Fluid flow
= Fluid flow
A <fluid flow> is motion described by a <velocity field> $\mathbf u(\mathbf x,t)$. The trajectories of <fluid elements> satisfy $d\mathbf x/dt=\mathbf u(\mathbf x,t)$; the <mass density> and other fields obey their <conservation laws> and <constitutive equations>. This physical motion differs from a <flow> on a <flow network>.