An assessment of PANS for simulation of turbulent cross flow over in-line tube bundles

The flow and heat transfer characteristics of turbulent cross flow over tube bundles are very complicated due to the phenomena of boundary layer separation, reattachment and wake disappearance. The method of Partially-Averaged Navier-Stokes (PANS) is considered as the bridge between Direct Numerical Simulation (DNS) and Reynolds-Averaged Navier-Stokes (RANS) and shows good prediction of separated flows with relatively lower computational resources. It may be the best choice to balance the prediction accuracy and computational resources when simulating large scale tube bundles for engineering applications. In current investigation, turbulent cross flows over in-line tube bundles are simulated with PANS method using OpenFOAM. In order to investigate the effects of unresolved-to-total kinetic energy ratio (f_k), the flow is simulated with both variable f_k and constant f_k. The St numbers corresponding to the main frequency for the cases with f_k = 0.5, f_k = 0.25 and four f_k expressions are all 0.1411. For the cases with f_k = 0.5, f_k = 0.25 and f_k expression from Luo et al. (2014), the pressure coefficient and velocity magnitude distribution agree well with the experimental data from Xie et al. (2023). More small-scale structures are resolved as the f_k value decreases. The numerical results show that the PANS models are capable to predict turbulent cross flow over in-line tube bundles for engineering applications.