Gorilla Koala

Hi Federico,

Thank you for answering my question. I have not consider about 'acoustic courant number'. Honestly I haven't understand how Fleunt calculate the acoustic pressure. Does the acoustic model use the explicit method? 

This is the additional information and questions of my calculation. I would be happy if you could answer my questions.

  • The narrow pipe has 0.01 [in] mesh, it is generated by face mesh. The wider pipe has 0.1 [in] mesh. Since I am thinking the acoustic source is at the narrow pipe. 
  • The time step size is 5e-5 [sec]. And acoustic far field speed is 1115.486 [ft/sec]. I'm not familiar with acoustic courant number, but it is C = Vdt/dx = 1115.486 [ft/sec] x 5e-5 [sec]/0.01 [in] = 80. This means that I should increase the mesh size or decrease the time step size.  Is this calculation correct?
  • Because I wanna see the frequency lower than 10,000 Hz, 5e-5 [sec] is enough in terms of frequency. 
  • I'm sorry I couldn't get 'A good rule of thumb is to have at least 10 points for a half-period of the pressure signal with highest frequency' means. What is the half-period of the pressure signal?

Please let me know if you need more information.