# Output Files Reference¶

## Overview¶

All data generated by the solver is printed to the /out directory. The data processed by MStarPost and MStarPost3D is saved here. Output data is provided in open formats , such that users can access and interrogate this data via common post-processing protocols. In general field data is provided in VTK format, and statistics/other data is provided in text files.

This directory contains (up to) three text files and three associated subdirectories. The three possible text files include BoundaryConditions.txt, Slices.txt, and Volumes.txt. As discussed above, these files are input to MStarPost and MStarPost3D for automated visualization and analysis in ParaView. This directory also contains (up to) three directories. The three possible directories are /Stats, /Output, and /BoundaryConditions. These directories contain numerical output, animation data, and a summary of the boundary conditions applied to the bounding geometry.

## /out/Output¶

This directory contains all the dynamic slice, volume, interface, solid object, and particle data generated by the solver for visualization. Note that each component is characterized by a .pvd file, and an associated subdirectory. PVD files are “ParaView Data” files. For each moving component, these files describe how the data block written by each data processor should be assembled in space and time to properly visualize the output data. In other words, the PVD files are recipe cards for assembling each component of the visual output, using the block data stored in each subdirectory as ingredients. The block data (ingredients) are stored as binary .vti file and/or .vtp. VTI and VTP files are part of the Visualization Toolkit, which is an open-source framework for 3D computer visualization. The PVD file is ASCII text and can be edited manually, should users want to exclude certain blocks from the visual representation. The nature of the data output is directly informed by the simulation set-up.

The following visualization files may be created in this directory:

Slice{x,y,z}_P.pvd

Time-evolution of the fluid properties in a 2D {x,y,z}-plane, located at position P along the direction of the vector defining the plane. For example, SliceX_0.250.pvd represents an x-plane positioned 0.250 m along the x-axis above the model domain origin.

Contents

• Velocity [m/s]

• Temperature [K]

• Pressure [Pa]

• Resolved Strain Rate [1/s]

• Vorticity [1/s]

• Eddy Dissipation Rate [W/kg]

• Total Kinetic Energy [W/kg]

• Fluid Viscosity [m^2/s]

• Species Concentration [mol/L]

• Mean Age [s]

• Mean Velocity [m/s]

• Time-average Eddy Dissipation Rate [W/kg]

• Time-average Species Concentration [mol/L]

• Time-average Resolved Strain Rate [1/s]

• Time-average Turbulent Kinetic Energy [W/kg]

• Species Exposure [mol/s]

• Volume Fraction [-]

Notes

By default M-Star CFD generates three slices, positioned at the centroid of the lattice domain. Additional output planes can be defined in the GUI. The output frequency of this slice data is governed by the Slice Output variable.

Volume.pvd

Time-evolution of the fluid properties across the 3D tank volume

Contents

• Velocity [m/s]

• Temperature [K]

• Pressure [Pa]

• Resolved Strain Rate [1/s]

• Vorticity [1/s]

• Eddy Dissipation Rate [W/kg]

• Total Kinetic Energy [W/kg]

• Fluid Viscosity [m^2/s]

• Species Concentration [mol/L]

• Mean Age [s]

• Mean Velocity [m/s]

• Time-average Eddy Dissipation Rate [W/kg]

• Time-average Species Concentration [mol/L]

• Time-average Resolved Strain Rate [1/s]

• Time-average Turbulent Kinetic Energy [W/kg]

• Species Exposure [mol/s]

• Volume Fraction [-]

Notes

To help with file size management, the data printed output to the volume file can be downselected in the GUI. The output frequency of this volume data is governed by the Volume Output variable.

SliceParticles.pvd

Positions of particles across the domain, printed at the output interval of the slices

Contents

• ParticleID [-]

• OriginID [-]

• Position [m]

• Velocity [m/s]

• Diameter [m]

Notes

This data describes the time-evolution of the position and velocity of each particle, in addition to reporting the particleID, originID, the time at which the particle entered the system, and the particle diameter. The output frequency of this particle data is governed by the Slice Output variable.

VolumeParticles.pvd

Positions of particles across the domain, printed at the output interval of the volumes

Contents

• ParticleID [-]

• OriginID [-]

• Position [m]

• Velocity [m/s]

• Diameter [m]

Notes

This data describes the time-evolution of the position and velocity of each particle, in addition to reporting the particleID, originID, the time at which the particle entered the system, and the particle diameter. The output frequency of this particle data is governed by the Volume Output variable.

SliceSolidN.pvd

Position and surface force distribution on the Nth surface imported into the in the system. Suitable for rendering with slice output

Contents

• Position [m]

• Force Distribution [N]

Notes

For moving objects, this data describes the time-evolution of the position and the time-varying surface force distribution. For static tank internals, this data represents the constant position and time-varying surface force distribution on each imported surface. The output frequency of this force data is governed by the Slice Output variable.

VolumeSolidN.pvd

Position and surface force distribution on the Nth surface imported into the in the system. Suitable for rendering with volume output

Contents

• Position [m]

• Force Distribution [N]

Notes

For moving objects, this data describes the time-evolution of the position and the time-varying surface force distribution. For static tank internals, this data represents the constant position and time-varying surface force distribution on each imported surface. The output frequency of this force is governed by the Volume Output variable.

SliceMovingProbesN.pvd

Time-evolution of the position and velocity Nth moving probe, suitable for animating the its trajectory with slices

Contents

• Position [m]

• Velocity [m/s]

Notes

This output can be used to visualize the trajectory of moving probes through the fluid domain. This visual output complements the MovingProbeN.txt data file discussed below. The output frequency of this particle data is governed by the Slice Output variable.

VolumeMovingProbesN.pvd

Time-evolution of the position and velocity Nth moving probe, suitable for animating the its trajectory with volumes

Contents

• Position [m]

• Velocity [m/s]

Notes

This output can be used to visualize the trajectory of moving probes through the fluid domain. This visual output complements the MovingProbeN.txt data file discussed below. The output frequency of this particle data is governed by the Volume Output variable.

SliceScreenParticlesN.pvd

Landpoints of the particles crossing the Nth particle screen, suitable for animating particle accumulation on a particle screen with slice output

Contents

• Land point position [m]

• Land point velocity [m/s]

• ParticleID of landed particle [-]

• OriginID of landed particle[-]

• Time at which the landed particle was added to the system [s]

• Diameter of of landed particle [m]

Notes

This output can be used to visualize the accumulation of particles along a particle screen, along with the age, diameter and origin of the particles that hit the screen. The output frequency of this particle data is governed by the Slice Output variable.

VolumeScreenParticlesN.pvd

Landpoints of the particles crossing the Nth particle screen, suitable for animating particle accumulation on a particle screen with volume output

Contents

• Land point position [-]

• Land point velocity [-]

• ParticleID of landed particle [-]

• OriginID of landed particle[-]

• Time at which the landed particle was added to the system [s]

• Diameter of of landed particle [m]

Notes

This output can be used to visualize the accumulation of particles along a particle screen, along with the age, diameter and origin of the particles that hit the screen. The output frequency of this particle data is governed by the Volume Output variable.

walls.stl

Bounding geometry output

Contents

• The topology of the bounding geometry

Notes

This file is a tessellated representation of the bounding geometry; only one file is created.

## /out/Stats¶

This directory contains all the numerical data generated by the solver for analysis. This data is presented as ASCII text which can be extracted and analyzed by users, independently of the MStarPost post-processing tools. The nature of the data output is informed by the simulation set-up.

Notes

• Probe data in this directory is printed at the user-specified Probe Output interval.

• All other data (slices, particles, moving probes, interfaces, etc.) are printed at the user-specified Data Output interval.

The following files may be created:

Fluid.txt

Time-evolution of total fluid mass, volume and kinetic energy

Contents

• Time [s]

• Total Fluid Mass [kg]

• Total Fluid Volume [m^3]

• Domain Volume [m^3]

• Total Fluid Kinetic Energy [J]

• Total Potential Energy [J]

Notes

Produced with each simulation. The time-evolution of the fluid kinetic energy is useful for quantifying the convergence to steady-state flow behavior. The time-evolution of the fluid mass/volume is useful for predicting fluid volume change as a function of time during filling/draining simulations.

Thermodynamics.txt

Time-evolution of power input, dissipation, and fluid temperature

Contents

• Time [s]

• Impeller shaft power [W]

• Total power dissipation [W]

• Resolved power dissipation [W]

• Average fluid temperature [K]

Notes

Produced with each simulation. Impeller shaft power is reported for each impeller. Total power dissipation represents the sum of the resolved and unresolved components of dissipation. The unresolved component describes energy dissipated by the LES filter. The fluid temperature is only reported when a thermal field is active. This output is useful in assessing conservation of energy, as related to power in, power dissipated, and temperature change.

Timing.txt

Time-evolution of runtime performance

Contents

• Iteration [-]

• Simulation Time [s]

• MLUPS [-]

• MLUPS Per Active Process [-]

• Wall Time [min]

• CPU Time [min]

• Initialization [%]

• Output [%]

• Statistics [%]

• Communication [%]

• Fluid Solver [%]

• Particles [%]

• Boundary Conditions [%]

• Mean Age[%]

• Species Transport[%]

• Immersed Boundary[%]

Notes

Produced with each simulation. Used to characterize runtime speed and efficiency. Particles, mean age, species transport, and immersed boundary are only produced when such features are present in the model.

InletOutletN.txt

Time-evolution of the fluid properties at the Nth opening.

Contents

• Time [s]

• Velocity X [m/s]

• Velocity Y [m/s]

• Velocity Z [m/s]

• Pressure [Pa]

• Age [s]

• Concentration [mol/L]

• Temperature [K]

Notes

Produced for each opening. Used to assess properties of the fluid, species field, temperature, and mean age leaving or entering the system through defined openings.

ImpellerN.txt

Time-evolution of force, torque, and pumping action of the Nth impeller

Contents

• Time [s]

• Force X [N]

• Force Y [N]

• Force Z [N]

• Force Axial [N]

• Torque X [N-m]

• Torque Y [N-m]

• Torque Z [N-m]

• Power Number [-]

• Pumping Number Top [-]

• Pumping Number Bottom [-]

• Pumping Number Side [-]

Notes

Produced for each impeller. Used to characterize the forces and torques on each rotating impeller. The x, y, and z-force are defined with respect to the global coordinate system. The axial and radial forces represent the components of this total force that are perpendicular to and colinear with the axis of rotation. The power number comes directly from the shaft torque, as normalized by the fluid density, impeller diameter, and impeller speed. The pumping number is calculated across the top, side, and bottom surface of a Gaussian pillbox surrounding the impeller geometry. Negative values for the pumping number imply flow into the pill box, positive values imply flow leaving the pill box. NAN values imply a pillbox that extends beyond the simulation domain.

SpeciesDataN.txt

Time-evolution of mean species concentration and the standard deviation in species concentration across the tank for species N.

Contents

• Time [s]

• Mean concentration [mol/L]

• Concentration standard deviation [mol/L]

Notes

Produced for each species. For reacting systems, can be used to predict species production and consumption. For closed, non-reacting systems, the species concentration coefficient of variation (standard deviation / mean) provides insight into species homogeneity.

MiscibleSpecies.txt

Time-evolution of Fluid B occupation fraction across the tank and the associated occupation standard deviation.

Contents

• Time [s]

• Fluid B volume occupation [%]

• Fluid B volume occupation standard deviation [-]

Notes

Produced only for miscible fluid systems. Describes the fraction of the fluid volume occupied by Fluid B, and how this second fluid is dispersed across the fluid volume (via the standard deviation).

ParticleCount.txt

Time-evolution of the total number of particles contained in the system.

Contents

• Time [s]

• Total Particle Count [-]

Notes

Produced only for systems with particles. Useful for open systems with continuous particle injection and loss, when trying to determine a steady state particle population.

exitParticlesN.txt

List of all particles that have exited the system through outlet N.

Contents

• ParticleID [-]

• OriginID [-]

• Outlet ID [-]

• Exit Age [s]

• Diameter [m]

• Position X [m]

• Position Y [m]

• Position Z [m]

• Velocity X [m/s]

• Velocity Y [m/s]

• Velocity Z [m/s]

Notes

Produced only for systems with particles and outlets. For each particle that exits the system, this file records (i) which particle exited, (ii) where this particle originally entered the system, (iii) which outlet this particle exited the system, (iv) the diameter of this particle upon exit, (v) the age of this particle upon exit, (vi) the position of this particle upon exit, and (vii) the velocity of this particle upon exit. This data is exceptionally useful in predicting residence time distributions (from the exit ages), in addition to developing correlations between mean residence times, particle diameters, and exit velocities.

FixedProbeN.txt

For each probe N, reports the time-evolution of the fluid and scalar properties at the given probe location.

Contents

• Time [s]

• Position X [m]

• Position Y [m]

• Position Z [m]

• Velocity X [m/s]

• Velocity Y [m/s]

• Velocity Z [m/s]

• Avg. Turb. KE [J/kg]

• Resolved Strain Rate [1/s]

• Eddy Dissipation Rate [W/kg]

• Temperature [K]

• Fluid B Volume Frac [-]

• Species Concentration [mol/L]

Notes

Produced only for systems with fixed probes. Useful for extracting point-specific velocity data for local energy spectrum analysis. The temperature, Fluid B Volume Fraction, and species concentrations are reported only when such parameters are defined in the system set-up.

MovingProbeN.txt

For each moving probe N, report the time-evolution of the fluid and scalar properties at the instantaneous probe location.

Contents

• Time [s]

• Position X [m]

• Position Y [m]

• Position Z [m]

• Particle Velocity X [m/s]

• Particle Velocity Y [m/s]

• Particle Velocity Z [m/s]

• Avg. Turb. KE [J/kg]

• Resolved Strain Rate [1/s]

• Eddy Dissipation Rate [W/kg]

Notes

Produced only for systems with moving probes. Useful for tracking how particles (with a given diameter and density) evolve through a system and experience different fluid conditions over time.

Blendtime.txt

For systems with the autoblendtime, automatically compute the time-evolution of the blending coefficient of variation (COV)

Contents

• Time [s]

• System COV [-]

• Bin concentration [-]

Notes

Produced only for systems with autoblendtime enabled. For fully blended systems, the COV should approach unity. The COV is evaluated by examining the distribution of particles across the user-defined sub-volumes.

FluidBlendtime.txt

For systems with the autoblendtime, this is the amount of fluid inside each subvolume.

Contents

• Time [s]

• Total Volume [m^3]

Notes

Produced only for systems with autoblendtime enables. For each bin defined by the user, this is the volume of fluid contained in the bin. If a bin has a very low fluid volume compare to other bins, user may consider ignoring its contribution to the total COV in the Blendtime.txt file.

ParticlesBlendTime.txt

For systems with the autoblendtime, this is the number of particles inside each subvolume.

Contents

• Time [s]

• Particle Count [-]

Notes

Produced only for systems with autoblendtime enabled. For each bin defined by the user, this is the number of tracer particles contained in the bin.

SliderN.txt

For each sliding object N, reports the time-evolution of the forces on the solid surface.

Contents

• Time [s]

• Position [m]

• Velocity [m/s]

• Force X [N]

• Force Y [N]

• Force Z [N]

Notes

Produced only for systems with oscillating objects. The x, y, and z-force are defined with respect to the global coordinate system. The position is defined relative to the initial mountpoint, along the direction of the motion axis defined at import.

TranslatorN.txt

For each translating object N, reports the time-evolution of the forces on the solid surface.

Contents

• Time [s]

• Position [m]

• Velocity [m/s]

• Force X [N]

• Force Y [N]

• Force Z [N]

Notes

Produced only for systems translating at a constant user-defined velocity. The x, y, and z-force are defined with respect to the global coordinate system. The position is defined relative to the initial mountpoint, along the direction of the motion axis defined at import.

FluxSurfaceN.txt

For each flux surface N, reports the time-evolution of the forces on the solid surface.

Contents

• Time [s]

• Force X [N]

• Force Y [N]

• Force Z [N]

Notes

Produced only for systems with a flux surface. The x, y, and z-forces are defined with respect to the global coordinate system.

InternalSurfaceN.txt

For each internal N, reports the time-evolution of the forces on the surface.

Contents

• Time [s]

• Force X [N]

• Force Y [N]

• Force Z [N]

Notes

Produced only for systems with internal surfaces. The x, y, and z-forces are defined with respect to the global coordinate system.

## /out/Checkpoint¶

Binary data used to restart simualtions. Not for post-processing.