i am working on flapping wing using FSI ANSYS and i want to compere between computational and experimental result. for the Computational with ANSYS i have problems such as: 1- For the transient structural part i make the wing root Revolute and make rotation angle varying with time at the root but the wing is distortion even if i solve the problem as a structural alone. 2- when i make coupling i got this massage from the fluent part (update-dynamic-mesh failed. negative cell volume detected). i appreciate your help.