[zikou55]

Hello,
gradU is a 9 components tensor, I want to know the arrangement of the components
gradU.compoent(0)=dudx
gradU.compoent(1)=dudy
gradU.compoent(2)=dudz
gradU.compoent(3)=dvdx
gradU.compoent(4)=dvdy
gradU.compoent(5)=dvdz
gradU.compoent(6)=dwdx
gradU.compoent(7)=dwdy
gradU.compoent(8)=dwdz


please am I right ?

[jackjiang1989@gmail.com]

Hi,
I got the same question, after some search found it should be like below,
gradU.compoent(0)=dudx
gradU.compoent(1)=dvdx
gradU.compoent(2)=dwdx
gradU.compoent(3)=dudy
gradU.compoent(4)=dvdy
gradU.compoent(5)=dwdy
gradU.compoent(6)=dudz
gradU.compoent(7)=dvdz
gradU.compoent(8)=dwdz

check below link,
discrepancy in fvc::grad(U)

BR/Jack

[Tobermory]

Yep - for confirmation, check out Tensor.H (https://cpp.openfoam.org/v8/Tensor_8H_source.html):

     //- Component labeling enumeration
     enum components { XX, XY, XZ, YX, YY, YZ, ZX, ZY, ZZ };

but remember that for partial derivatives, the derivative is the first index. So for the second component in the list above, XY, this is . Take a look at the link that Jack quotes for more discussion.