Aerospace Engineering

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Boundary Element Solutions to Wave Scattering by Surface Irregularities on a Fluid-solid Interface

1995 , Shenoy, S. , Rudolphi, Thomas , Rudolphi, Thomas , Rizzo, F. , Aerospace Engineering

The boundary element method is used to solve fluid-solid half-space problems with fluid-filled dimples and air bubbles on the solid surface. The problems, formulated in the Fourier (frequency) domain, are described by the fullspace three-dimensional acoustic and elastodynamic boundary integral equations (BIE), with pressure and displacement serving as primary variables. The techniques developed are general and may be with any kind of incident wave, however, plane waves are used in all numerical experiments. The equations governing the acoustic region are first converted mathematically to equations like those of an elastic region. The two regions are coupled and solved for the displacements using the interface conditions. On obtaining the displacements, the tractions, pressures and pressure gradients are computed using the same interface conditions. The numerical results obtained are verified using reciprocity relations and by comparison with solutions available for the halfspace elastodynamic problem

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Parallelizing a very high resolution climate model using clusters of workstations with PVM and performance and load balance analyses

1998 , Wang, Hao , Prabhu, Gurpur , Takle, Eugene , Takle, Eugene , Aerospace Engineering , Ames Laboratory , Computer Science , Agronomy , Geological and Atmospheric Sciences

Environment and climate change problems are very complicated, and their research and operational prediction heavily depend on powerful computer techniques. Even with today most powerful supercomputer, the climate and environmental models are still limited to very coarse resolution. In this paper, we report our recent effort in parallelizing our very-high-resolution numerical model systems. First, the mathematical equations, algorithms, and numerical schemes are designed and analyzed; then domain decomposition, data decomposition, and functional decomposition schemes are tested in our implementations on clusters of HP workstations and/or DEC Alpha stations with PVM; finally, the performance and load balance are analyzed. Shelterbelts cause significantly inhomogeneous computation distribution on the domain, therefore, common and easiest domain decomposition does not work well on our problem. Special care must be taken to treat computations around shelterbelts. With carefull design of algorithms, we found that cheap and still powerful workstations or PCs make it possible to run these models in clusters of workstations or PCs.