### Off-diagonal entries in matrix of Relative Diffusivity

· 3 · 2125

#### Ilona Glatt

• Posts: 6
##### Off-diagonal entries in matrix of Relative Diffusivity
« on: June 14, 2021, 11:56:32 AM »
Hi,
when I calculate the relative diffusivity, I get a complete matrix as a result. Can someone explain the meaning of the off-diagonal entries?
Thanks,Ilona

#### Aaron Widera

• Math2Market Employee
• Posts: 53
• Position: Sales Engineer Digital Material R&D
##### Re: Off-diagonal entries in matrix of Relative Diffusivity
« Reply #1 on: June 25, 2021, 10:06:15 AM »
Hello,
of course we can:
If you calculate the Diffusivity in x-direction, the entry in the main diagonal x_11 gives you the diffusivity in x-direction. The off-diagonal entries x_12, x_13, x_21 and x_31 give you the amount of diffusion going into y- and z-direction although the driving force, the concentration gradient, is only given in x -direction.
The same goes for Diffusivity in y- and z- direction.

Was that understandable?

#### Ilona Glatt

• Posts: 6
##### Re: Off-diagonal entries in matrix of Relative Diffusivity
« Reply #2 on: June 28, 2021, 10:16:48 AM »
Yes. That was very clear, thank you!