Problem with simple duct flow modelling
 

Hi,
I'm currently interested in flow inside the simple expansion duct(muffler).

Analysis conditions;
1. unsteady calculation with time step 5e-7
2. compressible flow using air ideal gas & total energy
3. boundary condition
; inlet -> inlet B.Cs with mass flow rate
-> at begin : one sinusoidal signal with 0.5 kg/s and 4000 Hz
-> after : constant flow rate as 0 kg/s
; outlet -> opening B.Cs with entrainment as relative 0 atm
; wall -> adiabatic wall B.Cs
4. used 2 monitoring point before and after expansion duct


My problem;
I observed un-physical pressure changes at the two monitoring points which means pressure is changed at the same time(simultaneously) although the distance between two points is 0.1 m. With my time step(5e-7), it can't be possible.


Is there any suggestions with my problem?

Thanks in advance.

Looks like your compressible flow model is not working. Please post your CCL.