- Local heat transfer coefficient distributions are investigated inside and downstream of various cavities on a flat surface. The effect of cavity size, depth, and shape are studied using a transient liquid crystal image method. Liquid crystals are sprayed on the test surface and a hot mainstream is imposed, suddenly causing a color change. The time of color change is obtained using an image processing system. An increase in cavity size for the same depth increases heat transfer coefficients on the test surface. An increase in cavity depth increases downstream heat transfer coefficients. Five cavity shapes are studied to compare local heat transfer behavior for the effect of various shapes. Copyright 1996 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.