On the Flow Past Rectangular Cylinders: Physical Aspects and Numerical Simulation

Abstract

This paper concerns with unsteady incompressible flows around rectangular cylinders with side ratio varying from 1 to 10. Phenomenological aspects are discussed and numerical simulations are performed using a SIMPLEC finite volume code. A third-order QUICK scheme is employed for the advective terms in the Navier-Stokes equations, while a second-order fully implicit method is used for the time discretization. For validation purpose, preliminary simulations are carried out at Re = 300. Afterwards, the flow patterns and the wake periodic features are examined at Re = 1,000, 5,000, and 22,000, for which turbulent effects should not be neglected. In some of those cases, large-eddy simulation (LES) is employed, using the classical sub-grid Smagorinsky model. Important physical mechanisms determining vortex shedding frequency are placed in evidence. The present predictions are compared with numerical and experimental results from other works and a good agreement is reached.

Active Flow Control Schemes for Bluff Body Drag Reduction

“…Presented next is work done by Almeida [6] on the flow past rectangular cylinders. Throughout this work the Large Eddy Simulation method is employed to study unsteady incompressible flows around rectangular cylinders with side ratios varying from one to ten.…”

“…Extensive research has been performed on these kinds of bluff body flows [2][3][4][5][6], but also on how to locally control the flow in an attempt to remove or delay the development of the recirculation zone and the separated vortices [7][8][9][10]. was noted at the lowest Reynolds numbers tested (5000), however this effect quickly became less prominent as Reynolds number increased.…”

Turbulent Flow Around a Semi-Submerged Rectangular Cylinder

“…Tamura and Ito [25] simulated the aerodynamic characteristics of various rectangular sections by employing higher order schemes. In recent years, an improvement in the computational capacity makes 3D simulations feasible, as shown by Hirano et al [26], Krajnovic and Davidson [27], Lam et al [28], Sohankar [29], Almeida et al [30], Noda and Nakayama [31], and Arslan et al [32].…”

Eight(y) mathematical questions on fluids and structures

“…where r is the fluid density, W is the upstream velocity, A f is the frontal area (the projected area seen by an observer looking towards the object from a direction parallel to the upstream velocity), and A p is the planform area (the projected area seen by an observer looking towards the object from a direction normal to the upstream velocity). In (1), C D and C L denote, respectively, the drag and lift coe‰cients, giving dimensionless forms of the drag and lift forces. They are usually determined by help of a simplified analysis, some numerical procedures or empirical rules based on (e.g.…”