Airfoil analysis - the output values differ from the theoretical ones

HSalwa · November 15, 2015, 07:13

Dear forum members,

The aim of my project is aerodynamical analysis of an airfoil. After making a simulation in Ansys CFX, I have recieved the output values of drag and lift coefficient that are far from theoretical ones.
I have made the simulation for other geometrical figures. For the sphere the drag coefficient was close to the theoretical one (simulation value: 0,55 theoretical: 0,47) but for the square it was much bigger (simulation: 2,18 , theoretical: 1,05).
As I want to describe the problem and my simulation steps clearly, I have described the problem in pdf file attached to the link: http://www33.zippyshare.com/v/mpBCLF6y/file.html

Thank you in advance for help with this problem, I also hope that's not a problem with describing the problem in pdf file, not in post.

ghorrocks · November 15, 2015, 18:15

This is an FAQ: http://www.cfd-online.com/Wiki/Ansys..._inaccurate.3F

In this case you comment that mesh and boundary position changes affect the results - this shows you have a problem in both these areas. You need a finer mesh and move the boundary further away.

November 15, 2015, 07:13	Airfoil analysis - the output values differ from the theoretical ones	#1
HSalwa New Member Hubert Join Date: Nov 2015 Posts: 1 Rep Power: 0	Dear forum members, The aim of my project is aerodynamical analysis of an airfoil. After making a simulation in Ansys CFX, I have recieved the output values of drag and lift coefficient that are far from theoretical ones. I have made the simulation for other geometrical figures. For the sphere the drag coefficient was close to the theoretical one (simulation value: 0,55 theoretical: 0,47) but for the square it was much bigger (simulation: 2,18 , theoretical: 1,05). As I want to describe the problem and my simulation steps clearly, I have described the problem in pdf file attached to the link: http://www33.zippyshare.com/v/mpBCLF6y/file.html Thank you in advance for help with this problem, I also hope that's not a problem with describing the problem in pdf file, not in post.

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November 15, 2015, 18:15		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	This is an FAQ: http://www.cfd-online.com/Wiki/Ansys..._inaccurate.3F In this case you comment that mesh and boundary position changes affect the results - this shows you have a problem in both these areas. You need a finer mesh and move the boundary further away.