Numerical Model Inter-comparison for Wind Flow and Turbulence Around Single-Block Buildings

Abstract

Wind flow and turbulence within the urban canopy layer can influence the heating and ventilation of buildings, affecting the health and comfort of pedestrians, commuters and building occupants. In addition, the predictive capability of pollutant dispersion models is heavily dependent on wind flow models. For that reason, well-validated microscale models are needed for the simulation of wind fields within built-up urban microenvironments. To address this need, an inter-comparison study of several such models was carried out within the European research network ATREUS. This work was conducted as part of an evaluation study for microscale numerical models, so they could be further implemented to provide reliable wind fields for building energy simulation and pollutant dispersion codes. Four computational fluid dynamics (CFD) models (CHENSI, MIMO, VADIS and FLUENT) were applied to reduced-scale single-block buildings, for which quality-assured and fully documented experimental data were obtained. Simulated wind and turbulence fields around two surface-mounted cubes of different dimensions and wall roughness were compared against experimental data produced in the wind tunnels of the Meteorological Institute of Hamburg University under different inflow and boundary conditions. The models reproduced reasonably well the general flow patterns around the single-block buildings, although over-predictions of the turbulent kinetic energy were observed near stagnation points in the upwind impingement region. Certain discrepancies between the CFD models were also identified and interpreted. Finally, some general recommendations for CFD model evaluation and use in environmental applications are presented

Evaluation of the atmospheric RAMS model in an obstacle resolving configuration

“…This vertical distribution of the tke also did not favour the development of the recirculation on the roof, which instead mildly occurred with RNG-kε, which underestimated the tke at all levels above the roof. Qualitatively, RAMS results appear to be generally in line with CFD performances as reported in the literature treating the flow around single obstacles: see, for instance [10,11,14,22,27].…”

“…In general, the results of RAMS simulations are encouraging, since in most cases the agreement between predictions and observations is comparable to the quality of results in literature (see for instance: [14,15,27,29,30]). The main characteristics of the flow and turbulence structure are captured and at some locations the accuracy of the prediction is very good.…”

On the use of numerical modelling for near-field pollutant dispersion in urban environments − A review

“…Meroney and Yang, 1970;Martinuzzi and Tropea, 1993;Hoxey et al, 2005) and numerical simulations (e.g. Murakami and Mochida, 1989;Paterson and Apelt, 1990;Lakehal and Rodi, 1997;Straw et al, 2000;Krajnovi c and Davidson, 2002;Wright and Easom, 2003;Gao and Chow, 2005;Yakhot et al, 2006;Paik et al, 2009;Kose and Dick, 2010;Vardoulakis et al, 2011). For this case, the features of the wind-flow pattern À as shown in Fig.…”

Influence of Thermal Effects on the Wind Field Within the Urban Environment

“…The described CFD code was used to simulate air flow and traffic pollutant dispersion at microscales, as well as to analyse the thermal effects of solar radiation on the airflow Baik 1999, 2001;Louka et al 2001;Kovar-Panskus et al 2002b). CHENSI has been employed also in several intercomparison studies (Ketzel et al 2001;Sahm et al 2002;Vardoulakis et al 2006).…”

“…More recently VADIS has been applied to the Lisbon downtown area, demonstrating good performance for the flow patterns and dispersion around obstacles under variable wind conditions (Borrego et al 2003(Borrego et al , 2004(Borrego et al , 2007. VADIS also has been used in previous model intercomparison studies (Sahm et al 2002;Vardoulakis et al 2006).…”