Reply To: Two-way FSI: It’s impossible to simulate a cantilever discharging pipe in Ansys

[Rahul Mule]

Before starting an FSI simulation, you should run separate fluids and structural simulations using representative loads.

• Check that the basic setup is correct for each side
• Use settings that are as close as possible to the planned FSI simulation (same time step size, etc)
• If it’s difficult to provide representative fluid loads, you could run a System Coupling simulation with loads passed 1-way from Fluent to Mechanical

There are a number of convergence controls, so it’s easy to head down the wrong path. In general start with:
‒ Default # of Coupling Iterations: Min: 1, Max 5 (for transients)
‒ Default Data Transfer Under Relaxation Factor: 1
‒ Perhaps 5 Fluent iterations per Coupling Iteration (for transients), but this is case dependent.
‒ A Time Step Size based on the physics you need to resolve
• 1/20th of the oscillation period corresponding to the highest structural frequency of interest
• Flow field Courant number.