# Yield stress used in non-Newtonian solver

Dear Dualsphysics users,

I am using non-Newtonian solver and I am uncertain about how to specify the yield stress as an input. Does the yield stress remain constant or does it depend on the pressure?

If it remains constant, can we use the simple formula to calculate the yield stress based on know material properties like cohesion and the friction angle?(yield stress= Cohesion+P * sin (friction angle)

Your suggestions would be greatly appreciated.

## Comments

@gfourtakas can help here