Control of Vortex Shedding From a Bluff Body Using Imposed Magnetic Field

Abstract

The two-dimensional incompressible laminar viscous flow of a conducting fluid past a square cylinder placed centrally in a channel subjected to an imposed transverse magnetic field has been simulated to study the effect of a magnetic field on vortex shedding from a bluff body at different Reynolds numbers varying from 50 to 250. The present staggered grid finite difference simulation shows that for a steady flow the separated zone behind the cylinder is reduced as the magnetic field strength is increased. For flows in the periodic vortex shedding and unsteady wake regime an imposed transverse magnetic field is found to have a considerable effect on the flow characteristics with marginal increase in Strouhal number and a marked drop in the unsteady lift amplitude indicating a reduction in the strength of the shed vortices. It has further been observed, that it is possible to completely eliminate the periodic vortex shedding at the higher Reynolds numbers and to establish a steady flow if a sufficiently strong magnetic field is imposed. The necessary strength of the magnetic field, however, depends on the flow Reynolds number and increases with the increase in Reynolds number. This paper describes the algorithm in detail and presents important results that show the effect of the magnetic field on the separated wake and on the periodic vortex shedding process.

Control of vortex shedding from a circular cylinder using imposed transverse magnetic field

“…The variation is nearly linear within the selected ranges of the parameters. In this respect the flow behaviour is identical to the flow about a square cylinder (Singha et al , 2007). The variations in Strouhal number with Hartmann number for different Reynolds numbers are shown in Figure 9(b).…”

“…It is seen that the unsteady flow at higher Reynolds numbers need stronger magnetic field to become steady. It is also observed that the threshold or critical Hartmann number for suppressing the shedding of vortices completely is marginally higher for the circular cylinder compared to a square cylinder (Singha et al , 2007). The difference is negligible at the Reynolds number of 150, but increases slowly with increasing Reynolds number.…”

“…Sekhar et al (2006) investigated laminar flow past a circular cylinder subjected to inline magnetic field and observed that parallel magnetic field reduced the wake length. Singha et al (2007) studied the effect of an applied transverse magnetic field on steady as well as periodic vortex‐shedding flow around a square cylinder using an explicit staggered grid finite difference method. Recently, Knaepen et al (2004), Kassinos et al (2007), Sarris et al (2007) have studied the structure of MHD turbulence and transport processes in MHD turbulent flows under different conditions using large eddy simulation and direct Navier‐Stokes simulation techniques.…”

Vortex shedding suppression and wake control: A review

“…Control of vortex shedding from a bluff body using imposed magnetic field was studied numerically by Singha et al (2007). A 2-D incompressible laminar viscous flow past a square obstacle placed inside the channel was considered.…”

Numerical investigation of MHD flow of non-Newtonian fluid over confined circular cylinder: a lattice Boltzmann approach

“…In addition to the above-mentioned methods, some researchers have introduced the effects of magnetic field on hydrodynamics and heat transfer. Singha et al [29] numerically studied the confined flow over a square cylinder in the presence of a transverse magnetic field. Their results show that the variation of Reynolds number and Hartmann number has the same trend for elimination of the vortex shedding.…”