shear stress

marye · May 26, 2010, 08:46

Hi,

I would like to know how to call wall shear stress in order to write a UDF function.

If someone could help me...
Thank you!

sosososo1114 · May 26, 2010, 11:02

I donot find macros to get shear stress either. I search through the whole udf manual. It seems that FLUENT does not provide such a macro. But you can use a UDF to calculate it by yourself and record it to UDMs.

By the way, althoudh I failed to find the data access macro for shear stress, it seems FLUENT itself does provide something to calculate it. There is a parameter named as SHEAR_BC_NOSLIP in the head file f_wall.h. I wonders how this parameter links to the shear stress.

marye · May 27, 2010, 05:05

Thank you for your answer.

Maybe I don't need a macro because basically I just want to create a program which do :
if fluid shear stress = 5 (just for example)
then viscosity = 1

I don't want to change the value of fluid shear stress, just use the value..

I know that in fluent we can have the values of wall shear stress in a file, maybe there is a way to call this file from fluent?

May 26, 2010, 08:46	shear stress	#1
marye New Member marie Join Date: May 2010 Posts: 21 Rep Power: 16	Hi, I would like to know how to call wall shear stress in order to write a UDF function. If someone could help me... Thank you!

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May 26, 2010, 11:02		#2
sosososo1114 Member Hongjin Wang Join Date: Mar 2010 Posts: 37 Rep Power: 16	I donot find macros to get shear stress either. I search through the whole udf manual. It seems that FLUENT does not provide such a macro. But you can use a UDF to calculate it by yourself and record it to UDMs. By the way, althoudh I failed to find the data access macro for shear stress, it seems FLUENT itself does provide something to calculate it. There is a parameter named as SHEAR_BC_NOSLIP in the head file f_wall.h. I wonders how this parameter links to the shear stress.

May 27, 2010, 05:05		#3
marye New Member marie Join Date: May 2010 Posts: 21 Rep Power: 16	Thank you for your answer. Maybe I don't need a macro because basically I just want to create a program which do : if fluid shear stress = 5 (just for example) then viscosity = 1 I don't want to change the value of fluid shear stress, just use the value.. I know that in fluent we can have the values of wall shear stress in a file, maybe there is a way to call this file from fluent?