Numerical Simulation of Natural Convection in a Square Cavity with Two Partitions and Two Fluids (original) (raw)
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Laminar Natural Convection Study in a Quadrantal Cavity Using Heater on Adjacent Walls
Frontiers in Heat and Mass Transfer, 2013
A numerical analysis of laminar natural convection in a quadrantal cavity filled with water having variable length heaters attached on the adjacent walls have been made to examine heat and fluid flow. Numerical solutions are obtained using a commercial computational fluid dynamics package, FLUENT, using the finite volume method. Effects of the Rayleigh number, Ra, on the Nusselt number, Nu, as well as velocity and temperature fields are investigated for the range of Ra from 10 3 to 10 7 . Computations were carried out for the non-dimensional heater lengths on the vertical wall (m=0.2, 0.4 and 0.6) and horizontal wall (n=0.2, 0.4 and 0.6). It is observed that heat transfer increases with increase in Rayleigh number and the flow strength increases with increase in size of heater on the vertical wall compared to the bottom wall and temperature fields are also affected. In contrast, with increase in size of heater on both side of adjacent walls flow strength does not changes significantly.
In this paper, we analyze the fluid flow and heat transfer characteristics inside a two dimensional quadrantal cavity filled with air. The cavity is heated non-uniformly from the bottom wall and the vertical wall is cooled to a constant temperature while the curved wall is thermally insulated. Finite element method is used to solve the transport equations. The results are illustrated in the form of streamlines, isotherms, local Nusselt number and average Nusselt number. It reveals that the local Nusselt number at the bottom wall follows a sinusoidal variation and moreover at some location, the Nusselt number is negative because of the imposed temperature distribution on the wall. It further reveals that the mechanism of heat transfer is conduction at lower values of Rayleigh number, while heat transfer is due to convection at higher values of Rayleigh number.
In the present study, natural convection problem has been solved in a cavity having three flat walls and the right vertical wall consisting of one undulation and three undulations. The two vertical and bottom walls are cold walls maintained at a fixed temperature whereas the top wall is heated with spatially varying temperature distribution. Air has been taken as the working fluid with Pr =0.71. This problem is solved by SIMPLE algorithm with deferred QUICK scheme in curvilinear coordinates. A wide range of Rayleigh number (10 3 to 10 6) has been chosen for this study. For small Ra, the heat transfer was dominated by conduction across the fluid layers. With increase of Ra, the process began to be dominated by convection. In the presence of undulation the peak point of the heat rejection (negative local Nusselt number) in the right wall increases by 5.54% than left wall for Ra = 10 4. The three undulations case had maximum heat transfer to the uppermost undulation compared to that of the one undulation case.
Simulation of Natural Convection in a Square Cavity with Partially Heated and Cooled Vertical Walls
Proceeding of 5th Thermal and Fluids Engineering Conference (TFEC)
Natural convection driven by temperature differences between partially heated and cooled vertical walls in a square cavity is studied numerically. Steady or unsteady cellular flow structures and temperature patterns are illustrated along with the evolution of heat transfer rates in terms of Nusselt number. The cavity is filled with fluids of various Prandtl number, including .024 (liquid metal), .71 (air), 6 (water), and 450 (silicon oil). The effect of Prandtl and Rayleigh numbers on the flow regime and heat transfer is established along with two different thermal boundary conditions.
International Journal of Heat and Mass Transfer, 2005
Natural convection in two-dimensional enclosure with three flat and one wavy walls is numerically investigated. One wall is having a sinusoidal temperature profile. Other three walls including the wavy wall are maintained at constant cold temperature. This problem is solved by SIMPLE algorithm with deferred QUICK scheme in curvilinear co-ordinates. The tests were carried out for different inclination angles, amplitudes and Rayleigh numbers while the Prandtl number was kept constant. The geometrical configurations considered were namely one, two and three undulations.
Laminar natural convection in an inclined cavity with a wavy wall
International Journal of Heat and Mass Transfer, 2002
In the present work, a numerical study of the effect of a hot wavy wall of a laminar natural convection in an inclined square cavity, differentially heated, was carried out. This problem is solved by using the partial differential equations, which are the vorticity transport, heat transfer and stream function in curvilinear co-ordinates. The tests were performed for different inclination angles, amplitudes and Rayleigh numbers while the Prandtl number was kept constant. Two geometrical configurations were used namely one and three undulations.
Effects of thermal boundary conditions on natural convection flows within a square cavity
International Journal of Heat and Mass Transfer, 2006
A numerical study to investigate the steady laminar natural convection flow in a square cavity with uniformly and non-uniformly heated bottom wall, and adiabatic top wall maintaining constant temperature of cold vertical walls has been performed. A penalty finite element method with bi-quadratic rectangular elements has been used to solve the governing mass, momentum and energy equations. The numerical procedure adopted in the present study yields consistent performance over a wide range of parameters (Rayleigh number Ra, 10 3 6 Ra 6 10 5 and Prandtl number Pr, 0.7 6 Pr 6 10) with respect to continuous and discontinuous Dirichlet boundary conditions. Non-uniform heating of the bottom wall produces greater heat transfer rates at the center of the bottom wall than the uniform heating case for all Rayleigh numbers; 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 dominated regimes, power law correlations between average Nusselt number and Rayleigh numbers are presented.
NATURAL CONVECTION FLOW IN A SQUARE CAVITY WITH TEMPERATURE DEPENDENT HEAT GENERATION
Unsteady natural convection laminar flows in a square cavity formed by insulated bottom and top walls, uniformly heated left wall and the cooled right wall has been investigated numerically. The governing equations are transformed into non-dimensional form and the resulting partial differential equations are solved applying upwind finite difference method together with Successive Over-Relaxation (SOR) scheme. The effect of the heat generation and the Rayleigh number on streamlines and isotherms as well as on the rate of heat transfer from the heated wall of the cavity are presented.
Computers & Fluids, 2007
In this article, we present a two-dimensional study of laminar natural convection in porous enclosure. The horizontal walls of the enclosure are thermally insulated , where as the left and right vertical walls are maintained respectively at different temperatures (warm temperature) and (cold temperature).we present the differential equations modeling the phenomenon studied according to Darcy-Brinkman-Forcheimer model. after the dimensionless form of the equation we have four dimensionless numbers : the Prandtl number the thermal Grashof , the aspect ratio A, the Darcy number .The results allowed us to conclude the following: Increasing of Grachof number with a constant Darcy number, so we areThe increase of convection and as a result the increase in flow velocity and heat transfer.at constant of Grachof number whith decreasing of the Darcy number, the medium is impermeable which slow motion of the convection phenomenon. so we are a degradation speed and heat transfer .Finaly We executed the program calculates with the real data of oil reservoir.
Simulation of Natural Convection in a Cavity: Cooling with Top versus Bottom Partition
Journal of Energy and Power Engineering, 2019
Natural convection in a square cavity is studied numerically with vertical hot walls and a cold partition located at the bottom or top walls. The effect of orientation of partition on isotherms, flow patterns, and heat transfer is analyzed for different fluids and Rayleigh numbers. The placement of partition is found to considerably influence the isotherms, flow patterns, and heat transfer. Heat transfer rate is observed always to increase when the partition is moved from bottom to top wall.