Is the proper orthogonal decomposition suitable to validate simulation of turbulent wake?

To evaluate the suitability of the proper orthogonal decomposition (POD) for validating a simulated flow dynamics, we selected the flow in the wake behind a circular cylinder at Reynolds number of $\approx 5000$ as a well studied canonical problem. The flow was simulated via $k$-$\omega$ _SST detached-eddy simulation (DES) and, on selected planes of measurement (PoM), investigated experimentally by a time-resolved variant of the particle image velocimetry (PIV) and stereo-PIV methods. A standard model validation comprising, among other, comparison of the drag coefficient, or separation angle, and of the averaged flow properties and turbulence spectra, was carried out. Subsequently, both the PIV and the numerical data on the selected planes in the geometry were analyzed by POD, and a fully 3D POD analysis of the numerical data was used to evaluate the credibility of the planar POD as a tool for dynamic model validation.