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#1 |
New Member
Join Date: Nov 2011
Posts: 7
Rep Power: 14 ![]() |
Hi there!
I would like to ask about the dimensionless wall distance. In many papers are three-dimensional domains described using ![]() ![]() ![]() ![]() ![]() Wall ![]() ![]() Where ![]() ![]() ** ![]() Where ![]() ![]() *** ![]() Where ![]() Is it computed for let's say ![]() ![]() but ![]() ![]() are without change? I am not sure about the wall shear stress component (gradient of u) Thank you for any hints or recommendations. |
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#2 |
Senior Member
Join Date: Jun 2012
Location: Germany, Bochum
Posts: 230
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As far as I know the dimensionless wall distance is measured orthogonal to the wall which is usually called yplus and sometimes zplus. Never heard of xplus but it might just be dependent on how you set you coordinate system.
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#3 |
New Member
Join Date: Nov 2011
Posts: 7
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Thank you. I thought as you do, but you can find
![]() ![]() I am not sure if ![]() ![]() ![]() Any idea guys? Thank you. |
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#4 |
Senior Member
Rami Ben-Zvi
Join Date: Mar 2009
Posts: 155
Rep Power: 17 ![]() |
Hi Messik,
I guess there are two issues in your post requiring consideration: 1. The "u" should actually be interpreted as the velocity parallel to the wall, not the x-velocity component. 2. The "y" in wall shear stress needs be interpreted as the normal-to the wall coordinate rather than the y-coordinate. Then the ![]() ![]() I hope this helps,
Rami |
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#5 |
Member
Join Date: Jun 2011
Posts: 51
Rep Power: 15 ![]() |
Hi messik,
In 3D flows u may have the other commonents of shear stress, which IMHO makes sense to have the dimless in all three components. Although the boudary layer develops mainly normal to the wall, the resolution of the mesh in all the other two components is also important for the accuracy of your results. If you consider that u are resolving the laminar sub-layer (y+=1) it may be also important that your mesh in the other components fits within (x+/z~30). I think that u use the half of the mesh size and the velocity gradients in the right directions u can find those dimless. Regards, |
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