Vibrating Micromirror with Viscous and Thermal Damping
Micromirrors are used in certain MEMS devices to control optic elements. This model of a vibrating micromirror surrounded by air uses the Thermoacoustic-Shell Interaction user interface to model the fluid-solid interaction, and it thus includes the correct viscous and thermal damping of the mirror from the surrounding air. The resonance frequency of the mirror when under a torquing load is ...
The Brüel & Kjær 4134 Condenser Microphone
This is a model of the Brüel and Kjær 4134 condenser microphone. The geometry and material parameters are those of the actual microphone. The modeled sensitivity level is compared to measurements performed on an actual microphone and shows good agreement. The membrane deformation, pressure, velocity, and electric field are also determined. The model is a true multiphysics problem that ...
Helmholtz Resonator Analyzed with Different Frequency Domain Solvers
This model simulates a simple three-dimensional axisymmetric Helmholtz resonator, a classic acoustics model of a resonating circuit with a known theoretical solution. The idealized version considered here consists of a tube and a closed volume in series which are exposed to a pulsatile pressure. Real-world phenomena explained by the resonator include amongst others the resonance from blowing ...
Ultrasound Flow Meter with Generic Time-of-Flight Configuration
Knowing the velocity of a moving fluid is important in all cases where the fluid is used to transport material or energy. In the time-of-flight or transit-time method for determining flow velocity, an ultrasonic signal is transmitted across the main flow in a pipe to noninvasively determine its velocity. By transmitting the signal at an angle relative to the main flow, the ultrasound signal will ...
Acoustic Streaming in a Microchannel Cross Section
Recent advances in the fabrication of microfluidic systems require handling of live cells and other micro particles as well as mixing. All this can, for example, be achieved using acoustic radiation forces and the viscous drag from the streaming flow. Streaming: Due to the nonlinear terms in the Navier-Stokes equations, harmonic perturbation of the flow will lead to a net time-averaged flow ...
Acoustic-Structure Interaction with a Perfectly Matched Layer (PML)
This small tutorial model shows how to set up a model with a solid mechanics and a pressure acoustics domain including a common perfectly matched layer (PML). The PML is used to model an open or infinite domain for both the elastic waves and the pressure waves. Two configurations of PMLs exist (this model describes the first case which is also the most difficult to handle): 1. One PML should ...
Small Concert Hall Acoustics
Designing structures and open spaces with respect to sound quality is important for concert halls, outdoor environments, and even the rooms of a house. Simulating acoustics in the high-frequency limit, where the wavelength is smaller than the geometrical features, can be done with ray acoustics. There are several advantages to modeling ray acoustics, including changing media properties and ...
Acoustic Reflections off a Water-Sediment Interface
This model determines the reflection coefficient of plane acoustic waves, at different frequencies and at different angles of incidence, off a water-sediment interface. The ability of the Poroelasitc Waves interface to model the coupled acoustic and elastic wave in any porous substance (Biot's theory) is used to describe the water-sediment system. The model results are in good agreement with ...
Optimizing the Shape of a Horn
A plane-wave mode feeds an axisymmetric horn radiating from an infinite baffle towards an open half space. The radius of the feeding waveguide is assumed to be fixed, as well as the depth of the horn and the size of the hole where the horn is attached to the baffle. By varying the curvature of the initially conical surface of the horn, its directivity and impedance can be changed. This model ...
Sedan Interior Acoustics
This is a model of the acoustics inside a sedan, that is inside a typical hard-top family car. The model sets up sources at loudspeaker locations as well as impedance conditions to model soft absorbing surfaces (seats and carpet). The model results in plots of the pressure, sound pressure level, and intensity inside the car. The frequency response at given points inside the cabin are also ...
