Workflow overview¶

A uDALES study follows the same sequence of steps regardless of whether you run on a laptop or an HPC cluster. This page gives the end-to-end picture; each step links to the detailed guide.

flowchart LR
  A["Install & build"] --> B["Set up experiment"]
  B --> C["Pre-process<br/>write_inputs.sh"]
  C --> D["Run<br/>ud_run machine sim"]
  D --> E["Merge outputs<br/>ud_run machine gather"]
  E --> F["Analyse<br/>udbase"]

1. Install and build¶

Install the prerequisites and build the uDALES executable, either manually with CMake or with the helper script tools/build_executable.sh. See Installation.

2. Set up an experiment¶

Each simulation lives in its own experiment directory (e.g. experiments/001), identified by a three-digit experiment number. It contains:

namoptions.001 — the simulation configuration; see the input parameters overview and boundary conditions,
an STL file describing the building geometry (except for special cases); see geometry generation,
config.sh — paths and settings used by the helper scripts.

The quickest way to start is to adapt one of the example simulations or copy an existing setup. Simulations with inflow-outflow boundary conditions may need a precursor (driver) simulation to generate inflow data.

3. Pre-process¶

The pre-processing step turns the namoptions file and geometry into the input files the model reads at startup (facets, grids, initial profiles, etc.):

./u-dales/tools/write_inputs.sh -m experiments/001

See Pre-processing for setup and options, including the Python route (-p) and running on clusters.

4. Run the simulation¶

Launch the solver with ud_run, naming your machine — common (desktop), icl or hx1 (Imperial clusters), archer (ARCHER2) or ecmwf (ECMWF HPC2020). It calls the matching machine-specific script in u-dales/tools:

./u-dales/bin/ud_run common sim experiments/001

See Running uDALES, and cluster workflows for cluster-specific notes.

5. Merge outputs¶

uDALES writes one NetCDF file per CPU. After the run, merge them into single output files with ud_run <machine> gather experiments/001 (done automatically at the end of ud_run common sim). See Post-processing.

6. Analyse¶

Load and analyse the merged NetCDF output with the udbase MATLAB class — see the udbase, fields, and facets tutorials. A Python package providing the same functionality is under active testing and will replace the MATLAB toolchain from uDALES v3.0 onwards.