Influence of eddy viscosity parameterisation on the characteristics of turbulence and wind flow: Assessment of steady RANS turbulence model

Eddy viscosity-based Reynolds-averaged Navier-Stokes (RANS) turbulence models remain a standard approach for accurately predicting the characteristics of turbulence and wind flow in computational wind engineering. RANS turbulence models have been widely studies; however, various types of deficiencies and numerical errors remain when they are used in numerical simulations. For overcoming these drawbacks associated with bluff body aerodynamics, numerous researchers have proposed modifications for eddy viscosity-based RANS turbulence models. However, deficiencies remain challenging. The main objective of this study is to explore the influence of eddy viscosity parameterisation on the characteristics of turbulence and wind flow. This exploration will help urban planners and researchers to modify existing numerical techniques and avoid the uncertainties that are present in the RANS turbulence models. The anisotmpic behaviour of the vorticity-to-strain ratio was investigated by varying the vorticity-to-strain ratio in the eddy viscosity formulation of a revised standard k-epsilon turbulence model. The results were validated using a wind tunnel experiment. A lower vorticity-to-strain ratio significantly reduced the uncertainty in predicting turbulent kinetic energy, particularly in the impingement regions around the building. However, varying the vorticity-to-strain ratio exerted only a minor effect on the wind flow parameters.