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Introduction to fluid mechanics simulation using
the OpenFOAM® technology
« Simulation in porous media from pore to large scale »
Part II: Mesh complex geometries, application to the evaluation
of permeability,
transport of passive scalars at the porescale
!tanford
November 10, 2014"ersion #$%
&ontact: cyprien$soulaine'stanford$edu
http://web.stanford.edu/~csoulain/
mailto:[email protected]://web.stanford.edu/~csoulain/http://web.stanford.edu/~csoulain/mailto:[email protected]
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O p e n F O A M ® i n i t i a t i o n
Previously in OpenFOAM training$$$
A case is always organized in the same way: time
directory, constant directory and systemdirectory.
To setup a case, it is recommanded to adapt an eisting
tutorial.
The initial and boundary conditions are defined in the
0 directory.
!or simple meshes, we can use blockMesh, otherwise we should use
an eternal gridder orsnappyHexMesh.
Two different algorithms to sol"e #a"ier$%to&es e'uations :
%()*+ -simpleFoam... and *(%-icoFoam, pisoFoam...
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O p e n F O A M ® i n i t i a t i o n
(eneral introduction to the OpenFOAM® technologyWhat is OpenFOAM
?
First simulations )ith OpenFOAM®
#1 – Heat i!!"sion
ene$al st$"ct"$e o! an OpenFOAM® case
#% – &a'ity
Whe$e one can !in help an oc"mentation ?
#( – )oise"ille !lo*
#+ – $aina-e expe$iment in a capilla$y t"be
*o) to mesh complex geometries )ith OpenFOAM® +
# – Mesh a po$e/space *ith snappyHexMesh
snappyHexMesh o'e$'ie*
# – cala$ t$anspo$t in po$o"s meia at the po$e/scale
Programming euations )ith OpenFOAM®
2asics o! OpenFOAM p$o-$ammin-
ene$al st$"ct"$e o! an application
*eat transfer in porous media )ith OpenFOAM®
#3 – 4empe$at"$e in po$o"s meia
#5 – &$eate a 6 a$cy 7 sol'e$
#8 – 4*o/e9"ations moel !o$ heat t$ans!e$ in po$o"s meia
*o) to solve -avier!to.es euation )ith OpenFOAM® +
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O p e n F O A M ® i n i t i a t i o n
snappyHexes! overvie) /0123
o p e n ! o a m . c o m
snappyHexMesh is an automatic and robust mesher able to
grid any complegeometry
)esh a region inside or/and around an obect described by a
surface mesh
(t is compatible with a lot of input formats resulting from 3A4
softwares ortomography imaging :;.stl , ;.ob
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snappyHexes! overvie) /2123
open!oam.com
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O p e n F O A M ® i n i t i a t i o n
4# 5 Mesh a porespace /0163
becti"e:• )esh the "oid space of a porous medium with
snappyHexMesh
o " t l e t
i n l e t
=oi space that nees to be-$ie
*all
*all
1
2
"
oli -$ains e!ine by
a s"$!ace mesh !ile
8enerate the surface mesh -here the solid grain.
3reate a suitable bac&ground mesh with blockMesh. (t needs
to be fine enough toha"e at least 9 cells in the pore$throat
thic&ness.
4etect the "oid space, remo"e the cells occupied by the solid
and snap them to fitas close as possible the initial surface obect
with snappyHexMesh.
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4# 5 Mesh a porespace /2163
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4# 5 Mesh a porespace /7163
The net step consists in creating a bac&ground mesh with
blockMesh. The size of this bac&grounddomain depends on the
bounding bo of the surface obect. (t can be obtained using the
s"$!ace&heck tool,
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4# 5 Mesh a porespace /8163
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4# 5 Mesh a porespace /#163
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4# 5 Mesh a porespace /6163
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46 5 !calar transport in the pore space /0193
becti"es:• %ol"e the flow in the "oid space gridded in the
pre"ious eercise• stimate the permeability of the porous
medium• %ol"e a passi"e scalar transport in the "oid space
The flow and the scalar transport are uncoupled. They can
therefore be sol"ed oneafter the other.
The flow is obtained sol"ing a %to&es problem with
simpleFoam. The case can be setupbased on o0 -or
T?(A+%/incompressible/simple!oam/pitz4aily
i n l e t
o " t l e t
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46 5 !calar transport in the pore space /2a193
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%witch off the turbulence model
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(t might be useful to plot the residuals on$the$fly to chec&
the simulation con"ergence. This can beachie"ed by redirecting the
simulation log into a file and etracting the residual "alues with
thefollowing gnuplot script :
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46 5 !calar transport in the pore space /8a193
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46 5 !calar transport in the pore space /8b193
o7ais : ?un the simulation with a multi$grid sol"er for the
pressure matri and compare theresiduals con"ergence.
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t0.0s
t0.10s
t0.1s
t0.%0s
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0 1 2 3 4 5 6
0
0.2
0.4
0.6
0.8
1
1.2
D5e-6
D1e-6
D5e-7
time (s)
T
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O p
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In the next parts$$$
Part III: First programs, development of a heat tranfer solver
in porous media
Part I": *o) to solve -avier!to.es euations )ith OpenFOAM+
http://web.stanford.edu/~csoulain/
http://web.stanford.edu/~csoulain/http://web.stanford.edu/~csoulain/
