La Galleria delle Applicazioni raccoglie un'ampia varietà di tutorial e di app dimostrative realizzati con COMSOL Multiphysics in diversi ambiti applicativi, inclusi quelli elettrico, meccanico, fluidico e chimico. E' possibile scaricare i file dei modelli e delle app demo pronti all'uso e le istruzioni step-by-step per costruirli, e utilizzarli come punto di partenza per le proprie simulazioni.

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Acoustic Cloaking

Two articles in the New Journal of Physics describe how to derive necessary conditions on an anisotropic density tensor to create a perfect acoustic cloak in 2D, and show how this material can be realized in practice as a layered shell with isotropic properties in each layer. These two example files illustrate simplest possible implementations using both anisotropic density and the layered ...

Ultrasonic Flow Meter with Piezoelectric Transducers: Coupling between FEM and DG

Ultrasonic flow meters determine the velocity of a fluid flowing through a pipe by sending an ultrasonic signal across the flow at a skew angle. When there is no flow, the transmitting time between the transmitter and the receiver is the same for the signals sent in the upstream and downstream directions. Otherwise, the wave traveling downstream moves faster than the one traveling upstream, ...

Lumped Loudspeaker Driver

This is a model of a moving-coil loudspeaker where a lumped parameter analogy represents the behavior of the electrical and mechanical speaker components. The Thiele-Small parameters (small-signal parameters) serve as input to the lumped model, which is represented by an Electric Circuit physics. The lumped model is coupled to a 2D axisymmetric Pressure Acoustics model describing the ...

Nonlinear Acoustics — Modeling of the 1D Westervelt Equation

This model example shows how to model nonlinear propagation of 1D finite-amplitude Acoustic waves in fluids using Acoustics Module of COMSOL Multiphysics. The model is based on the 2nd order Westervelt equation. The one dimensional nonlinear wave equation is solved in the time domain by adding the nonlinear term to the linear equation. The model does not include energy dissipation in order to ...

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 the *Pipe Acoustics* interface to the *Pressure Acoustics* interface. 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 ...

Multilayered Porous Material: Poroelastic Waves with Thermal and Viscous Losses (Biot-Allard Model)

In applications where pressure and elastic waves propagate in porous materials filled with air, both thermal and viscous losses are important. This is typically the case in insulation materials for rooms, lining materials in car cabins, or foams used in headsets and speakers. Another example is porous material in mufflers in the automotive industry. In many cases, these materials can be modeled ...

Shape Optimization of a Tweeter Waveguide

This application illustrates how to use COMSOL’s optimization capabilities to automatically develop novel designs satisfying critical design constraints. The model optimizes a simple speaker geometry. Examples of constraints could include the radius of the loudspeaker or a desired minimum achievable sound-pressure level. To exemplify the optimization capabilities this application studies the ...

Underwater Ray Tracing Tutorial in a 2D Axisymmetric Geometry

When computing ray intensity in 2D axisymmetric models, the wavefront associated with the propagating ray is treated as a spherical or ellipsoidal wave, instead of a cylindrical wave. This tutorial example illustrates how to set up several important features using the *Ray Acoustics* interface. It illustrates the intensity and phase calculation in graded media (speed of sound profile) including ...

Piezoelectric Tonpilz Transducer with a Prestressed Bolt

A tonpilz transducer is used for relatively low frequency, high power sound emission. It is one of the popular transducer configurations for SONAR applications. The transducer consists of piezoceramic rings stacked between a head mass and a tail mass which are connected by a central bolt. This example shows how to incorporate the effect of a pre-tension in the bolt. The bolt geometry is ...

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 ...