# Simple compressed air tank filling

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July 16, 2013, 17:24
Simple compressed air tank filling
#1
New Member

Abdel
Join Date: Sep 2012
Posts: 1
Rep Power: 0
Hello all,
I'm trying to simulate the transient filling process of a compressed air tank.
It's a simple case, the shape is cylindrical (10cm diameter by 20cm deep cylinder with 1cm diameter inlet), initial tank pressure is atmospheric (14.7 psi) and inlet pressure at a constant 60 psi.
I'm having many errors when applying the "pressure-inlet" BC type at the inlet. I can get the simulation running if I apply a "velocity-inlet" BC type, however, my goal is to simulate the air mass flow rate based on the pressure difference between the initial tank pressure (14.7 psi) and the external pressure (60 psi).

What I've done so far:
1- 3D Geometry: Extruded 1/4 of the cylinder due to symmetry. The whole domain is fluid (air) with the inlet being a surface.
2- Meshed using ANSYS Mesher (mesh is coarse for now)
3- Fluent:
- Used density-based
- Turned the energy model on.
- Used the K-E model
- Density Air (materials) selected to be "Ideal Gas"
- BCs: Inlet selected as "pressure inlet" with 70 psi gauge pressure
- Solution Initialization: Since the initial pressure I want is 14.7 psi I selected "Standard Initialization" with 14.7 psi gauge pressure.
- Step size (for now) is 0.01 seconds.

Please let me know if you could help me, I appreciate it.

Regards
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 August 26, 2018, 23:52 filling process #2 New Member   Join Date: Jan 2016 Posts: 1 Rep Power: 0 hello dear i have a problem right now like what you had! did your problem solve? if yes please guide me what can i do! i want to model filling process of a compressed gas cylinder but it doesn't solve! thanks best regards

 August 27, 2018, 00:41 #3 Senior Member   Lucky Tran Join Date: Apr 2011 Location: Orlando, FL USA Posts: 4,288 Rep Power: 51 Start with the pressure inlet at the same pressure as the initial pressure. Run this in transient mode until convergence. If you can't converge it here, then you have problems! If you can get a converged initial condition, then you can reset the flow-time and then change the inlet pressure to whatever pressure you like. And don't forget about temperature!