The SPH HTC Calculator module calculates the heat transfer coefficient, denoted as h, using the following equation:

(2–67)

where is the local Nusselt number, is the fluid thermal conductivity (user input) and L is a characteristic length (user input).

The Nusselt number is determined based on the and numbers, and it is expressed as:

(2–68)

where and are user-defined coefficients ( Coefficient (L) and Coefficient (T) , respectively). a, b, c, and d are exponents defined by the user ( Reynolds Number Exponent (L) , Prandtl Number Exponent (L) , Reynolds Number Exponent (T) , and Prandtl Number Exponent (T) ).

The module determines whether to use the laminar or turbulent coefficients based on the laminar-turbulent threshold, set by the user as the Threshold Reynolds Number.

The Prandtl number is calculated as follows:

(2–69)

where is the fluid specific heat, given as Specific Heat , and is the fluid dynamic viscosity, extracted from the fluid material.

A single Reynolds number is computed for each triangle using the formula:

(2–70)

where and are the fluid density and dynamic viscosity and L is the Characteristic Length.

The velocity is the parallel fluid velocity at a distance from the center point of the triangle in a direction perpendicular to its plane. The distance is computed as:

(2–71)

where is a distance factor specified by the Distance Factor and is the SPH element spacing.