Optimising the computational domain size in CFD simulations of tall buildings

Abstract

Recently, there has been a growing interest in utilizing computational fluid dynamics (CFD) for wind resistant design of tall buildings. A key factor that influences the accuracy and computational expense of CFD simulations is the size of the computational domain. In this paper, the effect of the computational domain on CFD predictions of wind loads on tall buildings is investigated with a series of sensitivity studies. Four distinct sources of domain error are identified which include wind-blocking effects caused by short upstream length, flow recirculation due to insufficient downstream length, global venturi effects due to large blockage ratios, and local venturi effects caused by insufficient clearance between the building and top and lateral domain boundaries. Domains based on computational wind engineering guidelines are found to be overly conservative when applied to tall buildings, resulting in uneconomic grids with a large cell count. A framework for optimizing the computational domain is proposed which is based on monitoring sensitivity of key output metrics to variations in domain dimensions. The findings of this paper help inform modellers of potential issues when optimizing the computational domain size for tall building simulations.

Ambient wind conditions impact on energy requirements of an offshore direct air capture plant

“…The domain size of external aerodynamic simulations can have a large impact on model accuracy, but also has a large impact on the number of cells in the mesh, and as a result computational effort. Abu-Zidan et al [49] aimed to optimize the domain size by comparing the results of many external simulations. They concluded that the previous recommendations by Franke et al [50] seemed overly conservative in most cases.…”

“…In this case, H refers to the tallest building height. Abu-Zidan et al [49] recommends 3H upstream, 3H downstream, 3H laterally, and 4H vertically. To remain conservative, the recommended domain size from Franke was used in this study, based on the height of the contactor units from the bottom of the domain.…”

“…The outlet of the domain commonly has different BCs applied. In some studies [40,41], the normal gradients of all variables are set to zero, whereas in others [38,49] the static pressure, or in other words the gauge pressure is set to 0. Here the outlet pressure is set to the free stream value, and all other parameters set to zero-gradient.…”

Prefabricated Building Systems—Design and Construction

“…For a complex prefab structure, such as a tall building or a building that covers a large area, a load evaluation merely according to the loading standard may not be adequate. In such cases, a complete set of wind studies using a physical or virtual wind tunnel (using computational fluid dynamics) will be necessary to estimate the complete wind effects on the particular building [28,29]. The types of wind studies to consider are:…”

Optimizing Building Orientation and Roof Angle of a Typhoon-Resilient Single-Family House Using Genetic Algorithm and Computational Fluid Dynamics

“…It advantageously provides flexibility to change parametric design parameters without changing the existing system of the model. Moreover, the authors in [14] argued that the CFD's computational domain should have an optimized size to avoid uneconomic grids with large meshes. Their framework involves parametrizing the domain dimensions based on sensitivity analyses, where optimal values are obtained from acceptable levels of the following four domain errors: the wind-blocking effect, flow circulation, global venturi effect, and local venturi effect.…”