Encyclopaedia Index

TITLE : Lid-driven flow in a radiating cavity

BY : Dr S V Zhubrin, CHAM Ltd

DATE : October, 2000

FOR : Demonstration case for V3.3.3.

INTRODUCTION

An IMMERSOL application is presented aimed at the demonstration of the method for the situation when both thermal radiation and convection affect the heat transfer.

THE STATEMENT OF THE PROBLEM

This simulation analyses the flow in a chamber, the floor of which moves with a constant velocity, 1m/s. The stationary walls are adiabatic, the moving wall is at a 300K.

A radiant heater panel is placed at the top of the chamber. It consists of a row of cylindrical electrical heating elements 1 cm in diameter, 150 cm long, spaced at a 3 cm pitch, and backed by a well insulated wall. The panel has dimensions 30x150 cm and is located 30 cm above a workpiece floor, which is also 30x150 cm. The heater elements are rated at 5 kW each. The emittances of the elements and back wall are 0.9 and 0.8, respectively; the workpiece floor is assumed black at 300K. The black side walls are supposed to be made from refractory (adiabatic) bricks.

The task is to calculate the operating temperatures of the heater elements, side wall temperatures from the velocity and temperature fields and radiative heat fluxes distributions.

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
• Velocity components, U1 and V1
• Temperature of the medium, TEM1 and

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 density is taken constant as for air at 20C with no absorption and scattering. The kinematic viscosity depends on the temperature as Sutherland relationship dictates.

THE RESULTS

The plots show the distribution of the velocity vectors, 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.