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January 29, 2011, 16:40 
Flow over a cylinder

#1 
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Ugly Kid Joe
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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 
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Ugly Kid Joe
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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 
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Glenn Horrocks
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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  
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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  
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Ugly Kid Joe
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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  
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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 
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Ugly Kid Joe
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Am sorry but I have never encountered such a problem.


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