Your drawing appears to be of a tube open on both ends. The drawing IHank wrote: ... Wave propagation. Figure out duct dimensions from the data you now have, Forrest.
have posted is useless for your case.
-fde
Moderator: Mike Everman
Your drawing appears to be of a tube open on both ends. The drawing IHank wrote: ... Wave propagation. Figure out duct dimensions from the data you now have, Forrest.
Nope. I am not assuming that. See graph.Sam wrote: I suspect that the discrepancy in the velocity plot is because my open-end boundary
condition is different to yours. I think I'm right in saying that you have been assuming that
the static pressure stays constant at one atmosphere at all times at the open boundary. This
is the usual "open-end boundary" assumption, and is used in UFLOW too.
Well, at points 0 and 6, there is outflow. By your admission, theSam wrote: NUDiS makes a different assumption: The static pressure is held constant during outflow
only.
Well, it's just a matter of preference. Don't take it personally. Mike E.'s front end is basedSam wrote: I'm sorry you don't particularly like the way that data is input. This method of data entry is very convenient for me, and I'm not really prepared to go changing this now. Mike E. is working on a frontend interface for the code which should alleviate any problems you may be having, if all goes well.
Forgive my ignorance, but how do you 'compute' the time step during the data input stage?Sam wrote: PS. The 'output frequency' basically tells the software how often you want to dump a solution to file. It has to be an integer >=1. e.g. If you set it to 50 then it dumps a solution every 50 timesteps.
Ah, the ol' Courant-Friedrichs-Lewy stability criterion, I should havesam wrote: The timestep is calculated by a stability criterion (or CFL criterion as its
usually called) ...
It's cool that your model matches my MOC analysis. It's not so cool Isam wrote: I've just checked my solution to the problem and I too get an initial
outflow Mach Number of 0.8, as your Method of Characteristic solution
suggests. I'm not sure where you went wrong... maybe you weren't
normalising the velocity by the correct speed of sound?
sam