This tutorial uses an example of an oscillating plate to demonstrate how to set up and run a simulation involving two-way Fluid-Structure Interaction (FSI) in ANSYS Workbench. In this tutorial, the structural physics is set up in the Transient Structural analysis system and the fluid physics is set up in Fluid Flow (CFX) analysis system, but both structural and fluid physics are solved together under the Solution cell of the Fluid system. Coupling between two analysis systems is required throughout the solution to model the interaction between structural and fluid systems as time progresses. The framework for the coupling is provided by the ANSYS Multi-field solver using the MFX setup.

The geometry consists of a 2D closed cavity and a thin plate, 1 m high, that is anchored to the bottom of the cavity as shown below:


Video 1: Video Animation of Oscillating Plate (two-way FSI) 

An initial pressure of 100 Pa is applied to one side of the thin plate for 0.5 s in order to distort it. Once this pressure is released, the plate oscillates backwards and forwards as it attempts to regain its equilibrium (vertical) position. The surrounding fluid damps the plate oscillations, thereby decreasing the amplitude of oscillations with time. The CFX solver calculates how the fluid responds to the motion of the plate, and the ANSYS solver calculates how the plate deforms as a result of both the initial applied pressure and the pressure resulting from the presence of the fluid. Coupling between the two solvers is required since the structural deformation affects the fluid solution, and the fluid solution affects the structural deformation.