The purpose of this project is to investigate the effects of mesh refinement for a standard 3:1 contraction. More specifically how increasing mesh refinment (or decrease in mesh element size) correlates to error in excess pressure drop. Figure 1, to the right shows visually how increased mesh refinement looks for a 3:1 contraction case. The 9 refinements shown to the right reflect 9 preset mesh refinement settings within COSMOL Multiphysics software package.

Figure 1. Spectrum of mesh refinment presets in COSMOL Multiphysics software.

Figure 2 . Error distribution of excessive pressure drop for a 3:1 contraction for different Reynolds numbers.

Figure 3 . Error in KL versus CPU time for different mesh refinment presets.

Figure 3, below is a graph of the CPU time versus error in excess pressure drop. As one can see between figures 2 and 3, we see that for lower Reynolds numbers there is a significant difference in the amoung of error between a normal refinement and extremely fine refinement settings. This difference is much smaller for higher Reynolds numbers.

Through this research we found when a finer refinment mesh is required and when a normal refinement is good enough. Although this analysis was done on a simple case with a simple geometry. We expect the same trends to hold for more complex geometries presented in COSMOL Multiphysics. For a more detailed calculations and discussion of this research please refer to the formal paper.

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