An American Method of Photographing Flow Patterns

FLOW visualization work was started at Notre Dame in 1937. Its initial aim was to improve lecture presentation and at the same time to shorten the lecture time given to flow patterns. By 1940 we had developed a semi‐portable, instant starting, two‐dimension smoke tunnel. It produced flow patterns almost indistinguishable from the calculated ideal patterns when the plate glass sides of the tunnel were moved within thirty‐five thousandths of an inch of one another and when the speed was kept under five feet per second (FIG. 1). This tunnel added nothing to the old Hele‐Shaw technique except that it was more flexible and much easier to use.