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## Calculators

Circuit Boards
• Effective Conductivity Model for Rectangular Heat Sources
This model predicts effective conductivity from a rectangular heat source, based on the composition of the substrate and boundary conditions on the source.

Fluid Properties
• Thermal Fluid Properties Calculator
Properties of air, Ar, N2 and H2 calculated based on correlations developed by Frank McQuillan. Properties of CO2, H2O(l) and the ethylene glycols are based on the correlations developed by Tom Lemczyk. The calculator takes the temperature of the fluid as input and outputs an array of properties at 1 atm.

Heat Sinks
• Natural Convection Model for Circular and Square-Finned Annular Heat Sinks
Based on the Ph.D. research of C.S. Wang, this model predicts heat transfer from natural convection horizontal annular heat sinks. The online model incorporates both fin efficiency and radiation functions.

• Natural Convection for Rectangular Heat Sinks
This model predicts heat transfer from natural convection rectangular heat sinks. The online model incorporates a fin efficiency function, and allows for both single and back-to-back configurations.

Special Functions
• Special Functions Calculator
Calculates special mathematical functions, including Gaussian error and complementary error functions, gamma functions, and Bessel functions of integer or fractional order.

• Spreading Resistance Calculator for Circular Sources on Compound and Isotropic Disks
Calculates the thermal spreading resistance for a circular source on an isotropic and two-layer circular disk, semi-infinite circular cylinder, or half space.
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• Spreading Resistance of a Circular Source on a Circular Disk with Edge Cooling
Calculates the thermal spreading resistance for a circular isoflux, parabolic or equivalent isothermal heat source on an isotropic circular disk, where the convection on the bottom and edges are described by two different heat transfer coefficients.
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• Spreading Resistance Calculator for Isoflux Rectangles and Strips on Compound Flux Channels
Calculates two- and three-dimensional thermal spreading resistance for isoflux rectangular and strip sources on an isotropic and two-layer rectangular disk, a semi-infinite rectangular cylinder, or half space.
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• Spreading Resistance of Rectangular Disk with Edge Cooling
Calculates the thermal spreading resistance for a square isoflux heat source on an isotropic square disk, where the convection on the bottom and edges are described by two different heat transfer coefficients.