Turbulent Kinetic Energy Budget and Dissipation in the Wake of 2D Obstacle: Analysis of the K-ε Closure Model

The prediction of the flow dynamics produced by the interaction between a sheared turbulent flow and a bluff body has important implications in the domain of the wind engineering and for what concerns the simulation of atmospheric dispersion of air-born pollutants.In this study we present the results of the experimental investigation on the wake of a 2D obstacle, immersed in a neutrally stratified boundary layer flow. Measurements are performed by means of two different techniques, namely Laser Doppler Anemometry and Stereo-Particle Image Velocimetry. These allow us to map the spatial evolution of the velocity statistics up to their third order moments.The study focuses in particular on the budget of the turbulent kinetic energy (t.k.e.) and the estimate of its mean dissipation rate. The experimental data-set is the basis for a detailed analysis of the reliability and the main limitations of a classical k-ϵ closure model. This has major implication for the numerical simulation of pollutant dispersion in the built environment.© 2014 ASME