Hi all! I defended my Ph.D. thesis back in 2019 and I also served as the creator and moderator for the subreddit r/FluidMechanics for a long time. I think with that I have gathered enough experience and courage to answer some of your queries. Some broad topics that I can answer questions on are:
- computation fluid mechanics
- scientific programming and HPC
- nonlinear shallow water equations
- statistical description of turbulence: spectra, energy budget etc.
- experimental methods: PIV
- stratified turbulence
- academia
- navigating your career pre- and post-Ph.D.
Ask away!
For geophysical CFD, what are typical values you deal with?
- Viscosity
- Density
- Velocity
- Reynolds number
- Simulation timestep
- Total simulation elapsed time
- Total number of simultaneous unknowns solved for
There are two kinds of geophysical flow studies one can do. 2D simulations where you use models like shallow water equations. Then you deal with
- Velocity
- Reynolds number (which implies some viscosity)
- Froude number (or gravity)
- Rossby number (or Coriolis force from Earth’s rotation)
- Total energy (so you know when it is in a statistically steady state)
- Density only if you add many layer
- Boundary conditions (only if it matters, can be avoided)
You can also do a 3D simulation, but often we use the Boussinesq equations, in which density is approximated as a passive scalar.
This is only the setup, but there is a rich set of phenomena one can aim to simulate with.
So are you treating the Earth’s crust as a shallow fluid layer? Or the mantle underneath? I would think the mantle is too thick for shallow water equations.
Usually for the troposphere or even the atmosphere and the ocean this can be a good model. As you said, I doubt if it can be used to represent lava flows under the earth - something a geologist would know and I am not one. 😀