# Probe Definitions

Probe particles are created in order to extract accurate post-processing information from a particular location, such as a FLUID or a WALL or a MOVINGWALL phase.

It is possible to define both static and moving probe particles.
probes
{
probe
{
probe_type            volumeprobe
probe_name            volumeprobeExample
probe_cntr            "0.0 0.0 0.0”
probe_phase           3
probe_shiftingaware   true
}
probe
{
probe_type            surfaceprobe
probe_name            surfaceprobeExample
probe_cntr            "0.0 0.0 0.0"
probe_thck            0.05
probe_thckodx         3
probe_nrmvec          "10.0 0.0 0.0"
probe_phase           3
probe_shiftingaware   true
}
probe
{
probe_type            solidprobe
probe_name            solidprobeExample
probe_cntr            "1.0 20.0 3.0"
probe_phase           2
probe_movewith        true
}
probe
{
probe_type            flowrateprobe
probe_name            flowrateprobeExample
probe_cntr            "1.0 -1.0 -100.0"
probe_thck            0.2
probe_thckodx         2.5
probe_nrmvec          "0.0 1.0 0.0"
probe_tanvec          "5.0 0.0 0.0"
probe_points_file     filename
probe_phase           3
probe_shiftingaware   true
}
}
probe_type
Type of the probe used.
• volumeprobe assesses fluid properties
• surfaceprobe assesses fluid properties (mass flow).
• solidprobe assesses solid body properties.
• flowrateprobe is essentially a MASSFLOW equivalent.
probe_name
Probe name.
probe_cntr
Probe particle location.
An exception is flowrateprobe, where it is likely that the flowrateprobe is comprised of multiple particles in which case the command represents sort of a reference point in case that the probe is supposed to move.
Radius of the probe particle (influences the sample size).
Unit: [m]
Radius of the probe as a function of dx, for example, when specified 3.0, implies 3.0*dx.
If both probe_rad and probe_radodx are specified, the latter one takes precedence.
Default: kernel cut-off size (3.0 for quintic spline)
probe_phase
In case of volumeprobe, surfaceprobe and flowrateprobe this command specifies which phase motion the probe should follow.
Example: If you specify phase 3, and that phase is a MOVINGWALL with assigned rotation, than the probes will follow the same motion.
In case of a solidprobe, this command specifies which solid phase is monitored.
probe_movewith
This command is applicable only to the solidprobe.
solidprobe already points to a particular phase for monitoring, whereas this command determines whether the probe is also moving with that phase or not.
Options: true/false
Default: false
probe_thck
flowrateprobe and surfaceprobe are effectively 2.5D-like entities, where their definition is 2D, but in order to function properly, they need to consider a certain space before and after them, thus the thickness parameter.
This command specifies the absolute thickness of the probes.
Unit: [m]
probe_thckodx
Same as the previous command, except that it specifies the probe thickness as a relative function of the kernel size, for example, when specified 3.0, implies 3.0*dx.
Default: 1.0*dx
probe_nrmvec
Vector specifying the surface normal of the probe.
Flow passing in the same direction as this vector will be noted as a positive value flow.
probe_tanvec
This command specifies a vector which is co-planar with probe surface and at the same time defines the probe grid direction.
This command is optional.
probe_points_file
Only applicable to flowrateprobe type.
It is possible to have a separate file with cloud point data (simple X, Y, Z coordinates; delimiter is space) and use it as a definition for the flowrateprobe probe particles.
probe_shiftingaware
This command enables the probes to consider the real convective velocity when using transport velocity or APD schemes.
It is recommended that this option remains true.
Default: true

Probes can provide a broad set of information about the area which they are monitoring. This data can be torque or forcing data (solid probes only), mass or volume flow rates, pressure values, density, viscosity or velocity. It is true that various applications require different measurements not just in terms of the monitored variable, but also in terms of time sampling or distinguishing the flow direction. In order to tackle all of these options, the PROBE output file can contain numerous columns.

Here is a list of several keywords which help explain the meaning of the columns, followed by a few examples.
Note: Where the * symbol denotes the fact that you can find other extension prior or after the keyword.
• i - instantaneous information
• pta - periodic time average (averaged over the time between two outputs)
• TIME - time
• CNTR* - probe center
• CVEL* - probe center velocity
• NRMVEC* - normal vector of the probe
• NPART - average number of particles per 1dx thickness of probe
• oap - summation over all fluid phases
• abs* - absolute (does not consider probe velocity)
• rel* - relative (relative to probe velocity)
• *Vol* - Volume flow rate
• *Mss* - Mass flow rate
• *Co* - Component of flow in the probe normal direction
• *Flow - flow rate

Here are a few examples of column headers:

pta_absVolFlow_1[m^3/s]
Periodic time averaged absolute volumetric flow of phase 2.
pta_relMssCoFlow_2[kg/s]
Periodic time averaged relative mass flow in the direction of the probe normal for phase 2.
pta_relVolFlow_oap[m^3/s]
Periodic time averaged relative volumetric flow overall all phases (volumetric flow of all fluid phases).
i_CNTR-Y[m]
Instantaneous location of the probe center in Y direction.
pta_absMssCoFlow_7[kg/s]
Periodic time averaged absolute mass flow in the direction of the probe normal for phase 7.

To clarify, the term periodic time average implies a value that is time averaged over the period between two required outputs (dt_phaseinfo). The ns_phaseinfo command defines the number of samples that will be taken over the period of dt_phaseinfo and then averaged to provide the periodic time average value in the output.