Move an air mass by changing surface. temperature

FrancisB

I am an architecture student and new to CFD so this may be a really simple question but please bare with me. I want to set up a 2d model that shows how I can move a static air mass by heating different surfaces in the model. For example if I had a box filled with some gas and I applied heat to the bottom how will I model the way the fluid moves inside the box with the applied heat. Like I said I am a student and I really appreciate any help.