EPJ Plus Highlight - An efficient Lattice-Boltzmann approach for studying compressible flow in nonlinear thermoacoustic engines

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Published on 16 February 2015

Thermoacoustics is the physics of the interaction of thermal and acoustic fields. The nonlinear acoustic effect and low Mach number compressible flow in thermoacoustic engines make the theoretical analysis of such systems extremely complicated. A new study investigates the nonlinear self-excited thermoacoustic onset in a Rijke tube via the lattice Boltzmann method (LBM), which simulates the fluid flow by tracking the evolution of particles and obtains flow stream and heat transfer patterns from the kinetic level. The adopted LBM model, which was developed by the authors, convincingly simulates the Navier-Stokes-Fourier equations, treating accurately the nonlinear process of wave excitation of coupled fields and providing reliable estimates for pressure, density, velocity and temperature in such a finite geometry.

A nonlinear self-excited standing wave in the Rijke tube is observed from simulations. Agreement is obtained with theoretical predictions when they exist. Instantaneous velocity fields and temperature fields are discussed. The maximal Mach number in the Rijke tube is about 0.035, indicating that the air flow under the limit cycle is the low Mach number compressible flow.