LES on vortex shedding from a rectangular cylinder with a section of various width/height ratios (relations between SGS dissipation and GS enstrophy)

Vortex shedding from a rectangular cylinder of which section has various width and height was studied numerically by using Large Eddy Simulation (LES) with Smagorinsky model. Simulations were performed for cases where width/height ratios are 1.0, 1.5, 2.0, 2.3, 2.5, 2.8, 3.0, 3.5 and 4.0. We focused on details of vortex shedding at the ratios of 2.3, 3.5 and 4.0 by visualization. As a conclusion, we considered the relations between Subgrid-Scale (SGS) dissipation and Grid-Scale (GS) enstrophy at each the ratio. They are correlated in various flow patterns for all the cases. Values of SGS dissipation in developing vortices are lower than values of SGS dissipation in the separated shear layers. On the other hand at a large ratio (3.5), the vortex coupling is occurred at the rear corner of the cylinder and the value of SGS dissipation of this case is 6.2 times higher than the value before coupling because of distortion of vortex.