Reply To: Issue with Intro to heat transfer course

[Karthik Remella]

Hello You are right about natural convection if the density of the gas is a function of temperature and if the gravitational vector is in the favorable direction (downward-pointing). We don't mention any of these details here and are simply assuming that there is no gravity and the density of the gas is constant. Under these conditions, conduction is the primary mode of heat transfer. I hope this helps.
Karthik