No abstract

Controlling the destructive behavior of the wake region and consequently drag reduction are great challenges in fluid mechanics and ocean engineering. In this paper, the effect of the non-uniform magnetic field on controlling the flow and consequently drag reduction has been studied in laminar flow of magnetic nanofluid around a circular cylinder. The source of the magnetic field is a single current-carrying wire located in the center of the cylinder. The nanofluid consists of Fe3O4 as nanoparticles and water as the base flow. The ranges of Reynolds number (Re), volume fraction (ϕ), and the diameters of nanoparticles are 1.6 < Re < 180, 0 < ϕ < 0.04 and 15 < dp < 25, respectively. The modified Buongiorno model that contains the magnetophoresis term is utilized to perform two-phase modeling of magnetic nanofluid flow. Finite volume method and PISO (Pressure-implicit With Splitting Of Operators) algorithm are utilized for the discretization of the governing unsteady equations including conservation laws of mass, volume fraction transport, and momentum equations by considering the ferrohydrodynamics (FHD) force as the source term. The results showed a significant effect of magnetic field intensity and volume fraction on the flow parameters such as drag coefficient, strouhal number, wake length, etc. In general, increasing the magnetic field in various volume fractions and various nanoparticle diameters reduces the amount of drag coefficient. The effective parameters for flow controlling are ordered as follows regarding their effectiveness: magnetic field intensity, volume fraction and diameter of the nanoparticles, respectively.