Thermoacoustic Engine 2D: Heat-Driven Standing-Wave Onset

A thermoacoustic engine turns a temperature difference directly into sound — and from there, into electricity or refrigeration — with no pistons, turbines or moving parts at all. This 2D cross-section renders a resonator tube with a stack of plates at an adjustable position, drives it with independent hot- and cold-face temperatures, and computes whether the resulting gradient crosses the critical onset threshold predicted by the Rayleigh–Kramers criterion. Below onset the gas sits still; above it, a standing acoustic wave grows exponentially and saturates onto a stable limit cycle, exactly like a real standing-wave engine "singing" into life. Live readouts track resonance frequency (set by the working gas and tube length), how far the current ΔT sits above or below critical, pressure amplitude and relative acoustic power output, while the working-gas selector and stack-position slider let you explore why engine geometry — not just heat input — determines whether the thing runs at all. Drag to pan and scroll to zoom the tube cross-section.