Port‑Hamiltonian Fluid‑Acoustic Engine Synthesis

Abstract: This document specifies a complete real‑time engine sound synthesiser built on the Port‑Hamiltonian System (PHS) formalism. All gas‑carrying pipes are modelled with the fully nonlinear, compressible Euler equations discretised on a staggered grid, capturing wave steepening, shock formation, and temperature‑dependent speed of sound. Multi‑port junctions, 0‑D thermodynamic cylinders, and an FW‑H acoustic radiator convert flow data into realistic bangs, cracks, and blast wind. The global implicit‑midpoint solver guarantees passivity and unconditional stability. No hybrid approximations are employed; the entire pipe network is solved with true nonlinear dynamics, yielding physically accurate acoustics across all pressure ratios.