velocity component dependent forcing for Navier stokes

[Makrand Ajay Khanwale]

Hello,

I am trying to add a linear forcing to Navier-Stokes that looks like this A_ij u_j.  Where u_j is a filtered velocity (to prevent box dependent statistics).

However, I am not able to set the forcing component wise correctly.

My script is below. I specifically point to lines 97-99. 

I am sure this is me misunderstanding the API. Any help is much appreciated. 

To clarify this is a simplification of the problem I raided in issue here: https://groups.google.com/g/dedalus-users/c/lt-7SW9DdTg/m/Ud3Cx_BMAAAJ

The script I am running is attached. Thank you again.

With sincere regards,

Makrand