Numerical Simulation of Laminar Confined Impinging Jet in a Composite Channel

2008 ◽  
Author(s):  
Marcelo J. S. de Lemos
Keyword(s):  
Porous Layer ◽  
Control Volume ◽  
Numerical Technique ◽  
Simple Algorithm ◽  
Local Distribution ◽  
Governing Equations ◽  
Stagnation Region ◽  
Volume Method ◽  
Material Porosity ◽  
Macroscopic Equations

This work shows numerical results for a jet impinging onto a flat plane covered with a layer of a porous material. Porosity of the porous layer is varied in order to analyze its effect on the local distribution of Nu. Macroscopic equations for mass and momentum ae obtained based on the volume-average concept. The numerical technique employed for discretizing the governing equations was the control volume method with a boundary-fitted non-orthogonal coordinate system. The SIMPLE algorithm was used to handle the pressure-velocity coupling. Results indicate that inclusion of a porous layer decreases the peak in Nu avoiding excessive heating or cooling near the stagnation region.

Turbulent Impinging Jet Into a Rigid Porous Layer

2011 ◽  
Author(s):  
Marcelo J. S. de Lemos
Keyword(s):  
Porous Layer ◽  
Control Volume ◽  
Numerical Technique ◽  
Simple Algorithm ◽  
Stagnation Region ◽  
Thermally Conducting ◽  
Energy Equations ◽  
Volume Method ◽  
Highly Porous ◽  
Macroscopic Equations

This work shows simulations for a turbulent jet impinging against a flat plane covered with a layer of permeable and thermally conducting material. Distinct energy equations are considered for the porous layer attached to the wall and for the fluid that impinges on it. Parameters such as Reynolds number, porosity, permeability, thickness and thermal conductivity of the porous layer are varied in order to analyze their effects on the local distribution of Nu. The macroscopic equations for mass, momentum and energy are obtained based on volume-average concept. The numerical technique employed for discretizing the governing equations was the control volume method with a boundary-fitted non-orthogonal coordinate system. The SIMPLE algorithm was used to handle the pressure-velocity coupling. Results indicate that inclusion of a porous layer eliminates the peak in Nu at the stagnation region. For highly porous and highly permeable material, simulations indicate that the integral heat flux from the wall is enhanced when a thermally conducting porous material is attached to the wall.

Laminar Heat Transfer on a Wall Covered With a Layer of Porous Material Simulated With a Two-Energy Equation Model

2010 ◽  
Author(s):  
Marcelo J. S. de Lemos ◽  
Felipe T. Do´rea
Keyword(s):  
Porous Material ◽  
Control Volume ◽  
Numerical Technique ◽  
Simple Algorithm ◽  
Porous Matrix ◽  
Equation Model ◽  
Energy Model ◽  
Governing Equations ◽  
Volume Method ◽  
Macroscopic Equations

This paper presents simulations for a jet impinging against a flat plane covered with a layer of a porous material. Macroscopic equations for mass, momentum and energy, for the fluid and for the porous matrix, are obtained based on the volume-average concept. The numerical technique employed for discretizing the governing equations was the control volume method with a boundary-fitted non-orthogonal coordinate system. The SIMPLE algorithm was used to handle the pressure-velocity coupling. The effect of porosity and energy model on the local distribution of Nu was analyzed. Results indicate that for low porosity materials, a substantially different Nu number is calculated depending on the energy model applied.

Turbulent Impinging Jet Into a Confined Porous Layer

2005 ◽  
Author(s):  
Marcelo J. S. de Lemos ◽  
Daniel R. Graminho
Keyword(s):  
Porous Layer ◽  
Control Volume ◽  
Numerical Technique ◽  
Flow Distribution ◽  
Simple Algorithm ◽  
Local Heat Transfer ◽  
Impinging Jet ◽  
Local Heat ◽  
Impinging Jets ◽  
Transfer Coefficients

Turbulent impinging jets on heated surfaces are widely used in industry to modify local heat transfer coefficients. The addition of a porous substrate covering the surface contributes to a better flow distribution, which favors many engineering applications. Motivated by this, the present work shows numerical results for a turbulent impinging jet against a cylindrical enclosure with and without a porous layer at the bottom. The macroscopic time-averaged equations for mass, momentum and energy are obtained based on a concept called double decomposition, which considers spatial deviations and temporal fluctuations of flow properties. The numerical technique employed for discretizing the governing equations is the control volume method in conjunction with a boundary-fitted non-orthogonal coordinate system. The SIMPLE algorithm is used to handle the pressure-velocity coupling. The influence of characteristics of the porous layer on the mean and statistical flow fields within the cylinder is presented.

Turbulent Flow and Heat Transfer in a Porous Chamber

2003 ◽  
Author(s):  
Marcelo Assato ◽  
Marcelo J. S. de Lemos
Keyword(s):  
Turbulent Flow ◽  
Control Volume ◽  
Numerical Technique ◽  
Turbulence Models ◽  
Simple Algorithm ◽  
Macroscopic Models ◽  
Flow And Heat Transfer ◽  
Non Linear ◽  
Porosity And Permeability ◽  
Volume Method

This work presents a numerical investigation of turbulent flow past a porous structure in a channel using linear and non-linear eddy viscosity macroscopic models. Parameters such as porosity and permeability of the porous material are varied in order to analyze their effects on the flow pattern, particularly on the damping of the recirculating bubble after the entrance and exit regions. The numerical technique employed for discretizing the governing equations is the control-volume method. The SIMPLE algorithm is used to correct the pressure field. The classical wall function is utilized in order to handle flow calculation near the wall. A discussion on the use of this technique for simulating the flow in question is presented. Comparisons of results simulated with both linear and non-linear turbulence models are shown.

Simulation of Axial Flow in a Bare Rod Bundle Using a Non-Linear Turbulence Model With High and Low Reynolds Approximations

2002 ◽  
Author(s):  
Marcelo J. S. de Lemos ◽  
Marcelo Assato
Keyword(s):  
Control Volume ◽  
Numerical Technique ◽  
Axial Flow ◽  
Simple Algorithm ◽  
Eddy Viscosity Model ◽  
Rod Bundle ◽  
Non Linear ◽  
Fully Developed Turbulent Flow ◽  
Low Reynolds ◽  
Volume Method

This work presents a numerical investigation of fully developed turbulent flow in a triangular sub-channel of a bare rod bundle using a Non-Linear Eddy Viscosity Model (NLEVM). The numerical technique employed for discretizing the governing equations is the control-volume method with a boundary-fitted non-orthogonal coordinate system. The SIMPLE algorithm was used to correct the pressure field. The classical wall function and a low Reynolds model were used in order to handle flow calculations near the wall. In this work, the influence of constants of calibration existing in the non-linear terms of the model is analyzed.

Use of Foam-Like Materials to Enhance Heat Transfer From Surfaces Subjected to Impinging Jets

2009 ◽  
Author(s):  
Marcelo J. S. de Lemos ◽  
Cleges Fischer
Keyword(s):  
Thermal Conductivity ◽  
Porous Layer ◽  
Control Volume ◽  
Simple Algorithm ◽  
Impinging Jets ◽  
Thermal Conductivity Ratio ◽  
Conductivity Ratio ◽  
System Pressure ◽  
Volume Method ◽  
Range Of Values

In this paper, numerical simulation of a jet impinging against a flat plane covered with a layer of a porous material is presented. The plate is kept at a temperature higher than that of the incoming fluid. Macroscopic transport equations are obtained based on a volume average concept. Discretization of such governing equations is accomplished by means of the control volume method applied with a boundary-fitted nonorthogonal coordinate system. Pressure-velocity coupling is treated with the use of the SIMPLE algorithm. Parameters such as permeability, thickness of the porous layer and thermal conductivity ratio are varied in order to analyze their effects on the local distribution of Nu. Results indicate that inclusion of a porous layer decreases the peak in Nu avoiding excessive heating or cooling at the stagnation point. Also found was that the integral heat flux from the wall is enhanced for certain range of values of layer thickness, porosity, and thermal conductivity ratio.

The Structure of Turbulence in a Moving Bed as a Function of Flow and Medium Properties

2014 ◽  
Author(s):  
Marcelo J. S. de Lemos
Keyword(s):  
Reynolds Number ◽  
Turbulent Flows ◽  
Control Volume ◽  
Mechanical Energy ◽  
Simple Algorithm ◽  
Darcy Number ◽  
Control Volume Method ◽  
Governing Equations ◽  
Bed Porosity ◽  
Volume Method

This article presents simulations for turbulent flows in a moving permeable bed making use of a macroscopic turbulence model. Intra-pore turbulence is considered by means of a two-equation closure. Governing equations for mean and turbulent flows are volume-averaged. The resulting set of transport equations is discretized using the control-volume method and the obtained algebraic equation set is relaxed via the SIMPLE algorithm. Results indicate that for larger values of Reynolds number, a greater amount of available mechanical energy is converted into turbulence. Simulations further indicate that for lower values of Darcy number and bed porosity, higher levels of turbulence kinetic energy are calculated.

scholarly journals A Framework and Numerical Solution of the Drying Process in Porous Media by Using a Continuous Model

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Hong Thai Vu ◽  
Evangelos Tsotsas
Keyword(s):  
Porous Media ◽  
Control Volume ◽  
Continuous Model ◽  
Control Volume Method ◽  
Drying Process ◽  
Transport Parameters ◽  
Governing Equations ◽  
Numerical Tools ◽  
Volume Method ◽  
The Continuum

The modelling and numerical simulation of the drying process in porous media are discussed in this work with the objective of presenting the drying problem as the system of governing equations, which is ready to be solved by many of the now widely available control-volume-based numerical tools. By reviewing the connection between the transport equations at the pore level and their up-scaled ones at the continuum level and then by transforming these equations into a format that can be solved by the control volume method, we would like to present an easy-to-use framework for studying the drying process in porous media. In order to take into account the microstructure of porous media in the format of pore-size distribution, the concept of bundle of capillaries is used to derive the needed transport parameters. Some numerical examples are presented to demonstrate the use of the presented formulas.

A Thermo-Mechanical Model for a Counterflow Biomass Gasifier

2014 ◽  
Vol 354 ◽  
pp. 227-235
Author(s):  
Marcelo J.S. de Lemos
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Control Volume ◽  
Simple Algorithm ◽  
Thermal Capacity ◽  
Macroscopic Model ◽  
Algebraic Equations ◽  
Medium Permeability ◽  
Mechanical Approach ◽  
Volume Method

This article presents a thermo-mechanical approach to investigate heat transfer between solid and fluid phases in a model gasifier. A two-temperature equation approach is applied in addition to a macroscopic model for laminar flow through a porous moving bed. Transport equations are discretized using the control-volume method and the system of algebraic equations is relaxed via the SIMPLE algorithm. The effects on inter-phase heat transfer due to variation of medium permeability, thermal conductivity and thermal capacity are analyzed. Results indicate that for smaller medium permeabilities, as well as for higher solid-to-fluid thermal capacity and thermal conductivity ratios, enhancement of heat transfer between phases is observed.

Turbulent Impinging Jets Into Permeable Media

2006 ◽  
Author(s):  
Marcelo J. S. de Lemos ◽  
Daniel R. Graminho
Keyword(s):  
Control Volume ◽  
Numerical Technique ◽  
Flow Distribution ◽  
Simple Algorithm ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Impinging Jets ◽  
Porous Substrate ◽  
Transfer Coefficients ◽  
Permeable Media

Impinging jets are widely used in industry to modify local heat transfer coefficients. The addition of a porous substrate covering the surface contributes to better flow distribution, which favors many engineering applications. Motivated by that, this work shows numerical results for a turbulent jet impinging against a cylindrical enclosure with a porous substrate at the bottom. Macroscopic time-averaged equations for mass and momentum are obtained based on a concept called double decomposition, which considers spatial deviations and temporal fluctuations of flow properties. The numerical technique employed for discretizing the governing equations is the control volume method in conjunction with a boundary-fitted coordinate system. The SIMPLE algorithm is used to handle the pressure-velocity coupling. The influence of the cylinder height on the mean and statistical flow fields within the entire cavity is presented.

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