Effect of non-uniform basic temperature gradient on the onset of Marangoni convection in a fluid with suspended particles

The effect of a non-uniform basic temperature gradient on the onset of convection driven by surface tension in a horizontal layer of a Boussinesq fluid with suspended particles confined between an upper free, constant heat flux boundary and a lower rigid isothermal boundary is considered. The microrotation is assumed to vanish at the boundaries. A linear stability analysis is performed. The Rayleigh-Ritz technique is used to obtain the eigenvalues. The influence of various parameters on the onset of convection has been analyzed. Six different non-uniform basic state temperature profiles are considered and their comparative influence on onset is discussed. It is observed that the fluid layer with suspended particles heated from below is more stable compared to the classical fluid layer without suspended particles. The problem has possible applications in microgravity situations

Convection in a ferromagnetic fluid occupying a vertical enclosure

423-426<span style="font-size:11.0pt;line-height:115%; font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;mso-fareast-font-family:="" "times="" new="" roman";mso-fareast-theme-font:minor-fareast;mso-hansi-theme-font:="" minor-latin;mso-bidi-font-family:arial;mso-ansi-language:en-us;mso-fareast-language:="" en-us;mso-bidi-language:ar-sa"="">Convection in ferromagnetic fluids occupying a rectangular vertical slot is studied with uniform heat flux along the vertical walls. The top and bottom walls of the two -dimensional cavity are impermeable and adiabatic, while the vertical walls are impermeable. A closed form solution based on the Oseen linearization technique and also similarity analysis is obtained. Magnetization and buoyancy arising due to differential heat flux at the walls give rise to convection. The effect of various parameters on the boundary layer velocity is clearly brought out. It is found that the effect of the magnetization is to increase the Nusselt number.</span

Couple-stress fluid flow through a varying gap channel

The flow of a couple-stress fluid through a channel of varying gap is studied analytically. Three different varying-gap channels are considered and analytical solution is obtained for the velocity and pressure distributions. The solution is applied to a smooth-constriction channel. The effect of fluid-suspensions on the resistance to flow and the shear stress is clearly brought out. The results of the study have possible biomechanical applications, both corporeal and extra-corporeal

Rayleigh-Benard convection in a viscoelastic fluid-filled high-porosity medium with nonuniform basic temperature gradient

The qualitative effect of nonuniform temperature gradient on the linear stability analysis of the Rayleigh-Benard convection problem in a Boussinesquian, viscoelastic fluid-filled, high-porosity medium is studied numerically using the single-term Galerkin technique. The eigenvalue is obtained for free-free, free-rigid, and rigid-rigid boundary combinations with isothermal temperature conditions. Thermodynamics and also the present stability analysis dictates the strain retardation time to be less than the stress relaxation time for convection to set in as oscillatory motions in a high-porosity medium. Furthermore, the analysis predicts the critical eigenvalue for the viscoelastic problem to be less than that of the corresponding Newtonian fluid problem

Effect of couple-stress on the ultrafiltration process

The effects of couple-stress and suction-Reynolds number on velocity and concentration distribution in the ultrafiltration process of a gel-polarization model are investigated. Both analytical and numerical techniques are used. The numerical method is based on an implicit finite difference scheme, and the analytical technique makes use of a regular perturbation. The calculations show that the effect of couple-stress is to inhibit the diffusive transport of solute molecules from the membrane surface to the bulk solution, in contrast to the suction effect. The ramification of the couple-stress in predicting the flux rates during ultrafiltration is examined