CFD modelling and PIV experimental validation of flow fields in urban environments

Abstract

Abstract. The problem of flow field in the urban boundary-layer (UBL) in aspects of wind comfort around buildings and pollutant dispersion has grown in importance since human activity has become so intense that it started to have considerable impact on environment. The issue of wind comfort in urban areas is the result of complex interactions of many flow phenomena and for a long time it arouses a great interest of the research centres. The aim of article is to study urban atmospheric flow at the local scale, which allows for both a detailed reproduction of the flow phenomena and the development of wind comfort criteria. The proposed methodology involves the use of PIV wind tunnel experiments as well as numerical simulations (Computational Fluid Dynamics, CFD) in order to enhance understanding of the flow phenomena at this particular scale in urban environments. The analysis has been performed for the 3D case of two surface-mounted buildings arranged in tandem, which were placed with one face normal to the oncoming flow. The local characteristics of flow were obtained by the use of commercial CFD code (ANSYS Fluent). The validation was carried out with reference to the PIV results.

The role of inflow boundary layer thickness for numerical modelling of flow around bluff bodies of built-up areas

“…This recommendation given above has determined the initial minimum grid resolution which is 174x74x48 per cube. The grid independent solution has been obtained for 298x130x70 by systematically refining the entire mesh in each direction, increasing the number of nodes by about 50% [5,6,11]. The inflow boundary layer has been prescribed according to methods proposed by Richards et al [8,9].…”

“…In front of a building exposed to the wind, a vortex forms below the stagnation point. This vortex is shed on each side of the building and it can produce excessively high winds at ground level, causing discomfort or danger [6].…”

Wind conditions in urban layout – Numerical and experimental research

“…The development of fluid mechanics computational methods, as well as the possibility to access computers with ever-increasing computing power, has made it possible for numerical research to supplement tunnel analysis of airflows around buildings and even to become an alternative research method [5][6][7][8][9][10][11][12][13][14][15]. Whole fields of interesting physical quantities (rather than their value in discrete measurement points) are obtained as a result of such analysis.…”

CFD validation of ABL in short wind tunnel chamber along an empty domain

“…The computational fluid dynamic (CFD) simulation of the ABL has become an important research subject. CFD is a tool, which is used more and more often to study wide type of processes in the ABL, where numerical modelling is called computational wind engineering (Koblitz, et al 2015, Gnatowska, et al 2017. CFD seems to be the obvious way to make a new contribution to understanding the behavior of the flow fields in short test section wind tunnel.…”