[adubois]

I am simulating the flow around an oscillating foil using the combination of two udf (zone_motion and cg_motion). I meshed a structured c-grid around the foil itself (which will move as 1 zone and does not deform within the zone) and created an unstructured grid around this c-grid. The motion of the foil-zone is defined using the zone_motion-udf, while the motion of the "gap" in the unstructured grid in which this zone is located is defined using the cg_motion-udf. The motion match up perfectly so that the domain deforms and oscillates as wanted.

But now this is where the problem shows up, apparently FLUENT lets the flow move over the moving zone (flow is deformed by the motion of the zone which is of course not realistic since it is only a modelling approach). This can be seen in the figure (transient), I added another figure of a steady state calculation on the still grid to show that the interfaces indeed work.

Any suggestions on how to solve this problem?