Increasing Hartmann Number Research Articles

The electrokinetic energy conversion and streaming potential analytical solutions of couple stress nanofluids in the circular polyelectrolyte-grafted nanochannel

The purpose of this study is to investigate the variation of streaming potential and EKEC efficiency of nanofluids with couple stress in the circular polyelectrolyte-grafted (PE-grafted) nanochannel under the combined effect of periodic pressure and magnetic field. The analytical solutions of the velocity field in the PEL region and electrolyte solution are obtained by solving the modified Navier-Stokes equation and the influence of several dimensionless parameters on the streaming potential and electrokinetic energy conversion (EKEC) efficiency are further discussed graphically. The results indicate that the streaming potential decreases with increasing Hartmann number and nanoparticle diameter within a certain parameter range. The dimensionless velocity shows an oscillating trend at different oscillating Reynolds numbers, and the oscillation is more pronounced at the interface between the PEL and the electrolyte solution. In addition, the EKEC efficiency of nanofluids in soft nanochannel is compared with that in a rigid one. It is shown that the EKEC efficiency is higher in PE-grafted nanochannel, and the couple stress plays an important role in improving the EKEC efficiency. We anticipate that these findings will help to reveal a novel understanding of energy conversion in the circular PE-grafted nanochannel.

Numerical computations of magnetohydrodynamic (MHD) thermal fluid flow in a permeable cavity: A time dependent based study

This study presents a comprehensive analysis of unsteady, two-dimensional flow with the interaction between cold walls and heated cylindrical obstacles. The investigation focuses on the interplay among fluid dynamics, heat transfer, and magnetic fields. The behavior of the conducting fluid with the effect of a magnetic field present is described using the MHD equations, while the obstacles are maintained at elevated temperatures. The unsteady nature of the flow introduces additional complexities. The analysis provides insights into various flow pattern formation, boundary layers, and thermal distributions. The impact of magnetic forces on fluid dynamics and heat transfer is examined, shedding light on the overall behavior of the system. The obtained results clearly indicate that changes in the spacing distance on cylindrical obstacles will induce deformations in the isotherms, especially near the obstacles, resulting in localized variations. As the Hartmann number increases, the impact of magnetic forces becomes more pronounced. An increase in the Eckert number, tends to improve convective heat transfer efficiency. This research contributes to a better understanding of MHD-driven flow with practical implications in areas such as magnetohydrodynamic power generation, astrophysical phenomena, and controlled fusion.

Heat absorption effect of magneto-natural convection flow in vertical concentric annuli with influence of radial and induced magnetic field

This paper aims to study the natural convective magneto-hydrodynamic flow of fluid through vertical concentric annuli with iso-flux heating under the conditions of constant internal heat absorption and an induced magnetic field. By solving the set of dimensionless coupled governing equations, we were able to obtain exact expressions for the temperature field, velocity field, and induced magnetic field. We also managed to derive the formulas for skin friction, mass flux, and induced current density. We also examined the effects of non-dimensional parameters on skin friction and mass flux. For easy comprehension and interpretation, the results are provided graphically and in tabular form. The heat absorption parameter, the induced current density, the induced magnetic field, and velocity exhibit a negative trend as the Hartmann number (Ha) value increases. The induced magnetic field has the effect of raising both the induced current density and velocity profile. It is found that, when a fluid absorbs heat, the heat absorption parameter experiences reverse flow. For the heat-absorbing fluids, the radii ratio has the effect of increasing velocity, induced magnetic field, and induced current density. The numerical values of skin friction and mass flux at cylindrical walls increase (decrease) with increasing heat absorption parameter and generally it has decreasing tendency with increasing Hartmann number

Thermo-magnetic convection of MHD Casson fluid in a wavy triangular porous cavity with embedded a cold inverted triangle obstacle

The design of enclosures is crucial in thermal engineering applications and technologies, encompassing areas such as electronics, heat transfer devices, power reactors, heating systems, solar panels, and nuclear power plants. Thermal efficiency in microchannels is optimized and improved by using triangular enclosures with varying aspect ratios. Specifically, the purpose of these triangular enclosures with cool cylinders is to reduce energy loss in nanoscale thermal sinks and thermal exchange devices. The current study aims to explore the thermal radiation effects on magnetohydrodynamic MHD Casson fluid flow within a wavy triangular cavity that includes an embedded cold inverted triangle. The inner inverted triangle is kept at a lower temperature, while the wavy bottom wall of the outer triangular cavity acts as an isothermal heat source at a higher temperature. The numerical solution for this mathematical model is obtained using the open-source finite element software COMSOL. In this study, the wavy triangular enclosure is analyzed for key parameters such as Casson parameter β , Hartmann number Ha , Rayleigh number Ra , numbers of undulation N , radiation Rd and inclination γ . The study presents the local distribution of streamlines, velocity profiles, isothermals, and entropy production, along with the Nu avg . The results reveal the rate of heat transport and total entropy production raise with the increasing number of undulations N and the Casson parameter β , while they decrease with increasing Hartmann number Ha . The number Nu avg rises with the increasing radiation parameter Rd and Rayleigh number Ra . The maximum stream function is observed at an inclination angle of 60 ° .

Thermophysical dynamics of magnetohydrodynamic electroosmotic two phase mixed convective flow in vertical annulus: neuro computation

ABSTRACT The thermophysical dynamics of electro – magnetohydrodynamic mixed convective electrically conducting fluid flow in the vertical cylindrical annulus are explored with electric and magnetic fields. The flow and heat transfer properties are explicitly examined in viscous fluid and electroosmotic flow regions. The coupling between an external pressure gradient, electroosmosis, and an extended electromagnetic field can control fluid flow and heat transfer. The governing equations associated with the physical phenomenon are addressed with the Galerkin finite element method. Eloquently, the analysis revealed that, in the absence of a lateral electric field, the flow velocity decelerates as the Hartmann number increases, which in turn ultimately, causes the Nusselt number to rise. Since a lateral electric field is involved, the flow field, temperature field, and Nusselt number profiles are presented in two regions. The artificial neural network model discusses the thermal transport phenomenon in both regions. The artificial neural network models regression, performance plots, weights, and bias are presented. The research outcome can be utilized to design exquisite and efficacious electromagnetic devices, particularly within a particular range of thermal physical properties.

Integrating artificial intelligence in investigating magneto-bioconvection flow of oxytactic microorganisms and nano-enhanced phase change material in H-type cavity

Nano-enhanced phase change materials is an effective way to improve the thermal characteristics and to minimize energy consumption. The bioconvection flow of nano-enhanced phase change materials is gaining more attention in recent investigations due to its significant applications in engineering and medical sciences. The present study aims to numerically explore magneto-bioconvection flow of nano-enhanced phase change materials in H-type cavity including oxytactic microorganisms. The cavity is constantly heated from the left and a right wall is maintained at cold temperature. The major focus of the current investigation is analyzing the flow and thermal features of the suspension of nano-enhanced phase change materials and a host fluid. The governing system is reduced to the dimensionless form by applying the appropriate transformation. Impact of pertinent parameters, porosity, cavity aspect ratio, Darcy, Hartmann, Lewis, Rayleigh, bioconvection Rayleigh numbers, radiation parameter, and Péclet number on bioconvection flow of oxytactic microorganisms in H-type cavity has been analyzed. Six various artificial neural network models are explored in order to estimate critical parameters with an artificial intelligence approach. It is found that the variations of a cavity aspect ratio are enhancing the bioconvection flow and phase change material. Increasing Hartmann number reduces the nanofluid velocity and distributions of oxygen and microorganisms. The Rayleigh and bioconvection Rayleigh numbers are playing an importance role in enhancing bioconvection flow and varying phase change material.As Ha increases from 10 to 100, at γ=900, there is a 1.67% decrease in the values of Nuavg and a 0.247% increase in Shavg. Among the study findings, the developed artificial neural networks can predict each parameter with high accuracy.

Research on electromagnetic electroosmotic flow of Jeffrey fluid through semicircular microchannel

This work extends the previous research on electroosmotic flow in semicircular microchannels, further investigating the electromagnetic electroosmotic flow of Jeffrey fluid under the combined action of the electric field force and electromagnetic force. The analytic solution of velocity is derived using the variable separation method. The influences of oscillation Reynolds number Hartmann number electric width relaxation time and retardation time on velocity are examined through graphical analysis. The results show that an increase in Reynolds number leads to stronger oscillations in the velocity profile at any Hartmann number and the change in velocity oscillations becomes more pronounced with increasing Hartmann number Specifically, at lower Hartmann numbers the velocity increases with an increase in electric width and relaxation time but decreases with an increase in retardation time An interesting finding is that, at higher Hartmann numbers the velocity of the Jeffrey fluid still decreases under the influence of obstruction in the channel. Furthermore, the results of this study are compared with those of previous scholars to validate their accuracy.

Numerical modeling of magnetohydrodynamic buoyancy-driven convection for enhanced energy applications

In the realm of thermal management for electronic systems, the efficacy of heat dissipation serves as a major predictor of the reliability and operational lifespan of electronic components. Simultaneously, within the realm of geothermal energy utilization, where harnessing the Earth’s inherent heat reservoirs is employed for power generation and direct heating applications, an intricate comprehension of temperature gradients and the dynamics governing heat transfer stands as an imperative prerequisite for optimizing the extraction of thermal energy. This work offers a complete mathematical model aimed at understanding the principles governing energy transfer inside naturally convected flows subjected to the impact of an external magnetic field. The analytical inspection involves a broad parametric study of the flow system, comprising variations in buoyancy-driven factors, as well as the magnetic field parameter, indicated as the Hartmann number (Ha), ranging from 0 to 50. This multifaceted study unveils the profound impact of magnetic fields on critical aspects of the flow, including isotherm alignment, velocity distributions, thereby paving the way for the development of advanced cooling systems poised to deliver elevated energy efficiency and enhanced performance in electronic devices. The computational analysis digs into the complicated temperature distributions, velocity profiles, and vorticity patterns. It is found that increment of the external magnetic force limits the variations in fluid’s horizontal and vertical velocities. Convective heat transfer is decreased with increasing Hartmann number at cold and hot sections of the fluid chamber. While for Rayleigh number this behavior is reversed.

MHD blood flow effects of Casson fluid with Caputo-Fabrizio fractional derivatives through an inclined blood vessels with thermal radiation

This study investigates a fractional-order time derivative model of non-Newtonian magnetic blood flow in the presence of thermal radiation and body acceleration through an inclined artery. The blood flow is formulated using the Casson fluid model under the control of a uniformly distributed magnetic field and an oscillating pressure gradient. Caputo-Fabrizio's fractional derivative mathematical model was used, along with Laplace transform and the finite Hankel transform technique. Analytical expressions were obtained for the velocity of blood flow, magnetic particle distribution, and temperature profile. These distributions are presented graphically using Mathcad software. The results show that the velocity increases with the time, Reynolds number and Casson fluid parameters, and diminishes when Hartmann number increases. Moreover, fractional parameters, radiation values, and metabolic heat source play an essential role in controlling the blood temperature. More precisely, these results are beneficial for the diagnosis and treatment of certain medical issues.

Controlling energy loss from roof structures equipped by round-corner double semi-hexagonal ferro- phase change material layer using magnetic field

Improving the thermal characteristics of building enclosures is a must in the context of rising global energy consumption. Heat losses through roof enclosures are one of the main causes of excessive energy consumption in the Heating, ventilation, and air conditioning systems in buildings. Designing novel roof structures to reduce heat losses is essential. The Phase Change Materials through their thermal properties can provide an effective passive solution in this regard. The present paper is dedicated to the analysis of a roof structure incorporating a Ferro-Phase Change Material enhanced with nanoparticles and subjected to an external magnetic field. The Ferro- Phase Change Material is placed in a round-corner semi-hexagonal block that can be oriented horizontally or vertically in the roof structure. The equations governing the heat and flow are developed and presented in the non-dimensional form. The set of equations were discretized and solve using control volume based finite element method. The effect of Hartmann number, the inclination of the magnetic field and the orientation of the Phase Change Material block on the flow and thermal behaviors of the Phase Change Material and on the thermal resistance of the roof structure are assessed. It is found that when the Ferro- Phase Change Material block is oriented vertically, it offers 30% less thermal resistance than the horizontal configuration in the absence of magnetic field. Increasing Hartmann number from 0 to 200 raises the thermal resistance by 80% for the vertical case and 45% for the horizontal case. Changing the inclination angle of the magnetic field has more effect on the Phase Change Material when its block is oriented vertically, with 30% faster melting and 45% decrease in the thermal resistance are found when the magnetic field is applied vertically instead of horizontally.

Pulse electromagnetic flow of Jeffrey fluid in parallel plate microchannels

This paper investigates the pulse electromagnetic flow of a Jeffery fluid between parallel plate microchannels, where the pulse is considered as a relatively stable and common rectangular pulse. The Laplace transform and residue theorem are employed to derive the analytical solutions for the velocity and volumetric flow rate of the pulse electromagnetic flow. Graphical representations depict the effects of several important parameters, including the Hartmann number pulse width relaxation time and retardation time on them. The study findings demonstrate that the Hartmann number plays a vital role in the investigation of pulse electromagnetic flow. During the first half-cycle of the pulse electric field, the magnitude of the velocity amplitude increases and then decreases with the Hartmann number An interesting observation is that in the second half-cycle, larger Hartmann number values result in a decrease in velocity followed by a reverse increase. The profiles of velocity and volumetric flow rate exhibit oscillations over a relatively short period of time, then gradually reach a stable state with time and display periodic variation characteristics. Moreover, a larger pulse width leads to a longer variation period and more stable profiles of velocity and volumetric flow rate. For smaller Hartmann numbers the magnitude of the volumetric flow rate amplitude grows with the relaxation time and reduces with the retardation time However, as the Hartmann number increases, the influence of relaxation time and retardation time on the volumetric flow rate becomes significantly weakened, especially the retardation time

Darcy-Forchheimer mangetized flow based on differential type nanoliquid capturing Ohmic dissipation effects

Hydromagnetic nanoliquid establish an extraordinary category of nanoliquids that unveil both liquid and magnetic attributes. The interest in the utilization of hydromagnetic nanoliquids as a heat transporting medium stem from a likelihood of regulating its flow along with heat transportation process subjected to an externally imposed magnetic field. This analysis reports the hydromagnetic nanoliquid impact on differential type (second-grade) liquid from a convectively heated extending surface. The well-known Darcy-Forchheimer aspect capturing porosity characteristics is introduced for nonlinear analysis. Robin conditions elaborating heat-mass transportation effect are considered. In addition, Ohmic dissipation and suction/injection aspects are also a part of this research. Mathematical analysis is done by implementing the basic relations of fluid mechanics. The modeled physical problem is simplified through order analysis. The resulting systems (partial differential expressions) are rendered to the ordinary ones by utilizing the apposite variables. Convergent solutions are constructed employing homotopy algorithm. Pictorial and numeric result are addressed comprehensively to elaborate the nature of sundry parameters against physical quantities. The velocity profile is suppressed with increasing Hartmann number (magnetic parameter) whereas it is enhanced with increment in material parameter (second-grade). With the elevation in thermophoresis parameter, temperature and concentration of nanoparticles are accelerated.

Nonlinear free convective pulsatile magnetohydrodynamic flow in a nonlinearly radiated and Ohmic heated porous channel filled with third-grade fluid properties and combinations of nanoparticles: Entropy generation

This work explores the effect of Ohmic heating, thermal radiation, and viscous dissipation on the third-grade hybrid nanofluid’s magnetohydrodynamic pulsatile flow in a porous channel. While alumina and Gold are nanoparticles, blood was recognized as a third-grade fluid. The significance of mathematical modelling of biological fluids is evident in many medical disciplines, using magnetic fields to regulate blood flow during surgery and radiation therapy for lung cancer treatment. In Maple 2018, a system of ODE was created from the governing PDE, and then shooting approach was used to resolve the scenario. The important characteristics of emergent factors are presented through graphical representations. The findings show that the velocity falls when the non-Newtonian parameter and Hartmann number increase. As the viscous dissipation rate grows, the temperature of the nanofluid increases whereas heat transfer rate also improved. But heat transfer rate was reduced when the thermal radiation and magnetic field was increased.

Numerical Simulation of Heat Transfer in a Wavy Enclosure with and without the Presence of Fins

This study focuses on numerically simulating heat transfer in an enclosure with a wavy shape, both with and without the presence of fins. The research paper specifically investigates the case of a single vertical fin attached to the lower heated wall of the enclosure. The lower wall is maintained at a constant cold temperature, while the upper wall is kept cold, and the wavy walls are assumed to be constant heated temperature. The top wall lid moves left to right and bottom wall lid moves right to left with constant velocity. Additionally, a magnetic field of certain strength is applied parallel to the x-axis. The flow inside the enclosure is characterized by a Prandtl number of 0.71. The results are presented through various graphical representations, such as streamlines, isotherms, velocity and temperature distributions, as well as the local Nusselt number. The researchers conducted a parametric study to examine the impact of the Richardson number on the fluid flow and heat transfer characteristics within the enclosure. The findings indicate that as the fluid flow and heat transfer characteristics within the enclosure. The findings indicate that as the Hartmann number increases (while keeping the Hartmann number constant) the heat transfer rate is enhanced. To validate their findings, the researchers compare their results with previously published works in the field.

Using a Magnetic Field to Reduce Thermocapillary Convection in Thin Annular Pools

This paper presents the investigation of thermocapillary convection in three-dimensional (3-D) thin pools with three cases of annular gaps containing silicon melt under a vertical magnetic field. The model was composed of two vertical walls: the inner is cold, and the outside is hot. Radiation is emitted upward from the free top surface, and the bottom is heated vertically. Both cases are considered in this study, electrically insulating all walls; and only the bottom wall is electrically conducting for three annular gaps. The governing equations were solved numerically through the finite volume method. The effects of different parameters such as the Hartmann number, annular gaps on the temperature distribution, the hydrothermal wave number, and azimuthal patterns, as well as the transition from 3-D steady to axisymmetric flows, were investigated. The results showed three hydrothermal waves are observed in a 3-D steady flow. It was also found that with the increasing Hartmann number, the azimuthal velocity, the temperature fluctuation, and the electric potential decreased. The results also revealed that a stronger magnetic field was needed for the transition from unsteady flow to a nonaxisymmetric steady flow and at the end to steady axisymmetric flow. The findings revealed that electromagnetic damping is more prominent when the bottom wall is electrically conducting than when all walls are insulating.

Numerical analysis of Magnetohydrodynamic convection heat flow in an enclosure

This article investigates the modeling and numerical simulation of Magnetohydrodynamic (MHD) buoyancy-driven convection flow in a differentially heated, square enclosure. Left vertical side is given a high temperature and the right vertical side is sustained at a low temperature. Horizontal sides of the enclosure are insulated. A constant magnetic field is presumed horizontally. Findings of the governing differential equations are explored numerically considering the impact of Magneto-hydrodynamic (MHD). Problem is deciphered by Galerkin finite element approach in COMSOL Multiphysics. Numerical solutions are computed for different values of Rayleigh number ranging 103≤Ra≤107 and Hartmann number ranging 0≤Ha≤40. Rate of heat that passes from the heated side is affected by increasing Rayleigh and Hartmann numbers. Comportment of MHD free convection heat flow from transient to steady state is numerically examined for a period of 0 to 1 s. The numerical solutions are discussed in respect of streamlines, iso-contours, and isotherms. In addition, physical quantities such as velocity and Nusselt number are studied. It is seen that with increasing values of Rayleigh number there is increase in local Nusselt number distribution on heated side of the cavity. Velocity distribution in the flow domain decreases in variations with increasing Hartmann number.

Analyzing overall thermal behaviour of conjugate MHD free convection in L-shaped chamber with a thick fin

This study examines the conjugate MHD free convection in an L-shaped chamber with a thick fin attached to one of its cold walls. The chamber's left and bottom parts have hot walls, whereas the ambient condition is maintained at the upper-right sides of the L-shaped chamber. A heat-conducting solid rectangular fin is vertically attached to the top of the mid-section of the chamber. The heat and fluid flow governed by heat energy and Navier-Stokes equations are numerically simulated with the help of finite element analysis. The influences of different governing and geometrical parameters such as Hartmann number (0 ≤ Ha ≤ 30), Rayleigh number (103 ≤ Ra ≤ 106), fin thickness (0.100 ≤ t/L ≤ 0.175, where L is the reference length of the chamber) and fin height (0.1 ≤ d/L ≤ 0.3) on the overall thermal characteristics of the system have been observed. The qualitative outcomes of this research are exhibited in the forms of streamline, isotherm, and heatline plots. The quantitative findings are presented utilizing the mean Nusselt number, the overall thermal performance ratio, and the average fluid temperature. These results confirm that the overall thermal improvement of the chamber due to the conjugate effects of heat transfer increases with increasing Hartmann number for a fin with the highest thickness and the shortest length. The overall thermal performance ratio increases by a maximum of 39.59% for an increase in Hartmann number from 0 to 30. Similarly, higher thickness and shorter length improve the overall thermal performance ratio by 45.18% and 415.06%, respectively.

Numerical Simulation of MHD Natural Convection and Entropy Generation in Semicircular Cavity Based on LBM

To study the natural convection and entropy generation of a semicircular cavity containing a heat source under the magnetic field, based on the single-phase lattice Boltzmann method, a closed cavity model with a heat source in the upper semicircular (Case 1) and lower semicircular cavity (Case 2) is proposed. The cavity is filled with CuO-H2O nanofluid, and the hot heat source is placed in the center of the cavity. The effects of Rayleigh number, Hartmann number and magnetic field inclination on the average Nusselt number and the entropy generation of the semicircular cavity are studied. The results show that the increase in the Rayleigh number can promote the heat transfer performance and entropy generation of nanofluids. When the Hartmann number is less than 30, the increasing function of the Hartmann number at the time of total entropy generation reaches its maximum when the Hartmann number reaches 30. As the Hartmann number increases, the total entropy generation is the decreasing function of the Hartmann number. The larger the Hartmann number, the greater the influence of the magnetic field angle system. Under the same Hartman number, with the increase in the Rayleigh number, the flow function of Case 2 increases by 29% compared with that of Case 1. The average Nusselt number of heat source surfaces in Case 2 increases by 5.77% compared with Case 1.

Numerical study of pulsatile thermal magnetohydrodynamic blood flow in an artery with aneurysm using lattice Boltzmann method (LBM)

Aneurysm is considered as one of the most common cardiovascular diseases with an important mortality rate. It is a serious pathology caused by a dilatation in the arterial wall. In this work, the influence of magnetic field on pulsatile blood flow and heat transfer in an artery with aneurysm is studied using the mesoscopic lattice Boltzmann method with BGK approximation (LBGK). Human blood is regarded as non-Newtonian and modeled by Carreau–Yasuda rheological model. The model findings are compared with recent data from the literature and demonstrate a good level of agreement, which confirms the effectiveness and accuracy of the suggested model. Results are depicted in terms of streamlines, temperature contours and wall shear stress (WSS) variation, for the certain pertinent non-dimensional Reynolds and Hartmann numbers. The findings demonstrate that the heat transfer is enhanced in the inlet zone of the aneurysm as the Hartmann number increases. Furthermore, it is found that the application of a magnetic field reduces the recirculation zones and increase the WSS, which prevent the progression of vascular diseases and rupture in the aneurysm region.

Thermal evaluation of MHD Jeffrey fluid flow in the presence of a heat source and chemical reaction

In this paper, the flow of an incompressible fluid is thermally studied. Investigations into the heat transfer process have been conducted in non-Newtonian fluid flows with chemical reactions and heat sources present. The application of this work is the fluid flow around the stretching sheet; fluid flow on a stretching sheet can be applied to polymer extrusion, drawing or plastic films, hot rolling, casting and other engineering problems. The novelty of this paper is that the governing equations have been solved by a new and efficient semi-analytical approach, the Akbari–Ganji method (AGM). In order to investigate the issue, the finite element method (FEM) has also been applied. Comparing the results of problem-solving with the applied methods with the results of the previous research shows a perfect agreement. The results show that the parameters of Hartmann number and interaction improve the velocity profiles. Additionally, for greater Hartmann number values, raising the parameter of interaction decreases the temperature value, but a smaller value has the reverse effect. As the Hartmann number increases, the fluid velocity decreases and it shows that with the increase of electromagnetic force, the velocity of fluid flow decreases.