Quote:Original post by Eelco
since the added mass is due to the mass of boundary layers that get dragged along, i think the most important factor to take into account is surface area.
Not only. Imagine you have large sphere with water and with small sphere inside, at center of large one. If you move small sphere, most of water will move in opposite direction. In case large sphere is very big or infinite, you get that added mass should be proportional to volume of small sphere...
Simple idea: as sphere moves in one direction, center of mass of water moves in opposite direction.
Water dragged along only increases amount of water that have to move in opposite direction...
Quote:Quote:
Looking at my fluid dynamics notes, the added mass is m* = 1/2*(density of fluid)*(volume of sphere)
that surprises me. what does the inner goemerty have to do with the outside flow?
also, using surface area is plausible cuase it has the desired effect of being significant on small objects whilst being insignificant on large objects.
area*mu*rho*someconstant would most probably do fine.