New Models in the Application Library in Version 5.2a

Gaussian Pulse in 2D Uniform Flow: Convected Wave Equation and Absorbing Layers

This tutorial model illustrates the use of the Convected Wave Equation interface to model the propagation of a transient Gaussian pulse in a 2D uniform flow. The model domain is truncated using the built-in absorbing layers. The results are compared to an analytical solution.

Transfer Impedance of a Perforate

This model determines the acoustic properties of a perforate (a plate with small holes). Specifically, the transfer impedance, surface normal impedance, and absorption coefficients are determined as function of frequency. The transfer impedance is compared to a semi-analytical model.

The holes are located in an xy-matrix with given parameterized x and y distances. When the hole radius is small or the frequency is low, thermal and viscous losses need to be included in the model. This is achieved by using the Thermoviscous Acoustics, Frequency Domain interface.

Ultrasound Flow Meter with Generic Time-of-Flight Configuration

This model illustrates how to simulate a generic wetted transient time-of-flight ultrasound flow meter in COMSOL Multiphysics. Wetted ultrasound flow meters have a dedicated signal tube for the ultrasound signal, and the whole device is therefore mounted into the tubing where the flow is measured. Two signals simultaneously traverse the flow upstream and downstream and use their difference in arrival times to estimate the speed of the main flow.

The model first uses the CFD Module to calculate the steady-state background flow in the flow meter. The Convected Wave Equation, Time Explicit interface is then used to model the ultrasound signal propagating in the device. The interface is well suited for modeling linear ultrasound problems, including many wavelengths, as it is very memory efficient.

This example requires the Acoustics Module and the CFD Module.