Flow in a pipe of rectangular cross-section

The object of the research was to investigate the flow of water in a pipe of rectangular cross-section. Much work has been done on similar problems with pipes of circular section, and pipes of rectangular section have been investigated by Fromm and Davies and White. Fromm avoided with pipes in which the ratio of the sides was never less than 6 to 1; his report deals only with turbulent flow. In the case of Davies and White's research, the minimum ratio of the sides was 40 to 1, so that the laminar flow could be calculated from the formula for flow between infinitely wide parallel plates. The present writer used a pipe of section 1·178 cms. by 0·404 cms, (ratio of sides = 2·92); this presents a fresh problem were stream line flow is concerned, and shows interesting results in the region of the critical velocity.