Sameh A. Hussein

This work proposes a new unified multi-physics framework for blood flow analysis in a stenosed artery immersed in a spatially varied porous medium. The application of a spatially varying pore size distribution has been made in the extended Tiwari–Das model of tetra-hybrid nanofluids in conjunction with the non-Newtonian Cross fluid model to consider the shear-thinning characteristic of blood for the first time. The overall construction of the study involves magnetohydrodynamics, oxytactic bioconvection, Arrhenius activation energy and nonlinear thermal radiation. The resulting dimensionless equations have been solved numerically with sufficient validation against conventional results. It can be seen from the results that the tetra-hybrid suspension has shown superior performance compared to mono-, di- and tri-hybrid systems in terms of heat transfer and microorganism diffusion. Very importantly, controlling spatial porosity is the main factor behind hemodynamic resistance, which demonstrates that classical constant-porosity models underestimate wall shear stress and heat transfer rates. Quantitatively, the Cross-fluid model shows 7–9% higher skin friction compared to the Newtonian model for all considered parameters. In addition, increasing the Biot number from 0.1 to 0.3 results in an approximately 180–190% increase in the local Nusselt number. Ultimately, the presented model provides a very realistic theoretical basis for drug delivery improvement, photothermal therapy and cardiovascular diagnosis.

Motivated by the need to enhance heat and mass transfer in advanced engineering and biomedical systems, this study investigates the complex behavior of an incompressible Williamson nanofluid subjected to an oblique magnetic field over a stretchable surface. The flow is assumed to occur through a porous medium, incorporating the graded permeability of the porous material, and is influenced by multiple physical mechanisms, including thermal radiation, internal heat generation or absorption, and nanoparticle migration due to Brownian motion and thermophoresis. In addition, the fluid contains a chemically reactive species governed by Arrhenius activation energy. To accurately capture microscale interfacial effects, slip boundary conditions for velocity, temperature, and concentration are applied at the wall. Similarity analysis of regulating equations yields a coupled system of nonlinear ordinary differential equations (ODEs) describing the boundary layer flows. MATLAB’s bvp4c solver performs numerical integration for this system with strict convergence criteria by using initial values that respect physical realism. Numerical results indicate that increasing the Hartmann number results in approximately an 18% increase in the surface friction coefficient, whereas thermophoretic effects reduce the Nusselt number by 12–15%, thus resulting in a reduction of thermal transport efficiency. Numerical code has been validated against previous benchmark solutions with relative deviations less than 1.2%, demonstrating the robustness and accuracy of the numerical procedure implemented in this study. Prnactically, these findings assist with advanced application improvements, like cooling machines in mining and petroleum exploration, polymer sheet extrusion, and nanofluid thermal management systems, that require precise control of non-Newtonian flow and coupled transport processes.

1. Significant opportunities exist in engineering and industrial fields to enhance heat transfer, where conventional fluids such as ethylene glycol, vegetable oil, paraffin oil, and mineral oil are...

This paper presents a computational study for the peristaltic pumping within vertical irregular divergence channels filled with magnetic Johnson—Segalman nanofluid. Various configurations of the outer boundaries are considered, namely, square wave, multi‐sinusoidal wave, trapezoidal wave, and triangular wave. An inclined magnetic field together with nanoparticles and mass concentrations is considered. Influences of the Dufour and Soret numbers are examined, and the cases of low Reynolds number and long wavelength are applied. All the computations are obtained numerically using Mathematica symbolical software (ND‐Solve), and the obtained results are presented in terms of the axial velocity , heat transfer rate , nanoparticle fraction profile , concentration profile , temperature profile , extra stress tensor , pressure gradient , pressure rise , and stream function . The major outcomes revealed that the square wave shape gives higher pressure gradients near the inlet and outlet parts while the multi‐sinusoidal wave gives periodic behaviors of . Also, the maximizing in thermophoresis parameter is better to obtain a higher rate of heat transfer while the increase in thermo‐diffusion and diffusion thermo effects causes a reduction in the rate of heat transfer. The discipline of biological and medical engineering, particularly for nanofluid peristaltic pumps, can benefit from the practical uses of such a model, which can be used to simulate the small vessel transport of particles in hemodynamics.

This paper focuses on flow structures and thermal fields of the Carreau–Yasuda (CY) nanofluid model through a two-dimensional, wavy, complicated vertical asymmetrical conduit filled with porous elements. Formulations of the viscous dissipation in the case of CY nanofluids are derived and nonlinear radiation flux as well as joule heating are examined. Buongiorno’s nanofluid approach, which involves Brownian motion and thermophoresis aspects is considered. The electrical conductivity of the suspension is considered as a variable where it depends upon the ambient temperature and concentration distributions and the Joule heating impacts are not neglected. The approach of solving the problem is contingent upon converting the system to dimensionless form then the lubrication approach with low magnetic Reynold numbers is applied. Numerical solutions are found for the resultant system, and wide ranges are considered for Weissenberg number We, non-Newtonian parameter n and Darcy number [ ], namely, [ ], [ ] and [ ], respectively. The major results indicated that gradients of the pressure are higher in case of shear thickening [ ] comparing to in the instance of shear thinning [ ]. Also, the velocity is enhanced, close to the channel’s lowest portion, as the Weissenberg number is growing. The variable electrical conductivity gives a higher mass transfer rate compared to the constant property.