Thermal characteristics of streaming potential mediated flows of non-newtonian fluids with asymmetric boundary conditions and steric effect

Electrokinetic flows through narrow confinements have mostly been studied with symmetric boundary conditions on the walls even though in practice it is very common to have these walls made of different materials which in turn lead to different surface charge conditions on them. Such a dearth of studies is particularly acute in streaming potential flows which are naturally predisposed to strongly influence even simple pressure-driven flows in such narrow confinements. Further, the very nature of the fluid may, in general cases, be of non-Newtonian nature; this is especially true for biomedical assays. Motivated by this, we address a model problem of a streaming potential mediated flow of a power-law fluid through a slit channel having different boundary conditions. Additionally, as an important new contribution to this line of investigation, we study the thermal characteristics of such flow. Noting, pertinently, that the streaming potential effects are especially stronger for high values of the surface charge (which translates into high magnitudes of the zeta potential), we present a general framework that incorporates steric effects of the ions. This is done to avoid the unphysical ionic distributions predicted by the traditional Boltzmann approximation

Electrohydrodynamics within electrical double layer in a pressure-driven flow in presence of finite temperature gradients

A wide spectrum of electrokinetic studies is modelled as isothermal ones to expedite analysis even when such conditions may be extremely difficult to realize in practice. As a clear and novel departure from this trend, we address the case of flow-induced electrohydrodynamics, commonly referred to as streaming potential, in a situation where finite temperature gradients do indeed exist. By way of analysing a model problem of flow through a narrow parallel plate channel, we show that the temperature gradients have a significant effect on the streaming potential, and, consequently, on the flow itself. We incorporate thermoelectric effects in our model by a full-fledged coupling among the electric potential, the ionic species distribution, the fluid velocity and the local fluid temperature fields without resorting to ad hoc simplifications. We expect this expository study to contribute towards more sophisticated future inquiries into practical micro-/nano-fluidic applications coupling thermal field focusing with electrokinetic effects.Comment: 13 pages, 5 figure

Combined influence of streaming potential and substrate compliance on load capacity of a planar slider bearing

In the present study, we investigate the combined interplay of streaming potential and substrate compliance with sliding dynamics on the load carrying capacity of a planar slider bearing. We relax previously utilized simplifying assumptions to model the electrokinetic effects and demonstrate that the streaming potential may augment the load carrying capacity of the bearing to a considerable extent. Interestingly, we also reveal that the electrokinetically augmented load carrying capacity exhibits strong dependencies on a combination of the compliance and the sliding dynamics, which have, hitherto, not been extensively explored. This rich interplay reveals certain parametric regimes of interest, which are significant from the viewpoint of practical design considerations