Modeling of Acoustic Wave Propagation in a Planar Waveguide With Bends

The study investigates the propagation of sound waves in a planar acoustic waveguide containing two bends. A mathematical model of the problemwas developed, allowing for the analysis of wave transmission through the geometric inhomogeneity of the waveguide depending on its geometric andphysical parameters. The method of partial domains was employed to simulate the acoustic field. Energy transmission coefficients of the wave throughthe inhomogeneous regions were calculated for a wide range of waveguide dimensions and bend angles. It was shown that the presence of bends leadsto significant changes in the spectral characteristics. For waveguide sizes that are multiples of half the wavelength, a sharp decrease in the transmissioncoefficient is observed, which is associated with the excitation of higher-order normal modes in the waveguide. In cases where the bend angle exceeds90, the amplitude-frequency response acquires a complex structure with alternating zones of increasing and decreasing transmission coefficient, indicating the presence of resonant phenomena in the corner region of the waveguide. This region functions as a resonant chamber where efficient energyconversion between different modes may occur. It was established that as the bend angle increases from 0 to 90, the transmission coefficientgradually decreases, but further angle increases lead to oscillations in this coefficient. The change in the dominant mode depending on the waveguidesize and bend angles was analyzed, and the possibility of efficient energy conversion between lower and higher modes at certain points in the frequencyrange was demonstrated, which has potential practical applications in acoustic filtering, sound energy direction control, and the design of waveguide resonators. The obtained results were verified by checking the fulfillment of the energy conservation law, the continuity conditions betweensubdomains, and the boundary conditions on the waveguide surface.