Nikhil Narale
Ansys Employee

It appears that the solution is diverging. Firstly, check the mesh quality, particularly the minimum orthogonal quality. Secondly, you can try reducing the time step size. A smaller time step allows for better accuracy in capturing the physics of the problem and can help stabilize the solution. It's recommended to keep the CFL number as close to 1 as possible, as this ensures stability and accuracy.