We assume in this section that the user has the calculation data files (calculation setup) at his disposal, or has already prepared it following for instance the step-by-step guidance provided in the code_saturne tutorials. The steps described below are intended to provide a way to quickly run through the Graphical User Interface (GUI).

Setting up your environment

It is recommended before running code_saturne to define an alias to the code_saturne script, for example:

alias cs='${install_prefix}/bin/code_saturne'

where '${install_prefix} is the base directory where code_saturne and its components have been installed.

More detailed instructions are provided in the dedicated setting up your environment section.

Preparing a case

The second thing is to prepare the computation directories. For instance, the T_JUNCTION study directory, containing a single calculation directory CASE1, will be created by typing the command (see [sec_prg_cscreate]):

code_saturne create -s T_JUNCTION

The mesh files should be copied in the MESH directory (though they may also be selected from another directory (see [sec:prg_stepbystepcalculation]) and the C++ or C and Fortran user files necessary for the calculation in the directory CASE1/SRC. Finally, the calculation data file setup.xml managed by the GUI should be copied to the CASE1/DATA directory. Once these steps are completed, the user should go in the directory CASE1/DATA and run

/code_saturne gui setup.xml

to load the calculation file into the interface. A window similar to the one below will appear.

Click on the "Run computation" button in the toolbar, as shown below. After having chosen the number of processors, press "start calculation" to run the calculation.

If no problem arises, the simulation results can be found in the CASE1/RESU directory and be read directly by ParaView or EnSight in CASE1/RESU/<YYYYMMDD-hhmm>/postprocessing. The main calculation log can be found in the file <YYYYMMDD-hhmm>/run_solver.log.

Troubleshooting

If the calculation does not run properly, the user is advised to check the following points in CASE1/RESU/<YYYYMMDD-hhmm>

if the calculation stops in the preprocessor, the user should check for error messages in the preprocessor*.log file;
if the problem is related to boundary conditions, the user should visualize the error.ensight file with ParaView or EnSight;
if the calculation stops in the code_saturne solver, the user should look for messages at the end of the files run_solver.log and error*. In addition, the user can track the following keywords in the log (these are specific error signals):
- SIGFPE: a floating point exception occurred. It happens when there is a division by 0, when the calculation did not converge, or when a real number reached a value over *10³⁰⁰*. Depending on the host architecture and build options, this type of exception may be caught or ignored.
- SIGSEGV: a memory error such as a segmentation violation occurred. An array may have exceeded its allocated memory size and a memory location in use was overwritten.

In order to easily find and fix the problem, it is also recommended to use a debug build of code_saturne (see the installation documentation), possibly in combination with the use of the Valgrind tool or a debugger. The use of such a tool can be specified in the GUI in the advanced options of the item "Prepare batch calculation", or without the GUI, in the cs_user_scripts.py file (which can be found in DATA/REFERENCE and should be copied in DATA, see the step by step calculation instructions).