Tutorial: Pulsating Sphere (gui)

We are going to use the supplied Java™ GUI to run AcouSTO for a classical case in acoustics: the radiation problem of a pulsating sphere for which we have an analytical solution.
Let's assume to have a unit radius kphere immersed in standard air that is pulsating with a radial velocity of unit amplitude. Microphones are places on the x axis.



The Java™ GUI can be started with the command:
We summarize here the most important parameters reported in the figure:



Since we declared 20 microphones, in the acousto.mics.mesh we have to declare the location (x,y and z) of the 20 microphones at which the solution will be evaluated, as follows:




We can now run AcouSTO with the parameters we configured above. We can start AcouSTO directly from the GUI by selecting the "Execute" tab and inserting the required parameters in the input boxes:

• The Run path is the directorty in which AcouSTO will run
• The Cfg file can be left blank
• in mpirun args we will insert the parameters to be given to the mpirun executable. We chose to have 2 process rows and 2 columns, thus we will run the program on four processes. Let's assume we want to run the process on the four nodes: node1, node2, node3, node4 of our cluster, we have to supply to mpirun the following parameters:
  mpirun -np 4 -host node1,node2,node3,node4 /usr/local/bin/acousto -f pulsatingsphere.cfg
• The run from gui checkbox must be selected

We can now click on the Run button and on the left side of the bottom panel the output from AcouSTO will be shown while on the right side we will see the plot of the Scattering Pressure at each frequency.



AcouSTO writes the output files only on the master node. The output is given in two different files, one for the microphones and one for the body, in terms of Pressure (Scattering and Total), Potential at the microphones and Potential at the body. The Pressure and Potential at the microphones are in a file named:

<run title>-mics-<freq in Hz>.out

Thus in this case, for the only frequency present, the file will be AcouSTO run-mics-99.0000Hz.out.
The file has 16 columns with the following values:

1. Microphone index
2. Microphone x
3. Microphone y
4. Microphone z
5. Solution (real part)
6. Solution (imaginary part)
7. Solution (absolute value)
8. Incident Potential (real part)
9. Incident Potential (imaginary part)
10. Incident Potential (absolute value)
11. Total pressure (real part)
12. Total pressure (imaginary part)
13. Total pressure (absolute value)
14. Scattering pressure (real part)
15. Scattering pressure (imaginary part)
16. Scattering pressure (absolute value)

The Potential at the surface is in the file:

<run title>-surf-<freq in Hz>.out

that has 10 columns with:

1. Panel index
2. Panel Control point x
3. Panel Control point y
4. Panel Control point z
5. Solution (real part)
6. Solution (imaginary part)
7. Solution (absolute value)
8. Incident Potential (real part)
9. Incident Potential (imaginary part)
10. Incident Potential (absolute value)