y+Factor: Help understanding?
Hi guys
I really have a problem understanding the wall y+ factor and its`range. Am I right, that the y+ factor is a number which shows the code when to switch between far field and wall treatment functions? In Star-CCM+ are three different types fo Wall-treatments I could choose implmented: High-Reynolds wall treatment, Low-Reynolds wall treatment and All-Two-Layer Treatment (mix of High and Low-Re). 1st question: What is the range of high- and or low Reynolds models? 2nd question: What is the range of wall y+: In the User Guide I found for ke-Model realizabel a range for high Reynolds y+ > 30 and for low-Re y~1, 2Layer: y+ ~30-50. -> This means if I have got an y+ value of 8 on a surface (ke_Modell RLZ:All-Layer Treatment), i need to optimize the mesh on surface so that the y+ factor is 30 in minumum? |
The Star-CCM+ "All y+" model is useful because you do not have to go through your model and specify which walls use a low Reynolds approach and which use a high y+ wall function. The model does not promise any sort of accuracy in the range of 1<y+>30. You should have the bulk of your y+ values be either <1 or between something like 20 and 200.
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