Different from conventional streamwise-aligned riblets, converging and diverging (C–D) riblets are arranged obliquely along the main-flow direction, intending to induce a large-scale secondary flow that modulates or controls existing vortical structures in wall turbulence. In this study, we perform direct numerical simulations of turbulent over C–D at low Reynolds number investigate impacts on ...

The diffraction characteristics of a volume grating (VG) illuminated by a three-dimensional (3-D) converging-diverging Gaussian beam at conical incidence are investigated by applying 3-D finite-beam (FB) rigorous coupled-wave analysis (RCWA) based on the conventional 3-D RCWA in conjunction with two-dimensional plane-wave decomposition. The Gaussian beam is assumed to have an arbitrary incidenc...

Self-similar solutions to converging (implosions) and diverging (explosions) shocks have been studied before, in planar, cylindrical, or spherical symmetry. Here, we offer a unified treatment of these apparently disconnected problems. We study the flow an ideal gas with adiabatic index ? initial density ? ? r ? ?, containing strong shock wave. characterize self-similar entirety parameter space ...