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Shear rate discretization in "Two-phase flow modeling of a dense suspension" tutorial
Posted 24 sept. 2012, 09:13 UTC−4 Fluid & Heat, Computational Fluid Dynamics (CFD), Modeling Tools & Definitions, Parameters, Variables, & Functions Version 4.2a, Version 4.3 0 Replies
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in the tutorial "Two-phase flow modeling of a dense suspension" the shear rate is discretized as an additional equation "because the particle flux contains derivatives of this quantity, which in turn depends on the derivatives of the velocity".
I do not understand why, using this procedure, we gain in accuracy. For example, the Source term of the additional PDE is defined as "gamma-sqrt(0.5*(4*ux^2+2*(uy+vx)^2+4*vy^2)+eps)" which has in it the derivatives of u, meaning that gamma contains the derivatives of u as it should. Then gamma is gonna be derived in order to get the particle flux, hence leading to a double derivation of u as expected.
From here I do not see the advantage of defining an additional PDE, since the double derivation is anyway present.
Does anyone have an explanation for this approach?
Thanks, J
Hello J
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