Velocity Gradient: Which component is which
 

Hello Foamers,


I want to work with the components of the velocity gradient tensor. I calculate the gradient via: fvc::grad(U) in OpenFoam-extend-4.0, but now I am unsure which component is which.

Definitions of the velocity gradient tensor I find online state that for example the [1,3] component is du/dz.

The Openfoam programmers guide (chapter 3.1.1) gives the transpose of this definition, saying that the [1,3] component is dw/dx (in terms of grad(U))

I am confused as to which one is right. How do I make sure I access the right components? I need du/dz and dv/dz. Does someone have experience with this?


Thankyou very much in advance :)
Kraneberger

Solved
 

After doing some more checking myself I am certain that the Programmers Guide Definition is the one being used. The velocity gradient fvc::grad(U) is structured like this:


du/dx dv/dx dw/dx


du/dy dv/dy dw/dy


du/dz dv/dz dw/dz