COMSOL中怎么通过特征频率模拟得到辐射衰减

The process of obtaining Q−1 leak and Q−1 loss. The resonant angular frequencies ωA and ωB are obtained from the Frequency-domain simulations by the commercial software COMSOL Multiphysics with the preset “Pressure Acoustics, Frequency Domain” module. In the simulations, the domain material is air (the static air density, ρ = 1.21 kg/m3 , the sound speed, c = 343 m/s, the dynamic viscosity of air, µ = 1.81×10−5 N·S/m2 , the preset environmental temperature, T = 293.15K (20 ◦C)). We perform two simulations to separately calculate the reflection curve (r) of individual cavity A and cavity B and extract ωA, ωB and the corresponding r0. The radiative decay rates γA and γB are obtained from the Eigen-frequency simulations with the same setup with the one obtaining ωA and ωB, except that now the thermal-viscous losses are neglected. The eigenfrequency of the target mode has a real part close to the resonant frequency and a small imaginary part, which can be expressed as (ω′ A(B) + i · γ′ A(B))/(2π). In Eigen-frequency simulations, due to the absence of the thermal-viscous losses, the resonant angular frequencies are slightly higher than the ones in practical systems, so there is a revision made by γA(B)/ωA(B) = γ′ A(B)/ω′ A(B). Then, we can obtain that Q−1 leakA(B) = 2γA(B)/ωA(B). (S1) Furthermore, based on Eq. (8), Eq. (S1) and the simulated results of r0, we can calculate Q−1 lossA and Q−1 lossB, where Q−1 lossA and Q−1 lossB are approximate to each other when the two cavities have the same cross-section. With a similar process performed on the coupled system, Q−1 leak and Q−1 loss of the whole system can be obtained.

第四章第四季补充文献_1_9_translate.pdf

F是如何计算出来的。