Proper orthogonal decomposition of direct numerical simulation data of by-pass transition

Reduced Order Modeling (ROM) of by-pass transition over a zero pressure gradient shear layer data is presented here in a Proper Orthogonal Decomposition (POD) framework. Here, by-pass transition is triggered by a convecting vortex outside the shear layer. POD analysis is relevant for those fluid-structure interaction problems where the fluid dynamical analysis necessarily requires solving the full Navier–Stokes equation. Two types of cases are reported here for which the vortex is either stationary or it convects with a constant speed. Analysis of the complex unsteady flow is performed by locating the eigenvalues and eigenvectors of the covariance matrix by using Lanczos iteration. The local description produces eigenvectors that match seamlessly due to the linearity property of POD.