Hairpin Vortex Formation a Case Study for Unsteady Visualization

To better understand the vortex dynamics of coherent structures in turbulent and transitional bound ary layers we consider direct numerical simulation of the interaction between a at plate boundary layer ow and an isolated hemispherical roughness element Of principal interest is the evolution of hairpin vortices that form an interlacing pattern in the wake of the hemisphere lift away from the wall and are stretched by the shearing action of the boundary layer Using animations of unsteady three dimensional representations of this ow produced by the vtk toolkit and enhanced to operate in a CAVE virtual environment we identify and study several key features in the evolution of this complex vortex topology not previously observed in other visualization formats