Experiments on Natural Convection Boundary Layers -The Role of Instabilities

摘要

In this paper, an experimental investigation of the transient behaviour of the flow adjacent to a suddenly heated vertical wall is described. The experiments confirm that the primary deviation from one dimensional to two dimensional flow at a particular location occurs at the time at which the fastest travelling wave arising from the perturbation caused at startup reaches that location. Further, a secondary instability is identified which simultaneously occurs along the full length of the boundary layer and, in some locations along the plate, evidently triggers a deviation ahead of the arrival of the fastest travelling wave.