Is there a way to use/setup Newtonian viscosity instead of diffusion and dislocation creeps for a continental extension model ?. Also is there a way to assign viscosity for each composition layer instead of averaging min/max viscosity values ?
Yes, this should be possible either through using only diffusion creep equation (Newtonian) or implementing a new viscosity formulation.
To use only diffusion creep in the Visco Plastic material model, use the following parameter setting:
set Viscous flow law = diffusion
For reference, here is a link to the diffusion creep viscosity formulation.
What is the specific equation you would like to use?
Thank you for the reply. I didn’t try only diffusion creep yet. i want to set grain size exponent to 0 in .prm file for diffusion creep formulation. Also the default value for stress exponent is 1. so to remove strain rate dependency i will set it to zero too. Any suggestions
I would simply use the diffusion creep flow law (see my previous post above) and then modify the grain size and others values accordingly to achieve the desired form of the equation.