Porous Terms Research Articles

Electro-osmotic peristaltic flow of non-Newtonian Sutterby TiO2 nanofluid inside a microchannel through porous medium with modified Darcy’s law

The primary aim of this study was to examine the peristaltic flow of an unsteady non-Newtonian TiO2 nanofluid through a uniformly symmetric channel under the influence of electro-osmosis. The fluid behavior was modeled by the Sutterby model. Furthermore, the flow took place through a porous medium, following a modified form of Darcy’s law. Additionally, the impacts of Dufour and Soret effects, chemical reaction, activation energy, viscous dissipation, heat generation, and thermal radiation were considered. A wave transformation was used to simplify the governing equations describing the velocity, temperature, and nanoparticle concentration. These simplified equations were then solved analytically using the homotopy perturbation method. Additionally, set figures were employed to illustrate and discuss the impact of the physical parameters involved in the problem on the obtained solutions. It is found that the presence of a modified Darcy’s medium in the Navier–Stokes equation results in a porous term that is dependent on the index of the Sutterby model. Furthermore, it is found that as the thermophoresis parameter increases, the nanoparticles are more concentrated, and their flow from the hot region to the cold region is more effective. Additionally, it is observed that in the presence of thermal radiation, the activation energy and the Brownian motion parameter have similar effects on the concentration profile.

Magnetohydrodynamic flow of Cu–Fe3O4/H2O hybrid nanofluid with effect of viscous dissipation: dual similarity solutions

This study shows multiple solutions, heat transfer characteristics, and stability analysis of the magnetohydrodynamic (MHD) flow of hybrid nanofluid caused by the nonlinear shrinking/stretching surface. To investigate the effects of high temperature on the porous surface, the energy dissipation function and porous term are considered in the momentum and energy equations. We used Tiwari and Das’s model for nanofluid in which water is considered as a base fluid. A new kind of fluid is made in which two kinds of nanoparticles, namely copper (Cu) and iron oxide ( $${\text{Fe}}_{3} {\text{O}}_{4}$$ ), are considered. The system of ordinary differential equations (ODEs) is obtained by applying similarity transformations on the modeled of partial differential equations. Both shooting and Runge–Kutta fourth-order methods are employed to solve the resultant ODEs. The equations for stability analysis have been derived and then solved by using a three-stage Lobatto IIIa formula for the smallest eigenvalue. It is noticed that the obtained value is in a good agreement with the previously published literature, hence validating the results of the shooting method. Furthermore, parametric studies also have been conducted and found that dual solutions only exist on the shrinking surface. In addition, it is also observed from the profile that dual solutions exist only for the case of suction where $$b_{{{\text{c}}1}} = - 3.0582$$ , $$b_{{{\text{c}}2}} = - 3.0788,$$ and $$b_{{{\text{c}}3}} = - 3.1249$$ are the critical values for the respective values of $$\phi_{{{\text{Fe}}_{3} {\text{O}}_{4} }} = 0.5\% ,5\% , 1\%$$ . Moreover, the velocity of hybrid nanofluid decreases (increases) in the first (second) solution when both magnetic and permeability coefficient parameters are increased.

A revised model of "Steady laminar natural convection of nanofluid under the impact of magnetic field on 2-D cavity with radiation" [AIP advances 9, 065008 (2019); https://doi.org/10.1063/1.5109192

This discussion exhibits the major scientific errors on the recent published paper, entitled "Steady Laminar Natural Convection of Nanofluid Under the Impact of Magnetic Field on 2-D Cavity with Radiation" and their corrections indifferently. In Saleem et al. [1], the authors stated in both of abstract and problem assumptions that the non-Darcy model is used for the porous medium, while the porous terms are incompatible with this assumption. In addition, the authors used a non-inclined geometry in their investigation, but the governing equations are conflicting with this hypothesis. Further, the used range of the Darcy number is between 10?2-102 and this range is very large and did not represent the porous media flow. All of these observations make the mathematical formulations and the obtained results of Saleem et al. [1] are wrong. In the following sections, these scientific errors and their corrections will be presented minutely.

In the dialectic of memory: rediscovering graced fatherhood in Farida Karodia's stories

This article considers Farida Karodia's construction of an alternative engagement with the violence of apartheid on the nuclear family. It proposes that central to her representation is the narration of this primary space of socialization in enunciations that reveal how apartheid interpellated kith and kin in the besieging of fatherhood. The suggestion is that depicting the family in these elocutions foregrounds it as a site of gender-specific casualties. I also propose that the healings of these wounds are revealed through textures that call for reflexivity. The discussion then proceeds to focus on how these inflections ratify the family and fatherhood in porous terms. Key to this analysis is, therefore, an attempt to demonstrate that the stories that let slip how the family members, who became implicated in the domino consequences set in motion by apartheid, define fatherhood in permeable lines. The exploration purports that this diplomacy highlights a productive tension between documenting atrocities, on the one hand, and taking an ironical distance from them, on the other hand. This examination suggests that the paradox, which is apparent in re-calling the family from inside it and through its gendered pivot, is pertinent to an enterprise on memory.