[thedal]

Hello everyone,


I was working on Flow over multiple square cylinder in tandem cases. I have done a Numerical scheme Validation case for single cylinder at Re 100 and also for two cylinder and tried to do a grid independent study for two cylinder case.

But Following the same grid independent case and Numerical scheme, I started three cylinders and four cylinder cases similarly. But It has run even ten times the flow time of two cylinder cases, With not any significant improvement in flow. The Cl curves keep on decreasing instead of growing up and their values are close to order to 10 e -10.

Numerical Scheme Details:
Transient PISO scheme

Momentum, Pressure Discretization: Second order
Transient discretization:
Second order implicit with Non-Iterative Time Advancement

Square cylinders of D, separated by 1.2D each, with upstream length of 7D and downstream length of 30D.
The mesh is valdated for single and two square cylinder cases.
And It took around 1.3 lakhs iterations to give the converged steady oscillations for 2 cylinders. However, for 3 cylinders even after 6 lakhs iterations, Flow doesn't even start shedding. Is there any problem with the Scheme that is affecting the solution after the increase of one more cylinder?

Is there any way to get my solutions faster?

Do help, please.


Always
Thedal