A concert hall: Acoustic waves simulation
Fluids6 application example
The wave propagation problem in a concert hall is simulated. This is just a simple example of the simulation of wave propagation. A more detailed analysis would require more resolution and more simulation experiments. The simulation is in 3D. The wave images shown here are the intersections of the velocity field by a vertical plane.
The stage is shown the left of the images. Both left and right sides of the shape are closed. On the stage there is a small sound source (the red ball) that generates a short pulse of pressure towards the audience. This is a small hall with total length of 30 meters.
The wave propagates through the hall and rebotes from the walls. Points with high and low acoustic pressure can be identified. An important data can be obtained from the frequency analysis. The Fluids6 program can store and plot the pressure changes in user-defined set of points inside the model volume. The "Pressure increment" plot below shows the pressure changes at a point near to one third of the hall length.
The frequency response analysis shows that the main resonance frequency is equal to 36.7 Hz. Smaller peaks are detected for f=20.22, f=29.55 and f=45.59 Hz. This data is of great importance for the overall shape desigh analysis. The resonance frequencies must be taken into account while setting up the sound equipment of the theater.
In this simulation it is supposed that the wave rebotes from the walls, the floor and the ceiling. Similar experiments can be done with sound-absorbing surfaces.
The last figure shows the 3D flow lines in the whole volume. The lines are calculated starting in randomly selected initial points. As the air movement is the result of multiples reflexions, the lines are quite complicated.
Consult the Fluids6 home page (see links above) for more information about Fluids6 program.