702-04

EP-702 Wind Tunnel Setup Procedure (ANSYS Design Modeler & Meshing)

Wikis > EP-702 Wind Tunnel Setup Procedure (ANSYS Design Modeler & Meshing)
  • ANSYS Meshing
    • Click on Solid (the box created above) in Outline
      • Graphics Properties > Transparency = 0.2
    • Figure to the right is what the setup should look similar to
    • RMB on Solid in Outline > Suppress Body
    • Basic options
      • Mouse selection:702-05 these allow seleciton of vertices, edges, faces, and bodies
      • View controls: 702-06 the leftmost button is the most useful because it allows you to set the center of rotation for the view by left clicking.
    • Click on Mesh > Statistics > Mesh Metric = Orthogonal Quality
      • Make sure that you can see the Metric Graph by clicking the button 702-07
      • It is important to check the quality of the Mesh each change and update through Orthogonal Quality and Metric Graph. (a surface mesh’s Min should be above about .4, and a full mesh’s Min should be above about .05) There is no reason to generate the full mesh when the surface mesh’s quality is not satisfactory.
    • Select the 6 faces of the enclosure > RMB on graphics window > Hide Face (F8)
      • This is to be able to select and work with the surface of Drone
      • When you need to select the enclosure’s faces, RMB on graphics window > Show Hidden Face(s)
    • RMB on Mesh in Outline > Preview > Surface Mesh
      • Use Surface Mesh to observe the mesh before generating the entire mesh. If the surface mesh has a bad quality there is no point in generating the entire mesh.
    • Click on New Section Plane 702-08
      • Make a section plane as shown below by drawing a vertical line slightly off the center of the front face.702-09
      • Create more section planes as needed throughout the steps
    • Click on Mesh
      • Change settings:
Defaults Physics Preference CFD
Solver Preference Fluent
Sizing Use Advanced Sizing Function On: Proximity and Curvature
Relevance Center Fine
Span Angle Center Fine
Curvature Normal Angle 10°

(should be adjusted depending on geometry)

Min Size .7 mm

This should be adjusted after examining the surface mesh. If there are features that are not well resolved because the cell size is not small enough, then decrease the size. However, wing features will be dealt with later, so if there are no problems except the wings, then leave this as default. Check the Orthogonal Quality after each change.

Patch Conforming Options Triangle Surface Mesher Advancing Front
Defeaturing Automatic Mesh Based Defeaturing On
  • Creating Named Selections
    • Select the faces on Drone that are not part of the wing (or parts that need more refining).
      • RMB on graphics window > Create Named Selection
      • Name it ‘wall_body’
    • Select the faces of the wings
      • RMB on graphics window > Create Named Selection
      • Name it ‘wall_wing’
    • RMB on graphics window > Show Hidden Face(s)
      • Using the same procedure as above, name the front side of the enclosure ‘inlet’.
      • Name the back side ‘outlet’.
      • Name the 4 remaining sides ‘walls’.
    • RMB on Mesh > Insert > Sizing
Scope Scoping Method Name Selection
Named Selection wall_wing
Definition Element Size 1 mm

Use appropriate size to get accurate results on the wings

Behavior Soft
Curvature Normal Angle
  • RMB on Solid (the suppressed box) > Unsuppress Body
    • RMB on Mesh > Insert > Sizing
Scope Scoping Method Geometry Selection
Geometry Select Tunnel
Definition Type Body of Influence
Bodies of Influence Select the box
Element Size 8.0 mm

Use appropriate size to refine the mesh around Drone.

  • RMB on Mesh > Insert > Inflation
Scope Scoping Method Geometry Selection
Geometry Select the entire body of the system
Definition Boundary Scoping Method Named Selections
Boundary wall_wing, wall_body (Ctrl to select multiple)
Inflation Option Smooth Transition
  • This example that the procedure follows employs Smooth Transition to inflate the subject because the resulting grid was found to be sufficient; however, it is recommended that you calculate the desired first cell height and use the other methods instead of Smooth Transition. Cases in which aerodynamic drag is important require y+ values less than 10 in order to resolve the viscous sublayer, so use First Cell Height Calculator.xlsx provided or an online tool to calculate the first cell height using appropriate values.
  • Click on Mesh
    • Inflation > View Advanced Options = Yes
    • Inflation > Maximum Angle = 180.0°
  • RMB on Mesh > Preview > Inflation
    • Check that the Min for Orthogonal Quality is above .05.
  • Click on Generate Mesh

 

NOTE: Options chosen and changed depend on the geometry of the model and the characteristics of the problem. Judgment should be based on what is learned in the courses and comparison of different settings. Other options for inflation and sizing should be explored for improvement.

3. Example Result702-10

  • Orthogonal Quality Min value should be above .05

 

4. TEST RECORDS

  • 1st setup

702-11

 

 

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