Acoustic multipole sources from the Boltzmann equation
Chapter, Conference object, Peer reviewed
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OriginalversjonKorneliussen, Rolf [Eds.] Proceedings of the 36th Scandinavian Symposium on Physical Acoustics, Norsk Fysisk Selskap, 2013
By adding a particle source term in the Boltzmann equation of kinetic theory, it is possible to represent particles appearing and disappearing throughout the fluid with a specified distribution of particle velocities. By deriving the wave equation from this modified Boltz- mann equation via the conservation equations of fluid mechanics, multipole source terms in the wave equation are found. These multipole source terms are given by the particle source term in the Boltzmann equation. To the Euler level in the momentum equation, a monopole and a dipole source term appear in the wave equation. To the Navier-Stokes level, a quadrupole term with negligible magnitude also appears.