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

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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

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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