MicroHH

This is a Julia port of the dynamical core of MicroHH, a 3D CFD code to simulate the atmospheric boundary layer. It is made for educational and exploratory research purposes, including machine learning. In comparison to its C++/CUDA reference it lacks all physical parameterizations, but it comes with the ability to run multiple simulations at the same time and let them interact.

A few example cases are in the cases folder.

MicroHH is by default precompiled for serial computing with Float64 precision. It can be run on a chosen number of threads:

• drycbl with 1 thread(s): julia --project -O3 drycbl_run.nl
• drycbl with 2 thread(s): julia --project -O3 -t2 drycbl_run.nl

MPI mode can be enabled via de set_use_mpi! function that can be run from Julia, and the settings are stored in LocalPreferences.toml.

using MicroHH
MicroHH.set_use_mpi!(true)

With MPI, the simulation should be started for instance as (if npx = 2 and npy = 2) drycbl with 4 tasks and 2 thread(s): mpiexec -n 4 julia --project -O3 -t2 drycbl_run.nl

MicroHH can be run at single precision by setting the use_sp flag to true.

using MicroHH
MicroHH.set_use_sp!(true)

In case of MPI enabled, it is recommended to manually precompile before starting a run, to avoid precompilation on all tasks simultaneously.

julia --project -e 'import Pkg; Pkg.precompile()'