Dear Dr Amine Sir,nSir, I am not sure the UDF I want to run whether the built-in approach covers it. Also there is a new window called Strain rate there isn't anything mentioned about Strain Rate and how it works in the User manual of Ansys 2020R2.nSir I wrote this code with the help of my supervisor, not sure how to run it though and if the build in approach covers this code or not. I am posting it here,nn#include udf.hnFILE *fp;nDEFINE_PROPERTY(hb_viscosity, c, t)n{nreal viscosity;nreal stress;nreal ys;nreal n, m;nreal k;nreal Max, Min;nn = 0.94; nys = 4.022; nk = 0.04; nm = 1000;nMax = 100000;nMin = 0.00000000001;nstress = C_STRAIN_RATE_MAG(c,t);nviscosity = ys*(1-exp(-m*stress))/stress + k*pow(stress,n-1);nreturn viscosity;n}nnCan you tell me how can I run this UDF? Every time I try to interpret the UDF and run it, I receive this error. Without the UDF the model runs fine.n