
[Sponsors] 
January 29, 2011, 16:40 
Flow over a cylinder

#1 
Senior Member
Ugly Kid Joe
Join Date: Aug 2010
Posts: 193
Rep Power: 8 
I am simulating a (1way FSI) flow over a cylinder case. My case is very similar to the one way FSI and mesh deformation Ch22 tutorial. My question is that I need to validate my displacements but the disp observed is very low. What can be the reason ??? Is there a problem with the .CEL expression written???
The water flows in the positive x direction and displacement in the transverse (i.e y) direction is to be measured ????? I am attaching the .CCL file. Thank you. 

January 29, 2011, 16:58 
wall shear data in result file ???

#2 
Senior Member
Ugly Kid Joe
Join Date: Aug 2010
Posts: 193
Rep Power: 8 
In the ANSYS CFX reference guide Ch: 14 Functions in ANSYS CFX Pg. 150 says the following;
In all case if the wall shear data exist in the result file, the viscous force is added to the calculated force. How do I do this ????? Thank you very much. 

January 30, 2011, 05:45 

#3 
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 12,831
Rep Power: 100 
First post  http://www.cfdonline.com/Wiki/Ansys..._inaccurate.3F
Second post  It is done by default, is it not? 

January 3, 2012, 22:31 

#4  
Member
^^
Join Date: Aug 2011
Posts: 70
Rep Power: 7 
Quote:
Hi, Did you solve why the disp is very low? I have also exactly same problem. if you figure out what the problem is, please kindly let me know it. Best Regards 

January 3, 2012, 23:21 
@ colopolo

#5  
Senior Member
Ugly Kid Joe
Join Date: Aug 2010
Posts: 193
Rep Power: 8 
Quote:
The first thing to do is use realistic values of spring stiffness (k) & damping values (c). I had actually assumed the values of k & C. The best paper to validate your simulations would be by Anagnostopoulos & bearman  "Response Characteristics of a vortex excited cylinder at low Re number". It is the only experimental paper I know that performed VIV at Re as low as 100. Also you might have low displacements because you vibrations must be in the lower or initial branch. Try to run simulations in the upper branch instead. Use the Strouhal relation given by Roshko (1988) to find the velocity at which your system vibrates in 2P mode of vortex shedding. If you need any papers related to VIV or any help with CFX just let me know, send me an email at vmlxb6@mail.mst.edu Hope that helped. 

February 3, 2012, 00:34 

#6  
Member
^^
Join Date: Aug 2011
Posts: 70
Rep Power: 7 
Quote:
then I turn on transient and put my ccl expression. the cylinder does not move ... do you have any idea about this situation? Best Regards, have you been experienced simulation at high re n 

February 3, 2012, 12:08 

#7 
Senior Member
Ugly Kid Joe
Join Date: Aug 2010
Posts: 193
Rep Power: 8 
Am sorry but I have never encountered such a problem.


Thread Tools  
Display Modes  


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
benchmark: flow over a circular cylinder  goodegg  Main CFD Forum  12  January 22, 2013 12:47 
Moving a Cylinder in cross flow after solving Dynamics equations of motion  maruthamuthu_venkatraman  OpenFOAM  1  November 19, 2009 14:55 
Flow over a flat plate & Flow over a cylinder  cfdxue  Main CFD Forum  0  November 27, 2007 00:26 
Anybody knows smth abt the flow around a cylinder?  Wenxuan  Main CFD Forum  3  March 20, 2007 17:19 
Flow over a cylinder  Anna  Main CFD Forum  9  March 24, 2006 15:32 