[petsc-users] TS question 1: how to stop explicit methods because they do not use SNES(VI)?

[Jed Brown]

Barry Smith <bsmith at mcs.anl.gov> writes:

> The function below absolutely should not be called TSComputeIFunction()! It does not just compute IFunction()

How is this different than SNESComputeFunction subtracting off the RHS?

> The current code entangles too much of the user API to the methods, this can be fixed.

I agree that the logic/naming is perhaps too overloaded.

>> If the user experiments with different ways of splitting the solution they would have to define RHS and IF or RHS and LHS in different ways (according to the splittings they experiment with). It may look disgusting, but I don't see another way around it unless you allow for a list of operators to be defined and then the user to assign them to LHS or RHS.
>
>    Jed suggested having any number of "RHS" functions. I don't think we need more than 2, 1 for left hand side and 1 for right. If that ends up being not enough we can change to have any number of them. Just to be clear. I suggest three functions
>
>    IFunction which defaults to u_t  plus TSSetMassMatrix() which changes the default IFunction to M u_t
>    LHS function which defaults to 0, if provided defaults to being treated implicitly by IMEX
>    RHS function which defaults to 0, if provided defaults to being treated explicitly by IMEX

Are you trolling me?  Reactive fluid-structure interaction:

1. fluid splitting to isolate the acoustic wave (stiff)

2. fluid containing everything but the acoustic wave (non-stiff)

3. fast reactions

4. slow reactions

5. structure


Note that when using conservative variables, every one of these splits
requires evaluation of the equation of state (reactions rate
coefficients depend on Temperature, structure boundary condition
requires pressure and shear stress).  This doesn't even have
viscoelastics, sedimentation, or a turbulence model.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 832 bytes
Desc: not available
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20170214/1a3a69a6/attachment.pgp>