Numerical study of obstacle geometry effect on the vortex shedding suppression and aerodynamic characteristics

Abstract

Purpose Two-dimensional incompressible fluid flows around a rectangular shape placed over a larger rectangular shape at low Reynolds numbers (Re) have been numerically analyzed in the present work. The vortex shedding is investigated at different arrangements of the two shapes allowing the investigation of three possible configurations. The calculations are carried out for several values of Re ranging from 1 to 200. The effect of the obstacle geometry on the vortex shedding is analyzed for crawling, steady and unsteady regimes. The analysis of the flow evolution shows that with increasing Re beyond a certain critical value, the flow becomes unstable and undergoes a bifurcation. This paper aims to observe that the transition of the unsteady regime is performed by a Hopf bifurcation. The critical Re beyond which the flow becomes unsteady is determined for each configuration. A special attention is paid to compute the drag and lift forces acting on the rectangular shapes, which allowed determining; the best configuration in terms of both drag and lift. The unsteady periodic wake is characterized by the Strouhal number, which varies with the Re and the obstacle geometry. Hence, the values of vortex shedding frequencies are calculated in this work. Design/methodology/approach The dimensionless Navier–Stokes equations were numerically solved using the following numerical technique based on the finite volume method. The temporal discretization of the time derivative is performed by an Euler backward second-order implicit scheme. Non-linear terms are evaluated explicitly; while, viscous terms are treated implicitly. The strong velocity–pressure coupling present in the continuity and the momentum equations are handled by implementing the projection method. Findings The present paper aims to numerically study the effect of the obstacle geometry on the vortex shedding and on the drag and lift forces to analyze the flow structure around three configurations at crawling, steady and unsteady regimes. Originality/value A special attention is paid to compute the drag and lift forces acting on the rectangular shapes, which allowed determining; the best shapes configuration in terms of both drag and lift.

Computational Examination of Aerodynamics Forces and Evolution of Vortex Shedding of Flow Past Three Square Cylinders at Two Symmetrical Vee Shapes

“…As observed, Figure 5 and Table 2 confirm that our results are in good agreement with the results of Breuer et al [29] & Galleti et al [30] and this comparison validates our computer code making confidence on the presented results. It is also worth noting that validation of the computer code has already been presented by Fezai et al [31,32] which is a contribution of the current investigation.…”

Numerical analysis of drag and lift forces acting on a group of square cylinders at various staggered arrangements

“…It is noted that validation of the computer code has already been presented by Fezai et al [23,24,28,29,31,30] which is a contribution of the current investigation.…”

Study of the flow mechanism and influencing factors of sputum excretion from the distal lung

“…Computational fluid dynamics (CFD) is an important means for studying the dynamic mechanism of sputum excretion (Deng et al , 2019; Fezai et al , 2020; Gao et al , 2020; Kim et al , 2019; Kulhánek et al , 2020). The difficulty of using CFD to study sputum excretion at the distal lung lies in the complex geometric modeling and the determination of the appropriate flow conditions.…”