Effective emissivity of a hole

Input(s)

e: Emissivity of the Cavity Walls (dimensionless)

f: Friction Factor (dimensionless)

Output(s)

$\boldsymbol{e}_{\boldsymbol{h}}$: Emissivity of Hole (dimensionless)

Formula(s)

$$ e_{h}=\frac{e}{e+f *(1-e)} $$

Reference(s)

Bird, R.B., Stewart, W.E. and Lightfoot, E.N. (2002). Transport Phenomena (Second Ed.). John Wiley \& Sons, Chapter: 16, Page: 493.