what's the purpose of integrate_energy now?

[zingale]

It is unclear what the purpose of setting integrator.integrate_energy = 0 is now. If we want to decouple the energy release from the temperature, e.g., to do a constant T burn, we do integrator.call_eos_in_rhs = 0. But we still want to include the energy equation in the integration, since that accumulates the energy release. If we turn off energy integration though, then the energy release from the burner will be 0, even if the composition changes. Is that something we want?

[maxpkatz]

We may not need to keep it. At the time when it was added, it was intended to be a variant on integrate_temperature = 0, to see how different these two ways of turning off self-heating would look. At the time, I was thinking about the so-called "hybrid" burning mode, which was intended to address cases near NSE where we expected that the net energy release would be approximately zero, so turning off energy integration might have been a way to make the burn easier. But not much ever came from us having those options, other than some unpublished comparisons to other papers years ago.