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tools
frackit
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73c6af5d
Commit
73c6af5d
authored
Nov 12, 2020
by
Dennis Gläser
Browse files
[paper] further editorial changes
parent
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paper.md
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73c6af5d
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@@ -91,8 +91,8 @@ numerical schemes, the mesh quality is of particular importance and should be
taken into account already during the network generation. In particular, small length
scales and angles at intersecting geometries should be avoided,
as well as small distances due to fractures being very close to each other or to the
domain boundary. Within the above-mentioned non-commercial packages,
to the authors
knowledge,
such a feature (without the check for small angles) is only available
domain boundary. Within the above-mentioned non-commercial packages,
such a feature (without the check for small angles) is only available
in @hyman2015dfnWorks. They describe fractures by polygons, which are also
used to approximate elliptical shapes, and the domains are restricted
to hexahedra. In
``Frackit``
, such checks can be performed between arbitrary, possibly
...
...
@@ -118,7 +118,7 @@ of all geometric entities involved, i.e. the intersection geometries between
all entities are computed. Thus, this information can be directly used in the
context of discrete fracture-matrix (dfm) simulations in a conforming way as
described before. For instance, the open-source simulator
[
DuMuX
][
3
]
[@Dumux; @Kochetal2020Dumux]
[
DuMuX
][
3
]
[
@Dumux; @Kochetal2020Dumux
; [dumux.org
][
3
]
]
contains a module for conforming dfm simulations of single- and multi-phase
flow through fractured porous media, which has been used in several works
[@glaeser2017; @glaeser2019; @andrianov2019].
...
...
@@ -132,7 +132,7 @@ by means of numerical simulations.
The design of
``Frackit``
is such that there is no predefined program flow, but
instead, users should implement their own applications using the provided classes
and functions. This allows for full customization of each step of the network
generation.
Besides this
, in the case of available measurement data, one could
generation.
Furthermore
, in the case of available measurement data, one could
skip the network generation process and use
``Frackit``
to compute the fragmentation
of the measured data and to generate CAD files for subsequent meshing. The code
is structured around three fundamental tasks involved in the generation of random
...
...
@@ -146,10 +146,9 @@ networks:
This paper focusses on the first two of the above-mentioned steps, and we refer
to the code documentation for details on further available functionalities.
Moreover, we focus on C++ code in the presented snippets, and refer to the examples
of the
``Frackit``
repository
(
[
git.iws.uni-stuttgart.de/tools/frackit
](
https://git.iws.uni-stuttgart.de/tools/frackit
)
)
for details on how to use it from Python.
The presented code snippets focus on the implementation in C++, and for details on
how to use
``Frackit``
from Python we refer to the examples provided in the repository
(
[
git.iws.uni-stuttgart.de/tools/frackit
][
0
]
).
## Random generation of fracture entities
...
...
@@ -242,9 +241,9 @@ const auto quad = quadSampler();
## Evaluation of geometric constraints
While the domain is populated with the raw fracture entities, users have the
possibility to enforce geometric constraints between them in order
to e
nforce
topological characteristics
as e.g.
fracture spacing.
Besides this,
constraints can be used to avoid very small length scales that could cause problems
possibility to enforce geometric constraints between them in order
for the network
to e
xhibit the desired
topological characteristics
such as, for instance,
fracture spacing.
Furthermore,
constraints can be used to avoid very small length scales that could cause problems
during mesh generation or could lead to ill-shaped elements. In the code, constraints
can be defined and evaluated using the
`EntityNetworkConstraints`
class. These have
to be fulfilled by a new fracture entity candidate against previously accepted
...
...
@@ -254,8 +253,8 @@ rejected and a new one is sampled. The current implementation of the
to define a minimum distance between two entities that do not intersect. If two
entities intersect, one can choose to enforce a minimum length of the intersection
curve, a minimum intersection angle and a minimum distance between the intersection
curve and the boundaries of the intersecting entities. An illustration of
this
is shown in
\a
utoref{fig:constraints}.
curve and the boundaries of the intersecting entities. An illustration of
such
situations
is shown in
\a
utoref{fig:constraints}.
![
Illustration of the geometric settings that can be avoided using geometric constraints.\label{fig:constraints}
](
doc/img/constraints.png
)
...
...
@@ -275,15 +274,16 @@ constraints.setMinIntersectingAngle(M_PI/4.0); // in radians
constraints
.
setMinIntersectionMagnitude
(
0.05
);
// in meter
constraints
.
setMinIntersectionDistance
(
0.05
);
// in meter
// define tolerance
value
to be used for intersections
// define
geometric
tolerance to be used for intersections
constraints
.
setIntersectionEpsilon
(
1e-6
);
```
When using the default constructor of
`EntityNetworkConstraints`
,
all constraints
When using the default constructor of
`EntityNetworkConstraints`
all constraints
are inactive, and when defining values for the different constraint types, these
get activated internally. Moreover, one can define the tolerance value that should
get activated internally. The last line in the above code snippet shows how to
define the geometric tolerance that should
be used in the intersection algorithms between entities. If no tolerance is set,
a default
toleranc
e is computed based on the size of the entities for which the
a default
valu
e is computed based on the size of the entities for which the
intersection is to be determined. For two quadrilaterals
`quad1`
and
`quad2`
, one
can then evaluate the defined constraints by writing:
...
...
@@ -316,11 +316,11 @@ and the documentation of that example in the repository. Note that this example
not meant to represent a realistic fracture network, but should rather highlight the
flexibility of the code with respect to the geometries that can be used.
Let us consider a domain consisting of three solid layers
,
of which we want to
generate a fracture network only in the center volume.
With t
he following piece
of code
we
read in the domain geometry from
the provided
file, extract
the three
volumes
of it
and select the middle one as the
one
in which
we want
to place
the
fracture network.
Let us consider a domain consisting of three solid layers of which we want to
generate a fracture network only in the center volume.
T
he following piece
of code
shows how to
read in the domain geometry from
a CAD
file, extract
its three
volumes and select the middle one as the
subdomain
in which to place
the
fracture network
(this assumes knowledge of the ordering of the volumes)
.
```
cpp
/////////////////////////////////////////////////////
...
...
@@ -356,7 +356,7 @@ of the `ContainedEntityNetwork` class. This can be used to define arbitrarily ma
The
`ContainedEntityNetwork`
computes and stores the fragments of all entities
and sub-domains resulting from mutual intersection. Output routines for instances
of this class are implemented, which generate geometry files that are ready to be
meshed using designated tools
, as for example,
[
Gmsh
][
2
]
.
meshed using designated tools
such as
[
Gmsh
][
2
]
.
The image below illustrates the workflow chosen in this example, using
``Frackit``
to generate a random fracture network,
[
Gmsh
][
2
]
to mesh the resulting geometry,
...
...
@@ -381,7 +381,7 @@ the generated fracture networks into graph representations.
# Acknowledgements
We thank the Deutsche Forschungsgemeinschaft
(DFG, German Research Foundation
)
We thank the
German Research Foundation (
Deutsche Forschungsgemeinschaft)
for supporting this work by funding SFB 1313, Project Number 327154368.
# References
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...
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