Pre-processing using SimLab

nanoFluidX uses two files to setup a simulation. Apart from the configuration file, which defines all relevant simulation parameters and phase properties, a geometry file is required that defines the initial discretization of the problem with particles.

The structure of this input file (geometry definition) is simply a table with the position of the particles and the assigned phase number, for example:

1 0.0 0.0 0.0
1 0.0 0.0 0.1
1 0.0 0.1 0.0
2 0.0 0.2 0.0
…

Alternatively, the geometry file can also contain initial velocity field (for FLUID phase type) or wall velocity (for WALL phase type). This alternative format is enabled through usage of the inputfileReadMode command in the Domain Parameters section. When set to INPTFL_PXYZUVW, the required geometry file needs to have added three columns for velocitiy components in X, Y and Z direction.

Simple geometries can be defined even manually, however, for real cases using complex geometries SimLab pre-processor from Altair Engineering can be used to generate initial geometry files. The idea is to read in the CAD data, modify the geometry if necessary, create SPH particles and export the data to a text file. Detailed instructions on the usage of SimLab are given in the hands-on tutorial material or during a nanoFluidX training.