Pulsating hydromagnetic flow of Au-blood micropolar nanofluid in a channel with Ohmic heating, thermal radiation and heat source/sink

The current work deals with the pulsating flow of Au-blood micropolar nanofluid with the existence of thermal radiation and Joule heating. Micropolar fluid is addressed as blood (base fluid) and Au (gold) as a nanoparticle. The flow has been mathematically modeled, resulting in a delicate system of partial differential equations (PDEs). A perturbation technique is used to convert the PDE system into ordinary differential equations (ODEs), which are subsequently solved by using the shooting method with the Runge–Kutta fourth-order scheme. The effects of various parameters on the velocity, microrotation, temperature, and heat transfer rate of Au-blood nanofluid are graphically depicted and explored successively. The obtained findings bring out that the velocity of nanofluid decreases over a rise in the coupling parameter, magnetic field, and nanoparticle volume fractions. The temperature is reducing with an increment of radiation parameter, frequency parameter, coupling parameter, magnetic field, and volume fraction of nanoparticles. Further, the results show that the Nusselt number against frequency distribution increasing with the rising values of the Eckert number

Effects of Joule heating, thermal radiation on MHD pulsating flow of a couple stress hybrid nanofluid in a permeable channel

The current work deals with the pulsatile hydromagnetic flow of blood-based couple stress hybrid nanofluid in a porous channel. For hybrid nanofluid, the fusion of gold (Au) and copper oxide (CuO) nanoparticles are suspended to the blood (base fluid). In this model, the employment of viscous dissipation, radiative heat, and Ohmic heating is incorporated. The governing flow equations (set of partial differential equations) are modernized to set of ordinary differential equations by using the perturbation technique. The nondimensional governing equations are solved by adopting the shooting procedure with the help of the Runge–Kutta fourth-order approach. Temperature distributions of hybrid nanofluid and conventional mono nanofluids are portrayed via pictorial results to claim that the hybrid nanofluid has better temperature distribution than mono nanofluids. Temperature is raising for the magnifying viscous dissipation, whereas the reverse behavior can be found with a rise in couple stress parameter. The heat transfer rate is getting high for the higher values of the Eckert number, and the same behavior is noticed with the uplifting magnetic field

Finite element analysis of non-Newtonian magnetohemodynamic flow conveying nanoparticles through a stenosed coronary artery

The present study considers two-dimensional mathematical modelling of non-Newtonian nanofluid hemodynamics with heat and mass transfer in a stenosed coronary artery in the presence of a radial magnetic field. The second-grade differential viscoelastic constitutive model is adopted for blood to mimic non-Newtonian characteristics and blood is considered to contain a homogenous suspension of nanoparticles. Vogel’s model is employed to simulate the variation of blood viscosity as a function of temperature. The governing equations are an extension of the Navier-Stokes equations with linear Boussinesq’s approximation and Buongiorno’s nanoscale model (which simulates both heat and mass transfer). The conservation equations are normalized by employing appropriate non-dimensional variables. It is assumed that the maximum height of the stenosis is small in comparison with the radius of the artery and furthermore that the radius of the artery and length of the stenotic region are of comparable magnitude. To study the influence of vessel geometry on blood flow and nano-particle transport, variation in the design and size of the stenosis is considered in the domain. The transformed equations are solved numerically by means of the finite element method based on the variational approach and simulated using the FreeFEM++ code. A detailed grid-independence study is included. Blood flow, heat and mass transfer characteristics are examined for the effects of selected geometric, nanoscale, rheological, viscosity and magnetic parameters i.e. stenotic diameter (d), viscoelastic parameter (), thermophoresis parameter (Ni), Brownian motion parameter (Nb) and magnetic body force parameter (M) at the throat of the stenosis and throughout the arterial domain. The velocity, temperature and nanoparticle concentration fields are also visualized through instantaneous patterns of contours. An increase in magnetic and thermophoresis parameters is found to enhance the temperature, nanoparticle concentration and skin-friction coefficient. Increasing Brownian motion parameter is observed to accelerate the blood flow. Narrower stenosis significantly alters the temperature and nano-particle distributions and magnitudes. The novelty of the study relates to the combination of geometric complexity, multi-physical nanoscale and thermomagnetic behaviour and also the simultaneous presence of bio-rheological behaviour (all of which arise in actual cardiovascular heat transfer phenomena) in a single work with extensive visualization of the flow, heat and mass transfer characteristics. The simulations are relevant to diffusion of nanodrugs in magnetic targeted treatment of stenosed arterial disease

EFFECT OF MAGNETIC FIELD AND SLIP VELOCITY ON THIRD GRADE BLOOD FLOW AND HEAT TRANSFER THROUGH A STENOSED ARTERY.

In this study, we considered the effect of magnetic field and slip velocity on blood flow and heat transfer through a stenosed artery using a third grade fluid model. The solution techniques employed are based on Galerkin weighted residual and Newton Raphson methods. Analytical expression for the flow velocity, temperature profile, volume flow rate, wall shear stress and resistance to flow were obtained and the results are presented graphically. The numerical simulation carried out reviewed that higher value of slip velocity significantly increased the flow velocity, flow rate, and wall shear stress but reduced the flow resistance and heat transfer rate while flow velocity, flow rate and shear stress gradually decreased with increased value of the magnetic field parameter but increased the flow resistance and heat transfer rate. Other parameter that enhance the flow velocity are the pressure gradient, shear thinning and Reynold number while that of heat transfer rate are the shear thinning, third grade parameter and Eckert number. Finally, it is reviewed from the results that the effect of slip velocity is more noticeable compare to that of magnetic field effect. Keywords: Stenosed artery, Slip Velocity, Magnetic Field, Pressure Gradient, Eckert number, Reynold number, Shear thinning

Challenges and progress on the modelling of entropy generation in porous media: a review

Depending upon the ultimate design, the use of porous media in thermal and chemical systems can provide significant operational advantages, including helping to maintain a uniform temperature distribution, increasing the heat transfer rate, controlling reaction rates, and improving heat flux absorption. For this reason, numerous experimental and numerical investigations have been performed on thermal and chemical systems that utilize various types of porous materials. Recently, previous thermal analyses of porous materials embedded in channels or cavities have been re-evaluated using a local thermal non-equilibrium (LTNE) modelling technique. Consequently, the second law analyses of these systems using the LTNE method have been a point of focus in a number of more recent investigations. This has resulted in a series of investigations in various porous systems, and comparisons of the results obtained from traditional local thermal equilibrium (LTE) and the more recent LTNE modelling approach. Moreover, the rapid development and deployment of micro-manufacturing techniques have resulted in an increase in manufacturing flexibility that has made the use of these materials much easier for many micro-thermal and chemical system applications, including emerging energy-related fields such as micro-reactors, micro-combustors, solar thermal collectors and many others. The result is a renewed interest in the thermal performance and the exergetic analysis of these porous thermochemical systems. This current investigation reviews the recent developments of the second law investigations and analyses in thermal and chemical problems in porous media. The effects of various parameters on the entropy generation in these systems are discussed, with particular attention given to the influence of local thermodynamic equilibrium and non-equilibrium upon the second law performance of these systems. This discussion is then followed by a review of the mathematical methods that have been used for simulations. Finally, conclusions and recommendations regarding the unexplored systems and the areas in the greatest need of further investigations are summarized