Scaling Airfoil

morteza08 · November 7, 2015, 10:12

Hi friends;
I am going to model an airfoil in Gambit/Fluent. I prefer to model airfoil with a chord rather than 1. All the airfoil databases provide dimensionless airfoil coordinates.
Which way do you suggest me:
1: Scaling the coordinates before inserting them to Gambit. This may help more precise grid generation(I think so).
2: Insert the dimensionless coordinates to Gambit and then scale them., (I do not know if Gambit has scaling feature.)
3:My last option is to generate the grid with the existing dimensionless coordinates and postpone the scaling to Fluent. Does scaling in Fluent affect the results?

Please help me by selecting the best option and explain the pros and cons of each way.

LuckyTran · November 9, 2015, 00:44

Numerical conversions tend introduce small roundoff/truncation/conversion errors. To avoid introducing these errors, it's best to do option 1 where you scale the coordinates before going into gambit. Also it's best to save the mesh in binary format and not ascii if you are worried about these small errors.

November 7, 2015, 10:12	Scaling Airfoil	#1
morteza08 Senior Member Morteza Join Date: May 2010 Location: Iran,Islamic Republic of Posts: 161 Rep Power: 15	Hi friends; I am going to model an airfoil in Gambit/Fluent. I prefer to model airfoil with a chord rather than 1. All the airfoil databases provide dimensionless airfoil coordinates. Which way do you suggest me: 1: Scaling the coordinates before inserting them to Gambit. This may help more precise grid generation(I think so). 2: Insert the dimensionless coordinates to Gambit and then scale them., (I do not know if Gambit has scaling feature.) 3:My last option is to generate the grid with the existing dimensionless coordinates and postpone the scaling to Fluent. Does scaling in Fluent affect the results? Please help me by selecting the best option and explain the pros and cons of each way.

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November 9, 2015, 00:44		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,668 Rep Power: 65	Numerical conversions tend introduce small roundoff/truncation/conversion errors. To avoid introducing these errors, it's best to do option 1 where you scale the coordinates before going into gambit. Also it's best to save the mesh in binary format and not ascii if you are worried about these small errors.