Estudo do colapso da turbulência em um canal aberto estratificado

Abstract

Shortly after sunset the surface starts its cooling by the emission of longwave radiation. As a result of this process, the air layers along with the surface are cooled, thus giving rise to a Stable Boundary Layer (SBL). This paper aims to perform a numerical simulation of a turbulent flow and observe the effects of stratification on it. To perform this study, a reproduction of a flow in an open channel was made due the fact that the upper wall did not influence the flow, in which a temperature gradient between the lower and upper plates was applied. The CFD software used in this paper was OpenFOAM 2.4.0. The most appropriate solver for the present study is the buoyantPimpleFoam, which is suitable for compressible, turbulent, transient and heat transfer flows. Analyzing the results, it can be observed that before the thermal stratification process was performed the levels are coupled as a function of the turbulence. When this occurs, it causes greater velocity and temperature homogenization in the central region of the domain. For larger temperature gradients, it can be observed a laminarization of the flow due the thermal forcing being bigger than the mechanical ones.