Natural Convection Heat Transfer from a Horizontal Surface. (Effect of the Size of a Rectangular Obstacle above the Heated Surface).

The effects of the width of a rectangular obstacle above an upward-facing horizontal surface on the natural convection were investigated both numerically and experimentally. The horizontal surface was heated at a uniform temperature with a strip heat source, while the downward-facing surface of the obstacle was kept in either adiabatic or uniform temperature condition. The width of the obstacle was varied in the range of one to four times the width of the strip heat source. From the result, the typical flow patterns were presented in detail, and they were discussed in connection with the heat transfer characteristics. In particular, the region where the heat transfer rate is small in the heated surface becomes widened with increasing of the width of the obstacle for the case of adiabatic condition when the distance between the heated surface and the downward-facing surface of the obstacle is small, while the heat transfer rate is insensitive to the width of the obstacle for the case of uniform temperature condition.