Debug output from Euler.F?

[Nathan Goldbaum]

Hi all,

I'm running a simulation with an accreting active particle.  This is the first time I've gotten this simulation to get past the first EvolveLevel after sink particle creation without crashing (woohoo!!) but now I'm seeing some strange debug print statements from inside a fortran routine.

The debug statements look like: http://paste.yt-project.org/show/2368/

This comes from line 248 in Euler.F, which looks like: http://paste.yt-project.org/show/2369/

I guess mass is not being transferred correctly from the grid to the accreting particle?  I've never seen this before so I'm hoping that someone on enzo-dev might have more insight.

Thanks for your help!

[Greg Bryan]

Nathan -- This is the part of the routine which adds the gravity source term to the energy.   I doubt this is going to help much, but the from the output you can see that this addition of (negative) energy to these cells drives the total energy below zero.  However, I doubt this is the fundamental issue, as the energy even before this step is positive, but less than 0.5 v^2.  All I can say from the output is that this is not due to the gravitational acceleration.  I suspect the problem is only detected here, but e is dropping below 0.5 v^2 somewhere earlier.  Maybe this comes from your changes somehow modifying the velocity of cells without changing their energy (in PPM, energy is the total specific thermal plus kinetic energy, so e should always be e = ge + 0.5 v^2, which means that if you change v, you need to change e).

Sorry not to be of more help...

Greg

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[Nathan Goldbaum]

Hi Greg,

No worries - that was actually very useful.  I do modify the grid energy during accretion by decrementing the grid velocity.  I probably made a unit conversion error or something similar somewhere in the the accretion routines.

Thanks for the context on Euler.F.

Cheers,

Nathan

[Nathan Goldbaum]

Hi Greg,

I seem to have fixed the issue - it was indeed a unit conversion error on my part.

As a side note, this fix means that the orion style sink particle I've been working on now runs without errors.  My thanks to all who worked on, offered advice, or helped out with the active particle stuff this year and last year :)

-Nathan

[Greg Bryan]

Nathan -- Great news!  Thanks for all your hard work on the active particles in general, and sink particles in particular.  I'm really excited about all of this new infrastructure. (And if you get a chance, now might be a good time to draft a bit of documentation while it's all fresh...)

Greg