Natural Convection Parameter Research Articles

Effect of natural convection on 3D MHD flow of MoS2–GO/H2O via porous surface due to multiple slip mechanisms

ABSTRACT The theme of this work is to examine the magnetized flow behaviour of hybrid nanofluid containing molybdenum disulphide (MoS2) and graphene oxide (GO) nanoparticles subject to multiple slip mechanisms, natural convection and chemical reaction of mth order. The working hybrid nanofluid is prepared by an amalgamation of nanoparticles, i.e. MoS2 and GO and conventional fluid (H2O). The existing equations of the model were solved by the techniques, i.e. shooting and bvp4c. To validate our codes, the comparison was presented by previous research. Here, we observed that, with an increase in thermal slip parameter values, only the thermal field profiles of MoS2–GO/H2O regularly depreciated. Moreover, when there was augmentation in velocity slip parameter, temperature and concentration functions rose, while both velocity outlines of MoS2–GO/H2O fluid declined. Furthermore, the velocity functions of MoS2–GO/H2O augmented and the concentration function declined with an increase in natural convection parameter values.

Thermal behaviour of convective‐radiative porous fins under periodic thermal conditions

AbstractIn the present study, the effects of non‐Fourier, convection, and radiation heat transfer are investigated in a porous fin under periodic thermal conditions. The porosity effect on the fin that allows the flow to infiltrate is formulated using Darcy's model. A nonlinear partial differential equation has been obtained by energy balance for the porous fin solved by a numerical method. The effects of buoyancy or natural convection parameter (Np), the radiation parameter (Nr), the convection parameter (Nc), dimensionless relaxation time (Ψ), and dimensionless frequency of the base temperature oscillation (ω) on temperature distribution are studied. Increasing the values of Ψ, as the non‐Fourier condition of heat transfer, led to a discontinuity in the dimensionless temperature distribution with smaller values of η. The heat transfer rate of the porous fin has been increased by increasing Nc, Nr, and Np, of which the Nr had the strongest effect on heat transfer in comparison with other parameters.

Heat Transfer Performance on Longitudinal Porous Fins with Temperature-Dependent Heat Generation, Heat Transfer Coefficient and Surface Emissivity

Analytical and numerical analyses have been performed to study the problem of the porous fin with temperature-dependent heat generation, heat transfer coefficient and thermal emissivity. This study is performed using Darcy’s model to formulate the heat transfer equation. The partial differential equations have been transformed into an ordinary differential equation using a similarity transformation. The powerful analytical methods called collocation method, the least square method and homotopy analysis method have been used to solve nonlinear differential equations. It has been attempted to show the capabilities and wide-range applications of the proposed methods in comparison with a type of numerical analysis as fourth-order Runge–Kutta numerical method in solving this problem. Also, temperature fields have been computed and shown graphically for various values of physical parameters. The objective of the present work is to investigate the effect of natural convection parameter Nc, radiation parameter Nr and porosity S h parameter on the heat transfer rate. As an important outcome, these proposed methods are able to solve a large class of nonlinear problems effectively, more easily and accurately; and thus, it has been widely applicable in engineering and physics.

MHD boundary layer flow of Casson nanofluid over a vertical exponentially stretching cylinder under Newtonian heating

In this paper, similarity solution of the steady boundary layer flow and heat transfer of a Casson nanofluid flowing over a vertical cylinder which is stretching exponentially along its radial direction in the presence of MHD and Newtonian heating is investigated. The governing partial differential equations are converted into nonlinear, ordinary, and coupled differential equations and are solved using bvp4c Matlab solver. The effects of important parameters such as Magnetic parameter, Reynolds number, Prandtl number, Lewis number. Natural convection parameter and the conjugate parameter for Newtonian heating are described through graphs. The numerical results are compared with the published data and are found to be in good agreement.”.

Non-Fourier Heat Conduction with Periodic Thermal Condition for Porous Fin

In this study, the porosity and non-Fourier effects have been studied for a porous fin under periodic thermal conditions. Darcy’s model has been applied to formulate the porosity effect on the fin that allows the flow to infiltrate through it. The non-Fourier effect should be considered due to the periodic oscillation of the base temperature. Energy balance equation for this problem leads to a nonlinear partial differential equation that has been numerically solved. The effects of buoyancy or natural convection parameter (N c), dimensionless relaxation time (Ψ), and dimensionless frequency of base temperature oscillation (ω) on temperature distribution have been investigated. The dimensionless relaxation time affects the location of discontinuity in dimensionless temperature while porosity and frequency have no influence on discontinuity in temperature. Heat transfer rate of the porous fin has been increased by increasing N c.

Natural convection and thermal radiation influence on nanofluid flow over a stretching cylinder in a porous medium with viscous dissipation

The purpose of the present work is to examine the collective influence of thermal radiation and convection flow of Cu-water nanofluid due to a stretching cylinder in a porous medium along with viscous dissipation and slip boundary conditions. The governing non-linear ODEs and auxiliary boundary conditions those obtained by applying assisting similarity transformations have been handled numerically with shooting scheme through Runge-Kutta-integration procedure of fourth-fifth order. The non-dimensional velocity and temperature distribution are designed and also skin friction coefficient as well as heat transfer rate are tabulated for various values of relatable parameters. The results explain that Nusselt number depreciates with boost in radiation parameter, thermal slip parameter and Eckert number. Moreover, it is accelerated with increase in velocity slip parameter and natural convection parameter. The results are distinguished via published ones and excellent accord has been detected.

Numerical Study of Convective Heat Transfer on the Power Law Fluid over a Vertical Exponentially Stretching Cylinder

The present paper is the study of boundary layer flow and heat transfer of Power law fluid flowing over a vertical exponentially stretching cylinder along its axial direction. The governing partial differential equations and the associated boundary conditions are reduced to nonlinear ordinary differential equations after using the boundary layer approximation and similarity transformations. The obtained system of nonlinear ordinary differential equations subject to the boundary conditions is solved numerically with the help of Fehlberg method. The effects of Power law index , Reynolds number , Prandtl number , the natural convection parameter and local Reynolds number are presented through graphs. The skin friction coefficient and Nusselt number are presented through tables for different parameters.The present paper is the study of boundary layer flow and heat transfer of Power law fluid flowing over a vertical exponentially stretching cylinder along its axial direction. The governing partial differential equations and the associated boundary conditions are reduced to nonlinear ordinary differential equations after using the boundary layer approximation and similarity transformations. The obtained system of nonlinear ordinary differential equations subject to the boundary conditions is solved numerically with the help of Fehlberg method. The effects of Power law index , Reynolds number , Prandtl number , the natural convection parameter λ and local Reynolds number Rea are presented through graphs. The skin friction coefficient and Nusselt number are presented through tables for different parameters.

The boundary layer flow of hyperbolic tangent fluid over a vertical exponentially stretching cylinder

The present problem is the steady boundary layer flow and heat transfer of a hyperbolic tangent fluid flowing over a vertical exponentially stretching cylinder in its axial direction. After applying usual boundary layer with a suitable similarity transformation to the given partial differential equations and the boundary conditions, a system of coupled nonlinear ordinary differential equations is obtained. This system of ordinary differential equations subject to the boundary conditions is solved with the help of Runge–Kutta–Fehlberg method. The effects of the involved parameters such as Reynolds numbers, Prandtl numbers, Weissenberg numbers and the natural convection parameter are presented through the graphs. The associated physical properties on the flow and heat transfer characteristics that is the skin friction coefficient and Nusselt numbers are presented for different parameters.

An analysis on free convection flow, heat transfer and entropy generation in an odd-shaped cavity filled with nanofluid

A study of natural convective flow, heat transfer and entropy generation in an odd-shaped geometry is presented here. The geometry considered is a combination of the horizontal and vertical enclosure shapes. The cavity is filled with Cu–water nanofluid. The numerical study focuses specifically on the effect of natural convection parameter and solid volume fraction of nanoparticle on the average Nusselt number, total entropy generation and Bejan number. Also isotherms, stream function and entropy generation due to heat transfer are presented for various Rayleigh number and solid volume fraction. The governing equations are solved by using penalty finite element method with Galerkins weighted residual technique. The results reveal that increasing Rayleigh number causes increase of the average Nusselt number as well as the heat transfer term of entropy generation and decrease of the viscous term. The proper choice of Rayleigh number could be able to maximize heat transfer rate simultaneously minimizing entropy generation.

Natural convection and radiation in a radial porous fin with variable thermal conductivity

In this study, the effects of radiation and convection heat transfer in a radial porous fin are considered. The geometry considered is that of a rectangular profile fin. The porous fin allows the flow to infiltrate through it and solid-fluid interaction takes place. This study is performed using Darcy’s model to formulate the heat transfer equation. The thermal conductivity is assumed to be a function of temperature. The effects of the natural convection parameter Nc , radiation parameter Nr and thermal conductivity parameter m on the dimensionless temperature distribution and heat transfer rate are discussed. The results suggest that the radiation transfers more heat than a similar model without radiation

The boundary layer flow of Casson nanofluid over a vertical exponentially stretching cylinder

In this paper, an analysis is carried out for the similarity solution of the steady boundary layer flow and heat transfer of a Casson nanofluid flowing over a vertical cylinder which is stretching exponentially along its radial direction. Using boundary layer approach and suitable similarity transformation the governing partial differential equations with the boundary conditions are reduced to a system of nonlinear ordinary differential equations. The resulting system is solved with the help of numerical technique, the Runge-Kutta Fehlberg method. The effects of important parameters such as Reynolds number, Prandtl number, Lewis number and the natural convection parameter are described through graphs.

Natural Convection Heat Transfer in an Asymmetrically Heated Vertical Channel Controlled by Through Flows.

The effort to solve the fundamental problem of convective flows and heat transfer in a vertical channel is continued in this work, considering a new control parameter for the thermal flow regime. A numerical investigation of the developing heat convection in the channel is presented, while considering the effects of a vertical forced flow on the Nusselt number at the cold wall for a wide range of related parameters. By the analysis of these results, it is possible to predict heat transfer behavior especially in cases when the Nusselt number at the cold wall becomes practically zero. The main results obtained from this study are the critical Reynolds number variation obtained for different geometrical aspect ratios (A=H/L=2 ; 4 ; 8; 16) and the natural convection parameter, Ra=10 4 -10 7 . Based on the scaling analysis it is determined that the critical Reynolds number is independent of Ra and scaled as R ect HT A 2 , where A is the aspect ratio

Characteriation of chaotic dynamics in the spontaneous combustion of coal stockpiles

This paper describes studies of some fundamental aspects of the spontaneous combustion of coal stock-piles by means of a transient, two-dimensional model in the presence of weak natural convection. The model includes mass, energy, and momentum balance equations. the main assumptions made in the model are: planar, two-dimensional symmetry. Boussinesq approximation for density changes in the gas-phase, quasi-steady conditions for momentum balance, and negligible consumption of the solid reactant. Results of numerical simulations are presented and discussed, illustrating the ignition process when achieving stationary combustion, as well as oscillating combustion conditions. The Rayleigh number is changed to study its influence on the dynamic behavior of the system. The use of nonlinear analysis tools allows the characterization of the oscillating behavior found. Such tools are: the calculation of the power spectra density of a sampled time series, and the estimation of the attractor dimension through the Grassberger-Procaccia algorithm. The dynamics of the system become chaotic for a range of values of the Rayleigh number. Further increase of the natural convection parameter leads to more stable periodic, and eventually stationary, long-term behavior.

Heat Transfer to Water in Downward Flow in a Uniform Wall Temperature Vertical Tube at Low Graetz Numbers

This paper presents an experimental investigation of heat transfer to water in vertical tube flow. Results from both Heating in Upflow and Heating in Downflow with the Natural Convection Parameter (Gr Pr D/L)w held constant at a value of 5.5 × 105 are compared with the expression developed by Martinelli and Boelter. The Nusselt numbers for Heating in Downflow were slightly higher but, within experimental error, equivalent to those values obtained for Heating in Upflow. A description of the flowfield is presented for one set of conditions for Heating in Downflow.