ABSTRACT
Dolapchiev contributed throughout his career to the development and understanding of vortex streets as introduced in 1912 by Theodor von Karman (1881-1963). These vortices appear typically downstream of a cylinder immersed in fluid flow if the Reynolds number of the approach flow is in a certain range. They consist of a number of individual elements arranged in two lines downstream of the disturbing agent of which the streamwise and the transverse spacing was predicted by von Karman as a constant. Dolapchiev in his PhD thesis demonstrated that this law is necessary but not sufficient for such vortices to be generated. He therefore considered the stability of von Karman vortices with a perturbation analysis and was able to present additional information on this important hydraulic feature. Vortex streets are a phenomenon responsible for a number of features in nature. These include the singing of telephone wires due to a certain wind stress, the formation of vortex streets in cloud formations or the collapse of the Tacoma Narrows Bridge WA in 1940. Because vortex streets are periodic, they may generate vibrations to a body. Under particular conditions resonance occurs resulting in the failure of the generating body, such as happened with the bridge mentioned.
