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#1 |
New Member
Join Date: May 2015
Location: Germany
Posts: 15
Rep Power: 11 ![]() |
Hello Everybody,
is it possible to simulate a chamber with just an outlet to see how the pressure changes by evacuating the chamber with a pump? I know the mass flow at the outlet. But when i say there is a specific Outlet mass flow the simulation got an error in the X-momentum. Is it even possible, because simply say i take mass out of the chamber so the density and pressure changes. How can i do that? Or is it impossible due to mass imbalances? I´m not afraid of UDF if it´s necessary. I hope you understand what i wanted to explain, my English is not the best. As Fluid i use air. Kind regards ![]() |
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#2 |
New Member
Join Date: May 2015
Location: Germany
Posts: 15
Rep Power: 11 ![]() |
When i use velocity at outlet, no pressure change occurs.
What else can i try? |
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#3 |
New Member
Join Date: May 2015
Location: Germany
Posts: 15
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So it´s me again.
I modeled a Volume surrounded by walls and one outlet. At the outlet i defined a mass-flow-inlet with my mass-flow by changing the direction vector so it flows out of the domain. Then i took air and in the material panel ideal gas for density (compressible). As operating pressure i choose floating pressure. For inital floating pressure i use 101325 Pa, my pressure at the beginning. I do transient calculation. When i start the calculation i got an error: Divergence detected in AMG solver: pressure correction. What am i doing wrong? ![]() |
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#4 |
Senior Member
Join Date: Jun 2014
Location: Taiwan
Posts: 100
Rep Power: 12 ![]() |
I think that it is not necessary to use floating pressure.
Maybe you can try a high-pressure chamber and mass-flow-inlet with negative mass flow? -- Sorry, my fault. You could try mass-flow-inlet with negative mass flow and floating pressure since there is no pressure-referenced boundary condition. -- The mass-flow-inlet could not be negative. Then I suggest 1. Using floating operating pressure and mass-flow-inlet with the outward direction since the mass flow could not be negative. 2. Using velocity inlet with negative velocity and proper absolute pressure(maybe 0?). Last edited by SJSW; June 20, 2017 at 05:15. |
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#5 |
New Member
Join Date: Jun 2017
Posts: 2
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hello,
I want to simulate the process of evacuating a chamber with just an outlet in FLUENT. But I am confused about the boundary condition of the outlet. Would you give me some advice? Thank you so much! |
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#6 |
Senior Member
Join Date: Jun 2014
Location: Taiwan
Posts: 100
Rep Power: 12 ![]() |
What is your confusion with the boundary condition of the outlet?
Maybe you could describe it more specifically. @@ |
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#7 |
New Member
Join Date: Jun 2017
Posts: 2
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Because this chamber is vacuumed by the vacuum pump, the velocity and the pressure of boundary are always changing. And I want to calculate the time to reach the specified pressure in the chamber.
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Tags |
evacuate, fluent, udf, vacuum, x-momentum |
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