Resonant gas oscillation in a tube of square cross section

Nonlinear resonant gas oscillations in a tube of square cross section are studied by solving the full system of Navier-Stokes equations for three-dimensional compressible gas flows with a finite-difference method. The nonlinear gas oscillations with and without shock waves and resulting time-averaged transport phenomena of mass, momentum and energy are investigated in the tube of square cross section. In particular, we find that there exist streamlines of acoustic streaming visiting both the inside and outside of boundary layer, which means that the mass, momentum and energy transports are confined neither in the inside nor in the outside of boundary layer on the tube wall, contrary to two-dimensional flows.