1. Bald Head Convective Calculator Jess Rose Jeff Amelang Winter 2009

2. Calculator Functionality Goal: Create a calculator that estimates skin temperature of a bald head under three different convective conditions: Free convection Forced convection (windy) Forced convection with a beanie

3. Basic Assumptions Head is modeled as a sphere of constant temperature with a layer of tissue Steady state One Dimensional Radial Conduction Constant Properties Neglect Radiation Properties calculated using the source code of the thermal properties calculator tissue D = 7 in T = 0.25 in T_c = 98°F T_inf

4. Free Convection Convective coefficient is calculated using Free convection on a sphere Total thermal circuit Partial thermal circuit

5. Forced Convection (windy) Convective coefficient is calculated using Forced convection on a sphere Total thermal circuit Partial thermal circuit Includes Free Convection if.1 < abs(Gr/Re^2 ) < 10

6. Forced Convection with Beanie Convective coefficient is calculated using Forced convection on a sphere Total thermal circuit Partial thermal circuit Assumptions: Two parallel thermal circuits Infinite Contact Resistance between hemispheres Y

7. The Calculator

8. Improvements Approximate head with volumetric head generation instead of a constant temperature Eliminate assumption of infinite contact resistance between hemispheres with beanie Include radiation

9. Conclusions When there is convective heating of Charlie Brown’s head, the beanie keeps the skin surface temperature lower, oddly enough. Changing the conductive coefficient of the tissue has a significant effect on the temperature of the skin.