Joule Dissipation Research Articles

Influence of interfacial electrokinetic on MHD radiative nanofluid flow in a permeable microchannel with Brownian motion and thermophoresis effects

AbstractIn this study, the behavior of a microchannel flow is examined. The fluid is considered to be a nanofluid, which moves between two parallel flat plates in the presence of an electrical double layer. The Buongiorno nanofluid is considered with body force. In this study, the unphysical supposition presented in the preceding work to the discontinuity of the flow fled where the electrostatic potential in the central of the canal must be equal to zero is removed. The incorrect supposition that the pressure constant is preserved, which is considered a known form, is corrected. The current fresh model equation is modified by using dimensionless parameters to convert partial differential equations into ordinary differential equations. The transformed nonlinear equations are solved by the homotopy analysis method. The physical parameters, magnetic parameters, Eckert number, Lewis number, Brownian motion parameters, thermophoresis parameters, and Prandtl number are analyzed. The influence of both the viscous and Joule dissipation in the presence of magnetohydrodynamic effect is examined.

Direct numerical simulation study on the mechanisms of the magnetic field influencing the turbulence in compressible magnetohydrodynamic flow

The magnetohydrodynamic (MHD) control has great potential in the applications of hypersonic vehicles. Typically, the MHD flowfield in these applications is low magnetic Reynolds (Rem ) compressible turbulent flow, which is different from that without magnetic field and within the high Rem range. This paper investigated the low Rem compressible MHD isotropic turbulence in different Taylor-scale Reynolds numbers and interaction parameters via the Direct Numerical Simulation (DNS), and the influence of the magnetic field on the turbulence is researched. Results indicate that the normal Reynolds stress decreases in the direction perpendicular to the magnetic field. Moreover, the eddies are stretched in the direction parallel to the magnetic field. Besides, the Joule dissipation quicken the decay of the turbulent kinetic energy, and occurs mainly in large scale vortex. Based on the DNS data, the correlation between fluctuating electric intensity and velocity is studied. Results indicate that the electric intensity agrees well with the first-order approximate solution of the electric potential equation. Accordingly, an improved closure model of the correlation terms is established, where a coefficient related to the local turbulent Mach number is proposed. Comparisons with the DNS results reveal that the proposed model could correctly predict the correlation terms.

Study of graphene Maxwell nanofluid flow past a linearly stretched sheet: A numerical and statistical approach

This study aims to unfold the significance of numerous physical parameters such as magnetic field, heat absorption, thermal radiation, viscous and Joule dissipations, etc. on the flow of graphene Maxwell nanofluid over a linearly stretched sheet with considerations of momentum and thermal slip conditions. The prevailing mathematical equations are reformed into extremely nonlinear coupled ordinary differential equations (ODE) utilizing similarity variables and then the equations are solved numerically by the scheme of Runge-Kutta Fehlberg method along with the shooting technique. The variations in graphene Maxwell nanofluid velocity and temperature owing to different physical parameters are shown via numerous graphs whereas numerical values of skin friction coefficients and Nusselt numbers are illustrated and reported in different tables. In addition, statistical approach is followed for the multiple regression estimation analysis on the numerical findings of wall velocity gradient and local Nusselt number and are reported in tabular form to demonstrate the relationship among the heat transfer rate and physical parameters. Our results reveal that the graphene Maxwell nanofluid velocity gets reduced owing to enhancement in magnetic field, angle of inclination of magnetic field, porosity and unsteadiness parameters whereas behavior of nanofluid velocity is reversed due to Maxwell parameter. Further, it is noticed that the heat transfer rate of nanofluid is augmented owing to heat absorption, radiation and thermal slip parameters while it is reduced due to increase in viscous dissipation and unsteadiness parameters. The numerical results of the paper are validated by making comparisons with the earlier published paper under the restricted conditions and we found an excellent agreement with those results. A careful review of research papers reported in literature reveals that none of the authors has attempted this problem earlier although the thoughts and methodology explained in this paper can be anticipated to lead to enormously prolific connections across disciplines.

Irreversibility analysis in Darcy-Forchheimer flow of CNTs with dissipation and Joule heating effects by a curved stretching sheet

Here, heat transfer analysis in convection magnetohydrodynamic flow of carbon nanotube-based Darcy–Forchheimer flow by a curved stretched surface is addressed. Carbon nanotubes (Single and multiple walls) are assumed to be nanoparticles and blood as a base fluid. The mathematical modeling for the nanoparticles transportation is accomplished through Xue model. Thermal radiation, dissipation and Joule heating are addressed in heat equation. Physical features of irreversibility in the isolated thermal system are deliberated. Entropy generation instigated as a result of irreversibility due to heat transfer, porosity irreversibility, irreversibility due to Joule heating and dissipation irreversibility by a curved stretched sheet. Mathematical formulation of entropy generation is developing by a second law of thermodynamics. The principal equation is developed in a curvilinear coordinate system. The nonlinear system is altered to ordinary differential system through compatible transformation. The proposed system is numerically solved by ND-solve technique. Variations of Bejan number, entropy rate, temperature and velocity against several interesting parameters for both carbon nanotubes are scrutinized. Nusselt number and gradient of velocity are examined for both carbon nanotubes in tabulated form. For higher magnetic variable, velocity is augmented for both CNTs. Velocity field reduces against higher porosity parameter for both carbon nanotubes. Temperature distribution rises against porosity and radiation variables. Entropy rate is boosted versus radiation and magnetic parameters for both SWCNTs and MWCNTs. Bejan number and entropy have reverse trend for solid volume fraction for both nanotubes. Higher Brinkman number raises the entropy rate for both SWCNTs and MWCNTs. Larger estimation of porosity variable reduces the Bejan number, while opposite effect is noticed for radiation parameter. Larger magnetic variable boosts up velocity gradients for both carbon nanotubes. But the drag force of SWCNTs is less than MWCNTs. Heat transfer rate is enhanced against curvature variable. Clearly we observed that amplification of heat transference processes is higher for SWCNTs than MWCNTs. Comparative studies are also present and found an excellent agreement.

Magnetohydrodynamics Fluid Flow and Heat Transfer over a Permeable Shrinking Sheet with Joule dissipation: Analytical Approach

A laminar, two dimensional, steady boundary layer Newtonian conducting fluid flow passes over a permeable shrinking sheet in the presence of a uniform magnetic field is investigated. The governing equations have converted to ordinary nonlinear differential equations (ODE) by using appropriate similarity transformations. The main idea is to transform ODE with infinite boundary condition into other sets of variables in a way that infinite boundary condition becomes a finite boundary condition. The effects of physical parameters affecting the velocity and temperature are shown. The results show that with increasing the magnetic and suction parameters, the normal velocity component of fluid increases over the sheet whereas the tangential velocity component of fluid decreases. Moreover, when the suction parameter, the Prandtl and Eckert numbers increase, the rate of the heat transfer increases. However, when the magnetic parameter increases, the rate of heat transfer reduces. Finally, the solution shows that the results of the analytical method using a special technique have an excellent agreement with numerical solutions.

Slip Effects on Unsteady Oblique Stagnation Point Flow of Nanofluid in a View of Inclined Magnetic Field

This study may be applicable in heavy power engine and cooling of a nuclear reactor, insulation for buildings, petroleum reservoir operations, and magnetic material processing solar energy collectors. In this manuscript, the slip results are evaluated for the non-Newtonian fluid on the oblique stagnation point flow of induced magnetic field over the oscillating surface. The valuation of heat flux is examined through the Fourier law of heat transfer. The metallic nanoparticle Copper Cu is within the base fluid, and water is utilized in the analysis. Nanofluids have benefits such as steadiness of the working fluid, decreasing blockage, clogs, decreasing prices, decreasing the friction coefficient, and decreasing the size of the heat transfer system. Similarity variables are utilized to convert the developed flow into higher nonlinear coupled ordinary differential equations (ODE) which are tackled numerically using a mathematical technique such as the bvp4c method in Maple and Matlab software. According to the present geometry, the flow behavior of the operating nanofluid has analyzed by stream lines. Disparities in velocity and temperature profile are demonstrated by graphs to describe the effects of controlling parameters. The Casson fluid parameter enhances the velocity of the fluid. The system heats up by the impact of Joule heating and dissipation.

Computational analysis of heat transfer in mixed convective flow of CNTs with entropy optimization by a curved stretching sheet

Here heat transfer analysis in the mixed convective flow of blood-based carbon nanotubes due to a curved stretching sheet is studied. Single and multiple walls carbon nanotubes are taken as nanoparticles and blood as a base liquid. The nanoparticle's transportation mechanism is achieved by using a theoretical model modified by Xue. Joule heating and dissipation effects in energy expression are incorporated. Physical characteristics of irreversibility in the thermodynamical system are studied. Entropy optimization expression is developed through thermodynamics second law. Additionally, the examination of entropy rate can be favorable for better consideration of the thermodynamical systems. Furthermore, entropy is used for the measurement of energy quality in a thermal system. The leading equation is established in a curvilinear coordinate system. The nonlinear PDEs are reduced by using compatible variables. The nonlinear ODEs are solved numerically by ND-solve method. Variation of entropy rate, Bejan number, velocity and temperature versus several engineering parameters for both CNTs are deliberated. The computational outcomes of heat transfer rate and velocity gradient for both CNTs are scrutinized in tabulated form. Velocity has a reverse trend versus curvature and magnetic parameters for both carbon nanotubes. For a higher approximation of Eckert number the temperature rises for both CNTs. Entropy generation is amplified for both SWCNTs and MWCNTs via Brinkman number. The surface drag force is augmented for the magnetic parameter for both CNTs. However, the skin friction of MWCNTs is greater than SWCNTs (which creates a higher drag force at the surface). Temperature gradient is improved versus curvature parameter. Here we noticed that augmentation of thermal conduction is more prominent for SWCNTs than MWCNTs.

Development in the Heat Transfer Properties of Nanofluid Due to the Interaction of Inclined Magnetic Field and Non-Uniform Heat Source

In the current scenario a new mathematical model is designed and examined for the unsteady course of nanofluid through permeable vertical surface due to the interaction of inclined magnetic field. Radiative heat transfer properties is included assuming the Cogley radiation, dissipative heat energy due to the conjunction o magnetic field i.e., Joule dissipation and the space and time-dependent heat source/sink amplifies the study as well. Depending upon todays need in various industries the implementation of nanofluid is vital. Therefore, present study involves the behavior of both metal and oxide nanoparticles in the base fluid kerosene. Involvement of transformation rules the problem is converted into nonlinear set of ODEs and further these are solved employing approximate analytical technique such as Variational Iteration Method (VIM). The characteristics of various flow parameters are analyzed via graphs and the numerical simulation along with the validation of the result is obtained through tables. The comparative study brings out the convergence criterion of the methodology adopted herein. However, the favorable results are; the fluid temperature augments with increasing nanoparticle volume fraction and suction enriches both the fluid velocity and temperature whereas injection retards it significantly.

Simulation and modeling of entropy optimized MHD flow of second grade fluid with dissipation effect

Here entropy optimized magnetohydrodynamic flow of second-grade fluid is addressed. The energy equation is developed through Joule heating and dissipation effects. Mass transportation along with an interface between two liquids due to surface tension gradient is called Gibbs–Marangoni effect (Marangoni effect). On the other hand, if there is thermal dependence case, then the phenomenon is called Bénard–Marangoni convection (thermo-capillary convection). Marangoni convection depends upon the difference of surface pressure computed by the gradient of temperature, magnetic effect, and concentration gradients. The basic concept of mass and heat transportation phenomenon in Marangoni boundary layer flow are comprehensively discussed. The physical feature of irreversibility exploration is developed with the help of thermodynamics second law. Here we discussed both first and second laws of thermodynamics. Nonlinear ODE's are obtained through adequate variables. Optimal homotopy analysis method (OHAM) is employed to construct the convergent solutions. Entropy optimization, temperature, Bejan number, concentration, and velocity variations for various secondary parameters are deliberated. Velocity enhances via the Marangoni ratio parameter. For larger Hartmann number the temperature and velocity have a reverse effect. The velocity field is amplifying against second grade fluid variable. A similar effect is noticed versus a larger fluid parameter and Eckert number. For a higher approximation of the Marangoni ratio variable, the concentration reduces. Larger fluid parameter rises the entropy generation rate.

Entropy generation on double diffusive MHD Casson nanofluid flow with convective heat transfer and activation energy

The viscous and Joule dissipation effects on stagnation point flow of thermally radiating Casson nanoliquid over a convectively heated stretching sheet under hydromagnetic assumptions are discussed. The influence of heat absorption on heat transfer and chemical reaction prompted by activation energy on mass transfer is also considered. The appropriate transformations are implemented for converting the governing partial differential equations into a set of coupled ordinary differential equations. BVP4C routine of MATLAB has been used to solve the coupled nonlinear ODEs. The way fluid velocity, concentration, temperature, Bejan number and entropy generation behave subject to change in the flow parameters, has been discussed through graphs, whereas the important physical quantities such as skin friction coefficient, Nusselt number and Sherwood number are analyzed on the basis of numerical values presented in tables. On the obtained numerical data of Nusselt number, linear and quadratic regression analyses have been performed. It is concluded that for larger values of thermal and concentration buoyancy parameters, fluid velocity tends to decrease inside the boundary layer region. It is also found that plastic dynamic viscosity of Casson nanoliquid tends to reduce the rate of entropy generation.

Heat and mass transfer flow over a stretching surface with Ohmic heating and chemical reaction

AbstractThe present study analyzes the effect of chemical reaction on an unsteady magnetohydrodynamic boundary layer viscous fluid over a stretching surface embedded in a porous medium with a uniform transverse magnetic field. A Darcy‐Forchheimer drag force model is employed to simulate the effect of second‐order porous resistance. Dissipative heat energy based on both viscous and Joule dissipation along with a heat source/sink is considered to enhance the energy equation. Similarity analysis is imposed to transform the governing differential equations into a set of nonlinear coupled ordinary differential equations. These sets of equations are solved numerically using the Runge‐Kutta fourth‐order scheme followed by the shooting algorithm. The effects of physical parameters such as magnetic field, Prandtl number, Eckert number, Schmidt number, unsteadiness parameter, and chemical reaction parameters have been discussed on velocity, temperature, and concentration fields. Computation for the coefficient of skin friction, rate of heat and mass transfer is done and presented in a table for validation of the present outcomes.

The layout of Boussinesq couple-stress fluid flow over an exponentially stretching sheet with slip in porous space subject to a variable magnetic field

PurposeThe purpose of this study is to present the significance of Joule heating, viscous dissipation, magnetic field and slip condition on the boundary layer flow of an electrically conducting Boussinesq couple-stress fluid induced by an exponentially stretching sheet embedded in a porous medium under the effect of the magnetic field of the variable kind. The heat transfer phenomenon is accounted for under thermal radiation, Joule and viscous dissipation effects.Design/methodology/approachThe governing nonlinear partial differential equations are transformed to the nonlinear ordinary differential equations (ODEs) by using some appropriate dimensionless variables and then the consequential nonlinear ODEs are solved numerically by making the use of the well-known shooting iteration technique along with the standard fourth-order Runge–Kutta integration scheme. The impact of emerging flow parameters on velocity and temperature profiles, streamlines, local skin friction coefficient and Nusselt number are described comprehensively through graphs and tables.FindingsResults reveal that the velocity profile is observed to diminish considerably within the boundary layer in the presence of a magnetic field and slip condition. The enhanced radiation parameter is to decline the temperature field. The slip effect is favorable for fluid flow.Originality/valueTill now, slip effect on Boussinesq couple-stress fluid over an exponentially stretching sheet embedded in a porous medium has not been explored. The present results are validated with the previously published study and found to be highly satisfactory.

Impact of Cattaneo-Christov heat flux on non-isothermal convective micropolar fluid flow in a hall MHD generator system

The flow of non-isothermal micropolar fluid over a nonlinear extending surface with heat flux model of Cattaneo-Christov is presented in this paper. The Joule and viscous dissipation influences are tackled in the fluid flow. A robust magnetic field strength is also operated perpendicular to the fluid flow. The correspondence transformations are used in conversion of PDEs to ODEs. The modeled equations are solved analytically. The convergence of applied technique is shown graphically. The variation in fluid flow via dimensionless parameters like; Grashof number, material parameter, magnetic parameter, Hall parameter, wall geometric parameter, micro-rotation parameter, thermal relaxation parameter, Eckert number, power law index, and Prandtl number are shown graphically and discussed sequentially. The variation in surface drag and thermal transmission factors are calculated through tables.

MHD natural convection nanofluid flows in a wavy trapezoidal porous enclosure with differentially heated side walls

Flow analysis of the Al2O3- water nanofluid in a porous trapezoidal enclosure is deliberated in this research work. The enclosure is bounded by four differentially heated walls with the bottom wall considered as wavy. The viscous and Joule dissipation effects are taken into account. The governing equations of the flow are non-dimensionalised, and the Galerkin finite element method is employed to solve the resulting unsteady initial and boundary value problem using Taylor-Hood elements to avoid instabilities. The numerical scheme is validated with available literature for a simplified case of a problem, and the results are found to be in good agreement. The influence of Darcy number and nanoparticle volume fraction on the dimensionless streamlines and isotherms are plotted and illustrated in detail. The rate of heat transfers near the bottom wall in a porous medium is analysed through simulated data. It is found that the heat transfer rate increases in the presence of a porous domain. Further, a sensitivity analysis has been performed using Response Surface Methodology (RSM) to identify the pertinent parameters of the problem such as Hartmann number, Darcy number, and nanoparticles whose variation have an important influence on the average Nusselt number. The analysis reveals that the Darcy number, Hartmann number and the nanoparticle volume fraction are related to the average Nusselt number. Thus, the finding suggests that the porous medium has a significant role in enhancing the heat transfer in a flow of MHD nanofluid within a wavy trapezoidal enclosure.

Effect of nonuniform heat source/sink, and viscous and Joule dissipation on 3D Eyring–Powell nanofluid flow over a stretching sheet

Abstract The aim of this paper is to explore the effect of heat source/sink, and space- and temperature-dependent viscous and Joule dissipation on 3D magnetohydrodynamic radiating Eyring–Powell nanofluid streamline flow with convective conditions past a stretching sheet. The coupled nonlinear flow, thermal, and species phenomena equations are transformed into a system of coupled nonlinear ordinary differential equations through suitable similarity transformations with corresponding boundary conditions. The transformed dimensionless equations are then solved analytically with the Adomian decomposition method. A comprehensive study is conducted on the influence of sundry physical dimensionless parameters governing the flow velocity, temperature, and concentration distributions. For parameters of engineering interest, the computed numerical results are presented with the aid of tables. Furthermore, the present solutions agree with the earlier reported results in specific cases, and an excellent correlation is witnessed. The present analysis is of great interest germane to cooling of metallic plates, polishing of artificial heart valves, oil pipeline friction reduction in the oil industry, flow tracers, enhanced oil recovery, and separation processes in chemical industries and petroleum extraction.

Human skin thermal properties determination using a calorimetric sensor

The purpose of the calorimetric sensor developed is to measure the heat flux transmitted by conduction between the human body surface and a thermostat located inside the sensor. The measurement surface has an area of 2 × 2 cm2. We have verified that the measured heat flux decreases linearly with the increase in the thermostat temperature. This allows us to define an equivalent thermal resistance between the internal temperature of the human body and the temperature of the thermostat. This equivalent thermal resistance can be determined by measuring the heat flux for different constant temperatures of the thermostat. An alternative is to perform a single measurement with linear programming of the thermostat temperature. With this type of measurement and from the calorimetric signal, it is also possible to determine an equivalent heat capacity of the skin in the measurement zone. In this article, we present the modelling and simulation of the sensor operation when the thermostat temperature varies linearly. We also present experimental measurements performed on the human body and with reference Joule dissipations.

Magnetic Reconnection Inside a Flux Rope Induced by Kelvin-Helmholtz Vortices.

On 5 May 2017, MMS observed a crater‐type flux rope on the dawnside tailward magnetopause with fluctuations. The boundary‐normal analysis shows that the fluctuations can be attributed to nonlinear Kelvin‐Helmholtz (KH) waves. Reconnection signatures such as flow reversals and Joule dissipation were identified at the leading and trailing edges of the flux rope. In particular, strong northward electron jets observed at the trailing edge indicated midlatitude reconnection associated with the 3‐D structure of the KH vortex. The scale size of the flux rope, together with reconnection signatures, strongly supports the interpretation that the flux rope was generated locally by KH vortex‐induced reconnection. The center of the flux rope also displayed signatures of guide‐field reconnection (out‐of‐plane electron jets, parallel electron heating, and Joule dissipation). These signatures indicate that an interface between two interlinked flux tubes was undergoing interaction, causing a local magnetic depression, resulting in an M‐shaped crater flux rope, as supported by reconstruction.

MHD Squeezing Flow of Casson Nanofluid with Chemical Reaction, Thermal Radiation and Heat Generation/Absorption

The heat and mass transfer characteristics on unsteady squeezing flow of magnetohydrodynamic (MHD) Casson nanofluid with chemical reaction, thermal radiation and heat generation/absorption effects is investigated in this study. The influences of viscous and joule dissipation are also examined. The flow is caused by squeezing between two parallel plates embedded in a porous medium. The highly coupled nonlinear partial differential equations are reduced to a system of nonlinear ordinary differential equations via similarity transformations. The transformed equations are solved using numerical scheme of Keller-box method. The accuracy of present method is validated through comparison of skin friction coefficient, Nusselt and Sherwood numbers with previously published results. Comparisons reveal that good agreements are achieved. Graphical results for velocity, temperature and nanoparticles concentration are analysed with various parameters. Findings demonstrate that the fluid velocity and temperature enhance when the plates move closer. Besides, increase in Hartmann number suppressed the fluid velocity and concentration due to the presence of strong Lorentz forces. The Brownian motion boosts the fluid temperature and concentration. Moreover, nanoparticles concentration is found to be higher in constructive chemical reaction and opposite effect is observed in destructive chemical reaction.

Performance evaluation and efficiency enhancement of a space thermionic fuel element for thermal energy conversion and utilization

Efficiency enhancement of thermal energy conversion and utilization is one of the critical issues in space exploitation and exploration. With the full consideration of material characteristics, space charge effect and Joule dissipation, thermionic conversion models were established based on Richardson's law. The models were coupled with a thermo-mechanical simulation code, developing the comprehensive simulation capability of the whole thermionic power system for the first time. This tool was validated by experiment data, and then used to conduct a parametric study for a space nuclear reactor named TOPAZ-II. The parametric study figured out key operating features and influencing factors of thermionic conversion. Based on the parametric study, the optimization for utilization efficiency enhancement was undertaken from the view of thermionic conversion performance improvement, electric circuit design optimization and radiation loss reduction. It was found that the conversion efficiency could be promoted from about 10% to over 15% and the utilization efficiency was increased from about 6% to over 8.5% by use of innovative materials or geometry designs, while ensure thermal parameters within the normal operating range. However, results also indicate that some efficiency enhancement strategies proposed without the consideration of the whole system in previous studies might to be useless.

Radiative MHD Casson Nanofluid Flow with Activation energy and chemical reaction over past nonlinearly stretching surface through Entropy generation

In the present research analysis we have addressed comparative investigation of radiative electrically conducting Casson nanofluid. Nanofluid Flow is assumed over a nonlinearly stretching sheet. Heat transport analysis is carried via joule dissipation, thermal behavior and convective boundary condition. To employ the radiative effect radiation was involved to show the diverse states of nanoparticles. Furthermore entropy optimization with activation energy and chemical reaction are considered. Thermodynamics 2nd law is applied to explore entropy generation rate. Nonlinear expression is simplified through similarity variables. The reduced ordinary system is tackled through optimal approach. Flow pattern was reported for wide range of scrutinized parameters. Computational consequences of velocity drag force, heat flux and concentration gradient are analyzed numerically in tables. Results verify that conduction mode augments with enhance of magnetic parameter.Increasing radiation boosts the temperature and entropy. Activation energy corresponds to augmented concentration. Heat transmission rate augments with the consideration of radiation source term.