The Acoustics Module User’s Guide gets you started with modeling acoustics using COMSOL Multiphysics. The information in this guide is specific to the Acoustics Module. Instructions on how to use COMSOL in general are included with the
COMSOL Multiphysics Reference Manual.
The Pressure Acoustics Interfaces chapter describes the following interfaces:
The Pressure Acoustics, Frequency Domain Interface is the core physics interface that models sound waves in the frequency domain, and
The Pressure Acoustics, Transient Interface is the core physics interface that models sound waves in the time domain with the possibility to include nonlinear effects.
The Pressure Acoustics, Boundary Mode Interface solves for modes that propagate through a cross section of waveguides in a geometry.
The Pressure Acoustics, Boundary Elements Interface uses the boundary element (BEM) method to solve the Helmholtz equation in the frequency domain. It is well suited for radiation and scattering problems and can be seamlessly coupled to structures and the finite element-based
The Pressure Acoustics, Frequency Domain Interface.
The Pressure Acoustics, Time Explicit Interface uses the discontinuous Galerkin (dG-FEM) formulation to solve transient models using a time-explicit method. The interface can solve large problems as the method is very computationally efficient.
The Pressure Acoustics, Asymptotic Scattering Interface and
The Pressure Acoustics, Kirchhoff–Helmholtz Interface are dedicated high-frequency interfaces. The method used is also referred to as high frequency BEM or HFB.
The Elastic Waves Interfaces chapter describes the following interfaces:
The Solid Mechanics (Elastic Waves) Interface is a shortcut to add the Solid Mechanics interface, which is used to compute the displacement field in solids with propagating elastic waves.
The Poroelastic Waves Interface is used to compute the displacement field and acoustic pressure fluctuation in porous materials with propagating poroelastic waves. Isotropic as well as anisotropic material models are supported.
The Elastic Waves, Time Explicit Interface uses the discontinuous Galerkin (dG-FEM) formulation to solve transient linear elastic wave models using a time explicit method. The interface can solve large problems as the method is very computationally efficient.
The Piezoelectric Waves, Time Explicit Interface is a multiphysics interface that couples
The Elastic Waves, Time Explicit Interface and Electrostatics in order to model the propagation of linear piezoelectric waves in the time domain, using a hybrid FEM-DG time-explicit approach. The method is very computationally efficient.
The Acoustic–Structure Interaction Interfaces chapter describes the following interfaces:
The Acoustic–Solid Interaction, Frequency Domain Interface is a combination of pressure acoustics and solid mechanics with predefined couplings and
The Acoustic–Solid Interaction, Transient Interface is a combination of transient pressure acoustics and solid mechanics with predefined couplings.
The Acoustic–Shell Interaction, Frequency Domain Interface and
The Acoustic–Shell Interaction, Transient Interface requires a Structural Mechanics Module license. This multiphysics interface combines the Pressure Acoustics, Frequency Domain (or the Pressure Acoustics, Transient) interface, the Shell interface, and the Acoustic–Structure Boundary multiphysics coupling. The physics interface is available for 2D axisymmetric and 3D geometries.
The Acoustic–Piezoelectric Interaction, Frequency Domain Interface is a combination of Pressure Acoustics, Frequency Domain; solid Mechanics; Electrostatics; Acoustic-structure boundary; Piezoelectric Effect.
The Acoustic–Piezoelectric Interaction, Transient Interface combines Pressure Acoustics, Transient; Solid Mechanics; Electrostatics; Acoustic-structure boundary; Piezoelectric Effect.
The Acoustic–Poroelastic Waves Interaction Interface combines Pressure Acoustics, Frequency Domain and Poroelastic Waves together with the Acoustic–Porous Boundary multiphysics coupling.
The Acoustic–Solid–Poroelastic Waves Interaction Interface combines Pressure Acoustics, Frequency Domain and Solid Mechanics together with the Acoustic–Structure Boundary and Acoustic–Porous Boundary multiphysics coupling.
The Acoustic–Solid Interaction, Time Explicit Interface combines Pressure Acoustics, Time Explicit and Elastic Waves, Time Explicit together with the Acoustic–Structure Boundary, Time Explicit multiphysics coupling.
The Aeroacoustics Interfaces chapter describes the following interfaces for modeling convected acoustic phenomena:
The Linearized Euler, Frequency Domain Interface and
The Linearized Euler, Transient Interface model the acoustic variations in density, velocity, and pressure in the presence of a stationary background mean-flow that is well approximated by an ideal gas flow. These physics interfaces are used for aeroacoustic simulations that can be described by the linearized Euler equations.
The Linearized Navier–Stokes, Frequency Domain Interface and
The Linearized Navier–Stokes, Transient Interface model the acoustic variations in pressure, velocity, and temperature in the presence of any stationary isothermal or nonisothermal background mean flow. These physics interfaces are used for aeroacoustic simulations that can be described by the linearized Navier–Stokes equations.
The Linearized Navier–Stokes, Boundary Mode Interface and
The Linearized Euler, Boundary Mode Interface are used to solve for modes that propagate through a cross section of waveguides in your geometry in the presence of a stationary mean-flow.
The Linearized Potential Flow, Frequency Domain Interface models acoustic waves in potential flow in the frequency domain and
The Linearized Potential Flow, Transient Interface models acoustic waves in potential flow in the time domain.
The Linearized Potential Flow, Boundary Mode Interface solves for modes that propagate through a cross section of your geometry.
The Compressible Potential Flow Interface models irrotational flow used as input for the background flow in the linearized potential flow interfaces.
The Imported Fluid Flow Interface is used to import and map imported CGNS flow data to an acoustics mesh for use in a subsequent aeroacoustic or vibroacoustic problem.
The Thermoviscous Acoustics Interfaces chapter describes
The Thermoviscous Acoustics, Frequency Domain Interface and
The Thermoviscous Acoustics, Transient Interface, which are necessary when modeling acoustics accurately in geometries with small dimensions. Near walls, viscosity and thermal conduction become important because they create a viscous and a thermal boundary layer where losses are significant. Nonlinear effects can be modeled in the time domain.
The Thermoviscous Acoustics, Boundary Mode Interface is used to identify propagating and nonpropagating modes in waveguides and ducts of small dimensions, including thermal and viscous losses.
The Thermoviscous Acoustics, SLNS Approximation Interface also solves the equations in the frequency domain, while using an approximate and computationally lean method valid in most cases.
The Acoustic–Thermoviscous Acoustic Interaction, Frequency Domain Interface combines the Thermoviscous Acoustics, Frequency Domain and Pressure Acoustics, Frequency Domain interfaces together with the Acoustic–Thermoviscous Acoustic Boundary multiphysics coupling.
The Thermoviscous Acoustic–Solid Interaction, Frequency Domain Interface is also described here. This physics interface combines the Thermoviscous Acoustics, Frequency Interface domain and Solid Mechanics Interface together with the Thermoviscous Acoustic–Structure Boundary multiphysics coupling.
The Thermoviscous Acoustic–Shell Interaction, Frequency Domain Interface requires a Structural Mechanics Module license. The multiphysics interface combines the Thermoviscous Acoustics, Frequency domain Interface and the Shell Interface together with the Thermoviscous Acoustic–Structure Boundary multiphysics coupling.
The Thermoviscous Acoustic–Thermoelasticity Interaction Multiphysics Interfaces requires a MEMS Module license. These multiphysics interfaces combine and couple thermoviscous acoustics in the fluid and thermoelasticity in the structures for detailed modeling of damping.
The Ultrasound Interfaces chapter describes the following interfaces:
The Convected Wave Equation, Time Explicit Interface uses the discontinuous Galerkin (dG-FEM) formulation to model the propagating of linear ultrasound waves in the time domain, including the effects of a stationary background flow.
The Nonlinear Pressure Acoustics, Time Explicit Interface uses the discontinuous Galerkin (dG-FEM) formulation to model the propagation of nonlinear high amplitude pressure waves in fluids including dissipation effects.
The Geometrical Acoustics Interfaces includes
The Ray Acoustics Interface, used to compute the trajectories, phase, and intensity of acoustic rays, and
The Acoustic Diffusion Equation Interface, which solves a diffusion equation for the acoustic energy density. The theory is also discussed for both physics interfaces.
The Pipe Acoustics Frequency Domain and Transient Interfaces have the equations and boundary conditions for modeling the propagation of sound waves in flexible pipe systems. The equations are formulated in a general way to include the possibility of a stationary background flow. There are two interfaces, one for transient analysis and one for frequency domain studies.
The Acoustic Streaming chapter described the multiphysics capabilities necessary to model the phenomenon of acoustic streaming, that is, fluid flow induced by sound. Two formulations exist; the full formulation coupling thermoviscous acoustics to fluid flow and the effective formulation coupling pressure acoustics to fluid flow.
The Multiphysics Couplings chapter describes all the multiphysics couplings available with the Acoustics Module. These are the built-in conditions that can couple the physics together; for example, the Acoustic–Structure Boundary couples pressure acoustics to any solid boundary.
The Structural Mechanics with the Acoustics Module chapter provides information about
The Solid Mechanics Interface used for modeling, for example, the structural part of acoustic-structure interaction. This is an extension of the Solid Mechanics interface in COMSOL Multiphysics, and you find it under the
Structural Mechanics branch, or using the shortcut
The Solid Mechanics (Elastic Waves) Interface under the
Elastic Waves branch.
The Piezoelectricity Interface interface is also shortly presented. It combines Solid Mechanics and Electrostatics together with the constitutive relationships required to model piezoelectrics. Both the direct and inverse piezoelectric effects can be modeled and the piezoelectric coupling can be formulated using either the strain-charge or stress-charge forms. This interfaces is based on the finite element method (FEM) and can be used in both frequency and time domain.
