presenter name is still not given

Because you would have to go back 40+ years to have used "cells" in PCB layout... when we used "cellophane" transparencies and markers and adhesive tape and "decals" to make 2x or 4x artwork for photo transfer to sensitized copper.

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.