Is this something you are still interested in having?
> On Sep 11, 2025, at 7:25 PM, Eirik Jaccheri Høydalsvik via petsc-users
> <[email protected]> wrote:
>
> Hi,
>
> I have made a two-phase flow code which computes motion of two phases in one
> dimension, where the phases are allowed to intermix. This code relies on a
> finite difference Jacobian computed using the standard coloring I get from
> the DMDA object:
>
> da = PETSc.DMDA().create(
> dim=(N_vertical,),
> dof=3,
> stencil_width=1,
> )
>
> I now want to add a variable for the interphase height L_z in addition to a
> velocity u_v, giving the velocity of the vapor flowing in to the interface.
> The interface will move throughout the grid, meaning that these two variables
> will not be coupled to a fixed set of grid cells, but will be coupled to
> different sets of three grid cells throughout the simulation.
>
> Questions:
>
> 1. Is it possible to create a custom coloring to efficiently compute the
> finite difference Jacobian including the interphase height and vapor velocity?
>
> 2. How do I revert to computing the full finite difference Jacobian with the
> purpose of testing if the interphase model works?
>
> Best regards,
> Eirik Jaccheri Høydalsvik
> Sintef ER and NTNU EPT
