Hi. I am new in this field and I found out about Burnman when I was searching for a tool to determine the sublimation temperature as a function of density, for dust grains of different ingredients.
Can I use Burnam to build a composite (e.g. a dust grain made of forsterite + enstatite) and then get Tsub(rho) or Tsub(P)? An important detail is that I want to apply this for physical conditions found in protoplanetary disks around young stars ( I already know an estimate of the range of temperatures and densities in these disks), which are very different from the physical conditions (T,P, rho) inside planets.
I would really apprecitate any help.Thank you.
Dear emanzo19,
Firstly, welcome, and thank you for posting to the forum!
BurnMan can do equilibrium thermodynamics calculations under any conditions, and that includes very low pressures and high temperatures.
In order to use BurnMan for your problem, appropriate thermodynamic modelsets would need to be implemented. In particular, we’d need equations of state describing the thermodynamic properties of a low density gas containing forsteritic and enstatitic components. I’m happy to help you implement this (with the caveat that I’m quite busy at the moment), and it might not be very much work to do this if the EoS is similar to those already implemented in the BurnMan code.
Best wishes,
Bob
Dear Bob,
Thank you for taking time to reply to my post. Yes I am very interested in this problem. Do you have any suggestion on where I can search for the equations of state describing the thermodynamic properties that I need for these type of problems and physical regimes? We have never worked before in these topics before, so I apologize if my questions are somehow obvious. Also, what would be needed if we want to vary the dust components, e.g. if we include other components such as olivine, etc?
You might start with the EoSes used in impact simulators, e.g. https://swift.strw.leidenuniv.nl/docs/Planetary/equations_of_state.html
That particular SPH code includes an EoS for Mg2SiO4 from this paper: [1910.04687] The Shock Physics of Giant Impacts: Key Requirements for the Equations of State
As you increase the number of components beyond 1, you will need “solution models” - that is, the equations of state of the “pure” endmember species plus some mixing terms describing how the different species interact in the phase.
Because you mentioned it, I think it’s worth pointing out that “olivine” is not a component - it is a phase (i.e., a structurally distinct, mechanically separable part of the system). Olivine is well approximated by a binary solid solution between the endmember species forsterite (Mg2SiO4) and fayalite (Fe2SiO4). In an (Mg,Fe)2SiO4-composition gas, you you may need to account for additional components and multiple species (MgO, FeO, SiO2, O2, …). This is why it’s good to start with existing models!
Ok I will try starting from where you suggest, i.e., the EoSes. Maybe I can start with the simplest cases, for instance, dust grains that are exclusively made of forsterite, or enstatite, or olivine, and for the moment do not try to consider dust grains made of more than 1 ingredient. This should also be really helpful for me.