Affiliations: Department of Mechanical Engineering, National
University of Singapore, 10 Kent Ridge Crescent, Singapore 119260, Singapore.
E-mail: [email protected]
Abstract: The development of Görtler vortices with pre-set wavelength of 15 mm
has been visualized in the boundary-layer on a concave surface of 2.0 m radius
of curvature at a free-stream velocity of 3.0 m/s. The wavelength of vortices
was pre-set by vertical wires of 0.2 mm diameter located 10 mm upstream of the
concave surface leading edge. The velocity contours in the cross-sectional
planes at several streamwise locations show the growth and breakdown of the
vortices. Three different regions can be identified based on different growth
rate of the vortices. The occurrence of a secondary instability mode is
indicated by the formation of a small horseshoe eddies generated between the
two neighboring vortices traveling streamwise, to form mushroom-like structures
as a consequence of the non-linear growth of the Görtler vortices.