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Calculate Torque from Shear stress in laminar flow 3D
Posted 2 mars 2017, 17:48 UTC−5 Fluid & Heat, Parameters, Variables, & Functions, Results & Visualization Version 5.2 0 Replies
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I have a 3D model with symmetry in xy plane. Rotation is around the z axis. I added a cylindrical coordinate system (sys2) to easily prescribe the motion as a boundary condition (moving wall) on the surface of the rotating object:
ux = -sin(sys2.phi)*sys2.r*omega
uy = cos(sys2.phi)*sys2.r*omega
uz = 0
(phi is angular coordinate, omega is the rotation rate)
Is this a correct way to prescribe a rotational steady state motion?
The velocity profile looks about right to me. Now to find the torque, I use surface integration on the surface of the rotating body with this expression
2*(spf.T_stressx*y+spf.T_stressy*x)
2* for the symmetry plane, the shear stress/force times the radius for the torque (both x and y components) and finally integrating over the surface to go from stress to force.
It seems to work, but I'm not sure how I can check if the result makes any sense.
Hello Stijn van Pelt
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