porousMicroTransport1 is a set of additional solvers and related libraries for OpenFOAM developed for the purposes of simulating flow and transport in porous media, with an emphasis on paper-based microfluidics
porousMicroTransport requires OpenFOAM, as distributed by OpenCFD (openfoam.com). Compatible OpenFOAM versions are v2112, v2206, v2212, v2306, v2312 and v2406.
Versions produced by the OpenFOAM Foundation (openfoam.org) (e.g. OpenFOAM 9, OpenFOAM 10) are not compatible. macOS users may want to consider OpenFOAM.app.
Download the source code of porousMicroTransport, or clone this repository with Git:
git clone https://github.com/gerlero/porousMicroTransport.git
To build and install porousMicroTransport, just invoke the top-level Allwmake
script:
cd porousMicroTransport
./Allwmake -j
If necessary, activate/source the correct OpenFOAM environment before running Allwmake
.
Optionally, you can verify the installation of porousMicroTransport by running the included test suite (requires Python 3.7 or later):
tests/Alltest
Alternatively, porousMicroTransport is also available in the form of Docker images. These images include porousMicroTransport precompiled and ready to use. Assuming Docker is installed, the following command will run the latest image and mount the current directory so that you can access the files inside:
docker run --rm -it -v $PWD:/root -w /root microfluidica/porousmicrotransport
Or, if you use OpenFOAM's openfoam-docker
script (which takes care of making the working directory available inside the container):
openfoam-docker -image=microfluidica/porousmicrotransport
A slimmer image variant that does not include source code, development tools or tutorial cases is available as microfluidica/porousmicrotransport:slim
.
Docker images can also be used with other compatible containerization software, such as Podman and Singularity/Apptainer.
(Unsaturated) capillarity-driven flow in a porous medium, governed by the moisture diffusivity equation2:
where
Transport by steady flow of any number of species in a porous medium, with optional reactions between the species. For each species (concentration
where
and
with
Capillary flow + reactive transport in a porous medium, coupling the moisture diffusivity equation for flow with the previous transport equation.
The layout of porousMicroTransport cases follows many conventions of porousMultiphaseFoam, especially in field names and entries in the transportProperties
dictionary. This allows for easy conversion of cases from porousMultiphaseFoam to porousMicroTransport (and to some extent, vice versa).
These variable fields are defined in the time directories:
-
theta
: moisture content (scalar). Optional forporousMicroTransportFoam
-
U
: Darcy velocity (vector). Optional for flow solvers
Defined as scalar fields in constant
or as dictionary entries in transportProperties
:
-
eps
orthetamax
: effective porosity ($\varepsilon$ ) -
K
: intrinsic permeability. Flow solvers only -
rs
: particle density ($\rho_s$ ). Transport solvers only -
epsTotal
: total porosity ($\varepsilon_\textrm{tot}$ ). Transport solvers only -
tau
: diffusive tortuosity ($\tau$ ). Transport solvers only -
alphaT
: transverse dispersion coefficient ($\alpha_T$ ). Transport solvers only -
alphaL
: longitudinal dispersion coefficient ($\alpha_L$ ). Transport solvers only
Flow solvers only.
Set these in a phase.theta
subdictionary in transportProperties
:
-
rho
: density -
mu
: dynamic viscosity
Flow solvers only.
Defined as scalar fields in constant
or as dictionary entries in transportProperties
:
-
thetamin
: minimum (a.k.a. residual) moisture content -
thetamax
: maximum moisture content (usually equal to the porosity)
Flow solvers only.
Supported models of unsaturated flow are:
-
BrooksAndCorey
: Brooks and Corey3 model- In coefficient dictionary
BrooksAndCoreyCoeffs
:pc0
,alpha
,n
,l
(optional)
- In coefficient dictionary
-
VanGenuchten
: Van Genuchten4 model- In coefficient dictionary
VanGenuchtenCoeffs
:pc0
,m
orn
,l
(optional)
- In coefficient dictionary
-
LETxs
: LETx + LETs model5- In coefficient dictionary
LETCoeffs
:pc0
,Lw
,Ew
,Tw
,Ls
,Es
,Ts
- In coefficient dictionary
-
LETd
: LETd6 model- In coefficient dictionary
LETCoeffs
:pc0
,L
,E
,T
- In coefficient dictionary
To choose a model for your simulation, set the unsaturatedFlowModel
entry in transportProperties
. Then set the model-specific parameters in the corresponding coefficient subdictionary.
Flow solvers only.
Besides the standard OpenFOAM boundary conditions (e.g. zeroGradient
, fixedValue
), the solvers support these additional boundary conditions for theta
:
-
darcyGradPressure
: follow the boundary condition set for velocity (same asdarcyGradPressure
in porousMultiphaseFoam). -
exhaustible
: models an inlet reservoir with a fixed volume of fluid that is gradually depleted as fluid flows into the domain. Aremaining
entry is required (volume remaining in the reservoir).
Transport solvers only.
A species
list in transportProperties
contains the names of all transported species.
Each species must also define its own scalar concentration field (named the same as the species).
For each species, the following entries can be set in transportProperties
:
-
Dm
: molecular diffusivity ($D_M$ ) -
Kd
: partitioning coefficient ($K_d$ )
Transport solvers only.
Reactions are defined in a reactions
subdictionary in transportProperties
. The reactions
dictionary contains a list of subdictionaries, each of which defines a single reaction. A reaction can have an arbitrary name and should contain the following entries:
-
reaction
: reaction equation. E.g."A^2 + B = 2C + D"
, whereA
,B
,C
andD
are names of defined species -
kf
: forward rate constant -
kr
: optional reverse rate constant (for reversible reactions)
To enable automatic timestep adjustment, set adjustTimeStep
to yes
in system/controlDict
. Then, configure it as follows:
-
For flow, set a
tolerance
value inside aPicard
dictionary insystem/fvSolution
-
For transport, add a
maxDeltaC
and/orrelMaxDeltaC
entry insystem/controlDict
Sample cases are available in the tutorials
directory.
-
porousMultiphaseFoam7: toolbox for OpenFOAM for modeling multiphase flow and transport. porousMicroTransport is mostly compatible with porousMultiphaseFoam in terms of case definitions, and can be installed alongside it.
-
electroMicroTransport8: toolbox for OpenFOAM dedicated to electromigrative separations. It includes support for modeling separations in paper-based media, and can also be installed alongside porousMicroTransport.
Footnotes
-
Gerlero, G. S., Guerenstein, Z. I., Franck, N., Berli, C. L. A., & Kler, P. A. (2024). Comprehensive numerical prototyping of paper-based microfluidic devices using open-source tools. Talanta Open, 10, 100350. https://doi.org/10.1016/j.talo.2024.100350 ↩
-
Bear, J., & Cheng, A. H. D. (2010). Modeling groundwater flow and contaminant transport (Vol. 23, p. 834). Dordrecht: Springer. https://doi.org/10.1007/978-1-4020-6682-5 ↩
-
Brooks, R., & Corey, T. (1964). Hydraulic properties of porous media. Hydrology Papers Colorado State University. https://mountainscholar.org/bitstream/handle/10217/61288/HydrologyPapers_n3.pdf ↩
-
Van Genuchten, M. T. (1980). A closed‐form equation for predicting the hydraulic conductivity of unsaturated soils. Soil Science Society of America Journal, 44(5), 892-898. https://doi.org/10.2136/sssaj1980.03615995004400050002x ↩
-
Lomeland, F. (2018). Overview of the LET family of versatile correlations for flow functions. In: Proceedings of the International Symposium of Core Analysts, SCA2018-056 http://www.jgmaas.com/SCA/2018/SCA2018-056.pdf ↩
-
Gerlero, G. S., Valdez, A. R., Urteaga, R., & Kler, P. A. (2022). Validity of capillary imbibition models in paper-based microfluidic applications. Transport in Porous Media, 141(2), 359-378. https://doi.org/10.1007/s11242-021-01724-w ↩
-
Horgue, P., Renard, F., Gerlero, G. S., Guibert, R., & Debenest, G. (2022). porousMultiphaseFoam v2107: An open-source tool for modeling saturated/unsaturated water flows and solute transfers at watershed scale. Computer Physics Communications, 273, 108278. https://doi.org/10.1016/j.cpc.2021.108278 ↩
-
Gerlero, G. S., Damián, S. M., & Kler, P. A. (2021). electroMicroTransport v2107: Open-source toolbox for paper-based electromigrative separations. Computer Physics Communications, 269, 108143. https://doi.org/10.1016/j.cpc.2021.108143 ↩