filling cylinder

f_panahizadeh · January 15, 2010, 04:55

i'm investigating about CFD simulation of filling a cylinder.
I consider asymmetric, unsteady, compressible, turbulent flow, real gas.
When I consider the pressure inlet boundary condition and applied variation of it by using a UDF the flow after about 10 second diverged. I think it caused by the variation of mass flow inlet so how I can control or specify mass flow inlet when use the pressure inlet boundary condition in Fluent?

herntan · January 18, 2010, 00:41

use mass flow inlet boundary condition.
Pressure inlet is impossible to control the mass flow. pressure and mass flow is inter-related to each other.

f_panahizadeh · January 18, 2010, 00:48

Thanks for your answer
please clear how i can define the pressure variation by using the mass boundary condition?
thanks in advance

herntan · January 18, 2010, 01:31

mass flow rate will automatically create the pressure.
flow always flow from high pressure to low pressure. When u define mass flow rate, the pressure is already there, its impossible to set something which already fixed.

I think u might dealing with something else, please carify ur problem with picture and explain in detail.

f_panahizadeh · January 18, 2010, 03:52

i should write a UDF for defining mass flow rate varation via time or not?( the pressure of the inlet flow varied from 1bar to 40 bar in 40 seconds and i'm investigating to find temperature field within cylinder via time)

January 15, 2010, 04:55	filling cylinder	#1
f_panahizadeh New Member Farshad Join Date: Jan 2010 Location: Iran Posts: 4 Rep Power: 16	i'm investigating about CFD simulation of filling a cylinder. I consider asymmetric, unsteady, compressible, turbulent flow, real gas. When I consider the pressure inlet boundary condition and applied variation of it by using a UDF the flow after about 10 second diverged. I think it caused by the variation of mass flow inlet so how I can control or specify mass flow inlet when use the pressure inlet boundary condition in Fluent?

January 18, 2010, 00:41		#2
herntan Senior Member YH Tan Join Date: Mar 2009 Location: Malaysia Posts: 119 Rep Power: 17	use mass flow inlet boundary condition. Pressure inlet is impossible to control the mass flow. pressure and mass flow is inter-related to each other. __________________ Herntan, Add Reputation if I am right

January 18, 2010, 01:31		#4
herntan Senior Member YH Tan Join Date: Mar 2009 Location: Malaysia Posts: 119 Rep Power: 17	mass flow rate will automatically create the pressure. flow always flow from high pressure to low pressure. When u define mass flow rate, the pressure is already there, its impossible to set something which already fixed. I think u might dealing with something else, please carify ur problem with picture and explain in detail. __________________ Herntan, Add Reputation if I am right

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January 18, 2010, 00:48		#3
f_panahizadeh New Member Farshad Join Date: Jan 2010 Location: Iran Posts: 4 Rep Power: 16	Thanks for your answer please clear how i can define the pressure variation by using the mass boundary condition? thanks in advance

January 18, 2010, 03:52		#5
f_panahizadeh New Member Farshad Join Date: Jan 2010 Location: Iran Posts: 4 Rep Power: 16	i should write a UDF for defining mass flow rate varation via time or not?( the pressure of the inlet flow varied from 1bar to 40 bar in 40 seconds and i'm investigating to find temperature field within cylinder via time)