Abstract
An experimental study has been made to investigate production mechanism of secondary currents generated by spanwise discontinuity of wall roughness. Spanwise discontinuity of roughness, which consists of k-type roughness, is located on the bottom surface of the fully developed two-dimensional channel flow. Mean velocity measurements certainly shows secondary currents accompanied with longitudinal vorticity along boundary between rough and smooth surfaces. The mechanism was studied by means of production terms involved with longitudinal vorticity transport equation; Prandtl's first and second kinds of production mechanisms. The experimental evidences state that non-uniform and non-isotropic Reynolds stress distribution is able to produce the longitudinal vorticity.
