Field FUnction

akshaybagi · January 6, 2016, 23:08

Hi, I want to create a field function to measure the shear stress in a fluid flow. I have written a field function but it is not giving me proper values.
The function is

($DynamicViscosity*grad($$Velocity[0]))

I want to use the value from this function to refine my mesh - basically I want to refine mesh wherever the value of shear stress is above some threshold value. When I do the refinement, I cant see any change from the previous mesh.
For mesh refinement, my function is

(mag2($DynamicViscosity * grad($$Velocity[0]))>1.0e-6)?0.75:0

What this does is it changes the cell size to 0.75 wherever the value of the function is greater than 1.0e-6. But I dont see any refinement using this function.

Please help.

fluid23 · January 11, 2016, 16:57

Have you done a scalar plot of your field function to verify that there are values greater than 1.0e-6? Also verify that the units are correct. That could screw things up as well.

January 6, 2016, 23:08	Field FUnction	#1
akshaybagi New Member Akshay Bagi Join Date: Feb 2013 Posts: 17 Rep Power: 13	Hi, I want to create a field function to measure the shear stress in a fluid flow. I have written a field function but it is not giving me proper values. The function is ($DynamicViscositygrad($$Velocity[0])) I want to use the value from this function to refine my mesh - basically I want to refine mesh wherever the value of shear stress is above some threshold value. When I do the refinement, I cant see any change from the previous mesh. For mesh refinement, my function is (mag2($DynamicViscosity grad($$Velocity[0]))>1.0e-6)?0.75:0 What this does is it changes the cell size to 0.75 wherever the value of the function is greater than 1.0e-6. But I dont see any refinement using this function. Please help.

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January 11, 2016, 16:57		#2
fluid23 Senior Member Matt Join Date: Aug 2014 Posts: 947 Rep Power: 18	Have you done a scalar plot of your field function to verify that there are values greater than 1.0e-6? Also verify that the units are correct. That could screw things up as well.