Wetsuit Thickness

ME340Winter 2008

Michael RoseDaniel Madsen

Project Objective

• To create a program which calculates the thickness for custom neoprene wetsuits that will maintain an individual at a comfortable body temperature.

Physical Model• The human body is modeled as a

cylinder with an internal core surrounded by:• a 3 mm layer of skin • a 1 mm layer of water• a wetsuit of unknown

thickness• forced convection currents

from surrounding water

mmC

r 321

4r

3r2r1r

H mmrr 312

tmmrr 414

mmrr 413

C = Diver’s waist size

KmWkskin 37.0

OHk 2

KmWkneo 05.0

Dependent on water temp.

Thermal AnalysiscT2R

T1R3R4R

SkinWater Layer

WetsuitForced Convectio

n

Hk

rr

Rskin

2

ln1

2

1

Hk

rr

Rneo

2

ln3

4

3 HrhR

4

42

1

Hk

r

r

ROH

2

2

ln2

3

2

Body Core Temperature

Outside Water

Temperature

4321 RRRR

TTq c

q

• Constant heat generation from body depending on weight:

Where Tc = 98.6 degrees Fahrenheit, and:

Thermal Analysis cont.

HV

H

Re

3/12/1 PrRe664.0 HHNu

H

kNuh OH

H2

• Calculating the convective coefficient:

• Velocities estimated at a maximum of 3-4 m/s due to swimming speed of diver.

• Nusselt number equation used for flat plate in parallel flow. (Outer surface of cylinder modeled as flat plate).

• Wetsuit thickness (t) is calculated from the above equations by the program using Newton-Rhapson numerical method.

User Interface

• User inputs:• Height (H) [in.]• Waist Size (C) [in.]• Weight (W) [lbs]• Water Temperature

• Outputs:• Wetsuit Thickness (t) [mm]

• Screen Shot of the User-Interface

)( T ][ Fo

How does it all work?

The program uses a series of algorithms to perform the necessary calculations. First, the input values are converted into metric values. The heat generation is calculated using a linear curve fit of data based on calories burned during scuba diving. The properties of water are determined based on the water temperature input by the user. This is done through a database lookup. Interpolation is used as needed. The forced convection of the water is determined using the properties of water at the given temperature. Finally, the Newton-Rhapson method is used to solve for the wetsuit thickness.