Regarding the y+ function

ari003 · December 23, 2020, 06:15

Hello everyone, its Ari here and I would like to have some suggestion from any profound CFD enthusiast. As per my theoretical knowledge is concerned with y+ value it is the dimensionless first cell center distance from the wall and it has a fixed value throughout the simulation time. But, when I used y-plus function by specifying it in controlDict it gave me the y-plus values as function of simulation time-steps.
https://www.openfoam.com/documentati...eld-yPlus.html

Can anyone tell me what does that physically means and which value of y-plus value should I consider to have an impression overall ?

Tobermory · December 29, 2020, 06:14

Can I suggest that you read up more about what y+ is.

Correct that it's the normalised near wall distance, but not correct that it's a constant. In fact, the normalisation uses the wall shear stress (often expressed as the friction velocity, u*). Can you see now why this might change during the simulation?

December 23, 2020, 06:15	Regarding the y+ function	#1
ari003 Senior Member Arijit Saha Join Date: Feb 2019 Location: Singapore Posts: 132 Rep Power: 7	Hello everyone, its Ari here and I would like to have some suggestion from any profound CFD enthusiast. As per my theoretical knowledge is concerned with y+ value it is the dimensionless first cell center distance from the wall and it has a fixed value throughout the simulation time. But, when I used y-plus function by specifying it in controlDict it gave me the y-plus values as function of simulation time-steps. https://www.openfoam.com/documentati...eld-yPlus.html Can anyone tell me what does that physically means and which value of y-plus value should I consider to have an impression overall ?

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December 29, 2020, 06:14		#2
Tobermory Senior Member Join Date: Apr 2020 Location: UK Posts: 668 Rep Power: 14	Can I suggest that you read up more about what y+ is. Correct that it's the normalised near wall distance, but not correct that it's a constant. In fact, the normalisation uses the wall shear stress (often expressed as the friction velocity, u*). Can you see now why this might change during the simulation?