Hi! I have been reading I.L. Bird's textbook on transport phenomenon for a while now, which deals with the topic of Momentum SHell Balances and such. It basically works on the concept of... [rate of Momentum in by convective transport] + [rate of momentum in by molecular transport] - [rate of momentum out by molecular transport] - [rate of momentum out by convective transport] + force of gravity acting on the system = 0 I know that all of this has been applied to flow processes and everything... but is there a good biological system whose analysis involves this fundamental equation? I am talking of anything - cells/cell transport/mitochondria/lungs/livers/kidneys/ you get the drift! Please let me know about this!!!