Why the material time derivative of a material field 𝐹 equals to the directional derivative of 𝐹 in the direction of the velocity vector 𝑣 ?

Hi guys! I am recently reading Nonlinear Solid Mechanics A Continuum Approach for Engineering by Gerhard A. Holzapfel, Chapter 2.3 and was confused with one equation. You can refer to this...

27 June 2020 5,354 2 View