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2014-10-14 14:32
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alphasand_driftFluxFoam_3.png (89,676 bytes) |
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2014-10-14 14:33
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alphasand_driftFluxFoam_wallFunctions_3.png (102,466 bytes) |
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2014-10-14 14:35
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2014-10-14 14:35
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Note: without wallFunctions the concentration gradient is very steep, whereas with wallFunctions a widely distributed concentration over height is obtained. |
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If you are using the high-Re k-epsilon model you will need to use wall-functions to obtain physical k and epsilon distributions near the wall. If you want to avoid wall-functions you will need to use a low-Re model and sufficient resolution near the wall. It would be useful to check that the latest formulation provides physically reasonable and stable distributions for laminar cases. |
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Thank you for the quick reply Henry. When taking U_axial = 0.01 m/s, the case should be laminar, Re~1100. The results are attached, alpha.sand and mag(U) over height. Also the velocity distribution doesn't look OK. The problem still occurs, when using no wallFunctions?! |
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2014-10-14 15:32
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alphasand_driftFluxFoam_laminar.png (97,799 bytes) |
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2014-10-14 15:32
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U_driftFluxFoam_laminar.png (165,163 bytes) |
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Wall-functions are not appropriate for laminar flow, in fact you will not be able to apply them anyway. At a Re of 1100 with the high gradients of viscosity it looks like the flow is unsteady, possibly physical, maybe numerical. You will either need to reduce the Re or choose more stable schemes for the momentum equation. |
- Anonymous
