The fluid is viewed as adjacent
fluid elements
The elements are taken as internally continuous, and surrounded by
neighboring elements, or an external boundary.
The elements are analyzed in two ways:
The first considers a spatially fixed well defined volume with respect
to which fluid flow in and out.
The latter considers a moving welldefined volume (attached to a given
element of the fluid).
In each case a respective element of fluid of given properties is
associated with a threedimensional velocity vector.
Given a reference state where all fluid elements have a known velocity
vector, and where all respective forces are well defined, and well
quantified, Newtonian mechanics claims to be able to predict all future
states in terms of the velocity and spatial attributes of the given
fluid.
