Behavior of Isolated Disturbances Superimposed on Laminar Flow in a Rectangular Pipe

An investigation was conducted in a horizontal transparent rectangular pipe to study the behavior, in laminar flow, of an isolated turbulent-like disturbance produced by injecting a quantity of dye into the pipe 39 feet from the entrance. As the resulting mass of colored water moved downstream, time-distance measurements were made for the front of the dye mass and for the rear of the disturbance. The experimental setup, which is described in some detail, permitted reasonable control over the mean flow rate from which Reynolds number was calculated. The utilization of the data unfolded a functional relationship among three quantities: The ratio of the velocity of the rear of the disturbance to the velocity of the front of the dye U(R)/U(F); the distance from the origin, X(F); and the Reynolds number R. The similarity of this work to that being done by Lindgren in Stockholm is mentioned.