Numerical simulation of sound pressure for calibration system of LS type measurement microphones

The are presented the results of sound pressure modeling at calibration system of LS type measurement microphones, based on the reciprocity method, using quasi-gas dynamic (QGD) approach at the frequency range from $1$ Hz to $10$ kHz. The numerical method based on QGD equations for a compressible viscous heat-conducting gas is constructed using explicit scheme, the finite difference method for a uniform grid with the approximation of spatial derivatives through central differences, and using the fictious domain method to approximate boundary conditions. A special feature of the computational problem at the studied frequency range is extremely low Mach numbers with the value from $7.3\cdot10^{-10}$ to $7.3\cdot10^{-6}$. The good agreement of the simulation results with the known analytical solution proves the applicability of the QGD approach for gas flow simulations with extremely low Mach numbers and problems of acoustics in particular.