CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > CFX

CFX Momentum Inputs Question

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   September 27, 2013, 14:50
Default CFX Momentum Inputs Question
  #1
New Member
 
G. Smith
Join Date: Sep 2013
Posts: 3
Rep Power: 13
gsmith is on a distinguished road
Hi all!

I am new to using CFX and a novice with CFD analysis. I'm working on a problem with a moving tank. To simulate the movement of the tank in the fluid, I am trying to input momentum source information. The momentum info I am using was calculated from Reynolds Transport. However, for a general Reynolds Transport in Momentum, the units come out to be kg*m/s. The CFX Momentum input asks for a momentum source coefficient with units kg/(m^3 s) and a vector with units kg/(m^2 s^2). How do I go from a general momentum case to the needed values/equations for the CFX momentum input?

Thank you,

G. Smith
gsmith is offline   Reply With Quote

Old   September 27, 2013, 18:09
Default
  #2
Senior Member
 
Erik
Join Date: Feb 2011
Location: Earth (Land portion)
Posts: 1,188
Rep Power: 23
evcelica is on a distinguished road
Don't use the momentum source coefficient. That is for making it a function of velocity.
Just use the Component option, which has units of kg/(m^2 s^2) = momentum per unit volume per second = (kg*m/s) / (m^3 s)
evcelica is offline   Reply With Quote

Old   October 21, 2013, 11:46
Default
  #3
New Member
 
G. Smith
Join Date: Sep 2013
Posts: 3
Rep Power: 13
gsmith is on a distinguished road
Thank you for the reply!
The per unit volume makes sense if I divide the general momentum case by the total fluid volume. But I still don't understand how to go from general momentum to the per time. Is the general momentum divided by the timestep? or by the overall time of the run?
gsmith is offline   Reply With Quote

Reply


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
Hi,I have a question about momentum equation in interFoam shchao OpenFOAM Programming & Development 7 December 18, 2017 18:40
Question about momentum thickness Reynolds number Anna Tian Main CFD Forum 2 March 4, 2013 11:45
Question about CFX transitional fluid model Anna Tian CFX 1 January 28, 2013 21:14
Derivation of Momentum Equation in Integral Form Demonwolf Main CFD Forum 2 October 29, 2009 20:53
CFX 10 question DAK565656 CFX 0 August 6, 2007 01:06


All times are GMT -4. The time now is 09:57.