Analysis Of Natural Convection Flow Research Articles

Entropy generation analysis of natural convection flow in porous diamond-shaped cavity

This study investigates the entropy generation analysis of natural convection flow within a diamond-shaped cavity filled with porous media. The research focuses on understanding the effects of a chamfered vertex and the introduction of one or two circular cold objects within the cavity. Using COMSOL Multiphysics software, the study examines various Rayleigh (Ra) and Darcy (Da) numbers to analyze the flow dynamics, heat transfer (HT), and entropy generation (Egen). Results indicate that the presence of cold objects significantly influences the flow patterns, enhances HT, and increases Egen due to fluid friction (FF). Higher Ra values lead to more vigorous convective currents, while lower Da values indicate a transition to conduction-dominated regimes. In addition, the heat transfer rate increases by 5 % by introducing a single cold cylinder inside the cavity for Da = 10−2 and Ra = 106. This enhancement rises to 16 % when two cold cylinders are introduced. The study provides valuable insights into optimizing cooling processes within diamond-shaped cavities by identifying key parameters that affect HT and irreversibility.

A comparative study and analysis of natural convection flow of MHD non-Newtonian fluid in the presence of heat source and first-order chemical reaction

Heat and mass transfer of fractional Jeffrey’s flow over infinite vertical plate moving exponentially with variable temperature and mass diffusion has been detailed. Additionally, first-order chemical reaction, magnetohydrodynamics and rate of heat absorption are also considered. The classical Jeffrey’s fluid model is generalized to a fractional model of non-integer-order ‘α.’ The present problem is solved by two approaches, namely, Caputo and Caputo–Fabrizio. The exact solutions for temperatures, concentrations and velocities have been obtained via Laplace transform method. The corresponding rates of heat, mass and skin friction are also computed. We have drawn a comparison approach between the solutions of two fractional models of Jeffrey’s fluid modeled with Caputo and Caputo–Fabrizio fractional derivatives by means of graphical illustration using MathCad software. Physical impact of fractional parameter ‘α’ on the Sherwood number, Nusselt number and skin friction was presented in a table and found that they are increased by increasing the value of ‘α.’ In comparison, the rates of heat and mass transfer and skin friction of Caputo fractional derivative have greater values than Caputo-Fabrizio.

Numerical and experimental analysis of natural convection flow boiling of water in internally heated vertical annulus

Numerical and experimental analysis of natural convection subcooled boiling flow in a high aspect ratio narrow vertical annulus operating at atmospheric pressure is carried out. The computational model is developed using RPI wall boiling model. The annular gap is 3.5 mm and aspect ratio is 352. A new empirical relation for nucleation site density is developed for the present geometrical configuration and implemented in the Fluent code with the help of user-defined function (UDF). The results from the numerical analysis are then compared with the experimental results which show excellent agreement. The wall superheat is found to be maximum at the point of boiling incipience which increases with heat input. The wall temperature shows a gradual decrease in the boiling region. The average heat transfer coefficient increases almost linearly for both subcooled and saturated boiling region.

Analysis of Natural Convection Flow in a Trapezoidal Cavity Containing a Rectangular Heated Body in Presence of External Oriented Magnetic Field

The laminar natural convection flow and heat transfer inside a trapezoidal cavity filled with air and containing a rectangular block is investigated numerically. The left and right walls of the cavity are cold, the top and bottom walls are adiabatic and the rectangular body is heated uniformly. Finite Element Method of Galerkin’s weighted residual scheme is used to solve the transport equations with appropriate boundary conditions. The main objective of this study is to explore the influence of pertinent parameters such as Rayleigh number, Hartmann number and orientation of the magnetic field on the flow and heat transfer performance of the fluid while the Prandtl number is considered fixed. Results indicate that the heat transfer rate is significantly affected by increasing the mentioned parameters.

Natural Convection Flow of Heat Generating/Absorbing Fluid near a Vertical Plate with Ramped Temperature

This study considers a theoretical analysis of natural convection flow of heat generating/absorbing fluid near an infinite vertical plate with ramped temperature. It is assumed that the bounding plate has a ramped temperature profile. Exact solutions of energy and momentum equations are obtained using the Laplace transform techniques. Solutions are obtained for different values of the Prandtl number (Pr) and the heat sink parameter (S). Results of the ramped and isothermal temperature and velocity as well as Nusselt number and skin friction have been compared and presented with the help of graphs.

Finite-difference analysis of natural convection flow of a viscous fluid in a porous channel with constant heat sources

The fully developed natural convection flow of a viscous fluid in a porous channel is modeled and studied numerically. The walls are kept at constant temperatures. The effects of various dimensionless parameters emerging in the model are studied graphically. It has been noted that the velocity and temperature both depend on the heat source and the free convection parameters.

Finite element analysis of natural convection flow in a isosceles triangular enclosure due to uniform and non-uniform heating at the side walls

A penalty finite element analysis with bi-quadratic elements is carried out to investigate the effects of uniform and non-uniform heating of inclined walls on natural convection flows within a isosceles triangular enclosure. Two cases of thermal boundary conditions are considered; case I: two inclined walls are uniformly heated while the bottom wall is cold isothermal and case II: two inclined walls are non-uniformly heated while the bottom wall is cold isothermal. The numerical solution of the problem is presented for various Rayleigh numbers ( Ra), ( 10 3 ⩽ Ra ⩽ 10 6 ) and Prandtl numbers ( Pr), ( 0.026 ⩽ Pr ⩽ 1000 ). It has been found that at small Prandtl numbers, geometry does not have much influence on flow structure while at Pr = 1000 , the stream function contours are nearly triangular showing that geometry has considerable effect on the flow pattern. In addition, the presence of multiple circulations are observed for small Pr ( Pr = 0.026 ) which causes wavy distribution of local Nusselt number. It is observed that non-uniform heating produces greater heat transfer rates at the center of the walls than the uniform heating; however, average Nusselt numbers show overall lower heat transfer rates for the non-uniform heating case. Critical Rayleigh numbers for conduction dominant heat transfer cases have been obtained and for convection dominant regimes, power law correlations between average Nusselt number and Rayleigh numbers are presented for specific Prandtl numbers.

An effective RBFN‐boundary integral approach for the analysis of natural convection flow

AbstractThis paper presents a new radial basis function network‐boundary integral approach for the analysis of natural convection flow. The use of integral equations (IEs) allows the set of simultaneous unknowns to be confined to the boundary only. In this study, all boundary values including geometries are represented by indirect radial basis function networks (IRBFNs), resulting in an effective boundary element method (BEM) especially for the achievement of high Rayleigh numbers with relatively coarse and uniform meshes. Convergence is obtained up to a Rayleigh number of 1.0e7 in the case of a square cavity using a uniform mesh of 31 × 31 and a Rayleigh number of 5.0e4 in the case of a horizontal concentric annulus using a uniform mesh of 11 × 21. Copyright © 2004 John Wiley & Sons, Ltd.

Analysis of Natural Convection Flow of Micropolar Fluid About a Sphere With Blowing and Suction

Analysis of Natural Convection Flow of Micropolar Fluid About a Sphere With Blowing and Suction