Time derivative following a fluid/material particle: D/Dt = ∂/∂t + (v·∇). Bridges Eulerian (field-fixed) and Lagrangian (particle-following) descriptions; central to Navier–Stokes and to large-deformation solid mechanics.
Time derivative following a fluid/material particle: D/Dt = ∂/∂t + (v·∇). Bridges Eulerian (field-fixed) and Lagrangian (particle-following) descriptions; central to Navier–Stokes and to large-deformation solid mechanics.