Reset Open Valve Pause load F: 0.30 piston mass: 1.0 T_left init: 2.0 ρ_left init: 4.0 dt (×h): 0.025 μ_mom (mom visc): 0.40 μ_diff (ρ,e diff): 0.40 t = 0.000

Half heat engine (expansion stroke only). A hot dense gas in the left chamber sits behind a closed valve (red bar). The right chamber starts at zero volume — the piston (black bar) is flush against the valve. Click "Open Valve": gas expands through the channel into the right chamber, pushes the piston outward, and the piston does work W = ∫F·v dt against an external load F. The experiment ends when the piston hits the right wall. Diagnostics report: W done on the load, the heat-energy loss Q_lost = U_L(0) − U_L(t) in the left chamber, and the half-engine efficiency η = W/Q_lost. The dissipation D in the channel jet (and elsewhere) sets a hard upper bound on η well below 1. EOS p = γe, γ = 0.1, T = e/ρ.