Heat transfer is conduction, convection and radiation?
Its all in the distance? Radiation is to the fourth power of distance? So the fins closer together will heat up the air more?
Convection is the least effective way of cooling or the reverse, heating air? It is mostly by displacement.
Conduction is direct heat transfer, by mechanical contact. How heat waves(long infrared wavelength or frequencies) travel is like elctrical current flow. Electrons pile up when they try to turn corners. Piling up electrons cause friction and create heat. This governs heatsink shape design? Use a collector of heat(to store the energy or heat), in the base of the heatsink as a researvoir and conducts into fins to be cooled.
Black body or paint assorbs more heat, metallic surface of fin reflects heat back to the black paint, but also rediates into the black paint.
So, we want to radiate heat from the metallic fins and let thin black paint assob it. Then we want the air heated by the black paint by radiation to be cooled by convection. Cool air replaces hot air by displacement.