1. Flow Simulation of a Maple Seed
Jake Holden
Thomas Caley
Dr. Mark Turner

2. Goals & Objectives
Question to answer: “How has time optimized this natural wind turbine?”
Understand/discover the physical and rotational properties of the maple seed
Simulate the flow field of a falling maple seed
Post-process the results to analyze and understand the flow field
Modify standard conditions and design to explore wind turbine potentials

3. Timeline
Task 1 2 3 4 5 6 7 8 9 10 11 12
Understand goals and review literature
Quantify seed specimens
Learn CFD tools
Simple ducted flow simulations
Full falling seed simulation
Solution analysis and concept testing
Final takeaways and deliverables

4. Accomplishments Collected Seed samples (12)
CT Scans of seeds to acquire 3D model
Recorded falling maple seeds with high-speed camera at 3000 frames/second
Quantified high-speed data (rotation speed, angle of rotation, and fluid velocity)
Computational Fluid Dynamics (CFD) simulation of seed falling in duct to analyze work done by seed

5. CT Scans
1. Seeds were placed in foam fixture on their back edge to prevent blade distortion and allow multiple parts per scan.
2. Fixture was placed in machine on turntable

6. 3D Geometry
CT scanning time takes about 1.5 hours, then final model must be constructed in proprietary software
*All geometry thanks to Exact Metrology donating time and expertise

7. High-Speed Data (1 of 2)
Species Species Species 3

8. High-Speed Data (2 of 2)
Species 1
Species 2
Species 3

9. Flow Physics

10. Computational Fluid Dynamics Workflow
Geometry (CT Scans)
Grid Fluid Volume
Establish Models & Assumptions
Run CFD Solver
Post Process Solution

11. Assumptions/Model Pressure outlet wall and rotating seed body
Incompressible Flow
Steady Flow
Three-Dimensional
Turbulence Modeling (k-ε)
No structural deflection (rigid body)

12. CFD Simulation (1 of 8) Cylindrical Domain Grid Generation
≈ 2 million pts

13. CFD Simulation (2 of 8)
Relative Velocity Stream tubes extended in both directions to show fluid as seen by the seed

14. CFD Simulation (3 of 8)
Relative Velocity Stream tubes on Pressure (bottom) and Suction (top) sides

15. CFD Simulation (4 of 8)
Relative Velocity Stream tubes on Pressure (bottom) and Suction (top) sides

16. CFD Simulation (5 of 8)
Relative Velocity Stream tubes at Leading Edge

17. CFD Simulation (6 of 8)
Relative Velocity Stream tubes looking from tip to seed illustrating Leading Edge incidences

18. Seed Static Pressure Contours
CFD Simulation (7 of 8)
Suction Side (Top)
Pressure Side (Bottom)
Seed Static Pressure Contours

19. CFD Simulation (8 of 8) Outlet Inlet
Relative Total Pressure contours on the inlet and outlet of the duct (*notice the average drop in Pt)

20. Performance Analysis (1 of 2)
Figures of Merit:
Axial Induction Factor
Lift vs. Weight

21. Performance Analysis (2 of 2)

22. Next Steps
Balance Lift & Weight by tweaking flow velocity and rotational velocity
Modify geometry to observe how specific features impact flow characteristics
Draw comparisons and continue analyzing in terms of wind turbine performance

23. References
Sairam, K. (2013) “The influence of Radial Area Variation on Wind Turbines to the Axial Induction Factor”, M.S. Thesis, University of Cincinnati, Cincinnati, Ohio
Normberg, R. A. “Auto-Rotation, Self-Stability, and Structure of Single-winged Fruits and Seeds (Samaras) with Comparative Remarks on Animal Flight” Biology Review 48 (1973), Print.
*Special Acknowledgement to Exact Metrology for scanning images