Unsteady Validation Metrics for CFD in a Cylinder Array

A validation study for various CFD models of the time-varying flow through a confined bank of cylinders is presented. The geometry approximates part of the lower plenum of a high temperature reactor and is arranged with the cylinders on equilateral triangles with pitch to diameter ratio of 1.7. Time-resolved Particle Image Velocimetry (PIV) measurement coupled with time-varying pressure measurements along the facilities walls are compared to both the Unsteady Reynolds Averaged Navier Stokes (URANS) k − ω model and Detached Eddy Simulation (DES) models. Spatial (i.e. time-averaged bulk velocity, local velocity distributions and pressure losses) and temporal (i.e. dominant frequencies and correlations) validation parameters on both the local and global scale are used for validation. It is found the DES model accurately predicts frequencies present in the pressure along the walls next to the cylinders in the first and the last cylinder, yet predicts other dominant frequencies in the remaining cylinders that are not found in the experiment. As expected, the temporal behavior of the DES was generally far superior to that of the URANS model.