Flow reproduction using Vortex Particle Methods for simulating wake buffeting response of bluff structures

Abstract The paper presents a novel extension of the two-dimensional Vortex Particle Method which allows complex transient flow features computed by an original simulation to be recreated for use as inflow conditions in other simulations. This is facilitated by recording velocity time signals of the original simulation and computing time traces of vortex particles to be seeded into the secondary simulation near its upstream domain boundary. The proposed Flow Reproduction Method (FRM) thus allows us to re-create the flow field, without the need to simulate the underlying physics responsible for the flow features. A natural field of application is the re-creation of wakes from flows past bluff bodies of arbitrarily complex geometry, the resolution of which is computationally expensive. The recording is performed on a sampling system of the velocity field. Reproduction of the sampled simulation is then performed by inserting vortex particles in defined positions and time intervals into the secondary simulation. This proceeds in a smaller domain with the advantage of significantly reduced computational cost. In the simulations presented here, wake flows of upstream cylinders are reproduced. Convergence studies are performed to validate the FRM. The quality of flow reproduction is assessed and quantified. The computational efficiency of the reproduction simulation is enhanced additionally by using different adaptive numerical techniques. The method is then applied to fluid-structure interaction simulations of a wake buffeting problem. Good agreement is found between the dynamic response quantities when comparing original simulations and those with reproduced flows, whereby the latter are performed up to five times faster.