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A new numerical simulation model for electrophoresis separation phenomena is presented. The proposed model employs a Petrov-Galerkin scheme to solve for the concentrations, the electric potential and its gradient via a mixed finite element formulation. This formulation does not involve any restrictions on the electric current density or the finite element mesh. The scheme is stable, accurate, and can be applied to intricate geometries in higher space dimensions without loss of generality. Moreover this formulation avoids the usage of higher order elements which can be expensive. Example simulations are performed in one and two space dimensions. The one-dimensional results closely agree with those from past publications. The success of the simulations in two dimensions indicates the potential of the scheme to address design strategies in practical separation techniques.

The present investigation is concerned with a fully discrete accuracy and stability analysis of the one-dimensional heat equation, taking into account the evaluation of two-pass explicit schemes which simultaneously employ lumped and coupled capacity matrices. Schemes of the considered characteristics are not amenable to uncoupled semidiscrete and ordinary differential equation analyses. The obtained results illustrate that superior behavior may be achieved by schemes of the employed type when compared with the performance of the standard one-pass explicit schemes. The key idea in the considered approach is related to the utilization of a reduced-quadrature capacity matrix in the evaluation of the right-hand-side residual.

A numerical simulation capability has been developed for electrochemical processes, in particular for electrophoresis separation techniques. The numerical method employed is based on the streamline upwind/Petrov-Galerkin formulations which have desirable stability and accuracy properties for the convection-diffusion-reaction type equations that govern these problems. Simulations are performed for various electrophoresis separation types in one and two dimensions. The results obtained are very satisfactory and show the potential of the numerical method to be a useful tool in understanding the physics involved and in helping the design of reliable and efficient separation techniques.

Tire dvnarnics of parachutes involve a r:ornplex interaction between the parachutc stnrcture and the surrounding florv fiel

SUMMARY In the near future, large ram-air parachutes are expected to provide the capability of delivering 21 ton payloads from altitudes as high as 25,000 ft. In development and test and evaluation of these parachutes the size of the parachute needed and the deployment stages involved make high-performance computing (HPC) simulations a desirable alternative to costly airdrop tests. Although computational simulations based on realistic, 3D, timedependent models will continue to be a major computational challenge, advanced finite element simulation techniques recently developed for this purpose and the execution of these techniques on "PC platforms are significant steps in the direction to meet this challenge. In this paper, two approaches for analysis of the inflation and gliding of ram-air parachutes are presented. In one of the approaches the point mass flight mechanics equations are solved with the time-varying drag and lift areas obtained from empirical data. This approach is limited to parachutes with similar configurations to those for which data are available. The other approach is 3D finite element computations based on the Navier-Stokes equations governing the airflow around the parachute canopy and Newton's law of motion governing the 3D dynamics of the canopy, with the forces acting on the canopy calculated from the simulated flow field. At the earlier stages of canopy inflation the parachute is modelled as an expanding box, whereas at the later stages, as it expands, the box transforms to a parafoil and glides. These finite element computations are carried out on the massively parallel supercomputers CRA Y T3D and Thinking Machines CM-5, typically with millions of coupled, non-linear finite elemeJIt equations solved simultaneously at every time step or pseudo-time step of the simulation. ~ 1997 by John Wiley & Sons, Ltd. Int. J. Numer. Meth. Fluids, 24: 1353-1369, 1997

A flow simulation tool, developed by the authors at the Army HPC Research Center, for compressible flows governed by the Navier-Stokes equations is used to study missile aerodynamics at supersonic speeds, high angles of attack and for large Reynolds numbers. The goal of this study is the evaluation of this Navier-Stokes computational technique for the prediction of separated flow fields around high-length-to-diameter (L/D) bodies. In particular, this paper addresses two issues: (i) turbulence modelling with a finite element computational technique and (ii) efficient performance of the computational technique on two different multiprocessor mainframes, the Thinking Machines CM-5 and CRAY T3D. The paper first provides a discussion of the Navier-Stokes computational technique and the algorithm issues for achieving efficient performance on the CM-5 and T3D. Next, comparisons are shown between the computation and experiment for supersonic ramp flow to evaluate the suitability of the turbulence model.