AcousticAnalogies.jl: A Propeller/Rotor Acoustics Code Especially Suitable for Gradient-Based Optimization(LEW-20281-1)

AcousticAnalogies.jl is an implementation of Farassat's "formulation 1A" (F1A), a mathematical technique used to predict the acoustics radiated by a fluid flow. The F1A method, like all acoustic analogies, is a solution to an inhomogeneous wave equation. The wave equation is derived by manipulating the Navier-Stokes equation into a "propagation" left-hand side and a "source" right-hand side. The wave equation is solved using the free-space Green's function, giving an expression with two surface integrals and one volume integral (typically ignored). The integrands of these integrals represent the acoustic sources in the flow, and computing them requires knowledge of the motion of and forces acting on the integration surfaces. These inputs may come from experiment, but more often are taken from the outputs of an aerodynamics code (e.g., one using blade element momentum theory, vortex lattice methods, or computational fluid dynamics).