MODELLING FSI PROBLEMS IN FLUENT: A GENERAL PURPOSE APPROACH BY MEANS OF UDF PROGRAMMING

摘要

Fluid-structure interaction (FSI) is an important and interesting phenomenon, but it is a difficult challenge for numerical modelling. However there are several cases in which the interaction between the fluid and adjoining structure governs the physical behaviour of the system. Fluid-structure interaction plays an important role in general problems such as flow-induced vibration, blood flow in vessels and heart valves, wind instruments and sailing. More automotive specific examples are aerodynamic induced deformation, aero noise, tire hydroplaning, air bags deployment, pressure driven engine valves, ducts deformation in high pressure injection systems. An FSI model has been developed for FLUENT 6.2 using a dedicated FEM solver, coded as a user-defined function (UDF). Arbitrary thin structures are handled by the model, and include non-linear effects, such as the contact between rigid and flexible walls. Special care was taken to manage boundary motion in FLUENT since the contact between moving surfaces is denied by FLUENT's remeshing algorithm. A special solution strategy that leaves the CFD simulation time virtually unaffected by the simultaneous working of the FEM code, is applied. The result is a general-purpose model, capable of solving a variety of problems without the need for significant modifications to the software each time. Some test cases and application examples are presented in order to validate the code and to demonstrate its functionality.