Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

How to analyze the equations of monopole point source when dealing with the acoustic pressure

Please login with a confirmed email address before reporting spam

Dear all,

I have been confused with the governing equations when conducting a case on room mode applying the monopole point source.

1/(ρc^2 ) · (∂^2 p)/(∂t^2 ) + ∇[-1/ρ · (∇p-q_d )]= Q_m

Q_m= 4π/ρ ∙ S ∙ δ(x-x_0)

S= e^iφ ∙ (iω · ρ_c · Q_s)/4π

Until now, I have checked many acoustic books, but only found the following similar equation.

∇^2 p- 1/c^2 ∙ (∂^2 p)/(∂t^2 ) = -ρ ∙ (Q_s (t) ) ̇ ∙ δ(x-x_0 )

So my questions are

1). While I put the monopole source as the initial condition, why there is a q_d that should be subtracted in the equation
1/(ρc^2 ) · (∂^2 p)/(∂t^2 )+ ∇[-1/ρ · (∇p-q_d )]= Q_m

2). What does φ mean in the equation
S= e^iφ ∙ (iω · ρ_c · Q_s)/4π
And what is the difference, in particular, between e^iφ and e^(i(ωt-kr)), which I have seen in many books?


0 Replies Last Post 2017年3月8日 GMT-5 11:20
COMSOL Moderator

Hello Li Dongfang

Your Discussion has gone 30 days without a reply. If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help.

If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base.

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.