摘要:

AbstractNumerical simulation of steam flush for clean‐up of non‐aqueous phase liquid (NAPL) contaminated groundwater sites involves solution of the multiphase, multicomponent subsurface flow equations. This paper describes techniques for discretizing problems with horizontal wells in a three‐dimensiontetrahedral mesh. The effectiveness of non‐linear flux limiters for reducing numerical dispersion is discussed. Primary variable selection and thermodynamic state transition rules will also be compared. Some example results for several steam flush scenarios will be pr

ISSN:0271-2091    

DOI:10.1002/fld.1650191202

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractIn this paper we present a finite‐element‐based methode for the calculation of the unsteady potential flow in rotor/stator configurations. A numerical algorithm was developed to calculate the two‐dimensional flow through a centrifugal volute pump, taking into account the width variation of the volute in the axial direction and the vortex wakes downstream of the impeller blades by a linearized vortex distribution. The pressure field was obtained from the unsteady Bernoulli equation, with the entire configuration of the pump being included in the calculations. For that purpose the computational domain was split into a region containing the rotor and one containing the stationary parts, each region being treated in a different co‐ordinate system. The corresponding finite element grids qare matched by an interface consisting of connect elements which move with time. The method is applied to a laboratory centrifugal pump set up at the Von Karman Institute for Fluid Dynamics, which made an experimental validation possible. The total head of the pump and the velocity and pressure fields were computed and analysed for various mass flows. The agreement with the experimental data was satisfactory. The deviation was largest at low mass flow, the maximum deviation in the velocity around the impeller being 10 per cent. The overall behaviour of the pump could be well pr

ISSN:0271-2091    

DOI:10.1002/fld.1650191203

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractIn application to the Gulf of Mexico (GOM), a new DieCAST ocean model, which uses a modified Arakawa ‘a’ grid, and the SOMS model, which uses an Arakawa ‘c’ grid, give remarkably similar results. The new model avoids ‘null space’ problems of the standard ‘a’ grid approach by first using fourth‐order interpolations to a ‘c’ grid advection velocity, then applying incompressibility to the result. Accuracy is further improved by using fourth‐order pressure gradient approximations at ‘a’ grid locations. Incompressibility with general geometry is satisfied efficiently by a fast‐converging iteration with a regular gteometry elliptic solver. Results are compared with satellite‐measured r.m.s. sea surface elevation anomaly and detailed front structures, climatological mean thermocline and empirical orthogonal f

ISSN:0271-2091    

DOI:10.1002/fld.1650191204

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractFluid flow through a significantly compressed elastic tube occurs in a variety of physiological situations. Laboratory experiments investigating such flows through finite lengths of tube mounted between rigid supports have demonstrated that the system is one of great dynamical complexity, displaying a rich variety of self‐excited oscillations. The physical mechanisms responsible for the onset of such oscillations are not yet fully understood, but simplified models indicate that energy loss by flow separation, variation in longitudinal wall tension and propagation of fluid elastic pressure waves may all be important. Direct numerical solution of the highly non‐linear equations governing even the most simplified two‐dimensional models aimed at capturing these basic features requires that both the flow field and the domain shape be determined as part of the solution, since neither is knowna priori. To accomplish this, previous algorithms have decoupled the solid and fluid mechanics, solving for each separately and converging iteratively on a solution which satisfies both. This paper describes a finite element technique which solves the incompressible Navier‐Stokes equatikons simultaneously with the elastic membrane equations on the flexible boundary. The elastic boundary position is parametized in terms of distances along spines in a manner similar to that which has been used successfully in studies of viscous free surface flows, but here the membrane curvature equation rather than the kinematic boundary condition of vanishing normal velocity is used to determine these diatances and the membrane tension varies with the shear stresses exerted on it by the fluid motions. Bothy the grid and the spine positions adjust in response to membrane deformation, and the coupled fluid and elastic equations are solved by a Newton‐Raphson scheme which displays quadratic convergence down to low membrane tensions and extreme states of collapse. Solutions to the steady problem are discussed, along with an indication of how the time‐dependent problem might be

ISSN:0271-2091    

DOI:10.1002/fld.1650191205

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650191206

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650191207

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650191208

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY