EFFECT OF LOW REYNOLDS NUMBER MIXED CONVECTION ON CHANNEL FLOWS STRUCTURE

The effect of wall heating on low Reynolds numbers channel flow has been investigated experimentally. The experiments were conducted at heated bottom wall temperatures from 30 degrees C to 50 degrees C for two flow rates 0.0210 and 0.0525 kg/s,. corresponding to the Reynolds number range of 150 and 750 (in the absence of heating). The results showed that the initially laminar flow became turbulent due to wall heating, and that wall heating has a significant influence on both the mean and turbulent velocity fields. The mean velocity profiles were altered by the convective currents. The magnitude of mean streamwise velocity near the heated wall increased with an increase in the wall temperature. A back flow near the upper channel wall was also observed primarily at the lower flow rate which diminished for the high flow rate. The magnitude of backflow increased with an increase in the wall temperature. The turbulent intensities were found to increase with an increase in the wall temperature for both flow rates. The result also showed the presence of strong vortices originating from the heated wall and advecting towards the central core of the channel.