Encyclopaedia Index

### TITLE : Buoyancy-induced cooling of radiating rod

BY : Dr S V Zhubrin, CHAM Ltd

DATE : October, 2000

FOR : Demonstration case for V3.3.1.

### INTRODUCTION

An IMMERSOL application is presented aimed at the demonstration
of the method for the situation when the thermal radiation is
coupled with natural convection to cool down the heated road.

### THE STATEMENT OF THE PROBLEM

This case deals with the free-convection flow of non-absorbing air
arising in an annular cavity the inner aluminium rod of which is heated
by the total heat flux of 150W. The emittance of the road is 0.5 and
the outer surface of black cylindrical wall is maintained at 20C.

### 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
no absorption and scattering.

### 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 3.3.1.

The relevant Q1 file can be inspected
by clicking here.