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Grid independence
Posted Nov 4, 2011, 4:43 a.m. EDT 0 Replies
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I'm running the mixture model: 2D axi-symmetric naturally convective, buoyancy driven bubbly flow. I'm trying to gain grid independence but I can't seem to get it: in parts of the flow, there seems to be fine structures emerging (not turbulent: pipe Re~ 70--100). Some dominant features, such as vortices, remain under all conditions but their shape changes slightly depending on the meshing. I've tried free tri, quad, stretched quad (the container's aspect ratio is 4:1) and numerous explicit distributions. In addition, I'm looking into stabilisation as a possible source of error.
Attached is a snapshot (at 10 seconds out of 60 seconds) of the void fraction and vertical velocity in a horizontal cut plane half-way up the container. I do it for two meshings: 2p0 has twice the number of horizontal gridlines of 1p0. The dof here are about 600,000 for 2p0 and 300,000 for 1p0. I can't think of a robust criteria for saying which one is "more correct" -- if any.
Has anyone ever gained grid independence in the mixture model interface? If so, which meshing did you find suitable and also, which stabilisation was helpful to gain independence.
Many thanks,
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Hello Cathal Cummins
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