Graphical representation of the method used to calculate the numerical perpendicular conductivity. The dots represent the final maximum temperature minus initial maximum temperature (∆T) in the simulations with different values of k_⊥ shown at the horizontal axis. The dashed line is the difference of temperature (∆T_num) in the simulation with κ_⊥ = 0. We fit the data to a hyperbolic tangent function (solid line). The numerical perpendicular conduction coefficient к_⊥,num is estimated by locating the position where the first derivative of the fit is 100 times smaller than its maximum value.