Effects of Inflow Condition on RANS and LES Predictions of the Flow around a High-Rise Building

Abstract

An increasing number of engineering applications require accurate predictions of the flow around buildings to guarantee performance and safety. This paper investigates the effects of variations in the turbulent inflow, as predicted in different numerical simulations, on the flow pattern prediction around buildings, compared to wind tunnel tests. Turbulence characteristics were assessed at several locations around a model square high-rise building, namely, above the roof region, at the pedestrian level, and in the wake. Both Reynolds-averaged Navier–Stokes (RANS, where turbulence is fully modelled) equations and large-eddy simulation (LES, where turbulence is partially resolved) were used to model an experimental setup providing validation for the roof region. The performances of both techniques were compared in ability to predict the flow features. It was found that RANS provides reliable results in regions of the flow heavily influenced by the building model, and it is unreliable where the flow is influenced by ambient conditions. In contrast, LES is generally reliable, provided that a suitable turbulent inflow is included in the simulation. RANS also benefits when a turbulent inflow is provided in simulations. In general, LES should be the methodology of choice if engineering applications are involved with the highly separated and turbulent flow features around the building, and RANS provides reliable information when regions of high wind speed and low turbulence are investigated.

Improving the Energy Efficiency of Buildings Based on Fluid Dynamics Models: A Critical Review

“…For LES validation and comparison with RANS models, Vita et al [122] simulated the flow pattens around high-rise buildings based on the turbulent inflow variations. It was found that RANS models are accurate only for some situations.…”

Large-eddy simulation of airflow dynamics around a cluster of buildings

“…For the high-rise skyscrapers, the mean velocities, turbulent kinetic energies, tracer concentrations, and Reynolds stresses were recently studied using adaptive LES by Aristodemou et al 39 to discover how they affect the local environment. Using RANS and LES, Vita et al 40 investigated the wind velocity around a high-rise building and provided a detailed analysis of the pedestrian level, roof and wake regions. Recently, indoor airflow dynamics in a room with a partition have been investigated using the large eddy-simulation lattice Boltzmann method by Haque et al 41 Very recently, Hassan et al 42 have investigated the airflow dynamics around a square shape high-rise building using the unsteady realizable k - ε RANS approach for Re = 12000 .…”