non newtonian viscosity problem
Dear all,
I am simulating the problem of blood flow through an artery in 2D considering laminar flow. For this I am using the Walburn and Scneck model to define the blood viscosity using the equation: mu_lam=K*(strain)^(n1), where K=14.67*10^(3) and n=0.7755. In order to define the viscosity I am using the following UDF: #include "udf.h" DEFINE_PROPERTY(cell_viscosity_power_law,c,t) { double mu_lam; double strain; double muinf = 14.67e3; double n = .7755; strain = pow(C_DUDX(c, t),2)+ pow(C_DVDY(c, t),2)+ 2*pow(C_DUDY(c, t)+ C_DVDX(c, t),2)+ 2*pow(C_DUDZ(c, t),2)+ 2*pow(C_DVDZ(c, t),2); strain = pow(strain, 0.5); strain =fabs(strain); mu_lam=muinf*pow(strain,n1); return mu_lam; } But, once I try to solve it the solver gives the error: Divergence detected in the AMG solver. Please help me.... 
You should repost this in the UDF section of the forum. You will likely get more help.

I think it is because when Strain = 0, you will be dividing by zero. Try adding an if statment in there that says if strain is below some value than mu_lam = some large value... or make stain = pow(C_DU...) + 1x10^(12),

Thanks for the reply. It works properly.

no problem.

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