acceleration
The rate of change with time of the velocity vector of a particle.
If u is the vector velocity, the acceleration may be written as Du/Dt, where D/Dt is the material (or total) derivative. For most purposes in hydrodynamics where Eulerian coordinates are employed, the acceleration is decomposed as follows:
where ∂u/∂t is called the local acceleration, and u · ∇u is called the convective acceleration.
