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-   -   Different lift coefficients for different grids for same geona headsail (http://www.cfd-online.com/Forums/fluent/103551-different-lift-coefficients-different-grids-same-geona-headsail.html)

abhiprayj June 20, 2012 12:27

Different lift coefficients for different grids for same geona headsail
 
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Hi all,
I imported the same mesh for different camber profiles of the headsail (6 different camber profiles with same mesh) and I changed the grids named Coarse, medium and Fine grid for all 6 cambers. Thus, total number of meshes become 18. After running simulations in Ansys 13.0 fluent I got values for lift coefficients and when i compared the lift coefficients for coarse, medium and fine grids for a particular camber it gives me a value of 1.7444,1.7455 and 1.663876 respectively. For other cambers the values are quite close to each other which is required and a uniform graph can be seen when a graph is plotted between Cl and X/Chord.

For analysing any mistake which i may have done in this particular mesh ( fine mesh which gives value of 1.663876) , I made 2 graphs between the Reattachment length and X/Chord : and between trailing edge separation length and X/Chord. Xr Vs X/Chord graph seems okie but Xtes Vs X/Chord gives a zigzag profile for all the 3 different grids.
While taking the values for Xr and Xtes , i understood that the values which i take for Xr and Xtes can be wrong as those values are taken on assumptions from the graphs.

Another way to find a mistake is to compare the Contours of Velocity magnitude. But I don't know how compare them and how to find the result.

These both methods were told by my supervisor and before going to him i want to know if I am doing right thing or not.


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