Fundamental study of hybrid wind tunnel integrating numerical simulation and experiment in analysis of flow field

This paper deals with a new flow analysis system, namely the hybrid wind tunnel, which integrates the experimental measurement with a wind tunnel and a corresponding numerical simulation with a computer. Analysis here is performed for the fundamental flow with the Karman vortex street in a wake of a square cylinder. A specific feature of the hybrid wind tunnel is existence of the feedback signal to compensate the error in the pressure on the side walls of the cylinder and the feed-forward signal to adjust the upstream velocity boundary condition. Investigation is focused on evaluating the hybrid wind tunnel as a flow analysis methodology with respect to the ordinary simulation and the experiment. As compared with the ordinary simulation, the hybrid wind tunnel substantially improves the accuracy and the efficiency in the analysis of the flow. Especially, the oscillation of the flow due to the Karman vortex street reproduced with the hybrid wind tunnel exactly synchronizes with that of the experiment, while that with the ordinary simulation never behave like that. In comparison with the experiment, the hybrid wind tunnel provides more detailed information of the flow than the experiment does.