Effect of rotation on the electrohydrodynamic instability of a fluid layer with an electrical conductivity gradient

Abstract

The electrohydrodynamic instability of a horizontal rotating fluid layer with a vertical electrical conductivity gradient is considered. An external electric field is applied across the fluid layer to induce an unstably stratified electrical body force. A linear stability analysis has been performed to study the effect of rotation on the onset of electrohydrodynamic instability in the fluid layer. Results show that the instability behaviors depend heavily on the boundary condition of bottom surface. In the case of stress-free condition, rotation enhances the stability and the onset of instability will be dominated by the oscillatory mode once the speed of rotation ͑or Taylor number͒ exceeds a critical value. In contrast, in the case of rigid bottom surface, rotation also tends to stabilize the fluid layer and the stationary mode will prevail eventually with increasing Taylor number. However rotation becomes destabilizing as the critical mode shifts from oscillatory to stationary. Moreover, under the same electrical conductivity gradient, the case with stress-free bottom surface is always more unstable than that with rigid bottom surface in the small Taylor number domain. However this situation is reversed at high Taylor number region since the stability of the stress-free case will be enhanced more rapidly than the rigid case.

Stability of natural convection in a vertical dielectric couple stress fluid layer in the presence of a horizontal AC electric field

“…Smorodin [19] investigated the instability of convective liquid dielectric flow in the alternating field of a vertical capacitor with boundaries heated to different tem peratures. The EHD instability of a horizontal rotating fluid layer with a vertical electrical conductivity gradient is considered by Ruo et al [20] .…”

The effect of rotation on the onset of electrohydrodynamic instability of an elastico-viscous dielectric fluid layer

“…A good account of thermal instability problems of a rotating viscoelastic fluid is given by Sharma and Rana [21] and Shivakumara et al [22], Rana and Jamwal [23], Chand and Rana [24] and Rana et al [25]. Ruo et al [26] studied the effect of rotation on the electrohydrodynamic instability of a fluid layer with an electrical conductivity gradient whereas Shivakumara et al [27] studied the electrohydrodynamic instability of rotation couple stress dielectric fluid layer and found that the effect of increasing AC electric field number is to increase the transfer of heat more effectively and hasten the onset of convection and rotation inhibits the onset of electrohydrodynamic instability.…”

Effect of Fe3O4nanoparticles on magnetic electrospun nanofibers

“…Macroscopic alignment of nanofibers has been improved in the past using different methods including the use of a rotating mandrel collector (Matthews, Wnek, Simpson, & Bowlin, 2002;Shields, Beckman, Bowlin, & Wayne, 2004), a copper wire drum (Katta, Alessandro, Ramsier, & Chase, 2004), and conducting plates (Li, Wang, & Xia, 2003). Recently, a novel approach to controlling instability in electrospinning is suggested, and the technology is termed as magnetic electrospinning (He et al, 2008;Ruo, Chang, & Chen, 2010;Wu, Yu, He, & Wan, 2007;Yang, Lu, Zhao, & Jiang, 2007;Yang, Zhang, Zhang, & Nie, 2008). In the magnetic electrospinning process (Ruo et al, 2010), the current in the jet under the magnetic field, produces a centripetal force, i.e.…”

“…Recently, a novel approach to controlling instability in electrospinning is suggested, and the technology is termed as magnetic electrospinning (He et al, 2008;Ruo, Chang, & Chen, 2010;Wu, Yu, He, & Wan, 2007;Yang, Lu, Zhao, & Jiang, 2007;Yang, Zhang, Zhang, & Nie, 2008). In the magnetic electrospinning process (Ruo et al, 2010), the current in the jet under the magnetic field, produces a centripetal force, i.e. the direction of the Ampere force is always towards the initial equilibrium point, leading to the shrinking of the radius of whipping circle.…”