Flow123d

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Processes in Fractured Media

Features

Flow123d is a simulator of mechanical and transport processes in fractured porous media. The simulator consistently uses the continuum-fracture approach combining classical continuum equations with similar equations on the discrete fractures represented as lower dimensional manifolds. The physically based equations on the fractures and coupling with the continuum are derived by the integration across the fracture aperture and suitable semi-approximation. The resulting method allows continuous transition between continuum and Discrete Fracture Network description of the fractured rock.

Support for complex geometries

  • Convenient for modeling 2D fractures and 1D channels in 3D ambient media.
  • The BGEM tool is well-suited for preparation of computational meshes including stochastic fracture networks. It essentially uses GMSH meshing software and its API.
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Darcian Flow in Fractured Media

  • Saturated and variably saturated model (Richard's equation).
  • Coupling on interfaces between adjacent dimensions.
  • Mixed-hybrid formulation providing accurate velocity approximation.
  • Efficient implementation using Schur complement.
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Advection-Diffusion Equation for Solute Transport

  • Finite Volumes model for convection-driven problems. Explicit time scheme.
  • Robust Discontinuous Galerkin + implicit time scheme for transport including hydrodynamic diffusion.
  • Support for arbitrary number of substances.
  • Efficient implementation of linear sorption model.
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Reaction term

  • Reaction term includes: dual porosity model, sorption, and first-order kinetic reactions (decays).
  • Coupled with transport models using the operator splitting method.
  • Support for general combination of several reaction processes.
  • Efficient computation of non-linear sorption via interpolation tables.

Heat transfer

  • Equilibrium heat transfer model including conduction in rock and conduction and convection in liquid phase.
  • Robust Discontinuous Galerkin + implicit time scheme.

Mechanics

  • Linear elasticity.
  • Coupled with Darcy flow leading to Biot's poroelasticity model (iterative coupling scheme).
  • Contacts on fractures, non-linear dependency of permeability.

Software specific

  • Languages: C++, MPI, Python, Shell
  • Libraries: PETSc, PERMON, Armadillo, YamlCpp.
  • BDDC solver, publication.
  • Parallel assembly, solvers, serial computational mesh.
  • Structured input using YAML file format.
  • All parameters can be arbitrary space-time field.
  • Output to GMSH and VTK format, including binary and compressed variations.
  • Output of quantities at observation points.
  • Output of quantities balance over domains and boundaries.
  • Read more about IO...