alaa_1973 wrote

If the viscosity is not constant but it is function change then how i can input this function for non-Newtonian fluid in navier-stokes equation with axisymmetric coordinate

You can use constants, expressions, and Matlab functions in equation, boundary, and postprocessing expressions as described here:

https://www.featool.com/doc/physics.html#phys_coefFor non-Newtonian viscosity you can just type in your expression, for example 2D powerlaw could be something like "mu0*K*(sqrt(2)*sqrt(1/2*(4*ux^2+(uy+vx)^2+4*vy^2)+eps))^(n-1)" where mu0, K, and n are constants describing the power law.