Release from Pressure Field
Use the Release from Pressure Field feature to create realistic sources extracted from a wave-based (near-field) simulation using the The Pressure Acoustics, Frequency Domain Interface (a sub-model). Here near-field is in relation to the source, meaning that the classical point source approximation of ray tracing is not necessary. Note that setting up classical point sources is covered by the Release from Exterior Field Calculation and the Source with Directivity features. An example, a near-field source could be a loudspeaker placed in a setup (like in the dashboard of a car) that causes local reflections and diffractions. These are wave phenomena that are not captured by the ray tracing method. The Release from Pressure Field is assigned to the radiating boundaries of the pressure acoustics sub-model.
When the Release from Pressure Field is added as a boundary source, rays are released in the direction of the acoustic intensity vector and the ray power distribution is weighted. The intensity vector is taken from the computed pressure acoustics sub-model.
Because this source approach combines wave based and ray tracing methods, some restrictions exist on the use of the Release from Pressure Field. These are:
•
When rays are released using the Release from Pressure Field, they are all released at the same time. Because of this, it should be assumed that the sound emanating from the source reaches and leaves every part of the release boundary at the same time. Hence the release boundary cannot be placed arbitrarily.
•
Because of the restriction mentioned in the previous point, internal reflections in the source domain cannot easily be taken into account. Sound can indeed travel different distances depending on the reflection path taken, which would lead to separate time events at the release boundary and in the impulse response.
•
Finally, the time delay (time of flight from the source to the release boundary) is not included in the impulse response computed in ray tracing. The release time is assumed to be 0 at the release boundary.
Solution Field
Select the Physics interface that defines the full-wave near-field solution. From this list choose the Pressure Acoustics, Frequency Domain interface that is used to solve the acoustic field inside the source region. In the pressure acoustics model the equivalent release boundary should be an open radiation condition.
Release from Pressure Field
Enter the Number of rays per release for the ray acoustics simulation.