Development of a new k−ε model for flow and pressure fields around bluff body

Abstract

It is well known that applications of the standard k−ε model to flowfields around bluff-shaped bodies, often yield serious errors such as overestimation of turbulence kinetic energy k in the impinging region. Murakami, Mochida and Kondo have proposed a new k−ε model which resolves these problems by modifying the expression for eddy viscosity approximation. This paper examines the applicability of this new k−ε model (MMK model) to flowfields around three types of bluff bodies, i.e. a 2D square rib, a cube and a low-rise building model with 1 : 1 : 0.5 shape. The first half of the paper investigates the accuracy of the MMK model in reproducing turbulence characteristics around a bluff body. Results of the MMK model are compared precisely with those of the standard k−ε model, a revised k−ε model proposed by Launder and Kato (LK model) and wind tunnel tests for flow fields around a 2D square rib and a cube. The MMK model is also applied to predicting surface pressures on a low-rise building model with 1 : 1 : 0.5 shape with various wind angles including an oblique one. The accuracy and applicability of the MMK model to wind engineering problems are then discussed by comparing its results with those of the standard k−ε model and of the wind tunnel tests.