Partially averaged Navier-Stokes simulation of flow around an isolated building model with a 1:1:2 shape: Fid-Bau Portal

Partially averaged Navier-Stokes simulation of flow around an isolated building model with a 1:1:2 shape

Jia, Hongyuan / Kikumoto, Hideki

Abstract This study analyzes the performance of a numerical model with partially averaged Navier–Stokes (PANS) equations for simulating the flow field around an isolated building model with a 1 (length): 1 (width): 2 (height) shape. The PANS model was based on the $k - ω S S T$ unsteady Reynolds-averaged Navier-Stokes equations (URANS) model, and three different values were imposed on the coefficient $f_{k}$ , which represents the proportion of modeled turbulence kinetic energy (TKE) in PANS. The simulation results were validated by experimental measurements and compared to those of large-eddy simulation (LES) and URANS. According to the results, it was found that the resolution ability of PANS can be adjusted between URANS and LES by tuning $f_{k}$ . When compared to URANS, PANS improved the performance in predicting the mean flow field around the target building and separation layers in the wake region. The prediction error in the reattachment length in the wake region was reduced by 88% compared to URANS. Because PANS can explicitly resolve more turbulence, the prediction accuracy of TKE against the experiment (FAC2: 0.85) is higher than that of URANS (FAC2: 0.45). Through power spectrum analysis, it was determined that PANS can reproduce the characteristic vortex shedding caused by the building with specific frequencies. When compared to LES, it resolved approximately 99% of turbulence fluctuations in the relatively low-frequency domain at the representative point in the wake region.

Highlights • The flow surrounding a high-rise building was simulated by a $k - ω$ PANS model. • PANS's predictions were compared to experiment, URANS, and LES results. • PANS's resolution ability can be adjusted between LES and URANS by $f_{k}$ • The accuracy of PANS for mean velocity field prediction is close to that of LES. • PANS resolves most turbulence fluctuations in the low-frequency domain.