THE TURBULENT BOUNDARY-LAYER OVER SINGLE V-SHAPED GROOVES

The photochromic tracer technique was used to study the turbulent boun dary layer over two transverse V-shaped grooves. The mean velocity pro files above the individual grooves were parallel to those seen in the outer regions for smooth surfaces, but displaced downwards. Also, the turbulence intensity just above the grooves was higher than the corres ponding smooth surface values. These results suggest that enhancement of heal and mass transfer rates by transverse grooves is due to energe tic bursts which effectively replace the liquid within the groove, wit h a contribution from an apparent increase in burst frequency.