Embedding Within Structured Multi-Block Computational Fluid Dynamics Simulation
Within a structured multiblock environment for CFD simulations, embedding capabilities have been developed by uniformly embedding whole blocks of grid by powers of 2 in each direction independantly, leaving discontinuities in grid density at block boundaries. The problem has two aspects which have been treated independantly. Firstly, the placement of new grid nodes in enriched blocks of grid. Secondly the modification of the cell centered finite volume flow simulation to cater for discontinuities in grid density at block boundaries.
New grid nodes are placed within enriched blocks so as to retain the curvature and stretch of the initial coarser grid. Variants of the Thompson (reverse Laplacian) system of elliptic partial differential equations are used with control functions defined on the initial coarse grid rescaled and applied to the update of new grid node positions of the resulting fine grid.
The flow simulation has been extended to cater for embedded block boundaries by modifying the way in which block boundary (halo) data is set. Halo data for fine blocks is set by iterpolation within neighbouring coarse blocks. That for coarse blocks is set by matching the total flux out of the cell faces bounding the fine block that match a cell face within the coarse block.
KeywordsControl Function Grid Node Grid Density Block Boundary Fine Block
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