Effect of Porous Insert on Heat Transfer in a Backward-Facing Step Flow

2016 ◽  
Author(s):  
Marcelo J. S. de Lemos ◽  
Wagner C. Galuppo
Keyword(s):  
Heat Transfer ◽  
Porous Materials ◽  
Control Volume ◽  
Numerical Technique ◽  
Heated Surface ◽  
Simple Algorithm ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Backward Facing Step ◽  
Porous Insert

We present numerical results for turbulent heat transfer past a backward-facing-step channel with a porous insert. A non-linear eddy viscosity model was applied to handle turbulence. For a constant Darcy number, the thickness of the porous insert was varied in order to analyze its effects on the flow pattern, particularly the damping of the recirculating bubble past the insert. Further, the reduction of the Nusselt number along the bottom heated surface, when using porous materials inside the channel, was investigated. The numerical technique employed for discretizing the governing equations was the control-volume method. The SIMPLE algorithm was used to correct the pressure field and the classical wall function approach was utilized in order to handle flow calculations near the wall. Comparisons of results simulated with different porous materials were presented.

Turbulent Heat Transfer in a Backward-Facing Step Flow Using a Non-Linear k-ε Model

2002 ◽  
Author(s):  
Marcelo Assato ◽  
Marcelo J. S. de Lemos
Keyword(s):  
Heat Transfer ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Backward Facing Step ◽  
Simple Method ◽  
Wall Functions ◽  
Non Linear ◽  
Standard Linear ◽  
Experimental Values ◽  
Better Than

This work presents numerical results for heat transfer in turbulent flow past a backward-facing step. It is shown that nonlinear k-ε models perform better than their linear counterparts when simulations are compared with experimental values. Wall functions are used for simplicity of the simulations. The finite-volume technique is employed for discretizing the transport equation set on a non-orthogonal grid system. The SIMPLE method is used for correcting the pressure field. Results for the reattachment length using the non-linear model are closer to the experimental values when compared with similar calculations using the standard linear closure.

Splattering and Heat Transfer During Impingement of a Turbulent Liquid Jet

1992 ◽  
Vol 114 (2) ◽  
pp. 362-372 ◽  
Author(s):  
J. H. Lienhard ◽  
X. Liu ◽  
L. A. Gabour
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Heated Surface ◽  
Film Surface ◽  
Turbulent Heat Transfer ◽  
Liquid Jet ◽  
Turbulent Heat ◽  
Disturbance Analysis ◽  
Momentum Integral ◽  
Surface Disturbances

Splattering and heat transfer due to impingement of an unsubmerged, fully turbulent liquid jet is investigated experimentally and analytically. Heat transfer measurements were made along a uniformly heated surface onto which a jet impacted, and a Phase Doppler Particle Analyzer was used to measure the size, velocity, and concentration of the droplets splattered after impingement. Splattering is found to occur in proportion to the magnitude of surface disturbances to the incoming jet, and it is observed to occur only within a certain radial range, rather than along the entire film surface. A nondimensional group developed from inviscid capillary disturbance analysis of the circular jet successfully scales the splattering data, yielding predictive results for the onset of splattering and for the mass splattered. A momentum integral analysis incorporating the splattering results is used to formulate a prediction of local Nusselt number. Both the prediction and the experimental data reveal that the Nusselt number is enhanced for radial locations immediately following splattering, but falls below the nonsplattering Nusselt number at larger radii. The turbulent heat transfer enhancement upstream of splattering is also characterized.

Heat Transfer in a Suddenly Expanded Turbulent Flow Past a Porous Insert Using Linear and Non-Linear Eddy-Viscosity Models

2002 ◽  
Author(s):  
Marcelo J. S. de Lemos ◽  
Marcelo Assato
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Eddy Viscosity ◽  
Control Volume ◽  
Numerical Technique ◽  
Turbulence Models ◽  
Wall Functions ◽  
Porous Insert ◽  
Flow Past ◽  
Non Linear

This work presents numerical results for heat transfer in turbulent flow past a backward-facing-step channel with a porous insert using linear and non-linear eddy viscosity macroscopic models. The non-linear turbulence models are known to perform better than classical eddy-diffusivity models due to their ability to simulate important characteristics of the flow. Parameters such as porosity, permeability and thickness of the porous insert are varied in order to analyze their effects on the flow pattern, particularly on the damping of the recirculating bubble after the porous insertion. The numerical technique employed for discretizing the governing equations is the control-volume method. The SIMPLE algorithm is used to correct the pressure field. Wall functions for velocity and temperature are used in order to bypass fine computational close to the wall. Comparisons of results simulated with both linear and non-linear turbulence models are presented.

Heat Transfer and Friction Characteristics Optimization with Compound Turbulators in Roughened Ducts

2009 ◽  
Vol 25 (3) ◽  
pp. 271-278 ◽  
Author(s):  
R. Kamali ◽  
A. R. Binesh
Keyword(s):  
Heat Transfer ◽  
Flow Direction ◽  
Numerical Technique ◽  
Computer Code ◽  
High Ratio ◽  
Turbulent Heat Transfer ◽  
Navier Stokes ◽  
Turbulent Heat ◽  
Turbulent Model ◽  
Design Variables

AbstractThe use of artificial roughness or turbulence promoters on a surface is an effective technique to enhance the rate of heat transfer of the fluid flowing in a duct. In this study, a computer code has been developed to perform a numerical simulation for optimizing the shape of two-dimensional channel with periodic ribs mounted on the bottom wall to enhance turbulent heat transfer. The Reynolds-Averaged Navier-Stokes analysis is used as a numerical technique and the SST k-(ω) turbulent model with near-wall treatment as a turbulent model. The simulations were performed for two rib shapes, trapezoidal with decreasing height in the flow direction with and without grooves between the ribs. The results are validated by comparing with existing experimental data and semi-empirical correlations. The Reynolds number, pitch-to-rib high ratio and relative groove position are chosen as design variables. The effects of roughness parameters on Nusselt number and friction factor have been discussed and the conditions for the best performance have been determined and presented.

Turbulent Heat Transfer Characteristics of a W-Baffled Channel Flow - Heat Transfer Aspect

2020 ◽  
Vol 401 ◽  
pp. 117-130
Author(s):  
Younes Menni ◽  
Ali J. Chamkha ◽  
Oluwole Daniel Makinde
Keyword(s):  
Heat Transfer ◽  
Rectangular Cross Section ◽  
Simple Algorithm ◽  
Industrial Applications ◽  
Turbulent Heat Transfer ◽  
Convection Flow ◽  
Turbulent Heat ◽  
Computational Domain ◽  
Mean Velocity ◽  
Energy Equations

In this work, the thermal behavior of a turbulent forced-convection flow of air in a rectangular cross section channel with attached W-shaped obstacles is investigated. The continuity, momentum and energy equations employed to control the heat and velocity in the computational domain. The turbulence model of k-ε is employed to simulate the turbulence effects. The finite volume method with SIMPLE algorithm is employed as the solution method. The results are reported temperature, local and average Nusselt numbers, and mean velocity contours. The subject is relevant and important for industrial applications.

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