# Substitution coefficient u

Substitution coefficient for the calculation of the thermal resistance of the equivalent radius of backfill to ambient.

Symbol
$u_b$
Formulae
 $\frac{L_b}{r_b}$ from $L_b$ and $r_b$ $\frac{e^{G_b}+1}{2e^{G_b}}$ from $G_b$
Related
$L_b$
$r_b$
Used in