Thanks for excellent informative video! I have a question, here @18:48 , for optimization 1, I know the cost function was to minimize the weight of sink. but didn't you at the same time win FloTHERM set the constraint of auction temperature at 95C? why you are talking about that you ran a separate CFD? maybe I did not get the point correctly.
How does the duct from a physical standpoint “force” the air through? Is there a pressure difference for example a pcb in a box with and without a duct around the heatsink?
As everything in nature tends to go towards minimum resistance path (thermal resistance, hydraulic resistance, electrical resistance,etc...) so does the flow. When you have a bypass fluid says "Ok, if I have 100 J of energy I will spend most of that energy to force most of my particles around the fin and force some of them in the fin". Contrary to that, when there is a duct fluid is forced to go through fins - it doesn't have that ability to make bypass. What happens is that fluid understands that there will be higher pressure drop, i.e. higher energy so he will say "Ok, I need a lot of energy but I don't have that much amount of energy to push with high velocity so I will decrease my velocity a bit (decrease the mass flow) just to push all my particles through it". I hope this kinda helps.
