[FLASH-USERS] ensuring div B = 0 when adjusting evolution

[Klaus Weide]

On Wed, 7 Jun 2017, Slavin, Jonathan wrote:

> Well I see your point about the declaration of dt in Simulation_interface.
> I will look at implementing my (currently working) solution in the Heat
> unit.  One issue could be that the call of Driver_computeDt calculates
> various dt's.  I believe that it would not set dt below dtmin.  Currently I
> use dtinit as mentioned, which is smaller than dtmin, since the state after
> the explosion is initiated involves such large gradients. Of course the
> timestep quickly gets increased, but the single short timestep may be
> what's necessary to  avoid numerical errors.

Jon,

I wonder why you think you need to use a dtmin greater than dtinit.

Generally dtinit should be so chosen so small that the time step actually 
taken does not depend on it. If some physics unit requests a smaller 
timestep (via Driver_computeDt), you should not normally have to 
(or want to) override it with dtmin.

Klaus