CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > General Forums > Main CFD Forum

Calculation of forces

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   January 17, 2001, 08:09
Default Calculation of forces
  #1
Michal Marcinkowski
Guest
 
Posts: n/a
Hi I hope nobody is offended that I am using this group for "technical details" but I couldn't get the response on Phoenics forum /for beginner like me )/

I would like to know what is the most efficient way for integrate pressures on some shape for getting the forces /like lift and drag/ in Phoenics V 3.2. I found two examples / Y113, Y114/ on Cham sites but I can't run them and check the results /some errors during EARTH's run/. Is it possible automatically ?

Thank you in advance

MM
  Reply With Quote

Old   January 17, 2001, 22:12
Default Re: Calculation of forces
  #2
John C. Chien
Guest
 
Posts: n/a
(1). I guess everything is possible, if you know what you are looking for. (2). First of all, you must have the wall geometry, because that the input to your code. And from the computed pressure distribution on the wall, you can compute the local lift force per cell surface on the wall. By the way, the pressure force is always normal to the wall surface. So, the local wall slope such as cos, and sin of the local wall angle is all you need to find the lift force component. (3). You also have to define the lift and the drag first. For example, the lift can be defined as the vertical component of the total pressure force acting on the surface. For the drag, it can include the other horizontal component of the total pressure force and the viscous component. So, you need to find the wall surface local skin friction, which is tangent to the surface of the wall. (4). So, try to resolve these forces on the local wall surface first. Once you have it, just sum it over the complete wall surface. Then you will have the total lift and the total drag forces. (5). By the way, nothing is automatic on a computer, someone has to write the program to compute it first. (Sometimes, it is included in the commercial program. In that case, all you have to do is to identify the wall boundary and the code will calculate the total lift and drag for you. If it is not included in the code, you can still do it by hand or write a small piece of code to compute the forces.)
  Reply With Quote

Old   January 18, 2001, 05:37
Default Re: Calculation of forces
  #3
Michal Marcinkowski
Guest
 
Posts: n/a
I am afraid that I chose wrong group,anyhow. Sorry. But thanks for little repetition : ) from Mr Chien. My problem is how to "just sum" the pressures over, let's say, 10000 cells of some complex, curvlinear geometry having Phoenics output file.

Everything is possible so... maybe something will happen on my computer "automatically"...

MM
  Reply With Quote

Reply

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
Calculation of forces sreekargomatam FLUENT 0 July 13, 2011 13:43
Forces calculation fusij OpenFOAM 4 October 29, 2010 12:38
Forces viscous calculation in VWT with OpenFOAM 15x terrybarnaby OpenFOAM Running, Solving & CFD 0 November 28, 2008 09:39
forces calculation Chien CFX 9 June 23, 2005 12:45
Warning 097- AB Siemens 6 November 15, 2004 05:41


All times are GMT -4. The time now is 09:43.