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Thermal resistance by convection, air to tunnel

Convection thermal resistance between air and inner wall of the tunnel.

Symbol
$T_{at}$
Unit
K.m/W
Formulae
$\frac{1}{0.023\pi k_{air} {\mathrm{Re}_{air}}^{0.8} {\mathrm{Pr}_{air}}^{0.4}}$ventilated tunnel
$\frac{1}{2\alpha_{at} \left(w_t+h_t\right)}$in channel (Heinhold)
Related
$\alpha_{at}$
Heat transfer coefficient to channel wall [W/(K.m$^2$)]
$h_t$
Inner height [m]
$k_{air}$
Thermal conductivity of air [W/(m.K)]
$\pi$
Archimedes' constant $\pi$
$\mathrm{Pr}_{air}$
Prandtl number for air
$\mathrm{Re}_{air}$
Reynolds number for air
$w_t$
Inner width [m]
Used in
$\Delta \theta_{air}$
Temperature increase of air [K]
$\Delta \theta_s$
Temperature difference surface to ambient [K]
$T_{4iii}$
Thermal resistance to ambient [K.m/W]
$T_a$
Star thermal resistance of air [K.m/W]
$T_s$
Star thermal resistance of object [K.m/W]
$T_t$
Star thermal resistance of tunnel [K.m/W]