• Formulation of a new modelled problem for a mixed convection flow of ionized ternary hybrid nanofluid through a channel under magnetic field and EDL effects. • Closed-form solution of modelled equations is established by means of an analytical approach. • Stability analysis of flow dynamics. • Dynamism of flow systems is noticeably amended due to the formation of EDL. Electro-osmotic transportation of conducting ionic nanofluids in vertically bounded arrangements has been expansively researched due to its vast assortment of engineering and medical applications, such as soil study, fluid dialysis, chemical processing, capillary electrophoresis, planar chromatography, separation techniques, and other real interests. On that account, in the manuscript, a theoretical model is constituted to simulate the fully developed mixed convective flow of ionic ternary hybrid nanofluid persuaded by electroosmosis and magnetohydrodynamics in a long vertical non-conducting channel under linearly changing temperature on channel walls. The classical Poisson-Boltzmann equation is employed to extract the electric double layer (EDL) impact on the flow formation via Debye-Hückel linearization conjuncture. The leading partial differential equations delineating the flow are formulated based on the general laws of conservation of momentum and energy. The relevant dimensionless setup transforms the flow model to a simplified equivalent model, which is solved analytically. The new results are comprehensively examined in terms of basic flow, magnetic, and thermal characteristics for various implanted parameters via multiple graphs and tables. Graphical outcomes confessed that the magnetic field and Debye-Hückel parameters have striking impacts on the stream features. Thin EDL supports speeding up the fluid motion through the channel domain. A noteworthy result noted from the examination is that the concentration of tri-hybridized nanoparticles in pure water is an issue that effectively delays the commencement of flow instability in the channel domain under the magnetic setting. The present study’s findings may be valuable for designing electromechanical devices, nanofluidic devices, micropumps, solar energy systems, etc. 

EDL impact on mixed magneto-convection in a vertical channel using ternary hybrid nanofluid

Geometric and chemical defects are frequently found or created on smooth graphene for applications of nanofluidics. In this work, imbibition dynamics and steady flows of water in graphene nanochannels with sparse defects are explored by molecular dynamics. The water contact angle is raised slightly by geometric defects (hole and protrusion) but lowered significantly by chemical defects (hydroxyl and epoxide groups). In steady flows, the mean velocity and slip length are always reduced by sparse defects and the effect of chemical defects is more significant than that of geometric defects. Moreover, it is interesting to find that the velocity profile is plug-like for geometric defects but becomes parabolic for chemical defects, regardless of the slip length. Sparse defects on graphene nanoslits also affect the imbibition dynamics remarkably, which generally follows Washburn's equation with the slip length. For chemical defects, surface friction (slip length) dominates over the driving force associated with surface wettability (contact angle). Nonetheless, for protrusion defects, the stick-slip behavior caused by contact line pinning and thermal fluctuations can be observed. Our simulation results indicate that the defect nature is crucial in nanoscale flows and imbibition processes, which the conventional hydrodynamic theory fails to depict.

https://pubs.aip.org/aip/pof/article-pdf/doi/10.1063/5.0114940/16577634/112003_1_online.pdf

Imbibition dynamics and steady flows in graphene nanochannels with sparse geometric and chemical defects

The electrokinetic energy conversion analysis of viscoelastic fluid under the periodic pressure in microtubes

Slippery electrokinetic flow of viscoelastic fluids with pressure-dependent viscosity and relaxation time

The effects of fluid slippage on the pressure‐driven electrokinetic energy conversion in conical nanochannels are systematically investigated in this paper. We present a multiphysical model that couples the Planck–Nernst–Poisson equations and the Navier–Stokes equation with a Navier slip condition to fulfill this purpose. We systematically look into the variation of various performance indicators of electrokinetic energy conversion, for example, streaming current, streaming potential, generation power, energy conversion efficiency, regulation parameter, and enchantment ratio, with the conicity of nanochannels and the slip length for two pressure differences of the same magnitude but opposite directions. Particularly, enhancement ratios related to streaming current, streaming potential, generation power, and energy conversion efficiency are defined to comprehensively measure the enhancement of the performance of electrokinetic energy conversion due to the slip length. The results demonstrate that a combination of large slip length and small conicity enhances the electrokinetic energy conversion performance significantly. Furthermore, the fluid slippage‐induced enhancement of the electrokinetic energy conversion in the backward pressure difference mode is stronger than that in the forward pressure difference mode. Our results provide design and operation guidelines for pressure‐driven electrokinetic energy conversion devices.

Yongjun Jian

Papers

Electrokinetic energy conversion of fluids with pressure-dependent viscosity in nanofluidic channels