Group 19Hing Lawrence LauJonathan LawsonBryan UrquhartSammy Zargaran
The Swimming D nut Sponsor: Dr. Lauga
Swimming Donut 2
Dr. Eric Lauga
Ph.D. in Applied Mathematics from Harvard in 2005
Assistant professor at MIT in the Mathematics department from 2006 to 2007
Professor Lauga's research focuses on physical hydrodynamics, micro-fluidics, biophysics and the biomechanics of locomotion
Sammy
Swimming Donut 3
Many microorganisms move by means of flagella. The motion of the flagella propagates down the length like a sine wave.
Real World Motivations IProject Objectives
Sammy
Swimming Donut 4
,2
30 1, 30 , 1 , 1 6 Re
21 6
3 5Rem msmUD mU D m Es s mE s
E
Similarity analysis can be performed to quantify flow characteristics:
-
This type of creeping flow with Re<<1 is called Stokes Flow
Real World Motivations IIProject Objectives
Sammy
Swimming Donut 5
Microorganisms live in the Stokes Flow regime
Viscosity effects dominate over momentum effects
Microorganisms move by means of flagella These flagella have many degrees of freedom
Why isn’t there a microorganism that moves Why isn’t there a microorganism that moves via via single degree of freedom motion?single degree of freedom motion?
Real World Motivations III
Sammy
Project Objectives
Swimming Donut 6
Single Degree of Freedom
Capable of motion in Stokes flow (Re << 1)
Never witnessed in nature
A Self-contained torus, designed to move in Stokes Flow, has never been constructed
Project goal was to create a torus that can move in the Stokes Flow regime
How does it work?
Enter The Swimming D nut
Project Description
Sammy
Swimming Donut 7
The surface of the torus rotates as shown which results in Torus motion.
ω ωuu
How it Moves I
Jonathan
Swimming Donut 8
How it Moves II
Flow Field
Jonathan
Swimming Donut 9
Final Design: Overview
Features: Two miniature geared motors to rotate surface Controlled with model aircraft motor driver for wireless
control
Jonathan
Swimming Donut 10
Actuation System
Motor
Lawrence
Motor MountDive Disk attachedto Motor Assembly
Swimming Donut 11
Power System
Battery Housing
PCB
Battery Protection Circuit and Motor Drive Housing
Lawrence
Cool Feature:snap fitting
base forhousings
Swimming Donut 12
Control System
Motor Driver Receiver Housing
Transmitter
Lawrence
Motor Driver Housing
Swimming Donut 13
Rotating Skin
Lawrence
Helical Coil as supportto maintain longitudinalcross-section
Swimming Donut 14
Demonstration
Swimming Donut 15
Heat Generation
Assumptions: The skin of the torus was
a perfect insulator and that no heat would be lost to the fluid
All energy consumed by components was converted into thermal energy
Material Mass (g)Specific Heat
(J/kg*K)
Acrylic 75 1172
Copper (In motor) 27 387
Steel 8 452
Silicon 5.25 700
Air ~0 1042
Total 115.25
Average (by mass) 908.9
The total increase in temperature when the system is run for 30 minutes is 35 K
Jonathan
Swimming Donut 16
Power Consumption
Jonathan
Component Power Dissipated as Heat (W) Quantity Total Power ΔQ (J)
Motors 0.57 2 1.14 2052
PCB board ~0 1 ~0 ~0
ESC 0.6 1 0.6 1080
Battery 0.08 4 0.31 560
Total 2.05 3692
Theoretical Power Consumption (not loaded):
Actual Power Consumption (loaded) is 3.7W
while the tested battery life is 52 mins
Theoretical battery life is 92 mins
Swimming Donut 17
Fluid Simulation I
To gain some initial insight to the torus motion, a MATLAB simulation was constructed.
Approximating a section as a cylinder, shear stresses were calculated.
Integrating the shear stress with respect to area leaves a net force on the torus which is the basis of its motion.
a ω
Bryan
2
A1 A2
Swimming Donut 18
Some results using current size parameters:
Velocity:
This may seem slow, but this is actually faster than the motion expected by our sponsor
Fluid Simulation II
2.2 , 100.6
a cm c cm
1cmu s
Bryan
Swimming Donut 19
Performance
The donut successfully rotates as intended around the internal components
Performance Characteristics: Runtime – 52 minutes Rotational Speed – 6 rpm
Bryan
Swimming Donut 20
Conclusions / Recommendations
Different Motor Controller Computer control
Actuation Data Acquisition
Fluid-Torus Interface Power
Battery Charging External Power Button
Slip Ring(s)
Bryan
Swimming Donut 21
Acknowledgments
Dr. Nathan Delson – Instructor, Mechanical Engineer
Dr. Eric Lauga – Project Sponsor, Mathematician
Chris Cassidy – Design Studio Manager, Development Engineer
Anne Tatlock – Faculty Assistant
Tom Chalfant – Machine Shop Manager, Development Engineer
Steve Roberts – Electronics Lab Manager, Development Engineer
Damon Lemmon – Teaching Assistant, UCSD Graduate Student
Shawn Thomson – Application Engineer, MicroMo Electronics
Dave Lischer – Project Design Lab Manager, Development Engineer
Bryan
Dr. NateDelson
Dr. Eric Lauga
Tom Chalfant
Dave Lischer
Chris Cassidy
Bryan
