Convective Thermal Conditions Research Articles

Quantification and assessment of the atmospheric boundary layer height measured during the AWAKEN experiment by a scanning LiDAR

The atmospheric boundary layer (ABL) height plays a key role in many atmospheric processes as one of the dominant flow length scales. However, a systematic quantification of the ABL height over the entire range of scales (i.e., with periods ranging from one minute to one year) is still lacking in literature. In this work, the ABL height is quantified based on high-resolution measurements collected by a scanning pulsed Doppler LiDAR during the recent American WAKE experimeNt (AWAKEN) campaign. The high availability of ABL height estimates (≈2200 collected over one year and each of them based on 10-min averaged statistics) allows to robustly assess five different ABL height models, i.e., one for convective thermal conditions and four for stable conditions. Thermal condition is quantified by a stability parameter spanning three orders of magnitude and probed by near-ground 3D sonic anemometry. The free-atmosphere stability, quantified by the Brunt–Väisälä frequency, is both calculated from simultaneous radiosonde measurements and obtained from the best fit of two of the chosen ABL height models. Good agreement is found between the data and three of the chosen models, quantified by mean absolute errors on the ABL height between 281 and 585 m. Furthermore, the seasonal variability of the convective ABL height model parameters (−15% to +23% with respect to the year baseline) agrees with the variability of buoyancy-generated turbulence caused by the variation in solar radiation throughout the year.

Computational analysis of MHD hybrid nanofluid over an inclined cylinder: Variable thermal conductivity and viscosity with buoyancy and radiation effects

Due to their widespread use in engineering, hybrid nanofluids have been the primary focus of mathematical and physical research. Only the improvement of hybrid nanofluids’ variable heat conductivity and viscosity has been considered so far. Hybrid nanofluid flow across an inclined cylinder has many potential uses, including heat transfer and cooling in electrical devices, energy storage, refrigerants, and the automobile industry. Examining the effects of buoyant force, variable viscosity, variable thermal conductivity, mass suction, convective thermal conditions, and a magnetic field on the stagnation point flow of a Al2O3–Cu/H2O hybrid nanofluid in an inclined cylinder is our objective in this work. In order to find solutions to boundary-condition flow-describing partial differential equations, we turn them into ordinary differential equations using similarity transformations. We achieve this by employing a numerical strategy known as the fourth-order Runge–Kutta technique, which incorporates shooting techniques. A graphical representation of the findings emphasizes the influence of many physical parameters on flow dynamics. In addition, we address the influence of drag force and rate of heat transfer on various elements, such as the Biot parameter, magnetic variable, viscosity variable, and thermal conductivity variable. The mixed convection and magnetic parameters cause the velocity profile to rise while the temperature profile falls. The research’s results elucidate the cause behind the rise in thermal contour of hybrid nanofluids, which is seen when there is an increment in thermal conductivity, radiation parameter, and Biot number. The heat transfer rate exhibits a significant increase of 36.87% in the aiding flow scenario when a 2.0 mass suction is applied in conjunction with a 0.01 hybrid nanofluid, as compared to the conventional fluid. In the scenario of opposing flow, the heat transfer rate exhibits a significant increase of 36.96% when compared to that of ordinary fluid. Heat transfer increases 43.00% when Rd increases from 0.1 to 0.5 for both assisting and opposing flow.

Thermal magnetization transport analysis featuring darcian and multi-physical rheological characteristics in chemically reactive dual convective tangent-hyperbolic nanomaterial confined by vertical cone

The Soret-Dufour characteristics elaborate the phenomena of cross-diffusion where solutal gradients yield heat flux (Dufour aspect) and thermal gradients engender mass flux (Soret effect). Such consideration finds significance in multi-component fluid systems, influencing both heat-mass transportation processes. This study evaluates the porous medium characteristics in convectively heated tangent-hyperbolic nanomaterial driven by a magnetized convected cone. The analysis features Buongiorno nanomaterial model which accounts Brownian motion together with thermophoresis. Thermal transport expression which reports heat transfer characteristics is modeled by considering thermal radiation, convective thermal conditions and heat generation while mass transfer considers the chemical reaction effects. Dimensional expressions are converted into dimensionless forms deploying similarity transformations ensuing in a set of ODEs (ordinary differential expressions) which are computed by deploying bvp4c algorithm. Graphical and tabular behavior of velocity, nanoparticles concentration and temperature fields is inspected corresponding to related variables. This research highlights key findings, revealing a decrease in Nusselt number with increasing heat generation, Dufour parameter and thermophoresis parameter values while opposite trends are verified for radiation parameter values. The velocity function declines for escalating Weissenberg number, magnetic field and permeability parameters but it upsurges with material and buoyancy parameters.

Stagnation-point flow of Williamson fluid along a stretched plate with convective thermal condition and activation energy

The implication of a stagnation-point flow together with the influence of activation energy in a Williamson fluid, which consists of tiny particles, over an expansive plate is analyzed numerically. Conditions of convective heat and mass motion with features of irregular movement and thermal-migration of particles influenced by viscous dissipation and convective heat surface condition are checked in the study. The conversion of the model equations from the initially formulated partial derivatives to ordinary ones is implemented by similarity transformations while an unconditionally stable Runge-Kutta-Fehlberg integration plus shooting technique are then used to complete the integration. Various interesting effects of the physical parameters are demonstrated graphically and explained appropriately in order to make accurate predictions. Moreover, the accuracy of the solution is verified by comparing the values of the skin friction factor with earlier reported ones in literature under limiting constraints. It is worth mentioning that the velocity profiles flatten down as the magnitude of the magnetic field factors expands but this causes a boost in the fluid’s temperature. The concentration field also appreciates with activation energy but depreciates with chemical reaction and Schmidt number.

Convective thermal conditions and the thermophoretic effect's impacts on a hybrid nanofluid over a moving thin needle

AbstractThis research focuses on the heat source/sink, chemical reaction, and thermophoretic particle deposition in the influence of hybrid nanofluid over a moving thin needle subjected to a magnetic field. Using the appropriate transformations, a group of nonlinear partial differential equations may be converted to ordinary differential equations. Additionally, with the aid of computational software, the RKF‐45 approach is used for the numerical assessment, as well as the shooting operation. It should be mentioned that the results' approval demonstrates a strong association with the previous findings. The resulting graphs mainly explain the fundamental characteristics of hybrid nanofluids and nanofluids, as well as the consequences of different restrictions. An increase in needle size enhances the velocity profile, temperature profile, and concentration profile. The radial and axial velocity profiles are reduced when the magnetic constraint is increased, whereas the thermal and concentration patterns are reversed. Improved heat source‐sink as well as Biot number values will enhance the thermal profile. The concentration profiles will decrease due to reaction rate restrictions and thermophoretic limits. The inclusion of solid volume fraction reduces surface drag forces while increasing the rate of mass transfer. In most circumstances, hybrid nanofluid plays a prominent role than nanofluid.

Applications of variable plastic viscosity and thermal conductivity for Casson fluid with slip effects and space dependent internal heat generation

It is well established face that the role of viscosity and thermal conductivity is quite important in heat flow problems. It is commonly observed that both thermal features fluctuated for distinct flow constraints and different types of fluid flow. In most of continuations, the researchers presented the heat transfer phenomenon in view of constant viscosity. In current investigation, we have attributed the role of variable viscosity and thermal conductivity while assessing the heat transfer inspection for Casson fluid due to moving plate. The variable plastic dynamic viscosity is used to identify the heat transfer problem. The analysis is performed in view of slip effects. Moreover, the space dependent internal heat generation. The convective thermal conditions are taken into focus to observe the flow. After capturing the dimensionless form of problem, BVP4C numerical technique is used for computation process. The physical dynamic governs to the flow is tested with different parameters.

Numerical treatment for processing the effect of convective thermal condition and Joule heating on Casson fluid flow past a stretching sheet

In this work, an approximate analytical solution for the problem of non-Newtonian Casson fluid flow past a porous exponentially stretching sheet with Joule heating and convective boundary condition is obtained using a relatively new technique; He’s homotopy perturbation (HPM). The major feature of HPM is that it does not need the small parameters in the equations, and hence the determination of classical perturbation can be discarded. Due to the complete efficiency of the HPM, it becomes practically well suited for use in this field of study. Also, the obtained solutions for both the velocity and temperature field are graphically sketched. The results reveal that the method is very effective, convenient and quite accurate to systems of nonlinear equations.

Characteristic of thermophoretic effect and convective thermal conditions on flow of hybrid nanofluid over a moving thin needle

This paper presents the impact of thermophoretic particle deposition in the flow of a hybrid nanofluid (Fe3O4-Go/H2O) over a moving thin needle in the presence of a convective boundary condition. The set of non-linear partial differential equations is transformed into ordinary differential equations with the implementation of suitable transformations. Further, the numerical evaluation is carried out by employing the RKF-45 method along with the shooting procedure via the aid of Maple 17 software. It should be noted that the approval of the results shows a good correlation with the existing results. The obtained graphs mainly explain the fundamental characteristics and impacts of different constraints on hybrid nanofluid and mano nanofluid. The main outcomes bring out that enhancement of thermophoretic parameter increases the concentration field and increase in Biot number increases thermal efficiency. Also, the velocity and concentration profiles of hybrid nanofluid reduce with the increment of the magnetic parameter. But the thermal profile of hybrid nanofluid exhibits contrasting behavior.

An approximate method for solving MHD boundary layer flow over a stretching sheet with Joule heating and convective thermal condition

In this paper, He’s homotopy perturbation method (HPM) is used, which is an approximate analytical method for solving numerically the problem of Newtonian fluid flow past a porous exponentially stretching sheet with Joule heating and convective boundary condition. The major feature of HPM is that it does not need the small parameters in the equations and hence the determination of classical perturbation can be discarded. Due to the complete efficiency of the HPM, it becomes practically well suited for use in this field of study. Also, the obtained solutions for both the velocity and temperature field are graphically sketched. The results reveal that the proposed method is very effective, convenient, and quite accurate to systems of nonlinear differential equations. Results of this study shed light on the accuracy and efficiency of the HPM in solving these types of nonlinear boundary layer equations.

Computational study of three-dimensional flow and heat transfer of 25 nm Cu–H2O nanoliquid with convective thermal condition and radiative heat flux using modified Buongiorno model

The three-dimensional steady flow of an incompressible 25 nm water-based copper nanoliquid over a bi-directional elongated surface with convective thermal boundary condition is studied. This work may meet various thermal engineering applications for instance thermal energy exchangers, solar energy collectors, geophysical transports, radiators, electronic cooling devices, and nuclear reactors. Corcione's model for effective thermal conductivity and dynamic viscosity is used in conjunction with correlations based on effective medium theory for density, specific heat, and electrical conductivity. The effects of radiative heat and convective thermal energy conditions are also taken into account. Modified Buongiorno inhomogeneous model-based governing equations transmuted to nonlinear ordinary boundary value problem. The subsequent system has been deciphered using computer algebraic system software. The method used is validated against the available data and found an exceptional agreement. Two dimensional charts are designed to analyze the impact of the key parameters involved in the model. Three dimensional surface plots are plotted for the study of the Nusselt number, friction coefficients, and Sherwood number values are tabulated for several key parameters. A regression analysis is also performed for the local Nusselt number.

Computational modeling of heat transfer in magneto‐non‐Newtonian material in a circular tube with viscous and Joule heating

AbstractNumerous industrial and engineering systems, like, heat exchangers, chemical action reactors, geothermic systems, geological setups, and many others, involve convective heat transfer through a porous medium. The diffusion rate, drag force, and mechanical phenomenon are dealt with in the Darcy–Forchheimer model, and hence this model is vital to study the fluid flow and heat transport analysis. Therefore, numerical simulation of the Darcy–Forchheimer dynamics of a Casson material in a circular tube subjected to the energy losses due to the viscous heating and Joule dissipation mechanisms is performed. The novelty of the present investigation is to scrutinize the convective heat transport characteristics in a circular tube saturated with Darcy–Forchheimer porous matrix by utilizing the non‐Newtonian Casson fluid. The flow occurs due to the elongation of the surface of a tube with a uniform heat‐based source/sink. The similarity solution of the nonlinear problem was obtained using dimensionless similarity variables. The effects of operating parameters related to the flow phenomena are analyzed. Further, the friction factor and Nusselt number are also analyzed in detail. The present flow model ensures no flow reversal and acts as a coolant of the heated cylindrical surface; the existence of the magnetic field, as well as an inertial coefficient, acts as the momentum‐breaking forces, whereas Casson fluidity builds it. The Joule heating phenomenon enhances the magnitude of temperature. The thermal field of the Casson fluid is higher at the surface of the circular pipe due to convective thermal conditions.

Radiative peristaltic transport of Ree-Eyring fluid through porous medium in asymmetric channel subjected to combined effect of inclined MHD and convective conditions

This study emphasizes the flow phenomenon of trapped bolus traveling along the interior walls of asymmetric inclined channels contains a non-Newtonian Ree-Eyring. The flow was exposed to influenced by inclined MHD field, thermal heat radiative, and porous media. Further, no slip and convective thermal conditions are considered. Mathematical expression for governing equations are reformulated and in accordance with lubrication approximations, nonlinear partial differential equations of the flow reduced into a system of ordinary differential equations associated with boundary conditions an approximate solution is deduced by implementing perturbation strategy for tiny A Ree-Eyring fluid parameter. Finally, a graphical description is presented to figure out the elevation behavior of flow quantities i.e. velocity profile, temperature distribution, pressure rise, and streamlines formulation due to variation of emerging involved parameters. The study analyzed that the velocity profile reveals mixed behavior via increment of Ree-Eyring parameters η, A as well as Hartman number H and Darcy number Da. whereas the thermal radiative parameter Rn accelerates the temperature distribution profile. The study calculations are made by the “Mathematica 11.3” package.

Carbon nanotubes (CNTs)-based flow between two spinning discs with porous medium, Cattaneo–Christov (non-Fourier) model and convective thermal condition

Inspired by various applications (ocean’s renewable power technologies, spinning disc reactor, engineering systems, etc.) of fluid flow between rotating disc, we have investigated magnetohydrodynamic flow of multi-wall and single-wall carbon nanotubes (MWCNTs and SWCNTs)-based fluid between two rotating, coaxial and parallel stretching discs with porous medium and convective thermal condition. The non-vanishing relaxation time in the dissipative process is assumed. The energy equation is developed by using Cattaneo–Christov heat flux model. ND-Solve command of MATHEMATICA software is used for the numerical solution of the governing equations. The physical behaviour of axial, radial and tangential velocity along with temperature of nanofluid is discussed in detail. When porous permeability parameter is small, then tangential velocity of MWCNTs-based fluid is higher than that of the SWCNTs-based fluid. Moreover, when porous permeability parameter is small, the Reynolds number retards the tangential velocity but when porous permeability parameter is large, Reynolds number boots the tangential velocity up.

Analysis of activation energy and thermal radiation on convective flow of a power‐law fluid under convective heating and chemical reaction

AbstractThe purpose of the present article is to explore the influence of activation energy in the mixed convective flow of a power‐law fluid over a permeable inclined plate. The energy expression is incorporated with thermal radiation effect. Additionally, the suction/injection effect and convective thermal conditions are considered at the surface of the inclined plate. The convection along with a nonlinear Boussinesq approximation (i.e., quadratic or nonlinear convection) and usual boundary‐layer assumptions are used in the mathematical formulation. A combined local non‐similarity and successive linearization techniques are used to evaluate the highly complicated governing equations. The effect of pertinent parameters on the fluid flow characteristics and its solutions are conferred using this study with the help of graphs. This kind of investigation is useful in the mechanism of combustion, aerosol technology, high‐temperature polymeric mixtures, and solar collectors, which operate at moderate to very high temperatures.

Effect of Joule heating on the flow over an exponentially stretching sheet with convective thermal condition

This article analyzes the Joule heating effect on the viscous fluid flow over a porous sheet stretching exponentially by employing convective boundary condition. The numerical solutions to the governing equations are obtained using a local similarity and non-similarity approach together with a successive linearization procedure and a Chebyshev collocation method. The influence of the slip parameter, suction/injection parameter, magnetic parameter, Joule heating parameter and Biot number on the velocity, temperature, concentration, skin friction, rate of heat transfer and rate of mass transfer is displayed in graphs. The velocity is found to decay for higher estimation of magnetic parameter, while a thermal field is enhanced for higher Joule heating and Biot number. It is also observed from the investigation that the rate of heat transfer reduces with Joule heating and enhances with increasing Biot number.

Flow over an Exponentially Stretching Sheet with Double Dispersion and Convective Thermal Condition

Flow over an Exponentially Stretching Sheet with Double Dispersion and Convective Thermal Condition

Effects of Nonlinear Boussinesq Approximation and Double Dispersion on Free Convective Flow of an Ostwald-de Waele Power-Law Fluid Along an Inclined Plate Under Convective Thermal Condition

Effects of Nonlinear Boussinesq Approximation and Double Dispersion on Free Convective Flow of an Ostwald-de Waele Power-Law Fluid Along an Inclined Plate Under Convective Thermal Condition

Effects of nonlinear Boussinesq approximation and double dispersion on a micropolar fluid flow under convective thermal condition

AbstractThis article investigates the effect of double dispersion on the natural convective flow of a micropolar fluid along an inclined plate in the presence of the convective thermal condition. In addition, the nonlinear convection is considered to analyze the heat and mass transfer phenomena of thermal systems, which are performed at moderate‐ and high‐level temperatures. A combination of local nonsimilarity and successive linearization techniques is used to evaluate the associated complicated nondimensional governing equations. This study discusses the impact of relevant factors on the fluid characteristics through graphs. The influence of nonlinear convection parameters on the heat and mass transfer rates seems to be more in Darcy porous media compared with that in non‐Darcy porous media.

Double dispersion effect on nonlinear convective flow over an inclined plate in a micropolar fluid saturated non-Darcy porous medium

This article explores the influence of double dispersion on micropolar fluid flow past an inclined plate in a homogeneous and isotropic non-Darcy porous medium. Additionally, the effect of nonlinear Boussinesq approximation (i.e., also known as nonlinear convection) with the convective thermal condition is considered to address the heat and mass transfer phenomena in some thermal systems which are operated at moderate to very high temperatures. The governing partial differential equations are transformed into a system of ordinary differential equations using a local non-similarity method, and the resulting boundary value problem is solved using a novel successive linearization method (SLM). The accuracy of the SLM has been established by comparing the results with the shooting technique. This numerical study discusses the influence of pertinent parameters on the fluid flow characteristics through graphs and the salient features are discussed in detail. Heat and mass transfer varies extensively with the increase of nonlinear convection parameters, which depends on aiding and opposing flow situations. In the both aiding and opposing flows, thermal dispersion favors the heat transfer, whereas the solutal dispersion parameter benefits the mass transfer. This kind of investigation is useful in the mechanism of combustion, aerosol technology, high-temperature polymeric mixtures, solar collectors which are operated at moderate to very high temperatures.

Nonlinear Boussinesq Approximation in an Ostwald-de Waele Power-Law Fluid Subject to Cross-Diffusion Effects and Convective Thermal Condition

Nonlinear Boussinesq Approximation in an Ostwald-de Waele Power-Law Fluid Subject to Cross-Diffusion Effects and Convective Thermal Condition