Muffler with Perforates
Reflective mufflers are best suited for the low frequency range where only plane waves can propagate in the system, while dissipative mufflers with fibers are efficient in the mid-to-high frequency range. Dissipative mufflers based on flow losses, on the other hand, work also at low frequencies. A typical automotive exhaust system is a hybrid construction consisting of a combination of ...
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 ...
Transfer Impedance of a Perforate
Perforates are plates with a distribution of small perforations or holes. They are used in muffler systems, sound absorbing panels, and in many other places as liners, where it is important to control attenuation precisely. As the perforations become smaller and smaller, viscous and thermal losses become more important. The attenuation behavior, which is also frequency dependent, can be ...
Flow Duct
The modeling of aircraft-engine noise is a central problem in the field of computational aeroacoustics. The acoustic field in a model of an axially symmetric aero-engine duct, generated by a noise source at the boundary, is computed and visualized. Results are presented for situations with as well as without a compressible irrotational background flow and for the cases of hard and lined duct ...
Sonic Well Logging
This model demonstrates how to simulate a piezoelectric transducer as both a sound transmitter and a receiver in a well logging setup. Other applications of this setup are, for example, in the field of nondestructive testing. A transmitting transducer is connected to an electrical circuit which is set up to send out a pulse as a detecting signal and also pick up the signals that come back to the ...
Acoustics of a Pipe System with 3D Bend and Junction
This tutorial shows how to model the propagation of acoustic waves in large pipe systems by coupling Pipe Acoustics to Pressure Acoustics. The tutorial is set up in both the time domain and the frequency domain. 1D pipe acoustics is used to model the propagation in the long straight pipe portions. A 3D model of a pipe junction and pipe bend is coupled to the 1D pipe model in order to model ...
Spherical Piezoacoustic Transducer
This tutorial provides a step-by-step instruction to setup a fully-coupled 3D structural-acoustic interaction problem. Interaction between a vibrating spherical piezoelectric structure with the surrounding fluid media is considered. The piezoelectric material PZT-5H from the materials library is used. Instructions on how to create a radially polarized piezoelectric material in spherical ...
Noise Radiation by a Compound Gear Train
Predicting the noise radiation from a dynamic system gives designers insight into the behavior of moving mechanisms early in the design process. For example, consider a gearbox in which the change in the gear mesh stiffness causes vibrations. These vibrations are transmitted to the gearbox housing through shafts and joints. The vibrating housing further transmits energy to the surrounding fluid, ...
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 ...
Gaussian Pulse in 2D Uniform Flow: Convected Wave Equation and Absorbing Layers
This tutorial simulates a standard test and benchmark model for nonreflecting conditions and sponge layers for linearized Euler-like systems. It involves the propagation of a transient Gaussian pulse in a 2D uniform flow. The *Convected Wave Equation, Time Explicit* interface solves the linearized Euler equations with an adiabatic equation of state and the interface uses the Absorbing Layers ...
