ABSTRACT
Theoretical and experimental studies in thermoacoustics successfully explained the
phenomena with linear inviscid theory at lower oscillation amplitudes. The theory is
inadequate at higher oscillations because of dominant nonlinear and multidimensional
effects. This study is part of a research into the simulation of the nonlinear behavior of fluid
in an acoustic chamber at near incompressible flow. A time-dependent compressible
Navier-Stokes system was solved for a two-dimensional rectangular chamber with a
membrane and a closed end on the other. The generation and progression of the
simulated velocity field observed is significantly complex which include beatings, vortex
motions, and cross-waves, among others. Computations have shown vortex shedding
behavior near the membrane acoustic driver as well as near heat exchanging plates when
they are included for both pure Helium and mixtures. Simulations also showed acoustic
streaming, a secondary flow forced by the acoustic waves. Quantitatively small, the
streaming flow increases steadily with time. The paper reports the simulation results
obtained. These complexities have only been previously reported independently and to
date many open questions still remain on some issues.