Steady vs Transient
 

Hello, I am currently trying to simulate the flow at a low Reynolds number (100) over an airfoil. Firstly, I selected steady state and the solution converged at 490 iterations and I got the values of Lift and Drag. I also have to get the transient solution and by a certain point, the solution starts converging for each time step but it oscilates over the steady state value of lift and drag and it never reaches an error smaller than 10%. My time step size is 0.1s and I have computed 7000 time steps with 20 iterations per time step.

Do I need to simulate for a longer time waiting for the solution to reach a steady state? or do I need to change any option in order to reach this statement faster?

Thanks in advance,

Pablo.

Hello Pablo,
I haven't a big experience in airfoil simulation, but it looks like you have chosen a time-step too high: with an appropriate time-step the results should not oscillate. Well, you could also check if you need to wait longer and do more iterations.

Best regards

Thanks Bionico, I'll try with a smaller time step.

Pablo.