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.


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.


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.


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:

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

Pictures are as follows :


All model settings have been made in VR-Editor of PHOENICS 3.3.1.

The relevant Q1 file can be inspected by clicking here.