Definition of the variation of velocity gradient in Abaqus

I am confused by the definition of the variation of the velocity gradient in the Abaqus Theory Manual (4.6.1).

Normally var(L) = var(grad(v)) = grad(var(v)), where var denotes the variational operator. But in the manual it is given as var(L) = grad(var(u)), where u is the displacement field.

Could someone explain how the definition in the Abaqus theory Manual came about? I have attached a screen capture of the specific part of the manual.

Thank You
Feby

You are right - that is odd. They must define [B]u[/B] as velocity field velocity. Otherwise [B]L[/B] would not be the velocity gradient.
I would double check the Abaqus definitions...

-Jorgen