I am creating a model of a Rayleigh Taylor instability using the Visco Plastic model. I am wondering what the purpose of the constant viscosity prefactor is in this type of model? Playing around with these prefactors, it seems to drastically change how the viscosity distribution looks in my model.
Hi @andersaj - indeed, this parameter will certainly have a large effect on the system dynamics.
The viscosity is multiplied by the value(s) assigned in this parameter (see documentation here), with the default value of 1 leading to now change in the viscosity.
A value of 2 will double the viscosity and a value of 0.5 will reduce it by a factor of 0.5.
My recommendation is to just use the default value of 1, unless there is a very specific scenario that requires manually reducing the viscosity of the entire model or a specific compositional field by some factor (i…e, it was originally implemented to handle very specific scenarios).
Cheers,
John