[mesa-users] Implementing extra p & energy terms - EOS question

[Ireland, Lewis]

Hello,

This is a slightly different question to my previous, and might be easier to interpret.

I have an extra pressure term, P_mag, and an extra specific internal energy term, χ, that I want to implement, where P_mag ~ χ * Rho.

I have edited the momentum equation: dP/dm = dP_0/dm + dP_mag/dm, where P_0 = P_g + P_rad. The energy transport/conservation equations are unchanged in this case.

Because P_mag performs no work, the first law of thermodynamics is:

dQ = Tds = dU + P_0 dV - P_mag dV

How do I modify the eos in MESA in order to fulfil this modified law, as dQ = Tds = dU + P_tot dV is what I am presuming to be “performed" at the moment, which is incorrect as it includes P_mag?

Cheers,

Lewis

P.S. If I am successful with the above, will this modify the specific internal energy (by adding χ) through this treatment, or would I need to add χ manually to U?
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