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We consider the equations of a rotating incompressible non-Newtonian fluid flow of grade two in a three dimensional torus. We prove two different results of global existence of strong solutions. In the first case, we consider that the elasticity coefficient α is arbitrary and we suppose that the third components of the vertical average of the initial data and of the forcing term are small compared to the horizontal components. In the second case, we consider a forcing term and initial data of arbitrary size but we restrict the size of α. In both cases, we show that the limit system is composed of a linear system and a second grade fluid system with two variables and three components.

Background Parabolic trough solar collectors (PTSCs) are used to focus the solar rays on absorber tube. The main aim of this paper is to investigate the effects of applying novel corrugated absorber tube filled with hybrid nanofluid on energy efficiency of a novel double fluid PTSC to achieve the maximum energy efficiency value. Method The Eulerian-Eulerian two-phase model is employed for modelling the PTSC and evaluating its energy efficiency. Numerical study is carried out for different values of Reynolds number (Re), nanoparticles volume fraction (ϕ) and geometrical parameters of novel corrugated absorber tube. Findings It is found that usage of corrugated absorber tube has a significant effect on energy efficiency of single- or double fluid parabolic trough solar collectors. Besides it is understood that usage of double fluid system for collector with smooth channel can also increase the energy efficiency, but not more than using corrugated channel for single fluid collector. Moreover, usage of double fluid system at higher Re is also efficient. The results also show that the efficiency of the PTSC enhances with increasing the nanoparticles concentration. Finally, the optimum model of corrugated absorber tube is presented.

We present regularized phase flield model for description of threephase «fluid–fluid–solid» system, where solid body obeys elastic rheology. It is assumed that one of the liquid phases chemically interacts with the solid one. As the corresponding equations of chemical kinetics, simple model equations describing a bimolecular reaction are considered. A feature of the model under consideration is its preliminary regularization according to quasi-hydrodynamic technique. A fully explicit finite difference approximation of this model is presented. Results of a simulation in two-dimensional setting are presented.

We numerically investigate the linear instability problem of Poiseuille flow in a channel partially filled with a porous medium on the bottom side. We are primarily interested in the influence of the interface momentum distribution including stress continuity and jump interface conditions. A spectral collocation method is applied in solving the fully coupled instability problem arising from the adjacent porous and free channel flows. The results show that the “interface stress coefficient” in a negative range has a larger effect on the trajectory of the eigenvalues than that in the positive range, especially the most unstable mode. Moreover, with a low permeability in the porous region, the interface momentum distribution has less effect on the stability of core flow. And when the “interface stress coefficient” is equal to its minimum negative value, the flow passing through the channel is at its most stable state. If the “interface stress coefficient” varies in a positive range, the degree of fluid stability is predicted to slightly diminish due to stress continuity condition at the interface.

In this paper, we discuss the interfacial internal waves with a rigid boundary in a three-layer fluid system, where the density of the upper layer fluid is smaller than that of the lower layer. With the Lagrangian matching conditions at the interfaces, the first-order solutions, the second-order solutions and the third-order asymptotic solutions for the interfacial internal waves are obtained in the Lagrangian description using the perturbation method, and the mass transport velocity, the wave frequency, the mean level and the particle trajectory are also given. The results show that the discontinuities across the interfaces appear for the mass transport velocity, wave frequency and mean level, but we find that these discontinuities may disappear if the water depth ratio and the density ratio of the three layer fluids satisfy certain conditions.

The kinetics of flow of a viscous incompressible fluid between two closely lying parabola-shaped inserts (plates) rotating with the same angular velocity around a common axis is studied. The flow, in the inter-plate gap of the separator drum, of a weakly concentrated liquid + solid type of two-phase fluid is modeled. Based on the postulates of the theory of fluid flows in “sliding” mode, the internal problem of hydrodynamics along the flow in the chosen working space of the centrifugal equipment is proposed to be solved in linear formulation. For an isolated small spherical particle moving in the flow, the critical diameter of the particle (settling in the working space of the separator), which determines the separation efficiency, is calculated by solving the external problem of hydrodynamics.

This paper presents an implicit conjugate heat transfer (CHT) model designed for 1D systems of both solids and fluids. It demonstrates that this approach can be extended to include 2D and 3D elements being co-solved in a 2D or 3D thermal product. The approach is applied to a simple analytical problem and then to a Secondary Air Cavity within a Gas Turbine to illustrate the potential of this technique to be applied to more complex thermo-fluid simulations. Such simulations are important in trade off studies to balance minimizing engine bleed whilst ensuring sufficient cooling. The benefits of this CHT model are presented by comparison with the traditional approach of explicit co-simulation in which the temperature from the fluid domain is applied as a boundary condition to the thermal simulation and heat flux from the thermal simulation is applied as a boundary condition to the fluid domain (or vice versa). The ability to replace 1D elements with 2D or 3D elements allows model continuity from conceptual to detailed design and the reverse process potentially offers a route for model reduction later in lifecycle to support operation and maintenance through the use of an executable digital twin.

The physical configuration of the problem is a porous-fluid layer which is horizontally unbounded, in the presence of uniform heat source/sink in the layers enclosed by adiabatic and isothermal boundaries. The problem of double diffusive Bènard-Marangoni convection in the presence of vertical magnetic field is investigated on this porous-fluid system for non-Darcian case and is subjected to uniform and nonuniform temperature gradients. The eigenvalue, thermal Marangoni number is obtained in the closed form for lower rigid and upper free with surface tension velocity boundary conditions. The influence of various parameters on the Marangoni number against thermal ratio is discussed. It is observed that the heat absorption in the fluid layer and the applied magnetic field play an important role in controlling Benard-Marangoni convection. The parameters which direct this convection are determined and the effect of porous parameter is relatively interesting.

We experimentally investigate internal coastal Kelvin waves in a two-layer fluid system on a rotating table. Waves in our system propagate in the prograde direction and are exponentially localized near the boundary. Our experiments verify the theoretical dispersion relation of the wave and show that the wave amplitude decays exponentially along the propagation direction. We further demonstrate that the waves can robustly propagate along boundaries of complex geometries without being scattered and that adding obstacles to the wave propagation path does not cause additional attenuation., 5 figures; to appear in PRF

This paper presents a novel approach that couples system modelling of both the thermo-fluid system and the thermal solid system by modelling conjugate heat transfer within a single 1D system analysis solver and applies it to the Secondary Air System of a Gas Turbine. The Secondary Air System design has to balance minimizing engine bleed whilst ensuring sufficient cooling. To achieve this, designers model both the secondary air flow and the temperature distribution in solid components. System CFD tools like Simcenter Flomaster may be used to solve flow, pressure and temperature distributions and a 3D thermal solver used to perform the thermal analysis of the blade and disc solids. The thermal interaction between the secondary flow system and the solid components is a key part of the model and is known as conjugate heat transfer analysis (CHT). This approach is problematic early in the design cycle when detailed or stable geometry information may not be available for the 3D thermal tool. An approach that couples the modelling of both the thermo-fluid system and the thermal solid system within a single 1D/system analysis tool offers the advantage of faster modelling and consistent model accuracy of both fluid and solid components, especially in the early concept design stage. This 1D-CHT approach has been implemented within Simcenter Flomaster and validated using an idealized analytical solution. It is shown that the model can be applied to the analysis of gas turbine secondary air systems including cavity flows and thermal analysis of the rotor and stator discs that form the thermal boundary of these cavities using Simcenter Flomaster alone.

A stationary nonwetting droplet in a constricted tube can attain resonance in response to external seismic stimulation. Key parameters controlling droplet resonance are analyzed through a proposed theoretical model. The nonlinear effect of a fluid system on the resonance is also addressed.

Large-amplitude internal solitary waves in a two-layer fluid system with a free surface are investigated in this paper. Laboratory experiments on strongly nonlinear internal solitary waves with a free surface for a deep configuration are conducted. After comparing the experimental data with the results of the Miyata–Choi–Camassa model that includes the free-surface effects (MCC-FS), we find that the MCC-FS model does not calculate accurately the internal solitary waves with a free surface. Thus, we develop a strongly nonlinear model for a deep configuration, namely the two-layer high-level Green–Naghdi (HLGN-FS) model that includes the free-surface effects. Numerical results of the HLGN-FS model, including the wave profile, velocity field and wave speed, are presented for three cases. The first case is a shallow configuration with . It is shown that the MCC-FS model can provide accurate results for the shallow configurations. Meanwhile, the HLGN-FS model is shown to be accurate for describing the internal solitary waves for both shallow and deep configurations.

In this work, a shallow-water system for interfacial waves in the case of a neutrally buoyant two-layer fluid system is considered. Such a situation arises in the case of large underwater lakes of ...

We study the Cauchy problem for the 212D incompressible magnetic Benard fluid system with partial viscosity and derive some blow-up criteria of smooth solutions. More precisely, we first obtain a b...

The phenomenon of emerging water jets from the holes of containers has been extensively studied; nevertheless, it continues to inspire researchers and teachers. The main aspects of the recent studies concern: the range of the jets trajectories; the extension of Bernoulli’s equation, of which Torricelli’s expression represents an ideal situation, to real fluids; and the measure of the jets’ speed and the drainage time in dependence on the fluid system geometry and wetting conditions. The focus of this paper is to discuss Torricelli’s relation between jet speed and hole depth in the case of a 19th-century glass bottle featuring three lateral holes. Measurements of the free water level displacements and jet speed from the holes have been carried out with 11th-grade students.

We revisit the approach proposed by F.L. Chernousko to modeling the dynamics of a rigid body with a cavity entirely filled with a highly viscous fluid. Within the approach, a finite-dimensional model of the body+fluid system is offered and the influence of the fluid is represented as a special torque acting upon the body with solidified fluid. Our aim is to develop further and expand a few technical aspects of the Chernousko model. In particular, we offer a coordinate-free form for some essential formulas and consider the case of constrained dynamics. To illustrate the results obtained we explore the motion of a physical pendulum with a fluid-filled cavity on a rotating platform.

Liquid-jet breakup in a co-flow system can occur in two regimes: dripping and jetting. A finite difference/front-tracking method is used to simulate the jet breakup. This method has rarely been used in cases where breakup or coalescence occurs during flow simulation. This is due to the lack of a general algorithm for topology change of the interface mesh. In this paper, three-dimensional liquid-jet breakup has been studied in dripping and jetting regimes. A new algorithm has been developed that is capable of changing the topology of the interface mesh. The dripping and jetting regimes are simulated numerically and a new transition criterion between two regimes is defined that is in agreement with existing studies. Also, the drop size formed after breakup in jetting regime is consistent with experimental data. The effect of the capillary number, the Weber number, the viscosity ratio and the density ratio on the size of drops formed is investigated. It is found that the drop size decreases when the Weber number is raised. The same trend is observed when the capillary number increases. The drops increase in size when the velocity ratio of the co-flowing medium increases (the velocity ratio is the ratio of the velocity of inner fluid to that of the surrounding medium). Increasing the density ratio also increases the drop size. The rate of increase in drop size is large at unity density ratio and it decays as the density ratio increases. Also, increasing the viscosity ratio reduces the drop size. Finally, the breakup of liquid jet exiting from an elliptic nozzle is investigated and its behavior is compared with a circular jet.

The vibro-acoustic response of a structure-liner-fluid system is predicted by application of a patch transfer function (PTF) coupling scheme. In contrast to existing numerical approaches, PTF matrices of structure and liner are determined by a direct experimental approach, avoiding the requirement of material parameters. Emphasis is placed on poroelastic lining materials. The method accounts for surface input and next-neighbour transfer terms and for cross and cross-transfer terms through the specimen. Shear stresses and transfer terms to further patches on the liner are neglected. A single test-rig characterisation procedure for layered poroelastic media is proposed. The specimen is considered as a single component – no separation of layers is performed. For this reason the characterisation procedure can serve as a complement to existing methods if separation of layers is not possible and as a tool for validation of more detailed material models. Problem specific boundary conditions for skeleton and fluid, which may cause non-reciprocal cross terms, are dealt with by the procedure. Methods of measurement for the assessment of PTF matrices are presented and their accuracy and limitations are discussed. An air gap correction method for surface impedance measurements is presented.

In the present paper, we investigate the asymptotic behavior of solutions to an electromagnetic fluid system for viscous compressible flow without heat conduction in three spatial dimensions. The global existence and time-decay estimates of classical solution are established when the initial data are small perturbations of some given constant state. The proof is based on some elaborate energy estimates and the decay estimates for the linearized system.

An analytical solution of the Boussinesq equations for the motion of a viscous stably stratified fluid driven by a surface thermal forcing with large horizontal gradients (step changes) is obtained. This analytical solution is one of the few available for wall-bounded buoyancy-driven flows. The solution can be used to verify that computer codes for Boussinesq fluid system simulations are free of errors in formulation of wall boundary conditions and to evaluate the relative performances of competing numerical algorithms. Because the solution pertains to flows driven by a surface thermal forcing, one of its main applications may be for testing the no-slip, impermeable wall boundary conditions for the pressure Poisson equation. Examples of such tests are presented.

© 2017 American Physical Society. A computational framework is proposed for the linear modal and nonmodal analysis of fluid systems consisting of a periodic array of n identical units. A formulation in either time or frequency domain is sought and the resulting block-circulant global system matrix is analyzed using roots-of-unity techniques, which reduce the computational effort to only one unit while still accounting for the coupling to linked components. Modal characteristics as well as nonmodal features are treated within the same framework, as are initial-value problems and direct-adjoint looping. The simple and efficient formalism is demonstrated on selected applications, ranging from a Ginzburg-Landau equation with an n-periodic growth function to interacting wakes to incompressible flow through a linear cascade consisting of 54 blades. The techniques showcased here are readily applicable to large-scale flow configurations consisting of n-periodic arrays of identical and coupled fluid components, as can be found, for example, in turbomachinery, ring flame holders, or nozzle exit corrugations. Only minor corrections to existing solvers have to be implemented to allow this present type of analysis.

Interfacial solitary waves (ISWs) can be observed in stratified ocean and laboratory flumes which generally comprise a pycnocline in finite thickness. This has led to the adoption of a two-layer or three-layer fluid system for studying the ISWs. However, this assumption has limited success for understanding the effects of variable pycnocline thicknesses on the wave generation and propagation. This paper discusses the broadening of pycnocline thickness on the generation of an ISW in a wave flume and its subsequent effects on wave amplitude and potential energy across a submerged trapezoidal obstacle under laboratory conditions. Three different definitions for the nominal pycnocline thickness are discussed, based on the measured fluid density profiles and the calculated buoyant frequency profiles. As the pycnocline thickness increased after repeated wave-makings, the incident ISW amplitude decreased as expected, as well as the wave speed across the obstacle. Moreover, as the thickness broadened, the fluid system appeared to contain two or multiple peaks rather than single peak when the pycnocline was thin and finite. This implies that the resultant wave might consist of several modes (at least mode-2) in the flume even at its generation stage.

Separation efficiencies for a scrubber containing only an inlet vane was investigated. In addition holdup distribution, pressure drop, separation efficiencies and droplet separation characteristics of two wire mesh pads mounted in a scrubber were investigated experimentally at 20,50 and 85 bars using N 2 /Exxsol and a synthetic Natural gas mix. The liquid holdup was recorded at five locations for the two pads. A new method was developed to allow for accurate determination of flooding point in wire mesh pads. The flooding point was determined at four inlet stream liquid volume fractions at a given pressure and fluid system. In addition droplet size measurements were performed above the wire mesh pads. The results show unexpected phenomena occurring when moving to higher pressures using liquids with low surface tensions.

We now look at linear flows with interfaces. These flows and their instability are elementary to the formation of the disperse phase in many gas–liquid two-phase flows, such as sprays and bubbly flows. We are interested in the instability of liquid sheets and jets submerged in another, immiscible fluid. For transport processes across the interface, oscillations of drops and bubbles may have a significant influence. We also look at the behaviour of drops upon impact on a solid substrate. The fluid system is a linear viscoelastic liquid in an outer immiscible host fluid. The correspondence principle allows for the derivation of the equations as for a Newtonian liquid, but with a frequency-dependent viscosity. The ambient medium is a gas for the liquid sheet flow, since the flow of a liquid sheet in an ambient liquid medium does not seem to be of much technical relevance. In the liquid jet and drop cases, we treat the ambient fluid such that it may be either a liquid or a gas.

Constitutive equations of thermoporoelasticity for two-phase fluid system derived by Coussy (2007) are extended to those for multiphase system with anisotropic micro-heterogeneous porous media. All the material coefficients are found to be expressed by coefficients common to saturated thermoporoelasticity and saturation-dependent effective stress coefficients. Experimental conditions to evaluate thermal pore expansivity and saturation dependent effective stress coefficients are also presented. Material coefficients for orthotropy and transverse isotropy, which are often seen in actual porous media, are explicitly listed to facilitate application.

Growing macroscale fold structures are one of the most dynamic and complex systems in geology, where during fold growth pore fluid pressure, fluid temperature, and fluid composition (PTX) conditions do not remain static but instead vary continually at all points within the deforming fold such that no two points within the fold will have the same deformation or fluid history. These PTX conditions in turn directly affect fluid storage and mobility as well as rock strength, which has direct feedback on the mechanical development of the fold. In this review, we first outline the research methodologies that have yielded significant insights, and review four examples of well-constrained fold-related fluid systems. We then discuss the fluid-related, fold-related, and mesoscopic deformation processes that are relevant to fold-related fluid systems. Finally, we close by presenting several conceptual models for fold-related fluid system structure, and highlighting key areas for future work.

At present, the domestic pipe string on layered polymer injection is mainly focused on the layered polymer injection technology with the hollow single pipe string, but it's limited by facts such as complicated operating and retrieving, subjecting to plugging, and single injection fluid system for each and every zones in a well. This paper starts with the idea of concentric string, directing at the construction about the profile controlling on the injection well which has 2-section or 3-section, the layered injection technique of 2-section with tubing-casing and 3-section with concentric string is investigated separately. Based on the actual formation section properties, relatively independent injecting channels are established from wellbore, and its technical proposal and corresponding tools are preceded. Now the technique has been successfully performed on 15 wells, meeting the requirements of the layered profile controlling by injecting different fluid system and displacement as well as different concentration to different layers.

The thermomechanical reaction of the joint–synovial fluid system to periodic and impulse actions has been investigated. The behavior of the body of the joint near the articular surface — resistance of the bone material of the joint to periodic mechanical actions — has been established. It has been shown that the most destructive actions for the joint are instantaneous impulse shock mechanical actions.

This article reviews the formulas determining the drag coefficient of spherical particles moving in a fluid system in the context of numerical modeling of spouted bed grain dryers. The study describes several formulas that have been implemented in code Fluent 6.3, in a simulation model of a spouted bed based on the Eulerian multiphase model. The article also analyzes the voidage function that accounts for the effect of particle density on the value of the drag coefficient. Simulation results were compared with the basic model, which has been discussed in detail in a different study carried out by the author. This study investigates the computer model's response to changes in the manner of computing the drag coefficient and the possibility of applying various computational formulas in spouted bed modeling. The experiment was conducted by the author in view of the scarcity of publications on the subject and the need to organize the existing knowledge on drag coefficient modeling, which is the main contribut...

To understand the effects of magnetic fields on the evolution behaviours of thermocapillary convection in a two-layer fluid system under the absence of gravity, we conducted a series of unsteady three-dimensional numerical simulations of thermocapillary flows in a rectangular cavity. The results show that the convective cell merging process under x direction magnetic field is decelerated in the encapsulant, but that in the melt is accelerated; magnetic field in z direction decelerates the convective cells merging in the melt and encapsulant greatly; the effect of magnetic field in y direction on the convective cell merging is weak. The maximum vorticity magnitude of thermocapillary convection 58.3 s-super- - 1 at fully developed without magnetic field is reduced to 53.4, 54.4 and 20.7 s-super- - 1 under magnetic fields in x, y and z directions, respectively. Copyright The Author 2009. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org, Oxford University Press.

The nonlinear thermocapillary and buoyant-thermocapillary flows in a three-layer system, filling a closed cavity and subjected to a temperature gradient directed along the interfaces, are investigated. The nonlinear simulations of convective regimes are performed by the finite-difference method. The process of transition of unicell structures into multicell structures is studied.

The lack of a first-principles derivation has made the hydrodynamic boundary condition a classical issue for the past century. The fact that the fluid can have interfacial structures adds additional complications and ambiguities to the problem. Here we report the use of molecular dynamics to identify from equilibrium thermal fluctuations the hydrodynamic modes in a fluid confined by solid walls, thereby extending the application of the fluctuation-dissipation theorem to yield not only the accurate location of the hydrodynamic boundary at the molecular scale, but also the relevant parameter value(s) for the description of the macroscopic boundary condition. We present molecular dynamics results on two examples to illustrate the application of this approach-one on the hydrophilic case and one on the hydrophobic case. It is shown that the use of the orthogonality condition of the modes can uniquely locate the hydrodynamic boundary to be inside the fluid in both cases, separated from the molecular solid-liquid interface by a small distance Δ that is a few molecules in size. The eigenvalue equation of the hydrodynamic modes directly yields the slip length, which is about equal to Δ in the hydrophilic case but is larger than Δ in the hydrophobic case. From the decay time we also obtain the bulk viscosity which is in good agreement with the value obtained from dynamic simulations. To complete the picture, we derive the Green-Kubo relation for a finite fluid system and show that the boundary fluctuations decouple from the bulk only in the infinite-fluid-channel limit; and in that limit we recover the interfacial fluctuation-dissipation theorem first presented by Bocquet and Barrat. The coupling between the bulk and the boundary fluctuations provides both the justification and the reason for the effectiveness of the present approach, which promises broad utility for probing the hydrodynamic boundary conditions relevant to structured or elastic interfaces, as well as two-phase immiscible flows.

Post-treatment production analyses for hydraulic fracturing treatments with conventional crosslinked gel or slickwater often indicate that the treatments do not achieve the designed stimulation effectiveness, which could be attributed to non-optimal proppant placement and/or significantly damaged fracture conductivity. Although conventional crosslinked fluids are observed to provide good proppant suspension in laboratory environments, they might not provide the desired proppant transport under downhole conditions. Crosslinked fluids are known to be difficult to clean up, and thus are notorious for imparting gel damage to proppant pack and formation. Slickwater can be used to mitigate gel damage by reducing the effective polymer loadings, but consequential extreme proppant settling and banking problems reduce the chance of achieving fracture performance. Several proppant placement techniques have been developed to generate highly conductive paths for hydrocarbons to flow from an unconventional reservoir to the wellbore, such as hybrid fracturing, reverse hybrid fracturing, and channel fracturing, each of which predominantly rely upon high viscosity fluids to carry the proppant to the designated location. This paper presents a non-traditional fracturing fluid system and application technique with near perfect proppant suspension and transport, high fracture conductivity, and self-diverting characteristics. The revolutionary fracturing fluid system employs engineered packing of particle domains for proppant suspension mechanics that are significantly different from crosslinked polymer systems which use polymer chain overlap and inter-chain crosslinking to generate viscosity governed proppant transport. The unique gel particle structure perfectly suspends proppant for several hours at reservoir conditions to facilitate better transverse and vertical placement of proppant in the fracture and significantly increases the fractured surface area, which is one of most important factors in unconventional reservoir production. The self-diverting tendencies offer the potential to maximize created fracture area while simultaneously reducing the treating fluid volumes without the addition of costly diverting additives. The degradability of the fluid can be controlled at reservoir conditions by fluid pH and/or breaker loading to yield near 100% regained proppant pack conductivity. This paper discusses the evolution of the technology, and laboratory results for this unique fluid system. The system can unlock reservoir potential in areas requiring high fractured surface area and high regained conductivity, such as unconventional liquid-rich formations.

The continuum flow of a dilute system through a porous sediment is considered. The fluid system is composed of a carrier fluid-phase and an oil-phase. Model equations governing the time-dependent flow of the incompressible two-phase fluid are developed based on volume averaging.

This paper is concerned with the development of the vibration system for the drop formation of magnetic fluid. The breakup of magnetic fluid jet generated by the longitudinal vibration of the permanent magnet-magnetic fluid system is studied experimentally with the three-dimensional motion analysis system. The detailed processes of the droplet production, capillary jet breakup, and jet formation are revealed.

A new flow theory is established through the objectivity requirement on the fluid dynamics. It was known that inhomogeneous fluid motion gave rise to viscous force while the selection of observers on different space-time points would change such an inhomogeneous character. Therefore, when the viscous force was considered as an objective existence foreign to the selection of observers, the form invariances of viscous force and momentum equation under local rotation transformation required a new dynamic field, namely the vortex field to be introduced. Then the dynamical equations of all flow fields were obtained through constructing the Lagrangian density of fluid system and using the variational approach of energy.

The centralized cooling system of a certain type of oil ship is a large-scale complex fluid network system. Fluid system simulation software (FLOWMASTER) was used to establish simulation model for steady operating conditions. The design of central cooling system was validated reasonably by simulation in steady-state condition. In this paper, the flow and heat transfer experiment was carried out. The experimental results were in good agreement with the simulation results, which suggested that using FLOWMASTER to validate the heat transfer performance of fluid system is reliable.

A model was developed using NASA's Generalized Fluid System Simulation Program (GFSSP) for the self-pressurization of a liquid hydrogen propellant tank due to boil-off to determine the significance of mixture non-idealities. The GFSSP model compared the tank performance for the traditional model that assumes no helium pressurant dissolves into the liquid hydrogen propellant to an updated model that accounts for dissolved helium pressurant. Traditional NASA models have been unable to account for this dissolved helium due to a lack of fundamental property information. Recent measurements of parahydrogen-helium mixtures enabled the development of the first multi-phase Equation Of State (EOS) for parahydrogen-helium mixtures. The self-pressurization GFSSP model was run assuming that the liquid propellant was pure liquid hydrogen and assuming helium dissolved into the liquid utilizing the new helium-hydrogen EOS. The analysis shows that having dissolved helium in the propellant does not have a significant effect on the tank pressurization rate for typical tank conditions (-423 °F and 30 psia).

Experimental physicists at Australian National University review research on the physical underpinnings of quasi-2D turbulence in 3D thick fluid layers.

In this study, a transient performance simulation model of AP1000 using SCDAP/RELAP5 4.0 is developed. The reactor coolant system (RCS) and passive core cooling system (PXS) are modeled respectively. Various kinds of hydrodynamic component including Volume, Junction, Separator, Accumulator, Branch, Pipe, Valve and Pump are adopted to simulate the fluid system of AP1000. The DECLG (double-end rupture of cold leg) accident is simulated and analyzed. To study the effect of axial heat conduction, two kinds of heat structure with and without reflooding model are employed to simulate the fuel rod respectively. The comparison shows that the 2D heat conduction play important role in the reflooding process.Copyright © 2014 by ASME

An improved numerical model and computational method are proposed here for the study of the effects of air valve characteristics on pressure surges during pump trip in fluid systems with air entrainment. Numerical experiments have shown that air valves with higher inflow characteristics installed at peak locations of a fluid system may reduce the magnitude of the extreme negative pressure surges. However, for near zero air entrainment levels in the fluid system, air valves with higher outflow characteristics tend to result in higher positive pressure surges

A visco - elastic fluid is represented frequently by the Generalized Hydrodynamic (GHD) model. Unlike Navier Stokes fluid such a system supports transverse shear waves. Thus, while a sheared flow structure in a Navier Stokes fluid system is marred by the development of the Kelvin - Helmholtz (KH) instability alone, in the case of visco - elastic GHD fluid, a shear flow pattern can be expected to be effected by both, namely the KH instability and the emission of transverse shear waves. The manuscript explores this feature in detail. For this purpose (a) the modifications on the KH instability mode due to strong correlations in linear as well as nonlinear regime and (b) the conditions under which either the KH mode and/or the transverse shear wave emission dominates have been identified in the manuscript.