With the vortices induced by the two opposite wavy sidewalls,
the near-wall flow structures along the obtuse and acute edges of
present two-pass ribbed channels are considerably modified from
those developed in the similar ribbed channels with flat sidewalls.
In this respect, the additional undulant spaces constructed by present
wavy sidewalls assist the relaxation of near-wall pressure gradients
and reduce the near-wall shear strains around the sectional
corners of the inlet and outlet legs. The degrees of f augmentations
are accordingly moderated from the typical results detected from
the ribbed two-pass channels with flat sidewalls, which will be later
demonstrated. Also referring to the conceptual vortical flow
structures depicted in Fig. 1, the two pairs of perpendicular vortical