vortices do not move

va-ta-cfd · February 1, 2011, 07:23

Hello
I am simulating a transient flow around a cylinder (the classical problem) with ansys-cfx12. the problem information is as follow:
cylinder diameter: 5 cm
air flow speed: 10 m/s
time step: 0.05 s
duration: 1 s
There are two main problems:
1. I can see to symmetrical vortices behind the structure in the shadow region in cfx post by velocity countors or by velocity streamline but unfortunately the vortices are steady in position and do not move by changing time step (I also have change the velocity to 20 m/s but the vortices didnt move any more)
2. CFX did not calculate helicity and i can not draw vortex core regein any more
I hope that there whould be anyone to solve my problems.

joey2007 · February 1, 2011, 17:01

How many mesh cells along the cylinder?

ad281 · February 1, 2011, 17:13

v cccxzzzzzzzzzzzzzzzz

ghorrocks · February 1, 2011, 18:36

http://www.cfd-online.com/Wiki/Ansys..._inaccurate.3F

February 1, 2011, 07:23	vortices do not move	#1
va-ta-cfd New Member Vahid Join Date: Jan 2011 Posts: 23 Rep Power: 15	Hello I am simulating a transient flow around a cylinder (the classical problem) with ansys-cfx12. the problem information is as follow: cylinder diameter: 5 cm air flow speed: 10 m/s time step: 0.05 s duration: 1 s There are two main problems: 1. I can see to symmetrical vortices behind the structure in the shadow region in cfx post by velocity countors or by velocity streamline but unfortunately the vortices are steady in position and do not move by changing time step (I also have change the velocity to 20 m/s but the vortices didnt move any more) 2. CFX did not calculate helicity and i can not draw vortex core regein any more I hope that there whould be anyone to solve my problems.

February 1, 2011, 17:01		#2
joey2007 Senior Member Join Date: Mar 2009 Location: Europe Posts: 169 Rep Power: 17	How many mesh cells along the cylinder? __________________ - - - - - ------------------------------------------------------------------------ Please do not forget: I am not paid for answering your questions. Thousands of issues can cause a division by zero. Please do not capture a thread, with the argument: "I have the same issue ...."

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February 1, 2011, 17:13		#3
ad281 New Member Adrian Dunne Join Date: Jan 2011 Location: Ireland Posts: 26 Rep Power: 15	v cccxzzzzzzzzzzzzzzzz

February 1, 2011, 18:36		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,872 Rep Power: 144	http://www.cfd-online.com/Wiki/Ansys..._inaccurate.3F