CFD analysis of cross-ventilation flow in a group of generic buildings: Comparison between steady RANS, LES and wind tunnel experiments

Abstract

Computational fluid dynamics (CFD) results generated by the steady Reynolds-averaged Navier-Stokes equations (SRANS) model and large eddy simulation (LES) are compared with wind tunnel experiments for investigating a cross-ventilation flow in a group of generic buildings. The mean flow structure and turbulence statistics are compared for SRANS based on different two-equation turbulence models with LES based on the Smagorinsky subgrid-scale turbulence model. The LES results show very close agreement with the experimental results in the prediction of the time-averaged velocity, wind surface pressure around and inside the building, and crossing flow through the openings. In contrast, SRANS fails to predict the most important features of cross-ventilation. LES reproduced well the anisotropic turbulence property around and inside the cross-ventilated building, which is closely related to the transient momentum transfer caused in street canyon flows and has a significant influence on the mean flow structure. In contrast, SRANS could not inherently reproduce such transient fluctuations and anisotropic turbulence property, and it results in low accurate predictions for the time-average velocity components, wind surface pressure distribution and crossing airflow rate up to 100% error.

Review of Research Advances in CFD Techniques for the Simulation of Urban Wind Environments

“…Therefore, it is recommended to use unstructured grids in areas of interest and structured grids far away from areas of interest for complex models. Some scholars used unstructured grids to simulate the wind environment outside the building, and it showed that the results were very satisfied [28,36,41,47,48]. Grid lines near the wall should be perpendicular to the wall.…”

CFD simulation study on wind load of perforated traffic sign board

“…Chao et al [ 36 ] demonstrated the feasibility of CFD simulation by using the empirical formula for traditional sign board wind loads. The Reynolds average NS model (RANS) was selected to solve the turbulence in the wind-borne simulation process.…”

“…Besides, Chao et al [35] demonstrated the feasibility of CFD simulation through the theoretical calculation method of wind load on traffic sign boards. Shirzadi et al [36] analysed steady-state the Reynolds average NS model (RANS), Large eddy simulation (LES), and wind tunnels using CFD. The difference between the simulation and experimental results provides a theoretical basis for the subsequent CFD simulation of the sign board.…”

Review of calculating models of unsteady natural ventilation rate due to wind fluctuations

“…39 As for Computational fluid dynamics (CFD) of simulation models, the Reynolds-averaged Navier-Stokes (RANS) simulation has no capability to simulate adequately in the case of modelling the inherently transient features of the airflow field, while Large Eddy Simulation (LES) undeniably has the potential to provide more accurate and more informative results. [40][41][42][43] Although unsteady RANS (URANS) has been reported to be valuable for working nonstationary problems such as periodic or quasi-periodic airflows involving deterministic structures, URANS still utilizes the mean airflow equations that have failed to capture the vortex shedding in various scales. 42,44 Moreover, some statistical analysis techniques have been applied to turbulence modelling.…”