Nonlinear flows in nearly incompressible hydrodynamic fluids
Nearly incompressible viscous hydrodynamic fluids are investigated using nonlinear fluid simulations. Nearly incompressible fluids possess acoustic modes through high frequency fluctuations associated with the subsonic fluid Mach number. These modes, in combination with the fluid modes, drive linearly unstable modes and nonlinearly excite flows. The nonlinear flows damp the long wavelengths in our simulations, and are dissipated resonantly when certain nonlinear conditions are satisfied. In agreement with our analytic analysis, the nonlinearly saturated flows in nearly incompressible fluids are generated through the action of the Reynolds stress forces.