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User Defined Shear Dependent Viscosity

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I came across the exact same problem as mentioned in the linked threat. I am trying to define a dynamic viscosity based on the temperature / shear rate. However, I see no way of using the shear rate as an argument without using a predefined non-newtonian model. I have defined an analytical function Mu(T,spf.sr) within my material.

Can someone help me?

Update, I get the following error: - Feature: Time-Dependent Solver 1 (sol2/t1) Failed to find consistent initial values. Error in user-defined function. Function: comp1.mat1.def.Mu Failed to evaluate variable. Variable: comp1.mat1.def.mu, Defined as: unit s cf(unit Pa cfcomp1.mat1.def.Mu(comp1.T/unit K cf,unit s cfcomp1.spf.sr)) Failed to evaluate variable. Variable: comp1.spf.mumat, Defined as: comp1.mat1.def.mu Failed to evaluate variable. Variable: comp1.spf.mu, Defined as: comp1.spf.mumat Failed to evaluate variable. Variable: comp1.spf.mu eff, Defined as: comp1.spf.mu Failed to evaluate variable. Variable: comp1.spf.K stress tensorrr, Defined as: comp1.ur(2comp1.spf.mu eff) Failed to evaluate expression. Expression: d((2((comp1.p-comp1.spf.K stress tensorrr)test(comp1.ur)-comp1.spf.K stress tensorrztest(comp1.uz)+(comp1.p-comp1.spf.K stress tensorphiphi)if(abs(r)<0.001h spatial,test(comp1.ur),test(comp1.u)/r)-comp1.spf.K stress tensorzrtest(comp1.wr)+(comp1.p-comp1.spf.K stress tensorzz)test(comp1.wz))pir)(dvol spatial),{test10}) Failed to evaluate Jacobian of expression. Expression: (2((comp1.p-comp1.spf.K stress tensorrr)test(comp1.ur)-comp1.spf.K stress tensorrztest(comp1.uz)+(comp1.p-comp1.spf.K stress tensorphiphi)if(abs(r)<0.001h spatial,test(comp1.ur),test(comp1.u)/r)-comp1.spf.K stress tensorzrtest(comp1.wr)+(comp1.p-comp1.spf.K stress tensorzz)test(comp1.wz))pir)*(dvol spatial) Last time step is not converged.


1 Reply Last Post Dec 20, 2018, 2:48 PM EST

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Posted: 12 months ago Dec 20, 2018, 2:48 PM EST

You may need to need to add eps to shear rate argrument so that at time zero it has some low of viscoity otherwise it become zero.

You may need to need to add eps to shear rate argrument so that at time zero it has some low of viscoity otherwise it become zero.

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