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Vortex shedding

AlwynHartman

New member
Hi everyone, this is my first post.


Anyway, Im trying to make an animation of vortex shedding from airflow over a cylinder. Ive done it in Floworks and the preview looks fantastic. The problem is that when I want to display theresults with flow trajectoriesafter the solver is done, I can only get a fixed point it time.


How can I make the animation so that it shows the development of the vortex over time?


Thanks!
 
Alwyn,


Hello, and welcome! It sounds like you have solved a steady state analysis. To create the classic vortex video (like this) you need to conduct a transient analysis. This will enable the tool to calculate the vortices as a function of time.


You will notice in the bottom left of the video above, that each frame of the video is a different time step. To get the proper resolution for your video, you may need to solve hundreds of time steps (computing-wise, this is the equivalent to solvinghundreds of steady state analyses!)


Good luck, and please share the video when its ready!


Jim Shaw
http://www.linkedin.com/in/shawengineering
 
Hi Jim, thanks!


Im assuming that the option "output step" under the "Time dependent" option can control this resolution you speak of. Its usually set to "0" but I found that if I put a value of say "0.1" then the solver wil save a flow state at 0.1 second intervals in the simulation's physical time progression.


Ill give it a try!
 
I forgot to mention but Im using Solidworks 2010 with their Flow simulation (not express).


On the DS website they are quick to say that transient analysis IS possible within Solidworks but I have yet to figure how. All other info I can find is the video on youtube with the manifold from Texas engineering. But since this in an internal study, I cant copy the procedure they used.
 
SUCCESS! ! ! !<?:namespace prefix = o ns = "urn:schemas-microsoft-com:eek:ffice:eek:ffice" /><O:p></O:p>


To all parties interested, I have successfully created an externaltransient flowanalysis in Solidworks. I suppose this wording is rather misleading since the creation of such a study is easy. The hard part is animating the actual development of the results over time.<O:p></O:p>


DS has made it deceptively difficult to create such representations but once you know how (as with all things) its quite simple. The trick lies in the "animation" option of the representation of your choosing. For example, lets say you want to see a set of flow trajectories as they develop over time. the procedure is then as follows;<O:p></O:p>


1. insert flow trajectories of whatever type you choose.<O:p></O:p>


2. right click on the created flow trajectory and click on "animation".<O:p></O:p>


3. look at the animation control at the bottom of the screen and find the icon that will give a tool tip of "more", click it.<O:p></O:p>


4. youshould see a time line with at least two lines, one for the entire animation and one for the feature animation (in this case the flow trajectory). <O:p></O:p>


5. find the "animation wizard" icon (camera with some stars), click it.<O:p></O:p>


6. the box comes up<O:p></O:p>


7. check the "delete all existing tracks" box and set the total time to what you want. Play around with it till you get acceptable results. Click next.<O:p></O:p>


8. select scenario. next<O:p></O:p>


9. here, I choose "proportional" and leave the rest as it is, read the help for a deeper explanation. next<O:p></O:p>


10. click finish if youre happy with the settings.<O:p></O:p>


11. a set of what looks like diamonds should now lie in the timeline window. Its very important to hover your mouse over the area to the left of the 00.00 time in line with the flow trajectories feature and right click. Select "insert control diamond".<O:p></O:p>


12. a new control point is created and displays as two diamonds with a line between them. Click and drag the latest one so its in line with the end time of the animation.<O:p></O:p>


13. Hit "play"!<O:p></O:p>


There are a few things that will influence the results that must be in place during the setup phase of the analysis. I will elaborate on that when I post the video of my results.
Edited by: AlwynHartman
 
I tried everything you said Mr. Hartman. But it still does not work. can
you kindly make a video of it and upload it. It would be real nice of
you. Thanks
 

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