UDF for wall shear stress

Anticip · March 27, 2020, 00:02

hello,
I want to define a wall boundary with different wall shear stress, but the other part in this wall I want to keep it to no-slip. So how can I DEFINE a no-slip boundary?
THANKS!

vinerm · March 27, 2020, 04:41

The simplest option would be to divide the wall into multiple sections. Apply shear stress on the sections you want stress to be applied and no-slip on the other sections. With UDF, it might be little difficult. UDF needs to be hooked somewhere. If you hook it for stress on the wall, it would not be easy to apply no-slip, since you will be able to apply the gradient of velocity while no-slip implies that velocity should be 0.

Anticip · March 27, 2020, 05:05

Quote:

Originally Posted by vinerm

The simplest option would be to divide the wall into multiple sections. Apply shear stress on the sections you want stress to be applied and no-slip on the other sections. With UDF, it might be little difficult. UDF needs to be hooked somewhere. If you hook it for stress on the wall, it would not be easy to apply no-slip, since you will be able to apply the gradient of velocity while no-slip implies that velocity should be 0.

Thanks for your suggestion.

March 27, 2020, 00:02	UDF for wall shear stress	#1
Anticip New Member HL Join Date: Oct 2019 Posts: 3 Rep Power: 7	hello, I want to define a wall boundary with different wall shear stress, but the other part in this wall I want to keep it to no-slip. So how can I DEFINE a no-slip boundary? THANKS!

March 27, 2020, 04:41	Wall Shear Stress and No-Slip	#2
vinerm Senior Member Vinerm Join Date: Jun 2009 Location: Nederland Posts: 2,946 Blog Entries: 1 Rep Power: 36	The simplest option would be to divide the wall into multiple sections. Apply shear stress on the sections you want stress to be applied and no-slip on the other sections. With UDF, it might be little difficult. UDF needs to be hooked somewhere. If you hook it for stress on the wall, it would not be easy to apply no-slip, since you will be able to apply the gradient of velocity while no-slip implies that velocity should be 0. __________________ Regards, Vinerm PM to be used if and only if you do not want something to be shared publicly. PM is considered to be of the least priority.

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