Flow in curved pipes.

This paper brings together recent information on flow in curved pipes. As to fully developed laminar flow, the appearance of additional vortices for curved pipes of particular cross-sectional forms, existence of dual solutions, and effects of the pitch on the flow in a helically coiled pipe are presented. In the case of developing laminar flow in a curved pipe, fascinating behavior of the separation of the secondary flow boundary layer near the inner wall is shown. Flow in a rotating curved pipe and a periodically curved pipe are also discussed. Different hydrodynamic conditions at the inlet greatly affect the flow in the bend ; a strong swirl is created downstream of two 90° bends in combination according to the combination angles. A brief description of the discharge coefficients for bend flowmeters, and unsteady flow in curved pipes are also given.