Flow past a Flat Plate-Hemisphere Juncture

These images illustrate the interaction of a flat plate boundary layer with a hemispherical protuberance. The Reynolds number based upon hemisphere radius is Re=600, and the boundary layer thickness is approximately equal to the radius. These results were computed using 512 elements of order 16 (2.1 M points) on the 512-node Intel Delta at Caltech. This flow has also been extensively studied experimentally under similar conditions by Acalar and Smith [ JFM }, 175 , 1987], and for thicker boundary layers by Klebanoff, Cleveland, and Tidstrom [ JFM }, 237 , 1992]. This work is part of the thesis work of Henry Tufo and is supported by NSF under Grant ASC-9405403 and by AFOSR Grant F49620-95-1-0074. Computer time was provided on the Intel Delta and Paragon at Caltech by the Center for Research on Parallel Computation under NSF Cooperative agreement CCR-8809615.

Centerplane contours of spanwise vorticity reveal hairpin vortices in the hemisphere wake.

Contours of spanwise vorticity (centerplane) and streamwise vorticity (foreground) illustrate the structure of the hairpin vortices.

Streamlines show the steady horseshoe vortex formed on the windward side of the hemisphere.

In these two figures the downstream hairpin vortices are identified using the definition of a vortex given by Jeong and Hussain [ JFM }, 285 , 1995] (as iso-surfaces of an eigenvalue of a symmetric tensor derived from the velocity gradient tensor).

Additional hairpin vortex information.

Other spectral element simulations.