Transient temperature rise of outer surface by object k

This is the temperature rise of cable p due to the total power $W_{tot}$ dissipated in cable k.

Symbol
$\Delta \theta_{kp,t}$
Unit
K
Formulae
$\frac{W_{tot} \rho_4}{4\pi} \left(-\operatorname{expi}\left(\frac{-\left(\frac{d_{pk2}}{1000}\right)^2}{4\tau \delta_{soil}}\right)+\operatorname{expi}\left(\frac{-\left(\frac{d_{pk1}}{1000}\right)^2}{4\tau \delta_{soil}}\right)\right)$