code_saturne#

code_saturne is a free open-source finite volume CFD solver for the Navier-Stokes equations, developped primarily by EDF. It solves the Navier-Stokes equations with scalar transport for 2D, 2D-axisymmetric, and 3D flows, whether steady or unsteady, laminar or turbulent, incompressible, dilatable, or weakly compressible, isothermal or not.

code_saturne contains modules dedicated to specific physics, namely for atmospheric flows. A detailed description of the modelling possibilities, including the atmospheric module, can be found in code_saturne’s online documentation. This page focuses on the modelling assumptions and added source files allowing to handle wind farm flow modelling in WIFA.

This API can be launched with version 8.0 of code_saturne and requires access to a high performance computer cluster.

Contents:

Configuration Options#

code_saturne-specific options are configured in the analysis.yaml file:

Run Type:

run_type: "simulate"    # Options: simulate, postprocess

HPC Configuration:

HPC_config:
  # Simulation run settings
  run_node_number: 1
  run_ntasks_per_node: 48
  run_wall_time_hours: 6
  run_partition: ""
  #
  # Meshing settings
  mesh_node_number: 1
  mesh_ntasks_per_node: 48
  mesh_wall_time_hours: 1
  mesh_partition: ""
  #
  wckey: ""              # Cluster accounting key

Mesh Configuration:

mesh:
  remesh: True           # Generate new mesh or use existing
  mesh_file_name: MESH/mesh.med

Workflow#

The code_saturne workflow consists of several automated steps:

Initialization: Parse WindIO input, create case directory structure
Meshing: Generate computational mesh using salome (if remesh: True)
Precursor (optional): Run precursor simulation for inflow profiles
Simulation: Submit main wind farm simulation to HPC queue
Postprocessing: Extract turbine power and flow field data

Input Requirements#

code_saturne supports two types of inflow specification:

Hub-height time series:

Wind speed and direction at hub height
Stability via LMO (Monin-Obukhov length)
Generates analytical profiles internally

Vertical profiles:

Full atmospheric profiles (u, v, temperature, TKE, epsilon)
Requires precursor simulation for turbulent inflow
Supports capping inversion for stable stratification

Simulation Modes#

Neutral boundary layer:

Uses log-law profiles
No precursor required
Energy equation disabled

Stable stratification with capping inversion:

Generates Nieuwstadt profiles or uses provided profiles
Precursor simulation for turbulent inflow
Damping layer for gravity waves
Energy equation enabled

API Reference#

Note

code_saturne simulations require access to an HPC cluster and pre-installed code_saturne (v8.0) and salome executables. See Install for setup instructions.

Usage#

Command Line:

wifa_saturne path/to/system.yaml

Python:

from wifa.cs_api.cs_modules.csLaunch.cs_run_function import run_code_saturne

# Run code_saturne simulation
run_code_saturne("path/to/system.yaml")

# Test mode (reduced iterations)
run_code_saturne("system.yaml", test_mode=True)

# Postprocess existing results
run_code_saturne("system.yaml", postprocess_only=True)

wifa.cs_api.cs_modules.csLaunch.cs_run_function.run_code_saturne(windio_input, test_mode=False, output_dir=None, postprocess_only=False)#

Run a code_saturne simulation from WindIO input.

Parameters:

windio_input (str) – Path to WindIO YAML file
test_mode (bool) – Enable test mode (reduced iterations for validation)
output_dir (str, optional) – Custom output directory
postprocess_only (bool) – Only run postprocessing on existing results

Example:

from wifa.cs_api.cs_modules.csLaunch.cs_run_function import run_code_saturne

# Production run
run_code_saturne("system.yaml")

# Quick validation
run_code_saturne("system.yaml", test_mode=True)

wifa.cs_api.cs_modules.csLaunch.cs_run_function.initialize_cs_case_from_windio(windio_input, output_dir)#

Initialize a code_saturne case from WindIO input without running.

Parameters:

windio_input (str) – Path to WindIO YAML file
output_dir (str) – Output directory for the case

Returns:

Configured CS_study object

Return type:

CS_study

Outputs#

Results are stored in the case directory:

Farm/RESU/<case_name>/power.txt: Turbine power time series
Farm/RESU/<case_name>/turbine_data.nc: Per-turbine NetCDF output
Farm/RESU/<case_name>/flow_field.nc: Flow field data (if requested)