$\mathrm{k}$	thermal conductivity
${\mathrm{k}}_{\mathrm{eff}}$	effective thermal conductivity
$\nabla \mathrm{T}$	temperature difference per unit thickness
$\mathsf{\rho }$	density of the coating material
${\mathrm{C}}_{\mathrm{p}}$	specific heat capacity of the coating material
${\mathrm{Q}}_{\mathrm{s}}$	total heat flow
${\mathrm{A}}_{\mathrm{s}}$	area of the top surface of the model
$∆\mathrm{T}$	temperature difference
θ	taper of the coarse column
S	the longest heat transfer path per unit thickness
γ	ratio of the height of fine column to coarse column
p	porosity of the coating
${\mathrm{h}}_{\mathrm{c}}$	height of the coarse column
${\mathrm{d}}_{\mathrm{c}}$	diameter of the coarse column
${\mathrm{h}}_{\mathrm{f}}$	height of the fine column
${\mathrm{d}}_{\mathrm{f}}$	diameter of the fine column
α	inclination angle of the entire columns
$\mathsf{\sigma }$	stress of the root of column
$\mathrm{M}$	bending moment
${\mathrm{I}}_{\mathrm{z}}$	moment of inertia of section to neutral axis z
p	external pressure on the top of the coating
${\mathrm{d}}_{\mathrm{b}}$	diameter of the root of the column
$\mathsf{\xi }$	rectangle factor of the column