Estimation of flow around a cylinder in a duct based on plane measurement by four-dimensional variational approach

Abstract

We apply a four-dimensional variational approach to estimate the unsteady three-dimensional flow field around a cylinder in a duct based on single-plane measurement downstream of the cylinder. It is shown that both the initial velocity field and the spatio-temporal distribution of a body force are simultaneously optimized so as to minimize the error between the measurements and their estimates. Consequently, the velocity field on the measurement plane is predicted fairly well even outside the measurement region. On the other hand, there remain discrepancies between the true and estimated velocity fields beyond the measurement plane, which could be overcome by assimilating measurements in a longer time period.