# SOWFA - confused by the input file named airfoilProperties **URL:** \ **Category:** Computer-Aided Engineering Software Tools\ **Created:** [April 13, 2014, 10:31am UTC](https://forums.nlr.gov/t/sowfa-confused-by-the-input-file-named-airfoilproperties/889 "2014-04-13T10:31:05Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Felix.Li](https://avatars.discourse-cdn.com/v4/letter/f/a3d4f5/32.png) [@Felix.Li](https://forums.nlr.gov/u/Felix.Li)\ **Post date:** [April 13, 2014, 10:31am UTC](https://forums.nlr.gov/t/sowfa-confused-by-the-input-file-named-airfoilproperties/889/1 "2014-04-13T10:31:05Z")
As we all known the lift and drag coefficients are the functions of AoA and Re. But why the value of C\_l and C\_d in the file airfoilProperties just change with AoA? Is the effect of Reynolds number neglected? Why? ---
**Author:** ![Jason.Jonkman](https://dub1.discourse-cdn.com/nrel/user_avatar/forums.nlr.gov/jason.jonkman/32/3086_2.png) [@Jason.Jonkman](https://forums.nlr.gov/u/Jason.Jonkman)\ **Post date:** [April 14, 2014, 1:17pm UTC](https://forums.nlr.gov/t/sowfa-confused-by-the-input-file-named-airfoilproperties/889/2 "2014-04-14T13:17:57Z")
Dear Felix, Often lift and drag coefficients do not vary enough with Reynolds number over the range of Reynolds numbers where a turbine operates to warrant modeling the variation of airfoil coefficients with Reynolds number. However, the ReNum option of AeroDyn can be used to model the variation of airfoil coefficients with Reynolds number if warranted. Best regards, ---
**Author:** ![Felix.Li](https://avatars.discourse-cdn.com/v4/letter/f/a3d4f5/32.png) [@Felix.Li](https://forums.nlr.gov/u/Felix.Li)\ **Post date:** [April 18, 2014, 3:45am UTC](https://forums.nlr.gov/t/sowfa-confused-by-the-input-file-named-airfoilproperties/889/3 "2014-04-18T03:45:32Z")
Dear Prof. Jonkman, Thanks for your explanation. I have understand. Best wishes, Felix Li