scholarly journals Free Convection in a MHD Open Cavity with a Linearly Heated Wall Using LBM

2020 ◽  
Author(s):  
Raoudha Chaabane
Keyword(s):  
Free Convection ◽  
Open Cavity ◽  
Heated Wall

Experimental Analysis of Opposing Flow in Mixed Convection in a Channel With an Open Cavity Below

2005 ◽  
Author(s):  
Oronzio Manca ◽  
Sergio Nardini ◽  
Kambiz Vafai
Keyword(s):  
Reynolds Number ◽  
Mixed Convection ◽  
Flow Visualization ◽  
Vortex Structure ◽  
Open Cavity ◽  
Forced Flow ◽  
Heated Wall ◽  
Heated Plate ◽  
Thermal Plume ◽  
Recirculation Flow

In this paper mixed convection in an open cavity with a heated wall bounded by a horizontal unheated plate is investigated experimentally. The cavity has the heated wall on the opposite side of the forced inflow. The results are reported in terms of wall temperature profiles of the heated wall and flow visualization for Reynolds number (Re) from 100 to 2000 and Richardson number (Ri) in the range 4.3–6400; the ratio between the length and the height of cavity (L/D) is in the range 0.5–2.0 and the ratio between the channel and cavity height (H/D) is equal to 1.0. The present results show that at the lowest investigated Reynolds number the surface temperatures are lower than the corresponding surface temperature for Re = 2000, at same the ohmic heat flux. The flow visualization points out that for Re = 1000 there are two nearly distinct fluid motions: a parallel forced flow in the channel and a recirculation flow inside the cavity. For Re = 100 the effect of a stronger buoyancy determines a penetration of thermal plume from the heated plate wall into the upper channel. Moreover, the flow visualization points out that for lower Reynolds numbers the forced motion penetrates inside the cavity and a vortex structure is adjacent to the unheated vertical plate. At higher Reynolds number the vortex structure has a larger extension at same L/D value.

Numerical Study on Mixed Convection in Porous Media in a Channel With an Open Cavity Below

2010 ◽  
Author(s):  
Bernardo Buonomo ◽  
Oronzio Manca ◽  
Paolo Mesolella ◽  
Sergio Nardini
Keyword(s):  
Mixed Convection ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Vertical Wall ◽  
Open Cavity ◽  
Temperature Fields ◽  
Forced Flow ◽  
Heated Wall ◽  
Local Thermal Equilibrium ◽  
Uniform Heat Flux

A numerical analysis of mixed convection in gas saturated metal foam in a horizontal channel with an open cavity heated at uniform heat flux on a vertical wall is studied numerically. Non-local thermal equilibrium and Brinkman-Forchheimer-extended Darcy model are assumed. Boussinesq approximation with constant thermophysical proprieties are considered. Results are carried out for an aluminium foam with 10 PPI and ε = 0.909, the fluid is air and for the assisting case. Results, for different Peclet and Rayleigh numbers, are given in terms of solid and fluid wall temperatures and local Nusselt numbers and stream function and temperature fields. Results show that diffusive effect determined lower temperature values inside the solid and the fluid temperatures are higher in all considered cases. The interaction between the forced flow in the channel and the buoyancy due to the heated wall determines different thermal and fluid dynamic behaviors.

Oberbeck-Boussinesq approximations and geometrical confinement effects of free convection in open cavity

2019 ◽  
Vol 55 (8) ◽  
pp. 2095-2102
Author(s):  
Rajesh Choudhary ◽  
Adarsh Saini ◽  
Sudhakar Subudhi
Keyword(s):  
Free Convection ◽  
Open Cavity ◽  
Confinement Effects

An Experimental Study on the Effect of Partition Angle on Free Convection Heat Transfer in a Partition Cavity by Laser Interferometry Method

2010 ◽  
Author(s):  
Tooraj Yousefi ◽  
Sajjad Mahmoodi Nezhad ◽  
Masood Bigharaz ◽  
Saeed Ebrahimi
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Rayleigh Number ◽  
Free Convection ◽  
Average Nusselt Number ◽  
Convection Heat Transfer ◽  
Laser Interferometry ◽  
Heated Wall ◽  
Convection Heat ◽  
Free Convection Heat

Steady state two-dimensional free convection heat transfer in a partitioned cavity with adiabatic horizontal and isothermally vertical walls and an adiabatic partition has been investigated experimentally. The experiments have been carried out using a Mach-Zehnder interferometer. The effects of the angel of the adiabatic partition and Rayleigh number on the heat transfer from the heated wall are investigated. Experiments are performed for the values of Rayleigh number based on the cavity side length in the range between 1.5×105 to 4.5×105 and various angle of the partition with respect to horizon from 0° to 90°. The results indicate that at each angle of the adiabatic partition, by increasing the Rayleigh number, the average Nusselt number and heat transfer increase and at each Rayleigh number, the maximum and the minimum heat transfer occur at θ=45° and θ=90°, respectively. A correlation based on the experimental data for the average Nusselt number of the heated wall as a function of Rayleigh number and the angel of the adiabatic partition is presented in the aforementioned ranges.

Similarity Solution of Free Convection in a Stratified Porous Medium With Variable Permeability

2005 ◽  
Author(s):  
A. Kalantarian ◽  
M. Khodabakhsh ◽  
M. H. Saidi
Keyword(s):  
Porous Medium ◽  
Free Convection ◽  
Inclination Angle ◽  
Similarity Solution ◽  
Energy Equation ◽  
Heated Wall ◽  
Velocity Boundary Layer ◽  
Variable Permeability ◽  
Variation Function ◽  
Variable Energy

In this paper, similarity solution of free convection from inclined permeable wall embedded in a stratified porous medium is investigated. It is assumed that the heated wall has constant temperature and permeability along the wall is variable. Energy equation and Darcy’s law as momentum have been used. Due to similarity solution we consider only large wall inclination angle. Effects of mass flux, permeability variation function, and wall inclination angle on thermal and velocity boundary layer thickness and heat transfer at the wall are investigated.

Secondary Flow Effects in High Tip Speed Free Convection

1987 ◽  
Vol 109 (1) ◽  
pp. 97-103 ◽  
Author(s):  
P. W. Eckels ◽  
J. H. Parker ◽  
A. Patterson
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
High Speed ◽  
Single Phase ◽  
Flow Boiling ◽  
Heat Fluxes ◽  
Secondary Flows ◽  
Heated Wall ◽  
Rotating Frame ◽  
Two Phase

Experimental analyses of the effects of secondary flows on heat transfer in high tip speed rotating apparatus are not readily available. This paper provides data on the heat transfer within two different test modules which were rotated at high speed with the heat transfer surfaces perpendicular and parallel to the Coriolis acceleration. One module contained a heated wall and another a parallel plate free convection experiment. Uniform heat fluxes were maintained. Rayleigh numbers in excess of 1015 were achieved with liquid helium as the transfer medium. Some of the findings are that secondary flows can reduce heat transfer by as much as 60 percent in single-phase heat transfer, the transitions to fully turbulent flow are in agreement with existing prediction methods, the critical heat flux in two-phase flow boiling is significantly increased, forced convection correlations underpredict single-phase thermosyphon performance, and the usual nondimensional parameters of free convection establish similitude between various fluids and speeds. These results suggest that techniques used to enhance heat transfer in the rotating frame should be verified by tests in the rotating frame.

Natural Convection Through an Open Cavity Heated From the Side and Filled With Fluid and Discrete Solid Blocks

2013 ◽  
Author(s):  
A. T. Franco ◽  
L. T. Loyola ◽  
F. C. De Lai ◽  
S. L. M. Junqueira ◽  
M. M. Ganzarolli ◽  
...  
Keyword(s):  
Nusselt Number ◽  
Natural Convection ◽  
Flow Rate ◽  
Volume Ratio ◽  
Volumetric Flow Rate ◽  
Open Cavity ◽  
Heated Wall ◽  
Left Wall ◽  
The Right ◽  
Fluid Reservoir

In this study, natural convection inside a square open cavity containing several solid obstructions is modeled and numerically simulated. The horizontal surfaces of the cavity are adiabatic, while the vertical left wall is isothermally heated. The cavity, opened on the right side to a fluid reservoir, is filled with equally spaced, disconnected, square conducting blocks. The total amount of solid constituent within the enclosure is kept constant by fixing the cavity solid volume-ratio at 36% (equivalent to porosity equal to 64%). The effects of varying the number of solid blocks used and the Rayleigh number on the Nusselt number (based on the surface-averaged heat transfer coefficient along the heated wall of the enclosure) and on the volumetric flow rate entering the cavity induced by the natural convection are considered in detail. The results show the Nusselt number to be affected by the phenomenon of interference caused by the blocks, which increases in predominance as Ra increases. The volumetric flow rate, on the other hand, shows less of an effect by the interference of the blocks to the boundary layer, and more the flow hindrance effect of the blocks within the entire cavity. This effect is shown, nevertheless, to predominate when Ra is small — similarly to the interference effect.

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