Simultaneous velocity-surface heat transfer behavior of turbulent spots

The properties of artificially initiated turbulent spots in a heated laminar boundary layer were investigated in a water channel facility. The instantaneous velocity field and surface heat transfer were determined simultaneously over a temporal sequence using a technique that combines traditional particle image velocimetry and thermochromic liquid crystal temperature measurements. The correlated results indicate that the highest surface heat transfer occurs in the trailing region of the spot where only the near-wall fluid is energetic. The results suggest that the body of the spot entrains, and subsequently recirculates, warm surface fluid within the spot, which reduces the effective heat transfer.