The spatial growth of small perturbations developing on a fully developed base flow in a duct with two inhomogeneous cross-flow directions is examined. For a laminar mean flow it is shown that optimally configured vortices at an upstream cross-section induce large transient amplification of a disturbance energy norm downstream. Such a linear growth is a likely initial stage of transition in duc...

The rotating-flow boundary layer is a special case of the more general threedimensional boundary layer in which the pressure gradient imposed by the outer flow (above the boundary layer) is not in the same direction as the outer flow. The rotating-flow boundary layer thus has motion that is transverse to the streamlines of the outer flow, that is, there is a secondary circulation to the primary...

channel flows have three components of velocity, 1component in flow direction and 2components in spanwise of channel. because of heterogeneity of velocity undulations, in the channel section the vortices are formed that are nominated “secondary current cells”. these cells cause the lateral shear stress in the channel walls and introduce the erosion and scour of the channel walls. heterogeneity ...

This paper will outline a steady flow control technique that augments the diffusion process within a stator passage via a continuous co-flowing secondary flow stream along the suction surface. The technique is similar to that used for flow vectoring in nozzles where a secondary flow stream is used to enhance the diffusion and vectoring of high speed jets. Diffusion factors in excess of 0.95 are...