Encyclopaedia Index

### TITLE : Convection affected by radiation

BY : Dr S V Zhubrin, CHAM Ltd

DATE : November, 2000

FOR : Demonstration case for V3.3.3

### INTRODUCTION

An IMMERSOL application is presented aimed at the demonstration
of the method for the radiation-affected buoyancy-induced convection
in a rectangular enclosure with thick conductive walls.

### THE STATEMENT OF THE PROBLEM

This case deals with conjugate heat transfer in the free-convected
flow of participating gas arising in a rectangular cavity the thick
walls of which are made from aluminium with an emmitance of 0.9.

The outer surfaces of the bottom and top walls are supposed to be
well insulated. The temperatures of side walls are different:
one has 300K at the outer surface, another is fixed at 600K.

The task is to compare the velocity and temperature distributions
for the different absorptive and scattering properties of the gas.

### COMPUTATIONAL DETAILS

### Conservation equations

The independent variables of the problem are the two components of
cartesian coordinate system, namely X and Y.

The main dependent (solved for) variables are:

- Pressure, P1
- Two velocity components, U1 and V1
- Temperature of the medium, TEM1 and
- Radiative temperature T3.

### Buoyancy model

The Boussinesq approximation is ised to incorporate the temperature
dependence of the density.

### Model of radiative transfer

The IMMERSOL model is used to simulate the distribution of T3 and TEM1
within the space filled with transparent air. From the temperature fields
the radiant heat fluxes, QRX and QRY, W/m^2, are calculated and used as
the heat sources in iterative manner.

### Properties and auxiliary relations

The gas physical properties are taken constant as for air at 20C with
the constant uniform values of absorption and scattering coefficients
being subject to parametric changes.

### THE RESULTS

The plots show the distribution of velocity, temperature and X-, Y-direction
radiant heat fluxes within the enclosure.

Pictures are as follows :

### THE IMPLEMENTATION

All model settings have been made in VR-Editor of PHOENICS 3.3.3.

The relevant Q1 file can be inspected
by clicking here.