CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Running, Solving & CFD

pressure surge in closed geometry, inlet only

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   April 28, 2022, 04:30
Default pressure surge in closed geometry, inlet only
  #1
New Member
 
Jonas Lönartz
Join Date: Jun 2020
Posts: 2
Rep Power: 0
JLoenartz is on a distinguished road
Dear colleges,


I came across some challenges, when I tried to simulate a pressure surge inside a closed domain. Attached is an image, that should give an idea, what I am trying to simulate and I will use this image to explain the problem.

In a transient calculation using rhoPimpleFoam, I want to simulate the flow into a sealed off domain, after a valve is abruptly opened. While the valve is closed, we have ambient pressure and temperature inside of the fluid-domain. When the valve is opened, air flows into the fluid-domain from a pressure vessel (pressure of 300bar and 60°C). The opening process of the valve is to be considered instantly. There is no outlet and the simulation is supposed to run, until there is an equiblibrium inside the fluid-domain.



The pressure-vessel is not modelled explicitely, instead I want to put the inlet on a cross-section of the pipe, as shown in the attached image.

My first questions are concering the boundary conditions. A velocity-inlet is of course out of the question, because at this point, the celocity at the inlet is unknown.



My idea was, to use a combination of the following boundary conditions on the inlet:


p:


Code:
    inlet
    {
        type    totalPressure;
        p0      uniform 300e+5;
        value   $internalField;
    }
T:
Code:
    inlet
    {
        type        totalTemperature;
        T0          uniform 333;
        gamma       1.4;
    }
and U:
Code:
    inlet
    {
        type    pressureInletOutletVelocity;
        value   $internalField;
    }
In theory, these bc's should account for the decrease of pressure and temperature, when the air accelerates while flowing into the pipe.


But I obtained some really questionable results from this set of boundary conditions. The flow reached velocities of more than double the speed of sound in the pipe, which should not be possible and temperatures fell to 40K. And after a short while the calculation crasehd, because of negative initial temperatures.



My next thought was, to approximate the flow conditions by using codedFixedValue for the boundary conditions, but this should prove very complicated and feels like guessing. So I thought I might ask in the forum, if maybe someone has encountered a problem like this before and has a reliable solution or setup ready.

Thank you very much in advance,
Jonas
Attached Images
File Type: jpg sketch.jpg (44.7 KB, 8 views)
JLoenartz is offline   Reply With Quote

Reply

Tags
compressible, inlet only, no outlet, pressure surge

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Adjuting oulet pressure till inlet pressure reaches a certain value in timestep pvpnrao OpenFOAM Running, Solving & CFD 2 September 11, 2018 10:14
Low pressure inlet problem Bisht FLUENT 10 March 28, 2018 09:04
Pressure Outlet Guage pressure Mohsin FLUENT 36 April 29, 2016 17:16
Neumann pressure BC and velocity field Antech Main CFD Forum 0 April 25, 2006 02:15
Hydrostatic pressure in 2-phase flow modeling (long) DS & HB Main CFD Forum 0 January 8, 2000 15:00


All times are GMT -4. The time now is 09:00.