SF_4
Function SF_4 provides the shape factor ([m] or [ft])for conduction between two cylinders that are buried in an infinite medium.
Inputs:
D_1 = diameter of cylinder 1 ([m] or [ft])
D_2 = diameter of cylinder 2 ([m] or [ft])
w = distance between cylinder centerlines ([m] or [ft])
L = length of cylinders ([m] or [ft])
Example: SF = SF_4(D_1, D_2, w, L)
Reference: Incropera, F. & DeWitt, D. (2002). Fundamentals of heat and mass transfer, 5th ed. Hoboken, New Jersey: John Wiley & Sons. p. 193-194.