Hello everybody,
I try to model an micro air bubble in water under an incident ultrasonic pressure field. In near future I hope to be able to add walls to the system, therefore I need a model which doesn't use the spherical symmetry of the bubble.
To do that I suppose that the water flow is potential and that the bubble's gas flow is isentropic. So I solve Laplace equation for the velocity potential in the liquid domain and transient Bernoulli's equation at the water-air interface.
For that I've decided to use a domain pde for the laplace equation and a boundary pde for transient Bernoulli's equation. I use a weak form pde to compute surface tension. I follow the interface using moving mesh
For the moment I don't succeed to model the gas bubble correctly for high pressure amplitude. I think mostly because of the non-linear term in Bernoulli's equation. Weak contribution, separate weak equation or explicit adding of this term in a boundary coefficient form pde doesn't succeed. Therefore I don't know what to do. Normally weak form pde's should be able to solve non-linear equations. But for my problem it doesn't work. I'm sure that I've well implemented the model because I have the right response for low amplitudes, so when the non-linear term can be neglected.
Do someone know at least why my model doesn't work or what I should do to make it work with Comsol?
Thank you!
Karl
I try to model an micro air bubble in water under an incident ultrasonic pressure field. In near future I hope to be able to add walls to the system, therefore I need a model which doesn't use the spherical symmetry of the bubble.
To do that I suppose that the water flow is potential and that the bubble's gas flow is isentropic. So I solve Laplace equation for the velocity potential in the liquid domain and transient Bernoulli's equation at the water-air interface.
For that I've decided to use a domain pde for the laplace equation and a boundary pde for transient Bernoulli's equation. I use a weak form pde to compute surface tension. I follow the interface using moving mesh
For the moment I don't succeed to model the gas bubble correctly for high pressure amplitude. I think mostly because of the non-linear term in Bernoulli's equation. Weak contribution, separate weak equation or explicit adding of this term in a boundary coefficient form pde doesn't succeed. Therefore I don't know what to do. Normally weak form pde's should be able to solve non-linear equations. But for my problem it doesn't work. I'm sure that I've well implemented the model because I have the right response for low amplitudes, so when the non-linear term can be neglected.
Do someone know at least why my model doesn't work or what I should do to make it work with Comsol?
Thank you!
Karl