Consider a laminar methane diffusion flame stabilized on a circular burner. The pressure is $1$ atm and the ambient temperature is $25.$

a$)$ For a fixed fuel mass flow rate, how does the flame height vary with ambient pressure?

Hint: the diffusivity is inversely proportional to pressure.

b$)$ If the height of the diffusion flame is Lf$,$ qualitatively sketch the axial $($centerline$)$ profiles of the following quantities from the base of the diffusion flame to a height of $2$Lf: temperature, methane, and carbon dioxide concentrations.