Variables Output Data

Voxel variables are represented as sets of continuous Eulerian fields defined throughout the computational domain. Because these fields exist everywhere in space and evolve in time, M-Star provides multiple mechanisms to extract and visualize them during a simulation. These mechanisms are configured through the Output Panel and associated sampling and output rate settings.

Two primary categories of voxel variable data are produced: reduced statistical scalar outputs for plotting aggregated scalar quantities over time, and surface and volume spatial visualization outputs for examining how scalar fields vary throughout the domain.

Reduced Statistical Scalar Output

The solver reports time-evolving descriptive statistics associated with a voxel-variable field. This output is written as a tab-separated ASCII .txt file and includes the mean, minimum, and maximum values of the variable across the computational domain. A preview of the data generated by this calculation is provided in the Statistics Output Data preview panel.

Surface and Volume Outputs

These are geometry-aware datasets that preserve spatial structure of the voxel variable. They are written in binary VTK formats  suitable for post-processing in M-Star Post and similar tools.

M-Star supports sampling at two levels:

  • 2D Slice Output: These planes and surfaces constitute a planar cut (or slice) through the domain that returns a spatial field map over an area. This is the most common visualization for examining spatial variations in the variable values. These outputs can be produced at specific locations by Output Planes or Output Surfaces to a model.

  • 3D Volume Output: This volume output constitutes full 3D field data for the domain or a specified region. Because of data size, volume output is typically written less frequently or under specified conditions. The extents of this output are automatically defined by the Main Lattice.

Fluid Interface Output

For multiphase or immiscible systems, M-Star can export voxel variables along Fluid Interfaces as an additional spatial dataset. The interface is defined as an isosurface of the phase-fraction (VOF) field, representing the boundary between fluid phases (e.g., gas–liquid or immiscible liquid–liquid interfaces). Reduced variables describing the mean, minimum and maximum values along the interface are printed as supplemental reduced statistical scalar output.

Sampling Probes and Sampling Lines

In addition to reduced statistical data (which is computed over the full domain), localized reductions and interrogation can be performed using sampling probes, sampling lines, control volumes, or global variables with local fluid reductions.