Abstract
This paper brings together recent information on flow development in curved pipes. In the case of curved pipes of circular cross section, the important flow properties are a crossover between shear maxima on the inside and outside of the pipe, a boundary-layer collision, subsequent formation of a separation bubble on the inside wall of the pipe, etc. In the case of curved pipes of square cross section, an additional pair of counter-rotating vortices is found to develop in the inlet region within a definite range of the Dean number.
Attention may specially be called to the occurrence of dual solutions of the Navier-Stokes equations for flow in curved pipes of circular and semi-circular cross sections, where a two-vortex solution bifurcate into a two-and four-vortex solution above some definite Dean number.
