2023-11-02T20:09:34.000-0400

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This article discusses the numerical diffusion dependency on the flow direction relative to the mesh and the mesh type in Simcenter STAR-CCM+

Attachments: | kA8f3000000k9gmCAA_en_US_1.sim.exe (713 KB) kA8f3000000k9gmCAA_en_US_2.sim.exe (668 KB) kA8f3000000k9gmCAA_en_US_3.dmprj.exe (604 KB) |

Consider two inviscid streams aligned to each other. Ideally they should not interact with each other since there ought to be no diffusion of momentum (viscosity). But in finite volume numerics there unfortunately is.

A velocity magnitude scalar scene clearly shows diffusion of momentum:

L2-Norm of the error vs. flow angle reads: Trimmed meshes show a vanishing numerical diffusion when the flow is aligned exactly with the grid.

If the flow is just slightly missaligned, the numerical diffusion in a trimmed mesh is identical to the numerical diffusion of a polyhedral mesh.

Numerical diffusion of the polyhedral mesher is always isotropic.