High pressure tank discharge

tesorieri · March 5, 2015, 16:05

Dear all,

I'm modelling the discharge of a high pressure tank to the atmosphere. The tank is very long, has 5mm diamater and is suddenly opened to atmosphere. I've already made some tests with an experimental unit at 70 bar and now I'm modelling it in Fuent ussing an axisymmetric model, with density based solver.

I'm having lots of trouble with the timestep as the solution blows up for timestep sizes bigger than 1e-6s. With this timestep, the simulation takes too long.

Does anybody has any idea on how to increase timestep size?
Thanks!

h1773 · March 23, 2021, 02:19

If you found the answer please update it on the feed.

tahar · March 23, 2021, 05:27

I think the time step is calculated using CFL condition . with 70 bar, the flow has a very high velocity and you are not able to increase timestep size
and why you modelling the full discharge????

March 5, 2015, 16:05	High pressure tank discharge	#1
tesorieri New Member hernan Join Date: Mar 2013 Posts: 8 Rep Power: 13	Dear all, I'm modelling the discharge of a high pressure tank to the atmosphere. The tank is very long, has 5mm diamater and is suddenly opened to atmosphere. I've already made some tests with an experimental unit at 70 bar and now I'm modelling it in Fuent ussing an axisymmetric model, with density based solver. I'm having lots of trouble with the timestep as the solution blows up for timestep sizes bigger than 1e-6s. With this timestep, the simulation takes too long. Does anybody has any idea on how to increase timestep size? Thanks!

March 23, 2021, 02:19	Did you find the answer?	#2
h1773 New Member Time Join Date: Feb 2021 Posts: 8 Rep Power: 6	If you found the answer please update it on the feed.

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March 23, 2021, 05:27		#3
tahar New Member moh Join Date: Jan 2014 Posts: 20 Rep Power: 12	I think the time step is calculated using CFL condition . with 70 bar, the flow has a very high velocity and you are not able to increase timestep size and why you modelling the full discharge????