Documentation regarding the SPPS code: Random vs. Energetic

[jonaskarlberg]

Hi @Picaut and @nicolas-f !

I noticed that there seem to be a mixup between the Random and Energetic approach in the documentation.

As far as I understand, by reading the published work regarding the SPPS code, this formulation is correct: https://i-simpa-wiki.readthedocs.io/fr/latest/code_SPPS_principle.html

"Random Modeling: In this mode, the energy of the particle is constant. The phenomena of absorption and atmospheric absorption are considered statistically: depending on the values ​​of the atmospheric absorption and the absorption coefficients of the materials, the particles can be made to disappear completely from the propagation domain, or to remain in the domain with the same energy. The other physical phenomena (diffusion by a congestion, diffuse reflection) are also treated statistically. As the number of sound particles decreases over time, the calculation time decreases gradually. Moreover, the density of sound energy at a point of the domain is then proportional to the number of sound particles at the same point.

Energetic modeling: In this mode, the energy of the particle is weighted according to the values ​​of the atmospheric absorption and the absorption coefficients of the materials. The other physical phenomena (diffusion by congestion, diffuse reflection) are also treated randomly. Since in this mode, the number of sound particles is constant, the duration of the numerical simulations is longer than for the first mode. Moreover, the sound energy density at a point of the domain is then proportional to the sum of the energy of the sound particles at this same point."

These pages seem to state the opposite:
https://i-simpa-wiki.readthedocs.io/fr/latest/code_SPPS.html
https://i-simpa.univ-gustave-eiffel.fr/presentation/embedded-codes/spps/

"The first approach (Energetic) is to consider that the energy of the particle is constant. In function of the phenomena, the particle may disappear from the domain or follows its propagation: the number of sound particles decreases along the time.
In the second approach (Random), the particle energy is varying according to the physical phenomena occurring during the propagation. In this case, the number of particles in the domain should be constant along the time."

Please let me know if I have misunderstood something.

Best,
Jonas