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Monopole source

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Hi, There is a monopole source with a power of 0.01 W and a frequency of 1kHz in two different radii (17cm and 170 cm) in an air filled sphere. When I take measurements in both spheres at a distance of 10 cm from the monopole source, the pressure values are different. The simulation parameters are the same. mesh, both physically controlled normal. On the outside of the spheres there is lambda / 8 pml. I am measuring 10ms with frequency domain and time to frequency fft. What could be the reason for this? (I do the simulations separately.) Thanks.


1 Reply Last Post Oct 13, 2020, 10:13 p.m. EDT

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Posted: 4 years ago Oct 13, 2020, 10:13 p.m. EDT

Hi I am using acoustics module in COMSOL 5.3a to simulate some thermoacoustic instabilities. So, to solve this problem, I'm using pressure acoustics Physics based on the inhomogeneous helmholtz equation.

A simple n-tau model was applied to Monopole domain source to combine the perturbation of velocity in the upstream of the heat release zone with the perturbation in pressure in the heat release zone.

As a result, we analyze Eigenfrequency.My problem now is that the eigenfrequency can be calculated when there is no monopole source. However, there is no change in the calculated eigenfrequency when the monopole source is added. No matter whether the monopole source term is added or not, the eigenfrequencyis not affected. Do you know what the problem is?

Hi I am using acoustics module in COMSOL 5.3a to simulate some thermoacoustic instabilities. So, to solve this problem, I'm using pressure acoustics Physics based on the inhomogeneous helmholtz equation. A simple n-tau model was applied to Monopole domain source to combine the perturbation of velocity in the upstream of the heat release zone with the perturbation in pressure in the heat release zone. As a result, we analyze Eigenfrequency.My problem now is that the eigenfrequency can be calculated when there is no monopole source. However, there is no change in the calculated eigenfrequency when the monopole source is added. No matter whether the monopole source term is added or not, the eigenfrequencyis not affected. Do you know what the problem is?

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