partir do modelo de Moyne e Murad proposto para descrever o comportamento de materiais argilosos a modelagem multiescala permite a derivação da resposta macroscópica do tecido a partir da informação microscópica. Na primeira parte o modelo é apresentado. Na escala do poro as equações da eletro-hidrodinâmica governantes do movimento dos eletrolitos são acopladas com a eletrostática local (equação de Gauss-Poisson e as equações de transporte iônico. Usando uma mudança de variáveis e o método de expansão assintótica a derivação macroscópica é conduzida. Resultados do modelo proposto são usados para salientar a importância dos efeitos de acoplamento sobre a transdução mecânica da remodelagem de ossos compactados.
Modelling reactive transport in a phosphogypsum dump, Venezia, Italia
Calcara, Massimo; Borgia, Andrea; Cattaneo, Laura; Bartolo, Sergio; Clemente, Gianni; Glauco Amoroso, Carlo; Lo Re, Fabio; Tozzato, Elena
2013-04-01
We develop a reactive-transport porous media flow model for a phosphogypsum dump located on the intertidal deposits of the Venetian Lagoon: 1. we construct a complex conceptual and geologic model from field data using the GMS™ graphical user interface; 2. the geological model is mapped onto a rectangular MODFLOW grid; 3. using the TMT2 FORTRAN90 code we translate this grid into the MESH, INCON and GENER input files for the TOUGH2 series of codes; 4. we run TOUGH-REACT to model flow and reactive transport in the dump and the sediments below it. The model includes 3 different dump materials (phosphogypsum, bituminous and hazardous wastes) with the pores saturated by specific fluids. The sediments below the dump are formed by an intertidal sequence of calcareous sands and silts, in addition to clays and organic deposits, all of which are initially saturated with lagoon salty waters. The recharge rain-water dilutes the dump fluids. In turn, the percolates from the dump react with the underlying sediments and the sea water that saturates them. Simulation results have been compared with chemical sampled analyses. In fact, in spite of the simplicity of our model we are able to show how the pH becomes neutral at a short distance below the dump, a fact observed during aquifer monitoring. The spatial and temporal evolution of dissolution and precipitation reactions occur in our model much alike reality. Mobility of some elements, such as divalent iron, are reduced by specific and concurrent conditions of pH from near-neutrality to moderately high values and positive redox potential; opposite conditions favour mobility of potentially toxic metals such as Cr, As Cd and Pb. Vertical movement are predominant. Trend should be therefore heavily influenced by pH and Eh values. If conditions are favourable to mobility, concentration of these substances in the bottom strata could be high. However, simulation suggest that the sediments tend to reduce the transport potential of
Unsteady Flow in a Supersonic Turbine with Variable Specific Heats
Dorney, Daniel J.; Griffin, Lisa W.; Huber, Frank; Sondak, Douglas L.; Turner, James (Technical Monitor)
2001-01-01
Modern high-work turbines can be compact, transonic, supersonic, counter-rotating, or use a dense drive gas. The vast majority of modern rocket turbine designs fall into these Categories. These turbines usually have large temperature variations across a given stage, and are characterized by large amounts of flow unsteadiness. The flow unsteadiness can have a major impact on the turbine performance and durability. For example, the Space Transportation Main Engine (STME) fuel turbine, a high work, transonic design, was found to have an unsteady inter-row shock which reduced efficiency by 2 points and increased dynamic loading by 24 percent. The Revolutionary Reusable Technology Turbopump (RRTT), which uses full flow oxygen for its drive gas, was found to shed vortices with such energy as to raise serious blade durability concerns. In both cases, the sources of the problems were uncovered (before turbopump testing) with the application of validated, unsteady computational fluid dynamics (CFD) to the designs. In the case of the RRTT and the Alternate Turbopump Development (ATD) turbines, the unsteady CFD codes have been used not just to identify problems, but to guide designs which mitigate problems due to unsteadiness. Using unsteady flow analyses as a part of the design process has led to turbine designs with higher performance (which affects temperature and mass flow rate) and fewer dynamics problems. One of the many assumptions made during the design and analysis of supersonic turbine stages is that the values of the specific heats are constant. In some analyses the value is based on an average of the expected upstream and downstream temperatures. In stages where the temperature can vary by 300 to 500 K, however, the assumption of constant fluid properties may lead to erroneous performance and durability predictions. In this study the suitability of assuming constant specific heats has been investigated by performing three-dimensional unsteady Navier
On highly focused supersonic microjets
Tagawa, Yoshiyuki; Willem, Claas; Peters, Ivo R; van der Meer, Deveraj; Sun, Chao; Prosperetti, Andrea; Lohse, Detlef
2011-01-01
By focusing a laser pulse in a liquid-filled glass-microcapillary open at one end, a small mass of liquid is instantaneously vapourised. This leads to a shock wave which travels towards the concave free surface where it generates a high-speed microjet. The initial shape of the meniscus plays a dominant role in the process. The velocity of the jet can reach supersonic speeds up to 850\\,m/s while maintaining a very sharp geometry. The entire evolution of the jet is observed by high-speed recordings of up to $10^6\\,$fps. A parametric study of the jet velocity as a function of the contact angle of the liquid-glass interface, the energy absorbed by the liquid, the diameter of the capillary tube, and the distance between the laser focus and the free surface is performed, and the results are rationalised. The method could be used for needle-free injection of vaccines or drugs.
The secret to successful solute-transport modeling
Konikow, L.F.
2011-01-01
Modeling subsurface solute transport is difﬁcult—more so than modeling heads and ﬂows. The classical governing equation does not always adequately represent what we see at the ﬁeld scale. In such cases, commonly used numerical models are solving the wrong equation. Also, the transport equation is hyperbolic where advection is dominant, and parabolic where hydrodynamic dispersion is dominant. No single numerical method works well for all conditions, and for any given complex ﬁeld problem, where seepage velocity is highly variable, no one method will be optimal everywhere. Although we normally expect a numerically accurate solution to the governing groundwater-ﬂow equation, errors in concentrations from numerical dispersion and/or oscillations may be large in some cases. The accuracy and efﬁciency of the numerical solution to the solute-transport equation are more sensitive to the numerical method chosen than for typical groundwater-ﬂow problems. However, numerical errors can be kept within acceptable limits if sufﬁcient computational effort is expended. But impractically long
Realtime capable first principle based modelling of tokamak turbulent transport
Citrin, Jonathan; Breton, Sarah; Felici, Federico; Imbeaux, Frederic; Redondo, Juan; Aniel, Thierry; Artaud, Jean-Francois; Baiocchi, Benedetta; Bourdelle, Clarisse; Camenen, Yann; Garcia, Jeronimo
2015-11-01
Transport in the tokamak core is dominated by turbulence driven by plasma microinstabilities. When calculating turbulent fluxes, maintaining both a first-principle-based model and computational tractability is a strong constraint. We present a pathway to circumvent this constraint by emulating quasilinear gyrokinetic transport code output through a nonlinear regression using multilayer perceptron neural networks. This recovers the original code output, while accelerating the computing time by five orders of magnitude, allowing realtime applications. A proof-of-principle is presented based on the QuaLiKiz quasilinear transport model, using a training set of five input dimensions, relevant for ITG turbulence. The model is implemented in the RAPTOR real-time capable tokamak simulator, and simulates a 300s ITER discharge in 10s. Progress in generalizing the emulation to include 12 input dimensions is presented. This opens up new possibilities for interpretation of present-day experiments, scenario preparation and open-loop optimization, realtime controller design, realtime discharge supervision, and closed-loop trajectory optimization.
Anisotropic Mesoscale Eddy Transport in Ocean General Circulation Models
Reckinger, S. J.; Fox-Kemper, B.; Bachman, S.; Bryan, F.; Dennis, J.; Danabasoglu, G.
2014-12-01
Modern climate models are limited to coarse-resolution representations of large-scale ocean circulation that rely on parameterizations for mesoscale eddies. The effects of eddies are typically introduced by relating subgrid eddy fluxes to the resolved gradients of buoyancy or other tracers, where the proportionality is, in general, governed by an eddy transport tensor. The symmetric part of the tensor, which represents the diffusive effects of mesoscale eddies, is universally treated isotropically in general circulation models. Thus, only a single parameter, namely the eddy diffusivity, is used at each spatial and temporal location to impart the influence of mesoscale eddies on the resolved flow. However, the diffusive processes that the parameterization approximates, such as shear dispersion, potential vorticity barriers, oceanic turbulence, and instabilities, typically have strongly anisotropic characteristics. Generalizing the eddy diffusivity tensor for anisotropy extends the number of parameters to three: a major diffusivity, a minor diffusivity, and the principal axis of alignment. The Community Earth System Model (CESM) with the anisotropic eddy parameterization is used to test various choices for the newly introduced parameters, which are motivated by observations and the eddy transport tensor diagnosed from high resolution simulations. Simply setting the ratio of major to minor diffusivities to a value of five globally, while aligning the major axis along the flow direction, improves biogeochemical tracer ventilation and reduces global temperature and salinity biases. These effects can be improved even further by parameterizing the anisotropic transport mechanisms in the ocean.
Locatelli, R.; Bousquet, P.; Chevallier, F.; Fortems-Cheney, A.; Szopa, S.; Saunois, M.; Agusti-Panareda, A.; Bergmann, D.; Bian, H.; Cameron-Smith, P.; Chipperfield, M.P.; Gloor, E.; Houweling, S.; Kawa, S.R.; Krol, M.C.; Patra, P.K.; Prinn, R.G.; Rigby, M.; Saito, R.; Wilson, C.
2013-01-01
A modelling experiment has been conceived to assess the impact of transport model errors on methane emissions estimated in an atmospheric inversion system. Synthetic methane observations, obtained from 10 different model outputs from the international TransCom-CH4 model inter-comparison exercise, ar
Mathematical modeling of normal pharyngeal bolus transport: a preliminary study.
Chang, M W; Rosendall, B; Finlayson, B A
1998-07-01
Dysphagia (difficulty in swallowing) is a common clinical symptom associated with many diseases, such as stroke, multiple sclerosis, neuromuscular diseases, and cancer. Its complications include choking, aspiration, malnutrition, cachexia, and dehydration. The goal in dysphagia management is to provide adequate nutrition and hydration while minimizing the risk of choking and aspiration. It is important to advance the individual toward oral feeding in a timely manner to enhance the recovery of swallowing function and preserve the quality of life. Current clinical assessments of dysphagia are limited in providing adequate guidelines for oral feeding. Mathematical modeling of the fluid dynamics of pharyngeal bolus transport provides a unique opportunity for studying the physiology and pathophysiology of swallowing. Finite element analysis (FEA) is a special case of computational fluid dynamics (CFD). In CFD, the flow of a fluid in a space is modeled by covering the space with a grid and predicting how the fluid moves from grid point to grid point. FEA is capable of solving problems with complex geometries and free surfaces. A preliminary pharyngeal model has been constructed using FEA. This model incorporates literature-reported, normal, anatomical data with time-dependent pharyngeal/upper esophageal sphincter (UES) wall motion obtained from videofluorography (VFG). This time-dependent wall motion can be implemented as a moving boundary condition in the model. Clinical kinematic data can be digitized from VFG studies to construct and test the mathematical model. The preliminary model demonstrates the feasibility of modeling pharyngeal bolus transport, which, to our knowledge, has not been attempted before. This model also addresses the need and the potential for CFD in understanding the physiology and pathophysiology of the pharyngeal phase of swallowing. Improvements of the model are underway. Combining the model with individualized clinical data should potentially
Analysis of Intelligent Transportation Systems Using Model-Driven Simulations
Directory of Open Access Journals (Sweden)
Alberto Fernández-Isabel
2015-06-01
Full Text Available Intelligent Transportation Systems (ITSs integrate information, sensor, control, and communication technologies to provide transport related services. Their users range from everyday commuters to policy makers and urban planners. Given the complexity of these systems and their environment, their study in real settings is frequently unfeasible. Simulations help to address this problem, but present their own issues: there can be unintended mistakes in the transition from models to code; their platforms frequently bias modeling; and it is difficult to compare works that use different models and tools. In order to overcome these problems, this paper proposes a framework for a model-driven development of these simulations. It is based on a specific modeling language that supports the integrated specification of the multiple facets of an ITS: people, their vehicles, and the external environment; and a network of sensors and actuators conveniently arranged and distributed that operates over them. The framework works with a model editor to generate specifications compliant with that language, and a code generator to produce code from them using platform specifications. There are also guidelines to help researchers in the application of this infrastructure. A case study on advanced management of traffic lights with cameras illustrates its use.
Analysis of Intelligent Transportation Systems Using Model-Driven Simulations
Fernández-Isabel, Alberto; Fuentes-Fernández, Rubén
2015-01-01
Intelligent Transportation Systems (ITSs) integrate information, sensor, control, and communication technologies to provide transport related services. Their users range from everyday commuters to policy makers and urban planners. Given the complexity of these systems and their environment, their study in real settings is frequently unfeasible. Simulations help to address this problem, but present their own issues: there can be unintended mistakes in the transition from models to code; their platforms frequently bias modeling; and it is difficult to compare works that use different models and tools. In order to overcome these problems, this paper proposes a framework for a model-driven development of these simulations. It is based on a specific modeling language that supports the integrated specification of the multiple facets of an ITS: people, their vehicles, and the external environment; and a network of sensors and actuators conveniently arranged and distributed that operates over them. The framework works with a model editor to generate specifications compliant with that language, and a code generator to produce code from them using platform specifications. There are also guidelines to help researchers in the application of this infrastructure. A case study on advanced management of traffic lights with cameras illustrates its use. PMID:26083232
Updated Delft Mass Transport model DMT-2: computation and validation
Hashemi Farahani, Hassan; Ditmar, Pavel; Inacio, Pedro; Klees, Roland; Guo, Jing; Guo, Xiang; Liu, Xianglin; Zhao, Qile; Didova, Olga; Ran, Jiangjun; Sun, Yu; Tangdamrongsub, Natthachet; Gunter, Brian; Riva, Ricardo; Steele-Dunne, Susan
2014-05-01
A number of research centers compute models of mass transport in the Earth's system using primarily K-Band Ranging (KBR) data from the Gravity Recovery And Climate Experiment (GRACE) satellite mission. These models typically consist of a time series of monthly solutions, each of which is defined in terms of a set of spherical harmonic coefficients up to degree 60-120. One of such models, the Delft Mass Transport, release 2 (DMT-2), is computed at the Delft University of Technology (The Netherlands) in collaboration with Wuhan University. An updated variant of this model has been produced recently. A unique feature of the computational scheme designed to compute DMT-2 is the preparation of an accurate stochastic description of data noise in the frequency domain using an Auto-Regressive Moving-Average (ARMA) model, which is derived for each particular month. The benefits of such an approach are a proper frequency-dependent data weighting in the data inversion and an accurate variance-covariance matrix of noise in the estimated spherical harmonic coefficients. Furthermore, the data prior to the inversion are subject to an advanced high-pass filtering, which makes use of a spatially-dependent weighting scheme, so that noise is primarily estimated on the basis of data collected over areas with minor mass transport signals (e.g., oceans). On the one hand, this procedure efficiently suppresses noise, which are caused by inaccuracies in satellite orbits and, on the other hand, preserves mass transport signals in the data. Finally, the unconstrained monthly solutions are filtered using a Wiener filter, which is based on estimates of the signal and noise variance-covariance matrices. In combination with a proper data weighting, this noticeably improves the spatial resolution of the monthly gravity models and the associated mass transport models.. For instance, the computed solutions allow long-term negative trends to be clearly seen in sufficiently small regions notorious
Energy Technology Data Exchange (ETDEWEB)
Reimus, Paul W [Los Alamos National Laboratory
2011-01-03
Transport parameter cross correlations are rarely considered in models used to predict radionuclide transport in natural systems. In this paper, it is shown that parameter cross correlations could have a significant impact on radionuclide transport predictions in saturated media. In fractured rock, the positive correlation between fracture apertures and groundwater residence times is shown to result in significantly less retardation due to matrix diffusion than is predicted without the correlation. The suppression of matrix diffusion is further amplified by a tendency toward larger apertures, smaller matrix diffusion coefficients, and less sorption capacity in rocks of lower matrix porosity. In a hypothetical example, strong cross correlations between these parameters result in a decrease in predicted radionuclide travel times of an order of magnitude or more relative to travel times calculated with uncorrelated parameters. In porous media, expected correlations between permeability, porosity, and sorption capacity also result in shorter predicted travel times than when the parameters are assumed to be uncorrelated. Individual parameter standard deviations can also have a significant influence on predicted radionuclide travel times, particularly when cross correlations are considered.
Uranium transport in a crushed granodiorite: experiments and reactive transport modeling.
Dittrich, T M; Reimus, P W
2015-01-01
The primary objective of this study was to develop and demonstrate an experimental method to refine and better parameterize process models for reactive contaminant transport in aqueous subsurface environments and to reduce conservatism in such models without attempting to fully describe the geochemical system. Uranium was used as an example of a moderately adsorbing contaminant because of its relevance in geologic disposal of spent nuclear fuel. A fractured granodiorite from the Grimsel Test Site (GTS) in Switzerland was selected because this system has been studied extensively and field experiments have been conducted with radionuclides including uranium. We evaluated the role of pH, porous media size fraction, and flow interruptions on uranium transport. Rock cores drilled from the GTS were shipped to Los Alamos National Laboratory, characterized by x-ray diffraction and optical microscopy, and used in uranium batch sorption and column breakthrough experiments. A synthetic water was prepared that represented the porewater that would be present after groundwater interacts with bentonite backfill material near a nuclear waste package. Uranium was conservatively transported at pH8.8. Significant adsorption and subsequent desorption was observed at pH ~7, with long desorption tails resulting after switching the column injection solution to uranium-free groundwater. Our experiments were designed to better interrogate this slow desorption behavior. A three-site model predicted sorption rate constants for a pH7.2 solution with a 75-150 μm granodiorite fraction to be 3.5, 0.012, and 0.012 mL/g-h for the forward reactions and 0.49, 0.0025, and 0.001 h(-1) for the reverse reactions. Surface site densities were 1.3, 0.042, and 0.042 μmol/g for the first, second, and third sites, respectively. 10-year simulations show that including a slow binding site increases the arrival time of a uranium pulse by ~70%.
Multiscale modelling of charge transport in organic electronic materials
Nelson, Jenny
2010-03-01
Charge transport in disordered organic semiconductors is controlled by a complex combination of phenomena that span a range of length and time scales. As a result, it is difficult to rationalize charge transport properties in terms of material parameters. Until now, efforts to improve charge mobilities in molecular semiconductors have proceeded largely by trial and error rather than through systematic design. However, recent developments have enabled the first predictive simulation studies of charge transport in disordered organic semiconductors. In this presentation we will show how a set of computational methods, namely molecular modelling methods to simulate molecular packing, quantum chemical calculations of charge transfer rates, and Monte Carlo simulations of charge transport can be used to reproduce experimental charge mobilities with few or no fitting parameters. Using case studies, we will show how such simulations can explain the relative values of electron and hole mobility and the effects of grain size, side chains and polymer molecular weight on charge mobility. Although currently applied to material systems of relatively high symmetry or well defined structure, this approach can be developed to address more complex systems such as multicomponent solids and conjugated polymers.
超-超引射器多目标优化设计%Multi-objective optimization of supersonic-supersonic ejector
Institute of Scientific and Technical Information of China (English)
陈钦; 陈吉明; 蔡光明; 任泽斌
2012-01-01
推导出了超-超引射器性能计算和优化设计模型,借助Pareto优胜、Pareto最优解和Pareto前端等概念,采用基于多目标进化/分解算法(MOEA/D)的多目标优化方法,计算得到超-超引射器多目标优化问题的Pareto前端,解决了超-超引射器多目标优化设计问题,并与常规参数分析方法进行了比较.结果表明:超超引射器性能影响参数相互关系复杂,增压比和引射系数作为引射器主要性能参数相互冲突,通过常规分析难以得到较清晰的设计准则,利用多目标优化设计方法可有效地辅助多属性决策和系统优化设计.%For supersonic-supersonic ejector, the design model and corresponding analysis were presented, and the relation of design parameters and the performance was partly revealed. The results revealed the confliction of two performance objectives and the complexity of the design problem. To clarify the entangled relation of design parameters and objectives and to afford facilities for the design process, the Pareto front(PF) concept was introduced and an MOEA/D algorithm was programmed to calculate the PFs of specific supersonic-supersonic ejector multi-objective optimization problems. The methodology adopted here proved to be effective and efficient for the supersonic-supersonic ejector design problem.
Cost damping and functional form in transport models
DEFF Research Database (Denmark)
Rich, Jeppe; Mabit, Stefan Lindhard
2015-01-01
take different forms and be represented as a non-linear-in-parameter form such as the well-known Box–Cox function. However, it could also be specified as non-linear-in-cost but linear-in-parameter forms, which are easier to estimate and improve model fit without increasing the number of parameters....... The specific contributions of the paper are as follows. Firstly, we discuss the phenomenon of cost damping in details and specifically why it occurs. Secondly, we provide a test of damping and an easy assessment of the (linear) damping rate for any variable by estimating two auxiliary linear models. This turns......Transport models allowing for cost damping are characterised by marginally decreasing cost sensitivities in demand. As a result, cost damping is a model extension of the simple linear-in-cost model requiring an appropriate non-linear link function between utility and cost. The link function may...
Mathematical modeling of urea transport in the kidney.
Layton, Anita T
2014-01-01
Mathematical modeling techniques have been useful in providing insights into biological systems, including the kidney. This article considers some of the mathematical models that concern urea transport in the kidney. Modeling simulations have been conducted to investigate, in the context of urea cycling and urine concentration, the effects of hypothetical active urea secretion into pars recta. Simulation results suggest that active urea secretion induces a "urea-selective" improvement in urine concentrating ability. Mathematical models have also been built to study the implications of the highly structured organization of tubules and vessels in the renal medulla on urea sequestration and cycling. The goal of this article is to show how physiological problems can be formulated and studied mathematically, and how such models may provide insights into renal functions.
A revised model of fluid transport optimization in Physarum polycephalum.
Bonifaci, Vincenzo
2017-02-01
Optimization of fluid transport in the slime mold Physarum polycephalum has been the subject of several modeling efforts in recent literature. Existing models assume that the tube adaptation mechanism in P. polycephalum's tubular network is controlled by the sheer amount of fluid flow through the tubes. We put forward the hypothesis that the controlling variable may instead be the flow's pressure gradient along the tube. We carry out the stability analysis of such a revised mathematical model for a parallel-edge network, proving that the revised model supports the global flow-optimizing behavior of the slime mold for a substantially wider class of response functions compared to previous models. Simulations also suggest that the same conclusion may be valid for arbitrary network topologies.
Impact of mineralogical heterogeneity on reactive transport modelling
Liu, Min; Shabaninejad, Mehdi; Mostaghimi, Peyman
2017-07-01
Impact of mineralogical heterogeneity of rocks in reactive modelling is investigated by applying a pore scale model based on the Lattice Boltzmann and Finite Volume Methods. Mass transport, chemical reaction and solid structure modification are included in the model. A two-dimensional mineral map of a sandstone rock is acquired using the imaging technique of QEMSCAN SEM with Energy-Dispersive X-ray Spectroscopy (EDS). The mineralogical heterogeneity is explored by conducting multi-mineral reaction simulations on images containing various minerals. The results are then compared with the prediction of single mineral dissolution modelling. Dissolution patterns and permeability variations of multi-mineral and single mineral reactions are presented. The errors of single mineral reaction modelling are also estimated. Numerical results show that mineralogical heterogeneity can cause significant errors in permeability prediction, if a uniform mineral distribution is assumed. The errors are smaller in high Péclet regimes than in low Péclet regimes in this sample.
Cost damping and functional form in transport models
DEFF Research Database (Denmark)
Rich, Jeppe; Mabit, Stefan Lindhard
2016-01-01
Transport models allowing for cost damping are characterised by marginally decreasing cost sensitivities in demand. As a result, cost damping is a model extension of the simple linear-in-cost model requiring an appropriate non-linear link function between utility and cost. The link function may...... take different forms and be represented as a non-linear-in-parameter form such as the well-known Box–Cox function. However, it could also be specified as non-linear-in-cost but linear-in-parameter forms, which are easier to estimate and improve model fit without increasing the number of parameters....... The specific contributions of the paper are as follows. Firstly, we discuss the phenomenon of cost damping in details and specifically why it occurs. Secondly, we provide a test of damping and an easy assessment of the (linear) damping rate for any variable by estimating two auxiliary linear models. This turns...
Silent and Efficient Supersonic Bi-Directional Flying Wing Project
National Aeronautics and Space Administration — We propose a Phase I study for a novel concept of a supersonic bi-directional (SBiDir) flying wing (FW) that has the potential to revolutionize supersonic flight...
Bhattarai, R.; Kalita, P. K.; Davidson, P. C.; Kuhlenschmidt, M. S.
2012-12-01
More than 3.5 million people die each year from a water related diseases in this world. Every 20 seconds, a child dies from a water-related illness. Even in a developed country like the United States, there have been at least 1870 outbreaks associated with drinking water during the period of 1920 to 2002, causing 883,806 illnesses. Most of these outbreaks are resulted due to the presence of microbial pathogens in drinking water. Rotavirus infection has been recognized as the most common cause of diarrhea in young children throughout the world. Laboratory experiments conducted at the University of Illinois have demonstrated that recovery of rotavirus has been significantly affected by climatic and soil-surface conditions like slope, soil types, and ground cover. The objective of this study is to simulate the fate and transport of Rotavirus in overland and near-surface flow using a process-based model. In order to capture the dynamics of sediment-bound pathogens, the Water Erosion Prediction Project (WEPP) is coupled with the pathogen transport model. Transport of pathogens in overland flow can be simulated mathematically by including terms for the concentration of the pathogens in the liquid phase (in suspension or free-floating) and the solid phase (adsorbed to the fine solid particles like clay and silt). Advection, adsorption, and decay processes are considered. The mass balance equations are solved using numerical technique to predict spatial and temporal changes in pathogen concentrations in two phases. Outputs from WEPP simulations (flow velocity, depth, saturated conductivity and the soil particle fraction exiting in flow) are transferred as input for the pathogen transport model. Three soil types and three different surface cover conditions have been used in the experimental investigations. Results from these conditions have been used in calibrating and validating the simulation results. Bare surface conditions have produced very good agreement between
Engineered Barrier System Degradation, Flow, and Transport Process Model Report
Energy Technology Data Exchange (ETDEWEB)
E.L. Hardin
2000-07-17
The Engineered Barrier System Degradation, Flow, and Transport Process Model Report (EBS PMR) is one of nine PMRs supporting the Total System Performance Assessment (TSPA) being developed by the Yucca Mountain Project for the Site Recommendation Report (SRR). The EBS PMR summarizes the development and abstraction of models for processes that govern the evolution of conditions within the emplacement drifts of a potential high-level nuclear waste repository at Yucca Mountain, Nye County, Nevada. Details of these individual models are documented in 23 supporting Analysis/Model Reports (AMRs). Nineteen of these AMRs are for process models, and the remaining 4 describe the abstraction of results for application in TSPA. The process models themselves cluster around four major topics: ''Water Distribution and Removal Model, Physical and Chemical Environment Model, Radionuclide Transport Model, and Multiscale Thermohydrologic Model''. One AMR (Engineered Barrier System-Features, Events, and Processes/Degradation Modes Analysis) summarizes the formal screening analysis used to select the Features, Events, and Processes (FEPs) included in TSPA and those excluded from further consideration. Performance of a potential Yucca Mountain high-level radioactive waste repository depends on both the natural barrier system (NBS) and the engineered barrier system (EBS) and on their interactions. Although the waste packages are generally considered as components of the EBS, the EBS as defined in the EBS PMR includes all engineered components outside the waste packages. The principal function of the EBS is to complement the geologic system in limiting the amount of water contacting nuclear waste. A number of alternatives were considered by the Project for different EBS designs that could provide better performance than the design analyzed for the Viability Assessment. The design concept selected was Enhanced Design Alternative II (EDA II).
Modelling of transport phenomena and defects in crystal growth processes
Indian Academy of Sciences (India)
S Pendurti; H Zhang; V Prasad
2001-02-01
A brief review of single crystal growth techniques and the associated problems is presented. Emphasis is placed on models for various transport and defect phenomena involoved in the growth process with the ultimate aim of integrating them into a comprehensive numerical model. The sources of dislocation nucleation in the growing crystal are discussed, and the propagation and multiplication of these under the action of thermal stresses is discussed. A brief description of a high-level numerical technique based on multiple adaptive grid generation and finite volume discretization is presented, followed by the result of a representative numerical simulation.
Jet propagation within a Linearized Boltzmann Transport model
Energy Technology Data Exchange (ETDEWEB)
Luo, Tan; He, Yayun [Key Laboratory of Quark and Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan 430079 (China); Wang, Xin-Nian [Key Laboratory of Quark and Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan 430079 (China); Nuclear Science Division, Mailstop 70R0319, Lawrence Berkeley National Laboratory, Berkeley, CA 94740 (United States); Zhu, Yan [Departamento de Física de Partículas and IGFAE, Universidade de Santiago de Compostela, E-15706 Santiago de Compostela, Galicia (Spain)
2014-12-15
A Linearized Boltzmann Transport (LBT) model has been developed for the study of parton propagation inside quark–gluon plasma. Both leading and thermal recoiled partons are tracked in order to include the effect of jet-induced medium excitation. In this talk, we present a study within the LBT model in which we implement the complete set of elastic parton scattering processes. We investigate elastic parton energy loss and their energy and length dependence. We further investigate energy loss and transverse shape of reconstructed jets. Contributions from the recoiled thermal partons and jet-induced medium excitations are found to have significant influences on the jet energy loss and transverse profile.
Transport Studies and Modeling in PEM Fuel Cells
Energy Technology Data Exchange (ETDEWEB)
Mittelsteadt, Cortney K. [Giner, Inc., Auburndale, MA (United States); Xu, Hui [Giner, Inc., Auburndale, MA (United States); Brawn, Shelly [Giner, Inc., Auburndale, MA (United States)
2014-07-30
This project’s aim was to develop fuel cell components (i.e. membranes, gas-diffusion media (GDM), bipolar plates and flow fields) that possess specific properties (i.e. water transport and conductivity). A computational fluid dynamics model was developed to elucidate the effect of certain parameters on these specific properties. Ultimately, the model will be used to determine sensitivity of fuel cell performance to component properties to determine limiting components and to guide research. We have successfully reached our objectives and achieved most of the milestones of this project. We have designed and synthesized a variety of hydrocarbon block polymer membranes with lower equivalent weight, structure, chemistry, phase separation and process conditions. These membranes provide a broad selection with optimized water transport properties. We have also designed and constructed a variety of devices that are capable of accurately measuring the water transport properties (water uptake, water diffusivity and electro-osmatic drag) of these membranes. These transport properties are correlated to the membranes’ structures derived from X-ray and microscopy techniques to determine the structure-property relationship. We successfully integrated hydrocarbon membrane MEAs with a current distribution board (CBD) to study the impact of hydrocarbon membrane on water transport in fuel cells. We have designed and fabricated various GDM with varying substrate, diffusivity and micro-porous layers (MPL) and characterized their pore structure, tortuosity and hydrophobicity. We have derived a universal chart (MacMullin number as function of wet proofing and porosity) that can be used to characterize various GDM. The abovementioned GDMs have been evaluated in operating fuel cells; their performance is correlated to various pore structure, tortuosity and hydrophobicity of the GDM. Unfortunately, determining a universal relationship between the MacMullin number and these properties
Numerical modelling of sediment transport in the Adriatic Sea
Directory of Open Access Journals (Sweden)
A. Guarnieri
2014-06-01
Full Text Available A new sediment transport model, considering currents, tides and waves is presented for the Adriatic Sea basin. The simulations concentrate on the winter of 2002–2003 because of field data availability and interesting intermittent processes occurrence. A process oriented analysis is performed to investigate the impact that Sirocco and Bora wind regimes have on sediment transport. The comparisons of the simulations with the observed data show that the model is capable to capture the main dynamics of sediment transport along the Italian coasts and the sediment concentration within the water column. This latter can reach values up to several g L−1, especially within the first centimetres above the bottom. The sediments are transported mainly southwards along the Italian coasts, consistently with the known literature results, except during Sirocco wind events, which can be responsible for reversing the coastal circulation in the northern area of the basin, and consequently the sediment transport. The resuspension of sediments is also related to the specific wave regimes induced by Bora and Sirocco, the former inducing resuspension events near the coasts while the latter causing a more diffused resuspension regime in the Northern Adriatic basin. Beside the realistic representation of short timescales resuspension/deposition events due to storms, the model was also used to investigate persistent erosion or deposition areas in the Adriatic Sea. Two main depocenters were identified: one, very pronounced, in the surroundings of the Po river delta, and another one a few kilometres off the coast in front of the Ancona promontory. A third region of accumulation, even if less intense, was found to be offshore the southernmost limit of the Gargano region. On the contrary the whole western coast within a distance of a few kilometres from the shore was found to be subject to prevailing erosion. The comparison with observed accumulation and erosion data shows
Meteorological implementation issues in chemistry and transport models
Directory of Open Access Journals (Sweden)
S. E. Strahan
2006-01-01
Full Text Available Offline chemistry and transport models (CTMs are versatile tools for studying composition and climate issues requiring multi-decadal simulations. They are computationally fast compared to coupled chemistry climate models, making them well-suited for integrating sensitivity experiments necessary for understanding model performance and interpreting results. The archived meteorological fields used by CTMs can be implemented with lower horizontal or vertical resolution than the original meteorological fields in order to shorten integration time, but the effects of these shortcuts on transport processes must be understood if the CTM is to have credibility. In this paper we present a series of sensitivity experiments on a CTM using the Lin and Rood advection scheme, each differing from another by a single feature of the wind field implementation. Transport effects arising from changes in resolution and model lid height are evaluated using process-oriented diagnostics that intercompare CH4, O3, and age tracer carried in the simulations. Some of the diagnostics used are derived from observations and are shown as a reality check for the model. Processes evaluated include tropical ascent, tropical-midlatitude exchange, poleward circulation in the upper stratosphere, and the development of the Antarctic vortex. We find that faithful representation of stratospheric transport in this CTM is possible with a full mesosphere, ~1 km resolution in the lower stratosphere, and relatively low vertical resolution (>4 km spacing in the middle stratosphere and above, but lowering the lid from the upper to lower mesosphere leads to less realistic constituent distributions in the upper stratosphere. Ultimately, this affects the polar lower stratosphere, but the effects are greater for the Antarctic than the Arctic. The fidelity of lower stratospheric transport requires realistic tropical and high latitude mixing barriers which are produced at 2°×2.5°, but not lower
Simulations and Transport Models for Imbalanced Magnetohydrodynamic Turbulence
Ng, Chung-Sang; Dennis, T.
2016-10-01
We present results from a series of three-dimensional simulations of magnetohydrodynamic (MHD) turbulence based on reduced MHD equations. Alfven waves are launched from both ends of a long tube along the background uniform magnetic field so that turbulence develops due to collision between counter propagating Alfven waves in the interior region. Waves are launched randomly with specified correlation time Tc such that the length of the tube, L, is greater than (but of the same order of) VA *Tc such that turbulence can fill most of the tube. While waves at both ends are launched with equal power, turbulence generated is imbalanced in general, with normalized cross-helicity gets close to -1 at one end and 1 at the other end. This simulation setup allows easier comparison of turbulence properties with one-dimensional turbulence transport models, which have been applied rather successfully in modeling solar wind turbulence. However, direct comparison of such models with full simulations of solar wind turbulence is difficult due to much higher level of complexity involved. We will present our latest simulations at different resolutions with decreasing dissipation (resistivity and viscosity) levels and compare with model outputs from turbulence transport models. This work is supported by a NASA Grant NNX15AU61G.
Building 235-F Goldsim Fate And Transport Model
Energy Technology Data Exchange (ETDEWEB)
Taylor, G. A.; Phifer, M. A.
2012-09-14
Savannah River National Laboratory (SRNL) personnel, at the request of Area Completion Projects (ACP), evaluated In-Situ Disposal (ISD) alternatives that are under consideration for deactivation and decommissioning (D&D) of Building 235-F and the Building 294-2F Sand Filter. SRNL personnel developed and used a GoldSim fate and transport model, which is consistent with Musall 2012, to evaluate relative to groundwater protection, ISD alternatives that involve either source removal and/or the grouting of portions or all of 235-F. This evaluation was conducted through the development and use of a Building 235-F GoldSim fate and transport model. The model simulates contaminant release from four 235-F process areas and the 294-2F Sand Filter. In addition, it simulates the fate and transport through the vadose zone, the Upper Three Runs (UTR) aquifer, and the Upper Three Runs (UTR) creek. The model is designed as a stochastic model, and as such it can provide both deterministic and stochastic (probabilistic) results. The results show that the median radium activity concentrations exceed the 5 ?Ci/L radium MCL at the edge of the building for all ISD alternatives after 10,000 years, except those with a sufficient amount of inventory removed. A very interesting result was that grouting was shown to basically have minimal effect on the radium activity concentration. During the first 1,000 years grouting may have some small positive benefit relative to radium, however after that it may have a slightly deleterious effect. The Pb-210 results, relative to its 0.06 ?Ci/L PRG, are essentially identical to the radium results, but the Pb-210 results exhibit a lesser degree of exceedance. In summary, some level of inventory removal will be required to ensure that groundwater standards are met.
Modeling atrazine transport in soil columns with HYDRUS-1D
Directory of Open Access Journals (Sweden)
John Leju CELESTINO LADU
2011-09-01
Full Text Available Both physical and chemical processes affect the fate and transport of herbicides. It is useful to simulate these processes with computer programs to predict solute movement. Simulations were run with HYDRUS-1D to identify the sorption and degradation parameters of atrazine through calibration from the breakthrough curves (BTCs. Data from undisturbed and disturbed soil column experiments were compared and analyzed using the dual-porosity model. The study results show that the values of dispersivity are slightly lower in disturbed columns, suggesting that the more heterogeneous the structure is, the higher the dispersivity. Sorption parameters also show slight variability, which is attributed to the differences in soil properties, experimental conditions and methods, or other ecological factors. For both of the columns, the degradation rates were similar. Potassium bromide was used as a conservative non-reactive tracer to characterize the water movement in columns. Atrazine BTCs exhibited significant tailing and asymmetry, indicating non-equilibrium sorption during solute transport. The dual-porosity model was verified to best fit the BTCs of the column experiments. Greater or lesser concentration of atrazine spreading to the bottom of the columns indicated risk of groundwater contamination. Overall, HYDRUS-1D successfully simulated the atrazine transport in soil columns.
Atomistic modeling of phonon transport in turbostratic graphitic structures
Mao, Rui; Chen, Yifeng; Kim, Ki Wook
2016-05-01
Thermal transport in turbostratic graphitic systems is investigated by using an atomistic analytical model based on the 4th-nearest-neighbor force constant approximation and a registry-dependent interlayer potential. The developed model is shown to produce an excellent agreement with the experimental data and ab initio results in the calculation of bulk properties. Subsequent analysis of phonon transport in combination with the Green's function method illustrates the significant dependence of key characteristics on the misorientation angle, clearly indicating the importance of this degree of freedom in multi-stacked structures. Selecting three angles with the smallest commensurate unit cells, the thermal resistance is evaluated at the twisted interface between two AB stacked graphite. The resulting values in the range of 35 × 10-10 K m2/W to 116 × 10-10 K m2/W are as large as those between two dissimilar material systems such as a metal and graphene. The strong rotational effect on the cross-plane thermal transport may offer an effective means of phonon engineering for applications such as thermoelectric materials.
Oil Refinery Supply Chain Modelling Using Pipe Transportation Simulator
Directory of Open Access Journals (Sweden)
Jakub Dyntar
2012-03-01
Full Text Available This paper describes an application of Pipe Transportation Simulator (PTS in oil refinery supply chain modelling. We develop the simulator in Witness simulation software environment using MS Excel for input data loading and outputs upgrading. PTS is particularly suitable for “what-if” analysis in the crude oil, fuels or gas supply chains where the products are transported among warehouses and refineries through the pipe lines. To discuss the basic functionality of proposed simulator we employ PTS to simulate a real oil refinery supply chain consisting of 16 warehouses and 3 refineries placed in the Czech Republic and Slovakia. The refineries and warehouses are connected together with 21 pipe lines. PTS is used to verify a plan of fuels movements among warehouses and refineries as well as a plan of repairs of certain pipe lines in the selected time period of the length of 30 days.
Modelling of Sediment Transport in Beris Fishery Port
Directory of Open Access Journals (Sweden)
Samira Ardani
2015-06-01
Full Text Available In this paper, the large amount of sedimentation and the resultant shoreline advancements at the breakwaters of Beris Fishery Port are studied. A series of numerical modeling of waves, sediment transport, and shoreline changes were conducted to predict the complicated equilibrium shoreline. The outputs show that the nearshore directions of wave components are not perpendicular to the coast which reveals the existence of longshore currents and consequently sediment transport along the bay. Considering the dynamic equilibrium condition of the bay, the effect of the existing sediment resources in the studied area is also investigated. The study also shows that in spite of the change of the diffraction point of Beris Bay after the construction of the fishery port, the bay is approaching its dynamic equilibrium condition, and the shoreline advancement behind secondary breakwater will stop before blocking the entrance of the port. The probable solutions to overcome the sedimentation problem at the main breakwater are also discussed.
Compendium of Material Composition Data for Radiation Transport Modeling
Energy Technology Data Exchange (ETDEWEB)
Williams, Ralph G.; Gesh, Christopher J.; Pagh, Richard T.
2006-10-31
Computational modeling of radiation transport problems including homeland security, radiation shielding and protection, and criticality safety all depend upon material definitions. This document has been created to serve two purposes: 1) to provide a quick reference of material compositions for analysts and 2) a standardized reference to reduce the differences between results from two independent analysts. Analysts are always encountering a variety of materials for which elemental definitions are not readily available or densities are not defined. This document provides a location where unique or hard to define materials will be located to reduce duplication in research for modeling purposes. Additionally, having a common set of material definitions helps to standardize modeling across PNNL and provide two separate researchers the ability to compare different modeling results from a common materials basis.
A model of the sediment transport on a river network
Wang, Xu-Ming; Hao, Rui; Zhang, Jin-Feng; Huo, Jie
2007-03-01
A dynamical model is proposed to mimic the sediment transport on a river network. A river can be divided into some segments. For the ith segment the schlepping sediment ability of the flow may be scouring or depositing, which is influenced by that of the (i- 1)th segment. In order to compare our model simulation results with the empirical data obtained in Yellow River, the model is equipped with an experiential relation between the flow rate and the depositing rate of the Yellow River. After this, the simulation results show an excellent agreement with the empirical conclusions obtained with the upper and middle parts of Yellow River when it is in the low-water periods (for instance, in Dec., Jan. and Feb.). This indicates that our model may successfully describe the scouring-depositing of river networks.
Qubit Transport Model for Unitary Black Hole Evaporation without Firewalls
Osuga, Kento
2016-01-01
We give an explicit toy qubit transport model for transferring information from the gravitational field of a black hole to the Hawking radiation by a continuous unitary transformation of the outgoing radiation and the black hole gravitational field. The model has no firewalls or other drama at the event horizon and fits the set of six physical constraints that Giddings has proposed for models of black hole evaporation. It does utilize nonlocal qubits for the gravitational field but assumes that the radiation interacts locally with these nonlocal qubits, so in some sense the nonlocality is confined to the gravitational sector. Although the qubit model is too crude to be quantitively correct for the detailed spectrum of Hawking radiation, it fits qualitatively with what is expected.
System convergence in transport models: algorithms efficiency and output uncertainty
DEFF Research Database (Denmark)
Rich, Jeppe; Nielsen, Otto Anker
2015-01-01
much in the literature. The paper first investigates several variants of the Method of Successive Averages (MSA) by simulation experiments on a toy-network. It is found that the simulation experiments produce support for a weighted MSA approach. The weighted MSA approach is then analysed on large......-scale in the Danish National Transport Model (DNTM). It is revealed that system convergence requires that either demand or supply is without random noise but not both. In that case, if MSA is applied to the model output with random noise, it will converge effectively as the random effects are gradually dampened...... in the MSA process. In connection to DNTM it is shown that MSA works well when applied to travel-time averaging, whereas trip averaging is generally infected by random noise resulting from the assignment model. The latter implies that the minimum uncertainty in the final model output is dictated...