Intermitência global no escoamento turbulento em um canal fechado estavelmente estratificado: um estudo utilizando simulações de grandes turbilhões

Abstract

The adequate description of the nocturnal flow by numerical models is still a great challenge, one of the main aspects is the reproduction of the atmospheric coupling. As the objective of this work is to study the effects of stable stratification on turbulent flow and transient, using a solver with energy transfer in for m of heat for incompressible fluids by a LES (Large Eddy Simulation) model. The flow is maintained at a fixed pressure gradient, which maintains the flow constant in the channel. On the lower surface lower temperatures are imposed than the flow temperature and the upper channel surface. The simulations show that in low speed conditions and with a large vertical temperature gradient, the flow turbulence is reduced by buoyancy effects. In addition, the effects of stratification are manifest even in the boundary layer generated by the interaction of the flow with the upper surface. It is important to note that only the average flow characteristics were analyzed until the present moment, and a more in-depth investigation of the proper ties of the flow as a function of the forcing is required, as well as the limits of applicability of the results. As an example of application in fluid mechanics and engineering, we have the wind tunnel, applications with orifice valves used in the oil industry, thermohydraulics in nuclear reactors and drilling operators in the oil and gas industry, among others. Keywords: turbulence; stratified flow; large eddy simulation.