Implementação de um microburst estático em um caso multifásico com perturbação de densidade adotando uma malha bidimensional axissimétrica

Abstract

Microbursts are phenomena that originate from a very strong storm cloud and are identified by a descending and dense column of cold air, which may or may not is accompanied by rain. The main aspect of this event is the formation of large eddies of divergent velocity when hitting the ground, called vortices. Due to its very short duration, approaches 4 to 5 minutes, its complete description from observations in nature is difficult. Thus, the study of microbursts is largely done through numerical simulations or laboratory tests. In this work, the phenomenon of nature is simulated through the open-source software Open-Foam 9, where a multiphase case was adopted combining incident jet effects and density disturbance, aiming to determine the influence of such characteristics on the behavior of the structural formation of the vortices of this meteorological phenomenon and thus carry out an analysis on their velocity profiles, especially close to the surface. Comparing the results obtained with this work to previous studies. Using a case already carried out in the laboratory as a base study, it was possible to define the parameters to be adopted, as well as to determine the analyses, a two-dimensional axissymmetric mesh of the wedge type was then elaborated, allowing this simplification to be carried out without losing information from the original flow, to include a high refinement in the mesh for a low computational cost, adopting the LES turbulence model, to capture the maximum of the characteristics of the vortices, the mesh has its geometry open to the atmosphere, wherein the upper part there is the entrance of a descending jet of dense fluid. Using the Interfoam solver, satisfactory results were obtained, consistent with previous works, the velocity peaks are close to the ground and close to the ends of the contact point with the jet, the propagation and structure of the vortices proved to be faithful to the event in nature, as well as the entire microburst behavior throughout the simulation. Keywords: Microburst, LES, CFD, incident jet, Turbulence.