CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > FLOW-3D

how to see the hydrodynamic drag

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

Reply
 
LinkBack Thread Tools Display Modes
Old   October 30, 2008, 05:26
Default how to see the hydrodynamic drag
  #1
Eleazar
Guest
 
Posts: n/a
hello

i am working on the version 9.2 , import an stl ship and make a simulation to calculate the hydrodynamic forces, but i do not know how to see them.

can anyone help me???????

thanks eleazar
  Reply With Quote

Old   October 30, 2008, 15:13
Default Re: how to see the hydrodynamic drag
  #2
George
Guest
 
Posts: n/a
You go to Analyze > Prob, select General history and Text or Graphical. From the list for Data Variables, you will find all the output data for GMO. Select Component # x (or y, z) comp. of GMO hydraulic force. Then click Render.

George
  Reply With Quote

Old   October 30, 2008, 17:58
Default Re: how to see the hydrodynamic drag
  #3
Eleazar
Guest
 
Posts: n/a
is this possible to have for a 60 meters yacht a number of 5*1e-13 drag force????????????????

what id i make wrong??? what are the units?????

thanks eleazar
  Reply With Quote

Old   October 31, 2008, 10:16
Default Re: how to see the hydrodynamic drag
  #4
George
Guest
 
Posts: n/a
You can use either SI or CGS unit. I have never met any case with so small drag force. Make sure you selected the correct item in the history data list. If it is still wrong, you may contact Flow Science if you have support.

  Reply With Quote

Old   October 31, 2008, 11:36
Default Re: how to see the hydrodynamic drag
  #5
Michael Barkhudarov
Guest
 
Posts: n/a
Hi Eleazar,

If the yacht is modeled as a stationary object, not a GMO component, then to get the fluid forces on it you need to define a force window in the input file (a 3d shoe-box around the object). Then run the simulation, and look for the force and moment components in Probe>General history data catalogue.

If the yacht is a moving (GMO) compnent, then these forces will be automatically computed and stored.
  Reply With Quote

Old   October 31, 2008, 16:38
Default Re: how to see the hydrodynamic drag
  #6
Eleazar
Guest
 
Posts: n/a
hello

i just take the example of the sphere from the flow 3d examples and delete the sphere with a stl file a yacht. this is one fluid free surface simulation where the yacht is 60 meters. two thing i did not understand yet....

1) the units are meter N sec etc... but the box is 300 000 units at Y , 400 000 units in X and 200 000 units in z , so if the units are in meters them the model is a little bit wrong because the box could not be 300 000 meters..... so what the box units are???

2) the correct way is the one flid and free surface or two fluids (to also include air?????

thanks a lot for the help i really have to see that as soon as possible.

eleazar
  Reply With Quote

Old   December 8, 2008, 20:17
Default Re: how to see the hydrodynamic drag
  #7
aginor
Guest
 
Posts: n/a
what did you do?? i have the same problem! i can see the correct force only in the direction that is coupled motion (free to move) i need the force in the not moving axis. i try the force window also but the same problem
  Reply With Quote

Old   January 9, 2009, 04:34
Default Re: how to see the hydrodynamic drag
  #8
eleazar
Guest
 
Posts: n/a
i found it !!!!!!!!!!!!!!!!!!!!!!!!!!!!
  Reply With Quote

Reply

Thread Tools
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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Evaluating CFD Packages for Hydrodynamic Drag in Underwater Vehicles Dundee Main CFD Forum 4 December 5, 2011 07:31
hydrodynamic drag and pressure drop of subchannels chenxi05 Main CFD Forum 0 June 24, 2011 12:37
anyone has got this paper? Al Main CFD Forum 3 October 8, 2007 02:04
Pressure drag, friction drag and total drag? Cheng CFX 4 December 2, 2006 23:19
Inviscid Drag at subsonic, subcritical Mach # Axel Rohde Main CFD Forum 1 November 19, 2001 13:19


All times are GMT -4. The time now is 03:35.