The solver that computes an analysis: the Backend field of a launch form. Permeability, for example, can run on waLBerla or Kabs Taichi.
Batch
A group of images, such as all the arrays from one .zip archive, that a tool can run on at once, one job per image. See Images.
BGK
Single-relaxation-time collision, after Bhatnagar, Gross and Krook: every lattice Boltzmann population relaxes towards its local equilibrium at the one rate set by the relaxation time. Every permeability backend uses it. See permeability.
Binary image
An image whose voxels hold only two values; the image page shows its Image type as Binary. With 0 as solid it's a segmented image, which every analysis takes. See Segmented images.
Blind / surface porosity beta
Pore volume in clusters with exactly one connected opening to the image's faces, as a share of the whole image. See connectivity analysis.
Bounce-back
The lattice Boltzmann way of imposing no slip on a wall: a fluid population that would stream into solid is reflected back the way it came. Halfway bounce-back puts the wall midway between the last fluid node and the first solid node.
Capillary pressure (entry pressure)
The pressure difference across the curved interface between two fluids. A non-wetting fluid enters a throat of radius \(r\) once the pressure exceeds its entry pressure, \(P_c = -2\sigma\cos\theta/r\). See mercury porosimetry.
Pore volume in clusters that touch no face of the image, as a share of the whole image: pores a gas couldn't reach. See connectivity analysis.
Compute tier
The hardware a job runs on, named by its memory and hardware, such as 48 GB GPU · A40/A6000. Auto runs the job on idle hardware that fits the image when some is free, and otherwise on the smallest tier that fits. The tier changes capacity and speed, not the answer. See Compute and hardware.
D3Q19
The lattice every permeability backend uses: 19 discrete velocities per node, at rest and towards its 6 face and 12 edge neighbours. See permeability.
Darcy velocity (superficial velocity)
Volumetric flow rate per unit total cross-section, \(u_D = Q/A\). It equals the mean pore velocity times the porosity.
Dirichlet condition
A boundary condition that fixes the value of the unknown, such as a pressure or a concentration, on a boundary.
Distance transform
For each pore voxel, the Euclidean distance to the nearest solid voxel, \(d(\mathbf{x})\).
Effective diffusivity
\(D_\text{eff}\): the diffusivity a homogeneous material would need to carry the same flux as the porous one under the same gradient. PoreStore reports \(D_\text{eff}/D_0\), which includes porosity.
Formation factor
\(F = D_0/D_\text{eff} = \tau/\varphi\), the reciprocal of the effective diffusivity ratio, after Archie. In conductivity terms it's \(\sigma_0/\sigma_\text{eff}\), with \(\sigma_0\) the conductivity of the fluid that fills the pores and \(\sigma_\text{eff}\) that of the sample filled with it, around an insulating solid. Diffusivity results show it next to the tortuosity factor. See diffusivity.
Greyscale image
An image that isn't binary, such as a CT scan whose voxels hold a range of intensities. Segmentation turns it into a segmented image.
Headline
The one number that sums up a result, shown first in the app and in reports, such as the median pore radius or \(k\) in mD. Each tool's page in the User guide names its headline.
Ingestion
The step after upload that reads the file, stores the array and measures it. The image shows as processing until it finishes.
Inlet and outlet faces
The two opposite faces of the image, normal to the transport direction, where a simulation fixes the pressure, concentration or potential. The inlet is the face at index 0. See permeability.
Job
One run of a tool on one image, with its settings, status, provenance and result. See Job states.
Lateral faces
The four faces of the image parallel to the transport direction. Permeability makes them periodic, and diffusivity and conductivity make them no-flux walls. See diffusivity.
Lattice Boltzmann method (LBM)
A kinetic method for fluid flow that evolves particle distribution functions on a lattice. At low velocity its steady state solves the incompressible Navier–Stokes equations, and so the Stokes equations at vanishing Reynolds number.
Lattice units
The units LBM works in: one voxel per unit length, one time step per unit time. Results in voxel units come from lattice units.
Local thickness
The radius of the largest sphere that fits in the pore space and contains a point. See pore size distribution.
No-flux condition
\(\partial c / \partial n = 0\): nothing crosses the boundary.
Non-wetting saturation
\(S_\text{nwp}\): the fraction of the pore volume filled by a non-wetting fluid, such as mercury. See mercury porosimetry.
Percolating porosity beta
Pore volume in clusters that touch both faces normal to an axis, as a share of the whole image. See connectivity analysis.
Periodic boundary
Opposite faces of the domain are joined: whatever leaves one face enters through the opposite one. Every permeability backend makes the lateral faces periodic.
Permeability
The constant \(k\) in Darcy's law, \(u_D = -(k/\mu)\nabla p\). Units of area: m², or darcy, where \(1\ \text{D} = 9.869233\times10^{-13}\ \text{m}^2\).
Pore network beta
A graph model of the pore space: pores are nodes and throats are edges. See Network Extraction.
Porosity
The pore fraction of the volume, \(\varphi\); \(\varphi(x)\), or \(\varphi\) of a named slice or region, for a local value. PoreStore's porosity is total porosity, which counts isolated pores too.
REV
Representative elementary volume: the smallest sample size whose properties don't depend on where it was cut. See REV porosity.
Saved field
A 3D array a job stores with its image, such as permeability's velocity or diffusivity's concentration, for viewing and export. It's deleted with the image; the job's numbers stay.
Segmentation
Turning a greyscale image into a segmented one by deciding which voxels are pore. See Basic Thresholding.
Segmented image
An image with 0 for solid and one other value for pore, such as a boolean, 0/1 or 0/255 image, which all give the same results. Every analysis takes one. See Segmented images.
Spanning path
A path of pore voxels, each sharing a face with the next, from the inlet face to the outlet face; for conductivity, a path of solid voxels. Without one, nothing flows or diffuses through the sample. See diffusivity.
Specific surface area
Pore–solid interface area per unit bulk volume, \(s_v\).Interfacial surface area reports it as area / bulk volume.
Team ID
A team's permanent eight-character identifier, used in the app's web addresses.
Threshold
The intensity that splits a greyscale image into pore and solid: voxels at or below it become pore, unless the segmentation is inverted. See Segmentation.
Throat
A constriction that joins two pores. Mercury enters the pore space throat by throat, which is why mercury porosimetry measures entry sizes rather than pore sizes.
Tortuosity factor
\(\tau = \varphi/(D_\text{eff}/D_0)\): how much the pore geometry slows transport beyond the loss of cross-section. Called Tortuosity factor in the app; conductivity reports the solid tortuosity factor\(\tau_s\) of the solid phase. See diffusivity.
Voxel size
The edge length of one cubic voxel, in micrometres. It converts results from voxel units to physical units when you read them.
Voxel units
Units in which the voxel edge is 1. All results are stored in voxel units.