You have two different ways to simulate a non-newtonian flows with Star CD :

• use the model given by Star CD

It allows you to simulate non-Newtonian flows which follow a power-law, also known as the Ostwald-de Waele model. It gives the viscosity as following :


You can choose only the values of m and n parameters.
How to proceed :
You had to go to the Molecular Properties item in the Star GUIde and select NonNewt in the Viscosity stream.
Then you had to specify the values of the model parameters m and n.
 
 

• modify the subroutine called by Star CD to programm the equations you want to simulate


You have access to the subroutine treating the molecular viscosity in the code called VISMOL. You can modify it as you want and then called it in the Star GUIde panel during the computation by choosing option User Subroutine in the Run Analysis Interactively.

As we can not have access to the value of tau in the subroutine in which the viscosity is calculated, we used the model of Bingham and Herschel-Bulkley, which can be defined as follows:
 


 
This flow has particular properties due to the two-viscosities model and the theory forsees a block-moving in the center of the domain, as shown on the following picture :



where y0 represents the half-domain of block-moving : 
 
 
Here is the listing of the modified subroutine VISMOL programming the model of Bingham and Herschel-Bulkley.
In the following program, the parameters eta0, etainf and tau0 could be modified in order to obtain different profiles (tau0 is set according to an expected value of y0)