Difference between snGrad(U) using swakExpression and wallgradU utility ?
Hello,
I am doing an LES of pipe flow. The streamwise direction is the z-direction. In my controlDict I enter the following "swakExpression" to keep track of my wall shear stress: Code:
wallShear Code:
Time However when I compute the wall shear stress using the wallShearStressLES utility, the output is as follows: Code:
(0.00922472 -0.00948885 -0.436616) Which one is correct and what is the difference between both using snGrad(U) in the first approach and then using the wallShearStressLES utility ?? Please help :confused: |
Can anyone help please?
|
Quote:
|
Test between nu*rho*snGrad(U) and nu*rho*wallGrad(U)
Hi Bernhard,
Thanks for your reply. So I did a small test to compare results of the wall Shear stress using snGrad(U) and using wallGrad(U) utility. Following are a couple of lines as output from wallGrad(U) -latestTime Code:
(158.301 -63.0679 9752.01) Code:
Time |
Quote:
You are comparing an averaged value at different times (swak) with the raw data at one timestep (wallGrad(U), snGrad(U)) Of course they differ. But if you average the wallShearStressLES-output you should get similar values to swak BTW: if your patch has faces of different sizhes you'll probably want to use weightedAverage as the accumulation |
All times are GMT -4. The time now is 23:36. |