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

calculating forces coeff

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   December 22, 2017, 11:25
Default calculating forces coeff
  #1
Senior Member
 
A. Min
Join Date: Mar 2015
Posts: 308
Rep Power: 12
alimea is on a distinguished road
Hi
I want to calculate forces for viscoelastic fluid flow. According to what I found out, just I should change the "fT" , i.e. tangential force. in forces.C code we can see:

-etaS*dev(twoSymm(fvc::grad(U)));

for shear stress.

I have three questions:

1- why did it use deviatoric form of twoSymm(fvc::grad(U)) tensor? As you know the shear stress tensor is calculated by:
-etaS*twoSymm(fvc::grad(U))
why deviatoric?!

2- why did it use minus in formula?

3- if I want to add it polymer stress tensor, what should I do? is it enough to write:
(+ or - ??)tau - etaS*dev(twoSymm(fvc::grad(U)));

thanks
alimea is offline   Reply With Quote

Reply

Tags
forces, openfoam, viscoelastic


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
Help! problems in calculating forces with SimpleFoam DLC OpenFOAM 3 April 26, 2022 00:43
Problem calculating forces on blades 2 (for finding forces) bye bye my blue OpenFOAM Running, Solving & CFD 16 April 19, 2018 11:48
problem with plotting both forces and coeff giammy92 OpenFOAM Post-Processing 2 March 23, 2016 05:25
Calculating forces on a non-closed surface ScottN FLUENT 0 March 1, 2011 18:18
How to update polyPatchbs localPoints liu OpenFOAM Running, Solving & CFD 6 December 30, 2005 18:27


All times are GMT -4. The time now is 17:14.