Evaluation of CFD URANS Turbulence Models for the Building under Environmental Wind Flow with Experimental Validation

Abstract

Wind flow on and around buildings attains more importance among architectures, builders, urban planners, structural engineers, and wind engineers. Wind tunnel experiments and wind flow assessments of full-scale buildings are expensive and complex in varied terrain conditions. Hence, wind flows are extensively assessed using Computational Fluid Dynamics (CFD). By following the turbulence parameters, CFD turbulence models create the wind tunnel and atmospheric environments. No literature has till elucidated which CFD turbulence model is more suitable for predicting the terrain wind flow on and around high-rise buildings. The efficiency of the CFD models, their performance, and their accuracy must be validated with experimental results, which is indispensable before using the turbulence model in practice. Therefore, this investigation aims to validate the Unsteady Reynolds-Averaged Navier-Stokes (URANS) simulations for a setback tall building under open terrain wind conditions enclosed within the wind tunnel dimensions. The URANS simulation is accompanied with Standard k-ε, Realizable k-ε, RNG k-ε, Standard k-ω, k-ω SST and RSM. The k -ω SST and RSM turbulence models have reproduced the wind pressure coefficients observed from the wind tunnel. However, all turbulence models failed to produce the same velocity profiles at downstream recirculation, as they vary with sampling time. The transient feature, RMS (Root Mean Square), is better reproduced by RSM and k-ω SST models, while the most unsteady features like across wind spectra and eddies were captured by Realizable, RSM and SST using iso-surface. k-ω SST and RSM models predict similar results with the experiment. Where less computational time was required for the SST, it is promising that this model provides both mean pressure and unsteady feature, encouraging more accurate simulation around the buildings.

Large eddy simulation of sneeze plumes and particles in a poorly ventilated outdoor air condition: A case study of the University of Houston main campus

“…There have been extensive efforts to produce more realistic representations of urban surface features that can affect ventilation efficiency by using generic buildings in tangible and digital forms crafted and generated based on the ground- and satellite-based light detection and ranging (LIDAR) measurements supported by computer-aided design (CAD) techniques ( Farea et al, 2015 ; Mohammadi and Calautit, 2021 ; Juan et al, 2022 ; Hadavi and Pasdarshahri, 2020 ; Brozovsky et al, 2021 ; Liu et al, 2019 ; Nikkho et al, 2017 ). Supported by such enhanced details of urban aerodynamics available for use, many CFD studies have effectively captured near-surface airflows and the consequent dispersion of air pollutants in outdoor environments supported by turbulence schemes, such as the Reynolds-Averaged Navier-Strokes (RANS) model ( Ding and Lam, 2019 ; Buccolieri et al, 2015 ; San Jose et al, 2021 ; Hadžiabdić et al, n.d. ) and Unsteady RANS (URANS) model ( Gousseau et al, 2011 ; Rajasekarababu et al, 2022 ). The URANS model has been widely adopted by many previous LES studies related to the unsteady nature of micro-scale urban airflows varying with time-specific boundary conditions (i.e., wind and temperature) above homogeneous surfaces ( Chen et al, 2021 ; Muñoz-Esparza et al, 2020 ; Chan and Leach, 2007 ).…”