|
[Sponsors] |
How do I set up atmospheric pressure for outlet? |
|
LinkBack | Thread Tools | Search this Thread | Display Modes |
April 10, 2018, 21:45 |
How do I set up atmospheric pressure for outlet?
|
#1 |
New Member
Swapnil Rane
Join Date: Sep 2017
Posts: 23
Rep Power: 9 |
I have two outlets at atmosphere exits.
How can I add pressure boundary conditions ? I'm confused about the reference/static/total pressure settings. |
|
April 11, 2018, 00:23 |
|
#2 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,870
Rep Power: 144 |
What do you mean by "add pressure boundary conditions"?
Total pressure: https://en.wikipedia.org/wiki/Total_pressure Static pressure: https://en.wikipedia.org/wiki/Static_pressure Reference pressure is used by CFX to reduce numerical round-off errors. For instance if a 1 Pa pressure difference exists in a body at 1 bar absolute pressure: * If the reference pressure is 0, then the pressure difference is 100001 [Pa] - 100000 [Pa] which is of course a 1 [Pa] difference, but if the numerics are only accurate to 4 significant figures you get 1.000e5 [Pa] - 1.000e5 [Pa] and the 1 [Pa] pressure difference has disappeared. A simulation based on this would have unexpected results as it cannot resolve the pressure variations. This effect is called round-off error. * If the reference pressure is 1 [bar], then the pressure difference is 1 [Pa] - 0 [Pa] which is of course a 1 [Pa] difference. Now if we consider numerics which is only accurate to 4 significant figures you get 1.000e0 [Pa] - 0.000e0 [Pa] and the 1 [Pa] pressure difference is still resolved. A simulation based on this would can work as the 1 [Pa] pressure difference is accurately resolved, despite the limited accuracy of the numerics.
__________________
Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum. |
|
Tags |
bounday condition, pressure |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Wind tunnel Boundary Conditions in Fluent | metmet | FLUENT | 6 | October 30, 2019 13:23 |
Discharge of Pressure Vessel into Pipe with Regulator | gajowni2 | System Analysis | 0 | October 31, 2015 19:57 |
Set inlet velocity and pressure in cavitational model | GerardX89 | FLUENT | 1 | July 5, 2012 17:17 |
Atmospheric Bounduary Layer - Problens with hidrostact pressure | camilo_costa | CFX | 5 | August 25, 2009 11:56 |
Gas pressure question | Dan Moskal | Main CFD Forum | 0 | October 24, 2002 23:02 |