Stagnation Point Heat Transfer Research Articles

Magnetohydrodynamic Stagnation Point Flow and Heat Transfer of Casson Fluids Over a Stretching Sheet

This research investigates the effects of heat transfer on the stagnation-point flow of a non-Newtonian Casson fluid in a two-dimensional magnetohydrodynamic (MHD) boundary layer over a stretched sheet, considering thermal radiation impacts. By employing similarity transformations, the governing partial differential equations are transformed into nonlinear ordinary differential equations. The obtained self-similar equations are numerically solved using the Optimal Homotopy Analysis Method (OHAM). The numerical results are graphically represented, showcasing the influence of various parameters on fluid flow and heat transfer characteristics. The study uncovers important dynamics in transport phenomena. Examining and illustrating the effects of dimensionless parameters on velocity, temperature, and concentration profiles reveal significant insights. Moreover, skin friction and Nusselt number results for Casson fluids are analyzed and presented. The findings indicate that the Casson parameter and Hartman number act in opposition to fluid momentum, while the thermal conductivity parameter enhances fluid temperature. Thus, this research provides valuable insights into MHD boundary layer flows of non-Newtonian Casson fluids with thermal radiation effects, and the OHAM solution method proves effective in predicting flow transport properties.

Stagnation point heat transfer under a free-surface jet

Laminar free-surface jet impingement is a crucial configuration for heat transfer processes. Focusing on the link between stagnation-point heat transfer and near-axis radial acceleration, its dependence on jet width and profile is studied. Thus, heat transfer depends on: fluid properties, flow rate, nozzle length, nozzle-to-plate spacing, surface tension and gravity (Pr, Re, L/d, H/d, We & Fr, accordingly). As existing theory is limited to specific cases, a new general description is developed from analogy to submerged jets. Validated by two-phase flow simulations, this description captures key jet dynamics evolution (centerline velocity, profile curvature). It reveals significant property changes during jet flight due to relaxation (L dependence) and contraction (Re/Fr dependence). Unlike submerged jets, contraction raises arrival Reynolds number, leading to additional dependencies Nu ∝ L and Nu ∝ H/Fr, and further deviations at low-We and -Re. The theory successfully predicts heat transfer across diverse conditions and converges to negligible gravity (horizontal jet) as expected.

Investigation of Surface-Catalycity Effects on Hypersonic Glide Vehicle Trajectory Optimization

The optimization of a hypersonic glide vehicle’s reachable domain is studied using different models to constrain the stagnation-point heat transfer. The vehicle is modeled as a high-lift common aero vehicle that uses bank-angle modulation for crossrange maneuvering with a leading-edge thermal protection system made of an ultra-high-temperature ceramic. A constrained nonlinear optimization problem is formulated to determine the range of feasible trajectories that satisfy aerodynamic heating and loading constraints. The optimal control profile is determined using a modified particle swarm optimization routine that employs a penalty function approach to handle path and terminal constraints. Baseline trajectories are determined using an existing convective heat-flux correlation, and the effect of surface catalycity on the optimized trajectories is investigated by applying a correction factor, derived from high-fidelity computational fluid dynamics simulations, to the heat-flux correlation. Results demonstrate a high sensitivity of the optimized trajectories to the underlying aerothermodynamics model such that accounting for surface catalycity expands the reachability by an order of magnitude.

Stagnation Point Flow and Heat transfer of Hybrid Nanofluid over a Stretching/Shrinking Cylinder with Suction/Injection Effects

The focus of this research is to observe how suction/injection affects the stagnation point flow and heat transfer in a hybrid nanofluid over stretching/shrinking cylinder. Silver (Ag) and copper oxide (CuO) nanoparticles are dispersed in pure water to create a hybrid nanofluid. By using similarity transformations, the governing partial differential equations are turned into a ordinary differential equations which are then solved by implementing bvp4c function in MATLAB software. The influence of the nanoparticle volume fraction, magnetic parameter, curvature parameter and suction/injection parameter, on velocity and temperature profiles, local skin friction and local Nusselt number are discussed and presented in graphical forms. The results indicate that all of the problems have dual solutions for a given range of parameters. It is noticed that with the suction effect, energy losses is reduced, thus the heat transfer increases and decreases the boundary layer separation. Furthermore, the presence of curvature parameter and suction effect expand the range of dual solutions. In addition, the rate of heat transfer for hybrid nanofluid was higher than viscous fluid and nanofluid.

Boundary Layer Stagnation Point Flow and Heat Transfer over a Nonlinear Stretching/Shrinking Sheet in Hybrid Carbon Nanotubes: Numerical Analysis and Response Surface Methodology under the Influence of Magnetohydrodynamics

The present study aims to offer new numerical solutions and optimisation strategies for the fluid flow and heat transfer behaviour at a stagnation point through a nonlinear sheet that is expanding or contracting in water-based hybrid nanofluids. Most hybrid nanofluids typically use metallic nanoparticles. However, we deliver a new approach by combining single- and multi-walled carbon nanotubes (SWCNTs-MWCNTs). The flow is presumptively steady, laminar, and surrounded by a constant temperature of the ambient and body walls. By using similarity variables, a model of partial differential equations (PDEs) with the magnetohydrodynamics (MHD) effect on the momentum equation is converted into a model of non-dimensional ordinary differential equations (ODEs). Then, the dimensionless first-order ODEs are solved numerically using the MATLAB R2022b bvp4C program. In order to explore the range of computational solutions and physical quantities, several dimensionless variables are manipulated, including the magnetic parameter, the stretching/shrinking parameter, and the volume fraction parameters of hybrid and mono carbon nanotubes. To enhance the originality and effectiveness of this study for practical applications, we optimise the heat transfer coefficient via the response surface methodology (RSM). We apply a face-centred central composite design (CCF) and perform the CCF using Minitab. All of our findings are presented and illustrated in tabular and graphic form. We have made notable contributions in the disciplines of mathematical analysis and fluid dynamics. From our observations, we find that multiple solutions appear when the magnetic parameter is less than 1. We also detect double solutions in the shrinking region. Furthermore, the increase in the magnetic parameter and SWCNTs-MWCNTs volume fraction parameter increases both the skin friction coefficient and the local Nusselt number. To compare the performance of hybrid nanofluids and mono nanofluids, we note that hybrid nanofluids work better than single nanofluids both in skin friction and heat transfer coefficients.

Numerical investigation of time-dependent axisymmetric stagnation point flow and heat transfer of $$A{l}_{2}{O}_{3}-{H}_{2}O$$ and $$Cu-{H}_{2}O$$ nanofluid over a stretching sheet with variable physical features

Numerical investigation of time-dependent axisymmetric stagnation point flow and heat transfer of $$A{l}_{2}{O}_{3}-{H}_{2}O$$ and $$Cu-{H}_{2}O$$ nanofluid over a stretching sheet with variable physical features

Analysis of GO-MoS2/EG Powell-Eyring Fluid Transportation in Stagnation Point Flow and Heat Transfer over a Shrinking Surface

Using ethylene glycol as the base fluid, nanomaterials graphene oxide (GO) and molybdenum disulfide (MoS2) are disseminated into the fluid. The heat transfer behaviour of a non-Newtonian Powell-Eyring fluid hybrid nanofluid is evaluated together with several effects such as magnetic, suction and radiation. Ordinary differential equations (ODEs) are acquired by deriving the mathematical model in partial differential equations (PDEs) with suitable similarity transformations. The formulas are numerically estimated with the assistance of the bvp4c solver in MATLAB. The impact of parameter effects on the skin friction coefficient, local Nusselt number, entropy generation, velocity profile and temperature profile are reviewed and discussed. The aftermath revealed that skin friction and suction effects are elevated along the magnetic field. The rate of heat transmission is enhanced by improving the value of the suction parameter. Magnetic field, Eckert number and suction boosted entropy over the shrinking plate.

Effects of thermal radiation on Hiemenz slip flow and heat transfer of MHD non-Newtonian fluid in porous media due to permeable plate

This article is to presents a numerical study on effects of thermal radiation on stagnation point slip flow and heat transfer of MHD fluid through porous media due to permeable plate. The governing equations are P DE’s which are transformed into ODE’s by using similarity method. These ODE’s are numerically solved. It is observed that, the heat transfer rate increases with enhancing parametric values of Prandtl number. The results of the present work revels a good correlation with earlier published work. It is noted that temperature enhances as Casson parametric values enhanced. The velocity and temperature gradients are analyzed through graphs and tables. Based on the obtained scientific computations, it is claimed that the reported results can play a useful role in manufacturing processes and improvement in energy and heat resources. It is found that the effect of nonlinear thermal radiation stabilizes the thermal boundary layer growth.

The stability of the MHD flow over a shrinking cylinder with surface heat flux and volumetric thermal power

In this analysis, the stability of MHD stagnation point flow and heat transfer of an electrically conducting viscous incompressible fluid on a horizontally stretching/shrinking permeable cylinder with volumetric heat source are investigated. The cylindrical surface is subjected to a cross flow and a heat flux. This analysis finds applications in the areas of polymeric processing unit due to stretching/shrinking of surface and biofluid flows with therapeutic effects through the arteries, vein and digestive system that have a tube-like structure. Other aspects of the analysis are: magnetic field intensity whose strength can be remotely controlled and embodied generating/absorbing thermal power. The solution of the boundary value problems (BVP) is carried out with MATLAB’s inbuilt solver bvp4c. The most significant findings are recorded as: an increase in magnetic field strength increases the skin friction at the solid surface which is consistent with progressive thinning of boundary layer. This striking result is of interest in industrial applications because it is easy to regulate the magnetic field strength by electromagnetic devices such as controlling the voltage in the electric circuit. There is a point of neutrality of thermal energy distribution during the high fluctuation of temperature irrespective of the presence of heat generation or absorption. This can be attributed to the dominating effect of stretching/shrinking of the surface. The first solution provides stability of the flow with an increase in velocity in the presence of heat sink that is commensurate with the strength.

Discussion on “Three-Dimensional Stagnation Point Flow and Heat Transfer of a Dusty Fluid Toward a Stretching Sheet, M. R. Mohaghegh, and A. B. Rahimi, 2016, ASME J. Heat Mass Transfer-Trans. ASME, 138(11), p. 112001”

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Numerical Computation of Stagnation Point Flow and Heat Transfer over a Nonlinear Stretching/Shrinking Sheet in Hybrid Nanofluid with Suction/Injection Effects

The steady, laminar, stagnation point flow of hybrid nanofluid past a nonlinearly stretching and shrinking sheet is studied. Hybrid nanofluid is regarded by disseminated two distinct nano-sized particles, silver (Ag) and copper oxide (CuO) in pure water. Similarity technique was used for the transformation of partial differential equations (PDEs) into an ordinary differential equation (ODEs). Obtained ODEs were solved using Matlab’s built-in function (bvp4c). The results of important governing parameters which are nonlinear parameter, suction/injection parameter, stretching/shrinking parameter and nanoparticle volume fraction are evaluated and discussed in graphical and tabular form for the velocity and temperature profiles, along with local skin friction, local Nusselt number. Nonunique solutions (first and second branch) are visible for some limit of shrinking parameter. It is noticed that suction parameter delays the boundary layer hastens flow separations.

Free surface oblique liquid jet impinging on a flat surface: Towards improved understanding of flow structures and heat transfer

We present a numerical study of inclined jet impingement on a heated flat surface. Previous research on such configuration focused on peak heat transfer rate and its location on the impingement surface. However, for the inclined jet, it is still unresolved whether the peak heat transfer rate location coincides with the stagnation point or not. Present investigation tries to resolve these locations, their importance, and their relevance to wall shear stress distribution and turbulence fluctuations. We carried out a numerical study using Scale Adaptive Simulation (SAS). Volume of Fluid (VOF) method was employed to capture the liquid–air interface. We used a circular pipe with an inner diameter of 6mm to produce a fully developed jet. The inclination angle varied from 45°to 0°(in the interval of 15°), where 0°is the orthogonal jet case. The numerical study was validated by comparing numerical findings with experimental data. It was found that locations of stagnation point and peak heat transfer locations are distinct. Shear stress distribution at the impingement surface is vital in determining peak heat transfer location. Also, increased turbulence fluctuations near the impact cause sharp variations in the Nu profile for the inclined jet.

A study under the impact of Soret and Dufour effects on MHD stagnation point flow and heat transfer towards a stretching sheet

This paper signifies the consequence of the thermal diffusion (Soret) and diffusion-Thermo (Dufour) effect on MHD stagnation point flow and transportation of thermal energy near a stretching plate. However, the inclusion of thermal radiation, heat generation/absorption, and chemical reaction enriches the profiles significantly. By using similarity transformation, the set of leading equations is altered into a set of dimensionless ordinary differential equations. After that, the aim is to convert boundary layer equations into dimensionless ones so that the set of converting equations is computed by using bvp4c solver on MATLAB software. The governing nonlinear equations were resolved with Runge–Kutta fourth-order technique numerically. The significance of radiation, magnetic field, suction, Schmidt number, velocity ratio parameter, heat absorption coefficient, permeability, thermo-diffusion number, diffusion-thermo number on momentum gradient, energy gradient and concentration gradient distribution is analyzed. The parameters, diffusion-thermo number Du and thermo-diffusion number Sr have opposite behaviors on both temperature and concentration fields. Here, also, it is observed that the heat sink parameter has a noticeable influence on the fluid temperature distribution profile.

MHD STAGNATION POINT FLOW WITH THERMAL RADIATION AND SLIP EFFECT OVER A LINEAR STRETCHING SHEET

This research investigates the flow of stagnation point magnetohydrodynamic (MHD) and heat transfer along the stretched sheet in the existence of radiation and slip effects. With the help of similarity variables, the governing partial differential equations (PDEs) are transformed into ordinary differential equations (ODEs). The BVP4C technique in Matlab function has been used to simplify the governing ODEs. The numerical outcomes for temperature and velocity profiles, coefficient of skin friction and Nusselt Number have been achieved and matched with the findings in literature. The findings are compared to previously reported results. In addition, the impacts of numerous related parameters on the profiles of velocity and temperature are shown, and the results of every related parameter are presented using graphs. The velocity profile decreases as the magnetic force, suction, and permeability parameters rise.

Stability analysis and dual solutions of time-dependent stagnation-point heat transport of Casson nanofluid by using Tiwari–Das model

Magnetohydrodynamic (MHD) time-dependent stagnation point flow and heat transfer characteristics of Casson base nanofluid over porous shrinking/stretching sheet with velocity slip and radiations effects is considered. The Tiwari–Das model is incorporated with silver (Ag), gold (Au), and iron (Fe) nanoparticles. The similarity variables are used to transfer the modeled partial differential equations into the system of ordinary differential equations. The shooting technique through Maple software is used to check the effects of different physical parameters used in equations and boundary conditions. The stability analysis at different values of the used parameters is performed due to existence of duality in the solutions. In the results, the second solution is found unstable while first one is physically reliable and stable. Numerically achieved findings of this problems show the skin friction coefficient is decreasing for and increasing for when the suction rate and nanoparticles volume-fraction are increased. The local Nusselt number is higher against the rising suction parameter and lower for the incremented nanoparticles volume fractions for both cases of Comparatively, the thermal conductivity and drag force of Au-nanoparticles is seen greater than Ag and Fe, while Fe greater than Ag in Casson nanofluid flow. The velocity profiles decrease with increase in nanoparticles volume fractions, Casson, suction and velocity slip parameters, while, an increase in unsteady parameter increases velocity profile. Moreover, radiation, nanoparticles volume fractions and magnetic parameters increase the temperature profiles.

Mutual impact of thermal radiations and temperature dependent thermal conductivity on non-Newtonian multiple flow regimes

The transfer of thermal energy is a specialized discipline of thermal engineering and hence own practical applications in an industrial thermal systems like refineries, air-conditioning plants, automotive engines, power plants, jet engines, refrigeration, food processing, and chemical processing plants to mention just a few. Owning such importance we have reported the collective impact of thermal radiations and temperature-dependent thermal conductivity for heat transfer in stagnation point magnetized Casson fluid flow field. The thermal flow regime of Casson fluid is manifested with a viscous dissipation effect as well. The flow equations are tackled numerically by the use of the shooting method. The outcomes are debated comparatively by considering various flow regimes namely (I) Thermal flow regime with thermal radiations (II) Thermal flow regime without thermal radiations (III) Heat flow with heat generation and (IV) Heat flow in the absence of heat generation. We believe that the present thermal comparative analysis will be helpful for the preceding studies which own thermal engineering standpoints for the transfer of thermal energy by means of fluid flow.

Haar wavelet collocation method for solving stagnation point over a nonlinearly stretching/shrinking sheet in a hybrid nanofluid with slip effect

The study of stagnation point flow and heat transfer over a stretching/shrinking sheet in a hybrid nanofluid has potential applications in a variety of fields. In order to investigate the properties of fluid flow and heat transfer, this study must solve the governing mathematical model(partial differential equations). By utilizing similarity variables, the model is transformed into a system of ordinary differential equations. The study employs a novel numerical scheme that combines the power of Haar wavelets with the collocation method to solve these ordinary differential equations. Through this approach, the study can predict several important values related to the fluid's flow and heat transfer, including the skin friction coefficient, local Nusselt number, and the profiles of velocity, temperature which can be influenced by the governing parameters of the model.

Mhd Stagnation Point Flow and Heat Transfer of Cu –Water Nanofluid over A Stretching Sheet

A comprehensive study of Magnetohydrodynamics flow (stagnation Point) with heat transferal properties of Cu–Water nanofluid along a stretched sheet in the existence of a transverse magnetic field is analyzed. The governing equalities along with their conditions on boundary points are firstly converted to ordinary differential equations of non-linear category by similarity transformations. Lastly finite difference discretization is utilized. The flow and heat transfer parameters, namely: stretching parameter, magnetic parameter, the Prandtl number and solid volume fraction are investigated by tablular and graphical representation.

Magnetohydrodynamics stagnation point flow and heat transfer over a non‐isothermal permeable shrinking sheet with variable surface temperature

AbstractThe present study is intended to analyse the effect of heat and mass transfer on boundary layer stagnation point flow of a viscous fluid over a non‐isothermal shrinking sheet subject to transverse magnetic field and variable surface temperature. The medium of flow is considered to be porous. Further, the effect of variable surface temperature and concentration are also taken care of in the present analysis. The governing partial differential equations (PDEs) are transformed into ordinary differential equations (ODEs) by suitable similarity transformations. The numerical simulation is carried out using Runge–Kutta method of fourth order with shooting technique. The physical significance of pertinent parameters of the flow phenomenon is studied with the help of graphs and tables. One striking outcome of the present analysis is that the unstable velocity profiles with inflection points are marked due to power law variation of temperature and concentration of the linearly stretchable bounding surface leaving aside the smooth fall in temperature and concentration (span wise) across the flow field. Further, it is noted that increase in magnetic field intensity, suction and thermal as well as mass buoyancy parameters enhance the skin friction concomitantly favouring the effective momentum transport.

Stagnation Point Heat Transfer to an Axisymmetric Impinging Jet at Transition to Turbulence

Abstract A round air jet issuing from a long straight pipe and impinging perpendicularly onto a heated flat plate was investigated experimentally. The Reynolds number (Re) covered the fully laminar, transitional, and fully turbulent regimes—Re = 850–15,400. The main focus of this investigation was the transition regime, which occurred at Re = 2250–3010. Various measurements were recorded during the experiments using a hot-wire anemometer, an infrared thermometer, and a thermopile heat flux sensor; the mass transfer was measured using the naphthalene sublimation technique. The stagnation point heat transfer was correlated to the laminar and turbulent regimes in the form of the stagnation point Nusselt number, Nu0 = CRemPr0.4, where the exponent m = 0.50 and 0.55, respectively. The Nu0–Re relationship exhibited nonmonotonic behavior (decrease) in the transition regime. Two counteracting mechanisms occur during transition—jet core shortening and an increase in velocity fluctuation; the former reduces Nu0, whereas the latter increases it.