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April 17, 2019, 06:55 |
Doubt in y+ value in Fluent
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#1 |
New Member
Bram
Join Date: Apr 2019
Posts: 13
Rep Power: 7 |
Hello,
I'm trying to simulate flow through corrugated channel. I have calculated reynolds number and the flow is turbulent. I'm using k-epsilon model. I have refined mesh near the wall. I'm getting average y+ value of 2.0, does that mean that I'm resolving viscous boundary layer to a good level? I read in a few forums that k-epsilon model works only 30<y+<300. Does that mean that I must change my turbulence model to capture the physics ? Thank you. |
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April 17, 2019, 12:04 |
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#2 | |
Senior Member
Lucky
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 5,760
Rep Power: 66 |
You don't need to change turbulence models. What model would you even change it to?
For resolving the boundary layer, what's more important than the y+ of the wall adjacent cells is how many cells you have within the boundary layer. Of course this is correlated to y+ of the 1st cell. The k-epsilon model with wall functions (in fluent) is quite robust and works down to any y+. Quote:
Are you talking about resolving the boundary layer in general (which is obviously viscous and you are being redundant) or are you talking about resolving the viscous/laminar sublayer (a tiny fraction of the overall boundary layer)? The viscous sublayer occupies y+<5. A y+ of 2 means you only have ~2 cells in the viscous sublayer which is not enough to resolve the viscous sublayer. |
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April 22, 2019, 16:26 |
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#3 |
New Member
Bram
Join Date: Apr 2019
Posts: 13
Rep Power: 7 |
Thanks for your response. I got an idea from your explanation. Sorry for the delay in replying.
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Tags |
internal flow, turbulence, wall function |
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