Inquiry on species transport in MOOSE Navier Stokes

[sanjuucsd2022-sketch]

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Question

I am Sanjay and I am using MOOSE for my project. However, I am stuck on the species transport equation(scalar transport).
For the advection kernel there seems to be only the INSScalarFieldAdvection kernel object.( I am appending species after solving for energy, navier stokes and continuity). The kernel doesn't allow me to multiply by density(which is a function of temp in my case) i.e I want to solve for Del .(rhovelmass_fraction) and not Del . (vel*mass_fraction)- which the kernel only supports. Please let me know how to proceed.
Thank you

Additional information

No response

[GiudGiud]

Hello

We currently do scalar advection using mostly the INSFV and WCNSLinearFV finite volume implementations. For those we have added the option for a density multiplier
If you need to change something with the regular INS finite element implementation, you will need to modify the kernels yourself on your local version of the code.

[GiudGiud]

The input looks fine to me

[sanjuucsd2022-sketch]

Actually I’m at the stage where I need to modify header/source code, not just input files. I’m specifically trying to understand the C++ used in MOOSE

Could you suggest:

Any documentation or tutorials focused on MOOSE C++ development
Any example classes that are good references for extending or modifying source-level objects

I’m trying to understand the underlying structure of the MOOSE framework rather than only working with input-file-level usage. It has been a while since I have done C++, just have to recall and learn things like const, static, void, override etc

[sanjuucsd2022-sketch]

I am asking this because, for the face_flux parameter requirement in the LinearFVDivergence kernel, I think I have to add the RhieChowMassFlux Userobject, but it cannot be parsed as a functor, so it should inherit some functionalities of the functor, but when I see the source and header file, I don't know most of what is going on, can you please suggest how should I go about this?

[GiudGiud]

Hello

Any documentation or tutorials focused on MOOSE C++ development

https://mooseframework.inl.gov/getting_started/examples_and_tutorials/index.html#5720fe4e-d1a1-4e03-b98e-8b0aa789908a

This particular section of the examples & tutorials has a tutorial for application development. It includes a bunch of C++ in MOOSE

Any example classes that are good references for extending or modifying source-level objects

You can look at how CoefTimeDerivative inherits from TimeDerivative and modifies its residual and Jacobian output.
If you are modifying INSFV though it's using automatic differentiation so you only modify the residual computation
If you are modifying LinearFV it's setting up an Ax = b -like problem so you modify computeRHS and computeMatrix instead

[GiudGiud]

I’m trying to understand the underlying structure of the MOOSE framework rather than only working with input-file-level usage. It has been a while since I have done C++, just have to recall and learn things like const, static, void, override etc

Feel free to use local coding assistants (claude, codex for example) or paste object code into chatgpt / copilot to get info on what they do. Fairly quickly you won't need to, the structure of MOOSE is fairly simple

I am asking this because, for the face_flux parameter requirement in the LinearFVDivergence kernel, I think I have to add the RhieChowMassFlux Userobject

No you don't need to pass the RCMF UO. you need to pass functors that are created by this RCMF.
There are examples in the NS module for using linearFV.
You can also use

[Debug]
  show_functors = true

to see which functors are available. The name of the functor that is expected in LinearFVDivergence should appear if it's created