Hello all.

I have a simulation with the following characteristics: Two concentric cylinders where the flow of a non newtonian fluid occurs in the annular region. The inner cylinder is swirling at 200 rpm. The outer cylinder is stationary.

I would like to track a particle inside the annular region using DPM. The flow can be considered as unchanged during the particle track. So I am using the steady tracking for DPM particles. Basically, the particle also swirls with the fluid.

However, I am having some issues by defining the time step parameters for the steady tracking (maximum number of step and length scale). How would be the right way to choose these values? Is there any kind of test (like a grid independence test) to define the time step by decreasing the value of the length scale (but keeping the max. number of steps) until the solution is unchanged? Is this correct to do?

I have observed that by changing these parameters, the solution also changes.

Thanks!