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VSS in a 2D Orifice Plate Model

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Hello,

I’m validating a 2D orifice plate model with COMSOL. The resulting velocity field components of the time dependent laminar flow COMSOL-model correspond quite accurate to the given results of the FD-approach (relative error less than 3%), especially for the finest quadrilateral mesh.

By calculating the viscous shear stress with spf.mu(d(u,y)+d(v,x)) or similar with spf.K_stress_tensorxy the maximum and minimum valves rises extremely, when they are calculated in COMSOL directly. Those extreme high VSS-values are located at the edge of the gap inlet and rises with the mesh fineness.

How does COMSOL calculate the partial derivatives of the VSS?

Do I consider singularities? How to read out the “true” shear stress level?

Thanks, Patrice



0 Replies Last Post 19.12.2017, 05:07 GMT-5
COMSOL Moderator

Hello Patrice Seifriz

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