The axisymmetric stagnation point flow of brick and blade-shaped Silver and Copper nanoparticles immersed in an ethylene glycol base fluid under the influence of an induced magnetic field over an ...unsteady radial stretching surface is investigated in this study. The unsteady phenomenon is considered because most flow issues in practice are unsteady. The fundamental laws of mass, momentum, and energy conservation are used to present the physical model. Heat transmission is also examined under the effects of magnetohydrodynamics, Joule heating, viscous dissipation, and convective boundary conditions to give a realistic physical investigation. Scaling analysis transforms the flow-governing issue into a collection of higher-order nonlinear ODEs. These are, then, solved numerically using the fourth-order Runge-Kutta and shooting techniques. Moreover, the numerical technique is validated by calculating residual error. It is concluded that, compared to the Ag-EG nanofluid, the Cu-EG nanofluid had the highest IMF, lowest temperature, minimum surface drag, and maximum heat flux, making it the ideal choice for creating a radial module.
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The steady boundary-layer flow near the stagnation point on an impermeable vertical surface with slip that is embedded in a fluid-saturated porous medium is investigated. Using appropriate similarity ...variables, the governing system of partial differential equations is transformed into a system of ordinary differential equations. This system is then solved numerically. The features of the flow and the heat transfer characteristics for different values of the governing parameters, namely, the Darcy–Brinkman, Γ, mixed convection, λ, and slip, γ, parameters, are analysed and discussed in detail for the cases of assisting and opposing flows. It is found that dual solutions exist for assisting flows, as well as those usually reported in the literature for opposing flows. A stability analysis of the steady flow solutions encountered for different values of the mixed convection parameter λ is performed using a linear temporal stability analysis. This analysis reveals that for γ = 0 (slip absent) and Γ = 1 the lower solution branch is unstable while the upper solution branch is stable.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The present work emphasizes the MHD mixed convective stagnation point flow over a shrinking/stretching surface saturated in a porous medium. The double stratification with heat source effects are ...also considered while the magnetic field is imposed normal to the sheet. The governing model (partial differential equations) is converted into a system of ordinary (similarity) differential equations using similarity transformations. The boundary value problem solver (bvp4c) in the MATLAB software is utilized for the numerical computations. Numerical results are graphically illustrated in the form of velocity, temperature and concentration profiles for several values of buoyancy, magnetic, thermal and solutal stratification parameters. The graphs of skin friction coefficient, local Nusselt and Sherwood numbers portray that the dual solutions are achievable within a certain range of the buoyancy and velocity ratio parameters. Both assisting and opposing flow cases can generate two solutions, whereas the forced convective flow only produces a unique solution. The execution of stability analysis affirms the reliability of the first solution. Both heat and mass transfer rates intensify with the increment of the velocity ratio parameter for all type of convective flows. The fluid temperature and concentration decrease with the increment of the thermal and solutal stratification parameters, respectively, whereas the magnetic and buoyancy parameters reduce both temperature and concentration profiles.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
•A high efficiency thermal extrusion sheet problem has been investigated.•Energy conversion is application for heat and mass transfer thermal system.•Heat transfer enhancement are observed with ...Maxwell fluids.•The stretching sheet is with mixed convection, radiation and electric MHD effects.•The results are comparison with other studies have been examined.
The present study is one kind of numerical application to a thermal extrusion manufacturing processing system energy conversion problem by using some improved parameters control method. Combined electrical MHD Ohmic dissipation forced and free convection of an incompressible Maxwell fluid on a stagnation point heat and mass transfer energy conversion problem have been studied. The governing equations are solved by an analysis similarity transformation method and an improved numerical finite difference method. The above two methods have been used to analyze present problem which is provided a different method to deal with the similar thermal system energy conversion problems by using parameter control method. The combination thermal system numerical solutions of the flow velocity field, temperature field, mass transfer and heat conduction had been produced out as functions of the viscoelastic number (E), Prandtl number (Pr) and buoyancy parameters (Gc, Gt), etc. The effects of related importance parameters have also been discussed in detail. The results are shown that it will be produced greater heat transfer effects with larger values of viscoelastic number, Prandtl number, free convection parameters, electric parameter (E1), heat source/sink (AL) and conduction-convection number (Ncc). At last, it can be obtained a higher efficiency thermal extrusion system.
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•Momentum boundary layer thickness decreases with an increase in ϕ, when a/c>1.•Cu–water velocity is higher than Al2O3–water and TiO2–water for stretching and shrinking sheets.•Skin-friction ...coefficient increases with increasing the value of volume fraction ϕ.•Decrease in suction parameter s>0 decreases velocity profiles for Cu–water.•Temperature for Cu–water increase with decreasing the suction parameter s>0.
In this paper, the effects of thermal radiation and viscous dissipation on a stagnation point flow and heat transfer over a flat stretching/shrinking surface in nanofluids are analyzed. The effects of suction/injection are also considered. Using a similarity transformation, the governing equations are transformed into a system of nonlinear ordinary differential equations. The resulting system is then solved numerically by Runge–Kutta–Fehlberg method with shooting technique. It is observed that the local Nusselt number increases with increment in the suction/injection parameter for stretching sheet whereas reverse effect is observed for shrinking sheet. It is found that skin-friction coefficient increases for both stretching/shrinking sheet with increase in volume fraction of the nanoparticles.
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•Here radiative flow of Casson nanoparticles is discussed.•Oblique stagnation point is considered.•Binary chemical reaction is considered with activation energy.•Flow behavior is ...discussed over a stretched surface of cylinder.
The flow of nanoparticles presents many dynamic applications in thermal sciences, solar systems, cooling and heating phenomenon, energy resources and much other multidisciplinary significance. Following to such valuable applications and motivations in mind, this research pronounced the thermal applications of radiative Casson nanoparticles in presence of radiative phenomenon and activation energy. The oblique stagnation point flow has been considered due to the stretching cylinder. To analyze the flow problem, the problem is formulated in the cylindrical coordinates. The numerical solution is computed via bvp4c built solver by using the MATLAB software. The impact of different involved parameters on skin fraction, heat transfer rate and mass transfer rate is reported and discussed in tables.
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We use theory and simulations to study how the out‐of‐plane (guide) magnetic field strength modifies the location where the energy conversion rate between the electric field and the plasma is ...appreciable during asymmetric magnetic reconnection, motivated by observations (Genestreti et al., 2017). For weak guide fields, energy conversion is maximum on the magnetospheric side of the X line, midway between the X line and electron stagnation point. As the guide field increases, the electron stagnation point gets closer to the X line, and energy conversion occurs closer to the electron stagnation point. We motivate one possible nonrigorous approach to extend the theory of the stagnation point location to include a guide field. The predictions are compared to two‐dimensional particle‐in‐cell (PIC) simulations with vastly different guide fields. The simulations have upstream parameters corresponding to three events observed with Magnetospheric Multiscale (MMS). The predictions agree reasonably well with the simulation results, capturing trends with the guide field. The theory correctly predicts that the X line and stagnation points approach each other as the guide field increases. The results are compared to MMS observations, Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) observations of each event, and a global resistive‐magnetohydrodynamics simulation of the 16 October 2015 event. The PIC simulation results agree well with the global observations and simulation but differ in the strong electric fields and energy conversion rates found in MMS observations. The observational, theoretical, and numerical results suggest that the strong electric fields observed by MMS do not represent a steady global reconnection rate.
Key Points
We motivate a theory of the guide field dependence of the location within the diffusion region of X line, stagnation points, and nonzero J · E′
Two‐dimensional PIC simulations of three MMS events confirm location of energy conversion moves toward electron stagnation point with increasing guide field
Reconnection rate in 2‐D PIC simulations agrees well with AMPERE observations and global simulations but are far lower than MMS observations
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The present work highlights the stagnation point flow with mixed convection induced by a Riga plate using a Cu-Al 2 O 3 /water hybrid nanofluid. The electromagnetohydrodynamic (EMHD) force generated ...from the Riga plate was influential in the heat transfer performance and applicable to delay the boundary layer separation. Similarity transformation was used to reduce the complexity of the governing model. MATLAB software, through the bvp4c function, was used to compute the resulting nonlinear ODEs. Pure forced convective flow has a distinctive solution, whereas two similarity solutions were attainable for the buoyancy assisting and opposing flows. The first solution was validated as the physical solution through the analysis of flow stability. The accretion of copper volumetric concentration inflated the heat transfer rate for the aiding and opposing flows. The heat transfer rate increased approximately up to an average of 10.216% when the copper volumetric concentration increased from 0.005 ( 0.5 % ) to 0.03 ( 3 % ) .
Purpose
The purpose of this study is to model and solve numerically the three-dimensional off-centered stagnation point flow and heat transfer of magnesium oxide–silver/water hybrid nanofluid ...impinging to a spinning disk.
Design/methodology/approach
The applied effective thermophysical properties of hybrid nanofluid including thermal conductivity and dynamics viscosity are according to the reported experimental relations that would be expanded by a mass-based algorithm. The single phase formulations coupled with experimental-based hybrid nanofluid model is implemented to derive the governing partial differential equations which are then transferred to a set of dimensionless ordinary differential equations (ODEs) with the use of the similarity transformation method. Afterward, the reduced ODEs are solved numerically by bvp4c function from MATLAB that is a trustworthy and efficient code according to three-stage Lobatto IIIa formula.
Findings
The effect of spinning parameter and nanoparticles masses (mMgO, mAg) on the hydrodynamics and thermal boundary layers behavior and also the quantities of engineering interest are presented in tabular and graphical forms. The recent work demonstrates that the analysis of flow and heat transfer becomes more complicated when there is a non-alignment between the impinging flow and the disk axes. From computational results demonstrate that, the radial and azimuthal velocities are, respectively, the increasing and decreasing functions of the disk spinning parameter. Further, for the greater values of the spinning parameter, an overshoot of the radial velocity owing to the centrifugal forces of the spinning disk is observed. Besides, the quantities of engineering interest gently enhance with first and second nanoparticle masses, while comparing their absolute values illustrates the fact that the effect of second nanoparticle mass (mAg) is greater. Further, it is inferred that the second nanoparticle’s mass enhancement results in the amplification of the heat transfer; although, the high skin friction and the relevant shear stress should be controlled.
Originality/value
The combination of experimental thermophysical properties with theoretical modeling of the problem can be the novelty of the present work. It is evident that the experimental relations of effective thermophysical properties can be trustable and flexible in the theoretical/mathematical modeling of hybrid nanofluids flows. Besides, to the best of the authors’ knowledge, no one has ever attempted to study the present problem through a mass-based model for hybrid nanofluid.
A cylinder that performs linear torsional motion with an applied magnetic field and heat transfer is the basic aim of our computational research which is associated with the impact of radial ...stagnation-point flow. This improves earlier research on the motion around a cylinder experiencing linear torsional motion without heat transfer. By transforming partial differential equations to ordinary differential equations, a nonlinear and coupled system of governing equations is created under the effect of many dimensionless variables. The Bvp4c method in MATLAB is used to numerically solve these equations. The nondimensional scale variable η=r*a2 plays an important role in finding the convergent solution, especially for the velocity components. The influence of different parameters on the axial velocity f′, azimuthal velocity g and temperature profile θ are illustrated graphically. Additionally, it also shows how the diverse character of physical parameters affects the azimuthal, and axial shear stresses, as well as the heat transport rates. The key findings of the study state that the f′′1 and g′1 wall stress are the strong function of R. Further f′′1 ids a weak function of σ whereas g′1 is a strong function of σ.
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