Search

A computational study is conducted on the magnetohydrodynamic peristaltic circulation of Casson nanofluid within a non-uniform conduit when Joule heating, thermal radiation, and combined mass/heat transportation impacts are present and the porous medium is saturated. The preparation of nanofluid involves the suspension of copper oxide nanoparticles in blood, with blood serving as the base fluid in this instance. Basic flow equations are linearized mathematically by assuming a high wavelength and a low Reynolds number. For both the fluid and particle phases, analytical formulae for temperature, velocity, concentration profiles, and volumetric flow rate are provided. Numerical integration is applied for estimating the friction force and the parameters of the pumping rate. The impact of the model’s different parameters is shown graphically in detail using the Mathematica program. The skin friction coefficient behavior as well as the Sherwood and Nusselt numbers behavior have been graphically illustrated for the relevant parameters. Notably, raising the medium permeability, Casson parameter, and Hartmann number improve temperature fields, velocity, Sherwood number, and skin friction coefficient; however, they have a reverse effect on concentration profiles and Nusselt number in the range −1

The study of magnetohydrodynamic (MHD) effects in a rectangular lid-driven enclosure containing a circular hollow cylinder aims at the utilization of nanofluids markedly enhances heat transmission, leading to enhanced thermal performance and more efficient cooling approaches. The governing equations along with the boundary conditions of the problem have been transformed into a non-dimensional formulation. Finite element method based on Galarkin weighted residual has been employed to figure out the outcome of the non-dimensional and non-linear PDEs. The computational investigations of the flow and thermal field inside the enclosure have been performed by varying the governing and physical parameters, namely: Richardson number (0.1 ≤ Ri ≤ 10), Hartman number (0 ≤ Ha ≤ 100), cylinder diameter (0.09 ≤ D ≤ 0.20), solid volume fraction (0.001 ≤ δ ≤ 0.05)), inclination of magnetic field (0° ≤ ϕ ≤ 90°), and non-dimensional time (0.1 ≤ τ ≤ 1). The numerical investigation shows that the flow pattern, temperature distribution, average Nusselt number (Nuav) at the heated surface, and average fluid temperature (θav) inside the enclosure are notably affected by the aforementioned parameters. In this study, six different water-based nanofluids containing different nanoparticles: Cu, Zn, ZnO, Al₂O₃, Fe₃O₄, and graphene have been considered. It was found that the graphene-water nanofluid demonstrated higher thermal efficiency than the other considered nanofluids. Computational results illustrate that the heat transfer rate increases by 41.66 % as the Richardson number increases from 0.1 to 10, indicating that the convective heat transfer mood is considerably improved. However, an increase in the Hartmann number from 0 to 100 leads to a 37.50 % reduction in average heat transfer within the cavity.

This study investigates the flow dynamics of magnetohydrodynamic Burgers' fluid induced by a stretching cylinder, emphasizing the effects of internal heat generation and absorption. A temperature-dependent heat source is integrated to examine the characteristics of thermal energy transfer within the system. By applying boundary layer theory, we transform the governing partial differential equations into a standard system of ordinary differential equations through similarity transformations. The BVP4C method is utilized to accurately solve the resulting equations for velocity and temperature profiles. Graphical representations illustrate the influence of various physical parameters on both thermal and flow profiles, supported by comprehensive analytical interpretations. To validate our findings, a comparison with existing literature is performed, confirming the consistency and significance of our results. This research offers valuable insights into the thermal and fluid behaviors of Burgers' fluids, with promising applications in the development of advanced biomedical devices.

This study comprehensively examines magnetohydrodynamic heat transport characteristics within a thin nanofluid film on a stretchable sheet embedded in a composite medium. By considering factors such as the unsteady nature of sheet velocity, Brownian motion, thermophoresis, thermally radiative heat, irregular heat generation/sink, chemical reactions, and dissipation due to viscous fluid, the research provides valuable insights into the variations in fluid velocity, temperature, and nanoparticles concentration. The computational solution utilizes the efficient numerical method that enables accurate predictions of system behavior under varying conditions. Notable findings include the influence of Schmidt numbers on nanoparticle concentration distribution, the opposing impact of thermophoresis parameter values, and the influence of Brownian motion and heat source/sink on temperature profiles in thin nanofluid film. Also, nanoliquid film thickness is reduced by enhancing the porous parameter values and Hartmann number values. The nanoliquid film becomes thinner when the space‐dependent heat source/sink parameter is considered compared to the temperature‐dependent heat source/sink coefficient. In space‐dependent and temperature‐dependent cases, the increase in these parameters leads to a decrease in the temperature gradient. Furthermore, it is observed that higher thermophoresis values correspond to reduced nanoparticle concentration gradient profiles. Also, enhancement in the chemical reaction values leads to an expansion in the solutal boundary region surrounding nanoparticles, and as a consequence, the concentration gradient of nanoparticles is enhanced. This research has significant potential for optimizing heat performance and advancing innovation in industrial and engineering processes. [ABSTRACT FROM AUTHOR]

The goal of this study is to investigate the fluid dynamics of a pseudoplastic Williamson nanofluid model, explicitly focusing on blood infused with magnetite (Fe2O3) and (Cu) copper nanoparticles, with the aim of enhancing its physiological and industrial applications. This research offers a novel approach by integrating the Williamson fluid model with magnetic nanoparticles, which has not been widely explored in biomedical applications like antitumor therapy and magnetic hyperthermia. The study is mathematically modeled using partial differential equations (PDEs) accounting for the deformation vortices of a stretching surface. These governing equations are transformed into ordinary differential equations (ODEs) via similarity transformations and solved numerically using the Runge-Kutta (R-K) 4th-order method coupled with the shooting technique. The velocity and temperature fields are then analyzed through MATLAB simulations. Results indicate that increasing the Williamson, radiation, and nanoparticle volume fraction parameters elevates the fluid temperature, whereas higher magnetic field strength, Prandtl number, and stretching parameter values reduce it. The novelty of this work lies in its application of the Williamson nanofluid model to real-time medical applications, such as cancer treatment through magnetic hyperthermia, and its potential use in advanced biomedical devices.

This study focuses on the numerical observation of the convective motion of chemically active magnetohydrodynamic (MHD) fluid through a vertically oriented permeable medium, incorporating variations in mass and heat transfer. The fluid type is assumed to be incompressible, chemically strongly ionized and viscous with some mass infusibility. The model associated with this problem is solved by a highly stable Implicit Finite Difference Method (IFDM). The method is used for small and large deflection of the physical parameters, which results in a noticeable fluid flow behavior. Numerical configuration is graphically depicted to scrutinize the fluid behavior. The momentum, energy, concentration diffusion, skin friction, Nusselt number and Sherwood number are investigated for numerous factors such as magnetic field, permeability and chemical reaction rate. The current study unveils significant findings, demonstrating that a heightened rate of chemical reaction in the presence of magnetic effects, coupled with specific porosity, diminishes ionization energy, resulting in a concurrent decrease in the concentration and momentum profiles of the fluid flow. The rise in the viscous diffusion rate is attributed to escalating values of the Schmidt number, causing an augmentation in dynamic viscosity and consequently resulting in an overall reduction in the momentum of the fluid flow. [ABSTRACT FROM AUTHOR]

We present results from three-dimensional, magnetohydrodynamic, core-collapse simulations of 16 progenitors following until 0.5 s after bounce. We use non-rotating solar-metallicity progenitor models with zero-age main-sequence mass between 9 and 24 |${\rm M}_{\odot }$|⁠. The examined progenitors cover a wide range of the compactness parameter including a peak around |$23 \, {\rm M}_{\odot }$|⁠. We find that neutrino-driven explosions occur for all models within 0.3 s after bounce. We also find that the properties of the explosions and the central remnants are well correlated with the compactness. Early shock evolution is sensitive to the mass accretion rate on to the central core, reflecting the density profile of the progenitor stars. The most powerful explosions with diagnostic explosion energy |$E_{\rm dia} \sim 0.75 \times 10^{51}$| erg are obtained by 23 and 24 |${\rm M}_{\odot }$| models, which have the highest compactness among the examined models. These two models exhibit spiral standing-accretion-shock-instability motions during 150–230 ms after bounce preceding a runaway shock expansion and leave a rapidly rotating neutron star with spin periods |$\sim 50$| ms. Our models predict the gravitational masses of the neutron star ranging between |$1.22$| and |$1.67 {\rm M}_{\odot }$| and their spin periods 0.04 – 4 s. The number distribution of these values roughly matches observation. On the other hand, our models predict small hydrodynamic kick velocity (15–260  |${\rm km \, s}^{-1}$|⁠), although they are still growing at the end of our simulations. Further systematic studies, including rotation and binary effects, as well as long-term simulations up to several seconds, will enable us to explore the origin of various core-collapse supernova explosions. [ABSTRACT FROM AUTHOR]

The paper's primary goal is to investigate mass and heat transfer processes in reactive nanofluid particles. Within Buongiorno's model, three chemical reactions are discussed. The main subject is on the nanoparticle fractions at the boundary. The characteristics of N t and N b with regard to the nanoparticle fraction have been found to be passively rather than actively controlled at the boundary. To put it another way, these qualities naturally develop and are controlled by the circumstances at the boundary or interface where the nanoparticles interact with the surrounding medium. They are not the result of active manipulation or outside forces. The system of partial differential equations was converted into ordinary differential equations using similarity transformations. To solve the system of ODEs, they combined the shooting method with a numerical technique known as RK-Fehlberg. The study examines various physical parameters and their effects using graphs. The paper also contains a table showing how different parameters affect the regional Nusselt and Sherwood numbers. This enables a deeper comprehension of the impact that these variables have on the heat and mass transfer within the reactive nanofluid particles. Core findings: Examining three chemical reactions involving nanofluids has led to the study's key discoveries. Additionally, it looks into how specific physical variables may affect the Nusselt and Sherwood numbers. [ABSTRACT FROM AUTHOR]

In this paper, we are concerned with the conservation of energy and magnetic helicity of weak solutions for both the electron and Hall magnetohydrodynamic equations. Various energy and magnetic helicity conservation criteria in Onsager's critical spaces B ̲ p , V M O α and B p , c (N) α in these systems are established. Furthermore, we observe that the conservation criteria for energy and magnetic helicity in the EMHD equations correspond to the helicity and energy conservation principles in ideal incompressible Euler equations, respectively. [ABSTRACT FROM AUTHOR]

In this paper, we consider the numerical approximation of incompressible magnetohydrodynamic (MHD) system with variable density. Firstly, we provide first- and second-order time discretization schemes based on the convective form of the Gauge-Uzawa method. Secondly, we prove that the proposed schemes are unconditionally stable. We also provide error estimates through rigorous theoretical analysis. Then, we construct a fully-discrete first-order scheme with finite elements in space and provide its stability result. Finally, we present some numerical experiments to validate the effectiveness of the proposed schemes. Furthermore, we also present the conserved scheme and its numerical results. • Decoupling of velocity and pressure in the Navier-Stokes equations with variable density. • First-order scheme does not need to give an initial value of the pressure. • Both schemes are unconditional energy stability. • Given error estimates for all unknowns. [ABSTRACT FROM AUTHOR]

This study investigates the forced convective flow in a horizontally extended parallel-plate channel filled with a sparsely packed, chemically inert porous medium under magnetohydrodynamic (MHD) effects. Utilizing the Forchheimer model to account for both viscous and inertial effects, the problem is formulated as a nonlinear boundary value problem and solved using the Differential Transformation Method (DTM). The key observations indicate that as the Darcy number increases, there is a decrease in flow velocity, eventually transitioning to plug flow at higher values. To investigate thermal characteristics, uniform Ohmic heating is employed, and the temperature distribution is determined using the steady-state thermal energy equation, which excludes axial conduction. The findings demonstrate that both the Darcy number and magnetohydrodynamic (MHD) effects have a substantial impact on the velocity and temperature profiles. The DTM solutions are validated against limiting cases in the literature and demonstrated good agreement. This study enhances the understanding of porous media and the effects of MHD on convective flow and thermal distribution, providing valuable insights for applications involving porous structures and electromagnetic fields.Article Highlights: Brinkman term enhances the temperature profile by influencing heat distribution. Magnetic field and Forchheimer number increase the temperature in porous media. Findings support optimization in porous media systems for heat transfer and flow. [ABSTRACT FROM AUTHOR]

Fluid flow across a Riga Plate is a specialized phenomenon studied in boundary layer flow and magnetohydrodynamic (MHD) applications. The Riga Plate is a magnetized surface used to manipulate boundary layer characteristics and control fluid flow properties. Understanding the behavior of fluid flow over a Riga Plate is critical in many applications, including aerodynamics, industrial, and heat transfer operations. The unsteady Micropolar nanofluid (UMNF) flow across a vertically oriented, nonlinearly stretchable Riga sheet is examined in the present study. The effects of variable thermal conductivity, thermophoretic force, and Brownian diffusion on flow and heat transfer are analyzed. The fluid flow has been expressed in the form of a nonlinear system of PDEs (partial differential equations), which are reduced into the non-dimensional form of ordinary differential (ODEs) by employing the similarity transformation approach. The dataset for training the ANNs using the Levenberg–Marquardt backpropagation (LMBP) technique is generated using numerical simulation methods. The influence of physical constraints on the dimensionless temperature, concentration, microrotation, and velocity distributions are graphically displayed and discussed. Numerical results for skin friction, Sherwood, and Nusselt numbers are presented in tabular form. The numerical outcomes are compared to both published numerical and experimental results for validity purposes. It can be noticed that the flow rate is enhanced with the rising influence of the Hartmann number, buoyancy force, and velocity slip parameter. The UMNF flow model is validated, tested, and trained with an average numerical error of 10−9, ensuring high accuracy in energy, velocity, microorganism motility, and concentration predictions. [ABSTRACT FROM AUTHOR]