1. PURPOSE / DESCRIPTION

• To set a standard procedure for airfoil simulation in ANSYS Fluent
• The procedure follows the wind tunnel simulation that was run for the NX Drone
• Useful resources:
  • “Workshop 07: Sliding Mesh” from ANSYS Fluent full course materials
  • Full course videos on ANSYS website for Fluent.
  • “Workshop 04: Airfoil” from ANSYS Fluent full course materials
  • Airfoil Tools: http://airfoiltools.com/airfoil/details?airfoil=naca0015-il
  • UIUC Airfoil Database: http://m-selig.ae.illinois.edu/ads/coord_database.html
  • How to import/plot points: http://pjotr.ru/ansys_dm_01/
  • General Tips: http://www.computationalfluiddynamics.com.au/category/tips-and-tricks/
  • Air Properties Calculator: http://www.mhtl.uwaterloo.ca/old/onlinetools/airprop/airprop.html
• If you have no experience with ANSYS, it is recommended that you go through the ETP for Learning ANSYS.

 

2. Geometry & Meshing PROCEDURE (without explicit inflation layer definition)

NOTE: These instructions match the steps taken in SimCafe’s tutorial on airfoil ( https://goo.gl/OLIX5g) and the tutorial regarding importing points (http://pjotr.ru/ansys_dm_01/)

• Find online the coordinates for the desired airfoil.
  • You need to write the points into a .txt file with the following format:
  • Any lines beginning with #’s are simply comments and do not have to be included.
  • There can be spaces and tabs between the numbers so do not worry too much about delimiting using only one space.
  • The first number is the group number and the second is the order within the group. The remaining three numbers are the XYZ coordinates of each point. You only need 1 group, however, for this procedure.
• Follow the first 5 steps in the tutorial about point importing. Because this is a 2D procedure, you will only have one surface (one group of points) to create.
  • Before creating the surface of the Make sure to zoom into the trailing edge and connect the open points after creating the curve from the points.
• After
  Use the same geometry made with the instructions from SimCafe but without the line projections.
  • The geometry should look similar to this:
• Open Meshing and change the settings of Mesh to match the settings below (except for Statistics):

• SETTINGS (especially Min Size) SHOULD BE ALTERED, TESTED, AND EXPERIMENTED WITH DEPENDING ON THE GEOMETRY.
• The statistics should be checked, as mentioned, each time the mesh generated.
• For 2D mesh, an orthogonal quality above 0.4 is preferred, but using inflation will most likely result in lower OQ, which is acceptable.

• RCLK on Mesh > Insert > Sizing

Scoping	Scoping Method	Geometry Selection
	Geometry	Select the main edge of the airfoil. (excluding the trailing edge)
Definition	Type	Number of Divisions You can also use Element Size.
	Number of Divisions	900 Adjust number of divisions as needed.
	Behavior	Soft
	Bias Type	_____  ___  _  ___  _____ This is to have smaller sizing near the trailing edge in order to improve orthogonal quality. Adjust according to the geometry.
	Bias Option	Bias Factor
	Bias Factor	35 Adjust bias factor as needed.

• RCLK on Mesh > Insert > Sizing

Scoping	Scoping Method	Geometry Selection
	Geometry	Select the trailing edge of the airfoil.
Definition	Type	Number of Divisions Or you can use Element Size and use a size that is about half the height of the trailing edge.
	Number of Divisions	2
	Behavior	Hard
	Bias Type	No Bias

• RCLK on Mesh > Insert > Inflation

Scoping	Scoping Method	Geometry Selection
	Geometry	Select the main surface (do not select it as a body)
Definition	Boundary Scoping Method	Geometry Selection
	Boundary	Select the main edge (excluding the trailing edge) of the airfoil
	Inflation Option	First Layer Thickness Choose appropriate option depending on the situation.
	First Layer Height	.1 mm This was the desired first cell height calculated for an Re of 3000000. Calculate and use an appropriate height, or use another method.
	Maximum Layers	20

• (Optional)
  • RCLK on Coordinate Systems > Insert > Coordinate System

Origin	Define By	Global Coordinates
	Origin X	1500 mm Select appropriate coordinates so that the sphere of influence is slightly to the right of the trailing edge.
	Origin Y	0
	Origin Z	0

• Mesh > Insert > Body Sizing

Scoping	Scoping Method	Geometry Selection
	Geometry	Select the main body (do not select it as a surface)
Definition	Type	Sphere of Influence
	Sphere Center	Coordinate System Or select the coordinate system created in the step above.
	Sphere Radius	2000 mm This can be altered as needed.
	Element Size	40 mm This can be altered as needed. You can change this to do mesh independence study as well.

• Creating Named Selections
  • Select the edges that form the airfoil
    • RCLK on the graphics window > Create Named Selections
    • Name it “wing”
  • Do the same for the edges for the inlet and outlet as shown:

Example of how it should look: