Estudo de efeitos de rugosidade superficial sobre escoamentos ao redor de dois corpos rombudos idênticos e alinhados in tandem utilizando o método de vórtices discretos

Abstract

This work numerically investigates new interference patterns on flows around two circular cylinders aligned in tandem at subcritical Reynolds number regime. The origin of these interference patterns is hitched to surface roughness effects; consequently, the interactions viscous wake-body and viscous wake-viscous wake establish new vorticity dynamics for the problem. Overall, the numerical results reveal the potentialities of the present numerical approach to capture drag reduction accompanied of base pressure increasing, intermittence of vortex shedding and wake destruction under certain interference patterns. There is a lack of data published in the literature discussing roughness interference on flows around cylindrical structures in cross flow, which motived the present study. The analysis of the main numerical results enables important conclusions and, mainly, contributes to science evolution. Two contributions of this work can be highlighted: (i) implementation of an in-house vortex code to include surface roughness effects from a two-dimensional Lagrangian vortex method with LES type turbulence modeling, and (ii) implementation and parallel programming of the vortex code using OpenMP with Fortran. The numerical results confirm that the present model of surface roughness effects is much more sensitive than a simple two dimensional turbulence modeling. However, the turbulence modeling provided earlier the development of the model of surface roughness effects utilized in the present study. The latter utilizes points set near every solid boundary combining the generation of vortex elements and instantaneous change in the vorticity field into the boundary layer by introducing momentum because of roughness protruding out of the surface.