Thank you very much for your reply. I have taken your suggestion and run with it. Here are the values (inlet and outlet mass flow) for various mesh settings using the Normal solution as an initial condition (to save time):
Normal:
Stationary Solver 1 in Solver 4: Solution time: 141 s (2 minutes, 21 seconds)
Physical memory: 1.96 GB
Virtual memory: 2.25 GB
w2*hmnf.rho (kg/(m*s)) w2*hmnf.rho (kg/(m*s))
0.05071 0.05476
Fine:
Stationary Solver 1 in Solver 2: Solution time: 77 s (1 minute, 17 seconds)
Physical memory: 2.41 GB
Virtual memory: 2.69 GB
w2*hmnf.rho (kg/(m*s)) w2*hmnf.rho (kg/(m*s))
0.0506 0.05473
Finer:
150 0.8000000 0.012 150 150 150 3.2e-012 9.7e-015
Stationary Solver 1 in Solver 2: Solution time: 3637 s (1 hour, 0 minutes, 37 seconds)
Physical memory: 4.3 GB
Virtual memory: 4.98 GB
Updated maximum iterations to 1E6, as maximum was reached with 150
2237 0.8000000 0.013 2237 2237 2237 4.8e-012 1e-014
Canceled
Stationary Solver 1 in Solver 2: Solution time: 62187 s (17 hours, 16 minutes, 27 seconds)
Physical memory: 11.91 GB
Virtual memory: 12.55 GB
Failed to converge after running overnight… Cancelled simulation, but the program then froze and would not give back GUI control. After waiting for 30 minutes, I had to kill the process via the program manager.
Next, I down-checked the Newtonian damping factor to 0.1, instead of 0.8 (default) and turned on pseudo-timestepping.
128 0.1000000 0.001 128 128 128 2.8e-011 7.9e-014
Stationary Solver 1 in Solver 2: Solution time: 2846 s (47 minutes, 26 seconds)
Physical memory: 4.22 GB
Virtual memory: 4.91 GB
w2*hmnf.rho (kg/(m*s)) w2*hmnf.rho (kg/(m*s))
0.05043 0.05511
Extra Fine:
163 0.1000000 0.00098 163 163 163 3e-011 1.3e-013
Stationary Solver 1 in Solver 2: Solution time: 10288 s (2 hours, 51 minutes, 28 seconds)
Physical memory: 8.09 GB
Virtual memory: 9.57 GB
w2*hmnf.rho (kg/(m*s)) w2*hmnf.rho (kg/(m*s))
0.05249 0.05742
Extremely Fine:
240 0.1000000 0.00099 240 240 240 2.7e-011 9.1e-014
Stationary Solver 1 in Solver 2: Solution time: 43360 s (12 hours, 2 minutes, 40 seconds)
Physical memory: 14.34 GB
Virtual memory: 18.97 GB
w2*hmnf.rho (kg/(m*s)) w2*hmnf.rho (kg/(m*s))
0.05286 0.05851
Since this was not as productive as I had hoped, are there any suggestions on how to get mass balance? I tried to make this setup as absolutely simple as possible. It is an axisymmetric tube, L/D=100, Pin/Pout=10, Nitrogen gas, inlet of Pin & 273.15, Ma=0, outlet of Hybrid. Pictures of the conditions are at the bottom. I then calculate the flow using Normal Mesh and the default solver. To check conservation, I took a line integral on the inlet and a line integral on the outlet, both of the z component of velocity times density.
Is there another example I may look to for a high pressure ratio pipe flow, a capillary flow maybe, which conserves mass?
-TCL