Hi

I am working on an FSI problem (flow past a circular cylinder). The tools I am using are the fluid solver Acusolve and the structural solver Abaqus. The fluid solver computes the forces on the body. Abaqus does the structural dynamics.

The issue - I have written a udf on the fluid solver side to compute the force on the body. I have written a user element on the Abaqus side for the structural dynamics. Now I have to create an interface between the two softwares, so that at each time step, the fluid solver passes the force values to Abaqus which does the structural part and feeds the motion of the body back to the fluid solver for the next time step.

Any ideas on this one? Please explain in as detail as possible.

Thanks tuhin

If you want to use Abaqus to solve structural dynamic, search on the net for MPCCI. Otherwise you can directly write a UDF which easily solves for the cylinder dynamics (I suppose you consider the cylinder as perfectly rigid...)Luca

Sorry I misundestood your question. Once you have solved the dynamic of the cylinder you have to move the mesh or use the transpiration method (if the movement is not too large). Then solve the flow-field, find pressure-forces, re-calculate the dynamic. Hope this helps you. Luca

Luca, I think he's asking if he can write a adapter/interface program that can communicate two software.

As far as I know, to be able to do this, at least one of the software needs to be able to handle your script or API at runtime.

I'd like to know the answer too.

Best Regards

If you want to connect a fluid and strcuture solver for FSI analysis you should run from the fluid solver, since it takes longer time than the structural one, the structural solver. From Fluent, for example, I lauch MSC-Nastran using the command system in C language. When the structural analysis is finished, I read nastran's output using another UDF. Then I run Fluent iterations (in time or in pseudo-time, it depends on what kind on analysis I'm doing...). If the dynamic is not so complicated to solve I suggest writing your own code to solve structural equations (if you consider to use a modal approch to solve the dynamic of your cylinder, with generalized stiffness, damping and mass, the task is not so difficult) Another thing is important: the interface processs between 2 grids (the strutural and the CFD one) which don't have the same topology ( nodes coordinates, numer of element, type of elements). In this case there's plenty of literature you can find on the net.

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