DEVELOPMENT OF A NEW KAPPA-EPSILON MODEL FOR FLOW AND PRESSURE FIELDSAROUND BLUFF-BODY

It is well known that applications of the standard k-epsilon model to flowfields around bluff-shaped bodies, often yield serious errors such as overestimation of turbulence kinetic energy k in the impinging reg ion. Murakami, Mochida and Kondo have proposed a new k-epsilon model w hich resolves these problems by modifying the expression for eddy visc osity approximation. This paper examines the applicability of this new k-epsilon 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 wi th 1:1:0.5 shape. The first half of the paper investigates the accurac y 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-epsilon model, a revised k-epsilon model proposed b y Launder and Kato (LK model) and wind tunnel tests for flow fields ar ound a 2D square rib and a cube. The MMK model is also applied to pred icting surface pressures on a low-rise building model with 1:1:0.5 sha pe 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-epsilo n model and of the wind tunnel tests.