Acoustic simulation tools are used to predict sound radiation, absorption and transmission. Acoustic simulations are indispensable for providing insight in the prediction of the acoustic performance of a system. Whether a system is designed to generate acoustic waves (speakers), or the produced noise is subject to (regulated) limits, acoustic simulations can help you to assure that you are on the right track.
ASCEE performs both Finite Element Method (FEM) simulations, as well as Boundary Element Method simulations. Both simulation types have their own advantages and drawbacks. From a utililization point of view, BEM is most often used to simulate acoustic radiation problems. FEM however is more flexible with boundary conditions, acousto-elastic interaction and acoustic simulations which involve flow (typical situation in acoustic silencers).
Besides acoustic FEM in the frequency domain, we use in-house numerical codes for computing high-amplitude acoustic problems and viscothermal acoustic problems. High amplitudes result in nonlinear effects, such as harmonics generation, shock formation and acoustic streaming. Dealing with these effects in simulations requires a nonlinear acoustic code, for which we have both time domain and frequency domain (time spectral) solvers.
Viscothermal acoustics is the field of acoustics where viscous and thermal interaction of the fluid cannot be neglected. This is typically the case in situations where the geometry size is in the order of the viscous and thermal boundary layer thickness. Viscothermal acoustics plays an important role in narrow waveguides, such as present in, for example, hearing aids. Viscothermal acoustic theory is also used to design resonant acoustic absorbers.
For solving viscothermal acoustic problems, the standard acoustic wave equation, or Helmholtz equation in the frequency domain, is not valid. A model is required which takes the viscous dissipation and thermal relaxation dissipation into account. For this, we make use of the the Sequential Linearized Navier Stokes (SLNS) model developed by Kampinga et al.