A correlation between drag and an integral property of the wake
J. Sci. Math. Res., vol. 1, pp.
T. S. Morton
University of Tennessee Space Institute
An integral quantity is presented that relates the wake of a body in nominally two-dimensional flow to its drag, for Reynolds numbers ranging from 9,000 to 144,000. It is defined as the ratio of the kinetic energy to the vorticity in the fluid boundary and, for the special case of laminar flow, is proportional to the angular momentum in the wake bubble. The new quantity is useful for correlating drag data for cylinders, wedges, v-gutters, and normal flat plates with and without splitter plates. The correlation indicates that the drag force is proportional to the flow speed and the mass flow rate stored in the wake bubble. Order-of-magnitude arguments indicate that, absent any quantization of vortex size, this mass flow rate, and hence the drag force, can become unbounded as the size of the vortices contained in the wake becomes smaller.
Published: 2007-Nov-9 3:37:45
Keywords: bluff-body, drag, wake, correlation, cylinder, flat plate