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-   -   [ICEM] Question about creating the geometry in ICEMCFD (http://www.cfd-online.com/Forums/ansys-meshing/76654-question-about-creating-geometry-icemcfd.html)

cxcxcx0505 June 1, 2010 04:50

Question about creating the geometry in ICEMCFD
 
I am meshing 2D airfoil in ICEMCFD.
I saw a tutorial in youtube,but it used "formatted point data" to input the geometry.The ratio of the far field boundary to the chord length of my project is much more bigger.I need many points in order to create a nice mesh.So,I plan to import the geometry using other method like DWG or something else.Is there any other method to build the geometry because I am quite blur how to input the function of y to create the geometry without using points or using points.
Thanks.

PSYMN June 2, 2010 10:28

Sure...
 
Yes, of course. If you have access to a real CAD tool, you should use it instead of the ICEM CFD Geometry tools... We are not in the geometry tool business, although the do help in many situations. If you have ACIS or DXF or DWG, that would be great. IGES and STEP also work, but are not as good. Direct CAD interfaces to Pro/E, UG, Solidworks, Catia, etc. are the best.

If you know your function, you can have an ICEM script create the points for you (or insert the "locations" in the curve creation tool instead of points, but points are probably easier). Just set up a loop where you increment "i". Then set X = i and calculate Y with your function, then create a point for each "i". This is basically what the Naca Airfoil generators do (but they have 2 functions, one for the upper and one for the lower).

However, I disagree with your premise that you need more points because you have a larger chord length. You simply need enough points to capture the curvature. If your airfoil is rippled or something with lots of extra curvature, then you may need more points. But 150 to 300 points is easily enough to capture any NACA airfoil. Keep in mind that the curve drawn thru the line segments is not composed of linear segments, but rather is "fit" thru the points.

I could easily edit that 2D airfoil script (seen on www.Youtube.com/ansysinc) and simply increase the dimensions used when creating the 5 Far field points to create a much larger (and more realistic) far field. I only did it small so you could see the process without a lot of zooming in and out.

cxcxcx0505 June 4, 2010 02:03

Thanks for the reply.Actually I am a beginner,I just enter CFD lab.I do according to the video at youtube,then the grid look weird,I ask my professor,he said the leading edge need more points,ask me to make around 500.But,I only get 50points from the NACA0012 profile.

cxcxcx0505 June 4, 2010 02:14

oops,sorry,I wrote wrongly,should be ratio of the chord length to the far field boundary is much more bigger.And,thanks for the video at youtube!

PSYMN June 4, 2010 09:12

Curved...
 
Your prof may think that it creates straight line segments between the points. Or perhaps he wants you to have more mesh points.

Because the curve is "curved" thru the points, you get good resolution with that number of points, even if you wanted 500 mesh points along the leading edge.

Simon

cxcxcx0505 June 7, 2010 06:48

1 Attachment(s)
actually I got another question to ask,when I first import the geometry from "formatted point data",the "Curves" do not appear at the left column of geometry as like the video tutorial at youtube ,only have "subsets" and "point",my version is 12.1.I face problem when I want to associate the edge with curve

cxcxcx0505 June 7, 2010 08:08

I found the problem,it is the setting in the profile data.


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