Multiphysics Modeling with the preCICE Coupling Library
Uncoupled simulation
Import preCICE
import numpy
# generate mesh
n = 20
y = numpy.linspace(0, 1, n + 1)
dt = 0.01
t = 0
while True:
print("Generating data")
u = 1 - 2 * numpy.random.rand(n)
t = t + dt
if(t > 0.1):
break
Import preCICE
import numpy
import precice
# generate mesh
n = 20
y = numpy.linspace(0, 1, n + 1)
dt = 0.01
t = 0
while True:
print("Generating data")
u = 1 - 2 * numpy.random.rand(n)
t = t + dt
if(t > 0.1):
break
Configure preCICE
import numpy
import precice
# generate mesh
n = 20
y = numpy.linspace(0, 1, n + 1)
# preCICE setup
participant_name = "Generator"
config_file_name = "precice-config.xml"
solver_process_index = 0
solver_process_size = 1
interface =
precice.Interface(
participant_name,
config_file_name,
solver_process_index,
solver_process_size
)
dt = 0.01
t = 0
while True:
print("Generating data")
u = 1 - 2 * numpy.random.rand(n)
t = t + dt
if(t > 0.1):
break
Define the coupling mesh
import numpy
import precice
# generate mesh
n = 20
y = numpy.linspace(0, 1, n + 1)
# preCICE setup
participant_name = "Generator"
config_file_name = "precice-config.xml"
solver_process_index = 0
solver_process_size = 1
interface =
precice.Interface(
participant_name,
config_file_name,
solver_process_index,
solver_process_size
)
# Get the preCICE mesh id
mesh_name = "Generator-Mesh"
mesh_id = interface.get_mesh_id(mesh_name)
# Define the coupling mesh
vertices = [[1, y0] for y0 in y[:-1]]
vertex_ids = interface.set_mesh_vertices(mesh_id, vertices)
dt = 0.01
t = 0
while True:
print("Generating data")
u = 1 - 2 * numpy.random.rand(n)
t = t + dt
if(t > 0.1):
break
Initialize and finalize preCICE
import numpy
import precice
# generate mesh
n = 20
y = numpy.linspace(0, 1, n + 1)
# preCICE setup
participant_name = "Generator"
config_file_name = "precice-config.xml"
solver_process_index = 0
solver_process_size = 1
interface =
precice.Interface(
participant_name,
config_file_name,
solver_process_index,
solver_process_size
)
# Get the preCICE mesh id
mesh_name = "Generator-Mesh"
mesh_id = interface.get_mesh_id(mesh_name)
# Define the coupling mesh
vertices = [[1, y0] for y0 in y[:-1]]
vertex_ids = interface.set_mesh_vertices(mesh_id, vertices)
interface.initialize()
dt = 0.01
t = 0
while True:
print("Generating data")
u = 1 - 2 * numpy.random.rand(n)
t = t + dt
if(t > 0.1):
break
interface.finalize()
Advance the coupling
import numpy
import precice
# generate mesh
n = 20
y = numpy.linspace(0, 1, n + 1)
# preCICE setup
participant_name = "Generator"
config_file_name = "precice-config.xml"
solver_process_index = 0
solver_process_size = 1
interface =
precice.Interface(
participant_name,
config_file_name,
solver_process_index,
solver_process_size
)
# Get the preCICE mesh id
mesh_name = "Generator-Mesh"
mesh_id = interface.get_mesh_id(mesh_name)
# Define the coupling mesh
vertices = [[1, y0] for y0 in y[:-1]]
vertex_ids = interface.set_mesh_vertices(mesh_id, vertices)
interface.initialize()
dt = 0.01
t = 0
while True:
print("Generating data")
u = 1 - 2 * numpy.random.rand(n)
t = t + dt
if(t > 0.1):
break
interface.finalize()
Advance the coupling
import numpy
import precice
# generate mesh
n = 20
y = numpy.linspace(0, 1, n + 1)
# preCICE setup
participant_name = "Generator"
config_file_name = "precice-config.xml"
solver_process_index = 0
solver_process_size = 1
interface =
precice.Interface(
participant_name,
config_file_name,
solver_process_index,
solver_process_size
)
# Get the preCICE mesh id
mesh_name = "Generator-Mesh"
mesh_id = interface.get_mesh_id(mesh_name)
# Define the coupling mesh
vertices = [[1, y0] for y0 in y[:-1]]
vertex_ids = interface.set_mesh_vertices(mesh_id, vertices)
interface.initialize()
dt = 0.01
t = 0
while True:
print("Generating data")
u = 1 - 2 * numpy.random.rand(n)
interface.advance(dt)
t = t + dt
if(t > 0.1):
break
interface.finalize()
Advance the coupling
import numpy
import precice
# generate mesh
n = 20
y = numpy.linspace(0, 1, n + 1)
# preCICE setup
participant_name = "Generator"
config_file_name = "precice-config.xml"
solver_process_index = 0
solver_process_size = 1
interface =
precice.Interface(
participant_name,
config_file_name,
solver_process_index,
solver_process_size
)
# Get the preCICE mesh id
mesh_name = "Generator-Mesh"
mesh_id = interface.get_mesh_id(mesh_name)
# Define the coupling mesh
vertices = [[1, y0] for y0 in y[:-1]]
vertex_ids = interface.set_mesh_vertices(mesh_id, vertices)
interface.initialize()
dt = 0.01
t = 0
while interface.is_coupling_ongoing():
print("Generating data")
u = 1 - 2 * numpy.random.rand(n)
interface.advance(dt)
t = t + dt
interface.finalize()
Advance the coupling
import numpy
import precice
# generate mesh
n = 20
y = numpy.linspace(0, 1, n + 1)
# preCICE setup
participant_name = "Generator"
config_file_name = "precice-config.xml"
solver_process_index = 0
solver_process_size = 1
interface =
precice.Interface(
participant_name,
config_file_name,
solver_process_index,
solver_process_size
)
# Get the preCICE mesh id
mesh_name = "Generator-Mesh"
mesh_id = interface.get_mesh_id(mesh_name)
# Define the coupling mesh
vertices = [[1, y0] for y0 in y[:-1]]
vertex_ids = interface.set_mesh_vertices(mesh_id, vertices)
interface.initialize()
dt = 0.01
t = 0
while interface.is_coupling_ongoing():
print("Generating data")
u = 1 - 2 * numpy.random.rand(n)
precice_dt = interface.advance(dt)
t = t + dt
interface.finalize()
Advance the coupling
import numpy
import precice
# generate mesh
n = 20
y = numpy.linspace(0, 1, n + 1)
# preCICE setup
participant_name = "Generator"
config_file_name = "precice-config.xml"
solver_process_index = 0
solver_process_size = 1
interface =
precice.Interface(
participant_name,
config_file_name,
solver_process_index,
solver_process_size
)
# Get the preCICE mesh id
mesh_name = "Generator-Mesh"
mesh_id = interface.get_mesh_id(mesh_name)
# Define the coupling mesh
vertices = [[1, y0] for y0 in y[:-1]]
vertex_ids = interface.set_mesh_vertices(mesh_id, vertices)
precice_dt = interface.initialize()
dt = 0.01
t = 0
while interface.is_coupling_ongoing():
dt = np.minimum(dt, precice_dt)
print("Generating data")
u = 1 - 2 * numpy.random.rand(n)
precice_dt = interface.advance(dt)
t = t + dt
interface.finalize()
(similar changes in propagator.py - try it at home)
Nothing happening?
Did we forget something?Write & read data
import numpy
import precice
# generate mesh
n = 20
y = numpy.linspace(0, 1, n + 1)
# preCICE setup
participant_name = "Generator"
config_file_name = "precice-config.xml"
solver_process_index = 0
solver_process_size = 1
interface =
precice.Interface(
participant_name,
config_file_name,
solver_process_index,
solver_process_size
)
# Get the preCICE mesh id
mesh_name = "Generator-Mesh"
mesh_id = interface.get_mesh_id(mesh_name)
# Define the coupling mesh
vertices = [[1, y0] for y0 in y[:-1]]
vertex_ids = interface.set_mesh_vertices(mesh_id, vertices)
precice_dt = interface.initialize()
dt = 0.01
t = 0
while interface.is_coupling_ongoing():
dt = np.minimum(dt, precice_dt)
print("Generating data")
u = 1 - 2 * numpy.random.rand(n)
precice_dt = interface.advance(dt)
t = t + dt
interface.finalize()
Write & read data
import numpy
import precice
# generate mesh
n = 20
y = numpy.linspace(0, 1, n + 1)
# preCICE setup
participant_name = "Generator"
config_file_name = "precice-config.xml"
solver_process_index = 0
solver_process_size = 1
interface =
precice.Interface(
participant_name,
config_file_name,
solver_process_index,
solver_process_size
)
# Get the preCICE mesh id
mesh_name = "Generator-Mesh"
mesh_id = interface.get_mesh_id(mesh_name)
# Define the coupling mesh
vertices = [[1, y0] for y0 in y[:-1]]
vertex_ids = interface.set_mesh_vertices(mesh_id, vertices)
# Get the exchanged data id
data_name = "Data"
data_id = interface.get_data_id(data_name, mesh_id)
precice_dt = interface.initialize()
dt = 0.01
t = 0
while interface.is_coupling_ongoing():
dt = np.minimum(dt, precice_dt)
print("Generating data")
u = 1 - 2 * numpy.random.rand(n)
interface.write_block_scalar_data(data_id, vertex_ids, u)
precice_dt = interface.advance(dt)
# interface.read_block_scalar_data(data_id, vertex_ids, u)
t = t + dt
interface.finalize()
Data is being transfered!
Most basic case: uni-directional, serial-explicit, nearest-neighbor mapping, ...Side note: Subcycling
preCICE configuration file
<precice-configuration>
<solver-interface dimensions="2">
<data:scalar name="Data"/>
<mesh name="Generator-Mesh">
<use-data name="Data"/>
</mesh>
<mesh name="Propagator-Mesh">
<use-data name="Data" />
</mesh>
<participant name="Generator">
<use-mesh name="Generator-Mesh" provide="yes"/>
<write-data name="Data" mesh="Generator-Mesh"/>
</participant>
<participant name="Propagator">
<use-mesh name="Generator-Mesh" from="Generator"/>
<use-mesh name="Propagator-Mesh" provide="yes"/>
<mapping:nearest-neighbor direction="read"
from="Generator-Mesh" to="Propagator-Mesh"
constraint="consistent"/>
<read-data name="Data" mesh="Propagator-Mesh" />
</participant>
<m2n:sockets from="Generator" to="Propagator"/>
<coupling-scheme:serial-explicit>
<participants first="Generator" second="Propagator"/>
<time-window-size value="0.01"/>
<max-time value="0.1"/>
<exchange data="Data" mesh="Generator-Mesh"
from="Generator" to="Propagator"/>
</coupling-scheme:serial-explicit>
</solver-interface>
</precice-configuration>
Enabling the adapter
// Fluid/system/controlDict
functions
{
preCICE_Adapter
{
type preciceAdapterFunctionObject;
libs ("libpreciceAdapterFunctionObject.so");
}
}
// Solid/system/controlDict
functions
{
preCICE_Adapter
{
type preciceAdapterFunctionObject;
libs ("libpreciceAdapterFunctionObject.so");
}
}
OpenFOAM adapter config
// Fluid/system/preciceDict
preciceConfig "precice-config.xml";
participant Fluid;
modules (CHT);
interfaces
{
Interface1
{
mesh Fluid-Mesh;
patches (interface);
readData
(
Heat-Flux
);
writeData
(
Temperature
);
};
};
// Solid/system/preciceDict
preciceConfig "precice-config.xml";
participant Solid;
modules (CHT);
interfaces
{
Interface1
{
mesh Solid-Mesh;
patches (interface);
readData
(
Temperature
);
writeData
(
Heat-Flux
);
};
};
CHT
{
k [ 1 1 -3 -1 0 0 0 ] 100;
solverType "basic";
};
The interface patch
// Fluid/system/blockMeshDict
boundary
(
interface
{
type wall;
faces
(
(4 0 1 5)
);
}
// ...
);
// Solid/system/blockMeshDict
boundary
(
interface
{
type wall;
faces
(
(7 6 2 3)
);
}
// ...
);
OpenFOAM boundary conditions
// Fluid/0/T
internalField uniform 300;
boundaryField
{
interface
{
type fixedGradient;
gradient uniform 0;
}
inlet
{
type fixedValue;
value $internalField;
}
outlet
{
type zeroGradient;
}
// ...
}
// Solid/0/T
internalField uniform 310;
boundaryField
{
interface
{
type fixedValue;
value $internalField;
}
left
{
type zeroGradient;
}
// ...
}
precice-config.xml
<precice-configuration>
<solver-interface dimensions="3">
<data:scalar name="Temperature"/>
<data:scalar name="Heat-Flux"/>
<mesh name="Fluid-Mesh">
<use-data name="Temperature"/>
<use-data name="Heat-Flux"/>
</mesh>
<mesh name="Solid-Mesh">
<use-data name="Temperature"/>
<use-data name="Heat-Flux"/>
</mesh>
<participant name="Fluid">
<use-mesh name="Fluid-Mesh" provide="yes"/>
<use-mesh name="Solid-Mesh" from="Solid"/>
<read-data name="Heat-Flux" mesh="Fluid-Mesh"/>
<write-data name="Temperature" mesh="Fluid-Mesh"/>
<mapping:nearest-neighbor direction="read"
from="Solid-Mesh" to="Fluid-Mesh"
constraint="consistent"/>
</participant>
<participant name="Solid">
<use-mesh name="Fluid-Mesh" from="Fluid"/>
<use-mesh name="Solid-Mesh" provide="yes"/>
<read-data name="Temperature" mesh="Solid-Mesh"/>
<write-data name="Heat-Flux" mesh="Solid-Mesh"/>
<mapping:nearest-neighbor direction="read"
from="Fluid-Mesh" to="Solid-Mesh"
constraint="consistent"/>
</participant>
<m2n:sockets from="Fluid" to="Solid"/>
<coupling-scheme:serial-implicit>
<time-window-size value="0.01"/>
<max-time value="1"/>
<participants first="Fluid" second="Solid"/>
<exchange data="Temperature" mesh="Fluid-Mesh"
from="Fluid" to="Solid"/>
<exchange data="Heat-Flux" mesh="Solid-Mesh"
from="Solid" to="Fluid"/>
<max-iterations value="200"/>
<relative-convergence-measure limit="1.0e-6"
data="Temperature" mesh="Fluid-Mesh"/>
<acceleration:IQN-ILS>
<data mesh="Solid-Mesh" name="Heat-Flux" />
<initial-relaxation value="0.01" />
<max-used-iterations value="80" />
<time-windows-reused value="10" />
<filter type="QR1" limit="1e-8" />
</acceleration:IQN-ILS>
</coupling-scheme:serial-implicit>
</solver-interface>
</precice-configuration>
precice-config.xml
Visual representation of precice-config.xml using the config visualizer
Configure OpenFOAM
// Fluid/0.orig/U
flap
{
type movingWallVelocity;
value uniform (0 0 0);
}
// Fluid/0.orig/pointDisplacement
flap
{
type fixedValue;
value $internalField;
}
// Fluid/constant/dynamicMeshDict
solver displacementLaplacian;
Configure the OpenFOAM adapter
// Fluid/system/preciceDict
preciceConfig "precice-config.xml";
participant Fluid;
modules (FSI);
interfaces
{
Interface1
{
mesh Fluid-Mesh-Centers;
patches (flap);
locations faceCenters;
readData
(
);
writeData
(
Stress
);
};
Interface2
{
mesh Fluid-Mesh-Nodes;
patches (flap);
locations faceNodes;
readData
(
Displacement
);
writeData
(
);
};
};
FSI
{
rho rho [1 -3 0 0 0 0 0] 1;
}
Configure the deal.ii adapter
// Solid/linear_elasticity.prm
subsection precice configuration
# Cases: FSI3 or PF for perpendicular flap
set Scenario = PF
# Name of the precice configuration file
set precice config-file = precice-config.xml
# Name of the participant in the precice-config.xml file
set Participant name = Solid
# Name of the coupling mesh in the precice-config.xml file
set Mesh name = Solid_mesh
# Name of the read data in the precice-config.xml file
set Read data name = Stress
# Name of the write data in the precice-config.xml file
set Write data name = Displacement
end
Configure preCICE
<precice-configuration>
<solver-interface dimensions="2">
<data:vector name="Stress"/>
<data:vector name="Displacement"/>
<mesh name="Fluid-Mesh-Centers">
<use-data name="Stress"/>
</mesh>
<mesh name="Fluid-Mesh-Nodes">
<use-data name="Displacement"/>
</mesh>
<mesh name="Solid_mesh">
<use-data name="Displacement"/>
<use-data name="Stress"/>
</mesh>
<participant name="Fluid">
<use-mesh name="Fluid-Mesh-Nodes" provide="yes"/>
<use-mesh name="Fluid-Mesh-Centers" provide="yes"/>
<use-mesh name="Solid_mesh" from="Solid"/>
<read-data name="Displacement" mesh="Fluid-Mesh-Nodes"/>
<write-data name="Stress" mesh="Fluid-Mesh-Centers"/>
<mapping:rbf-thin-plate-splines direction="read"
from="Solid_mesh" to="Fluid-Mesh-Nodes"
constraint="consistent"/>
</participant>
<participant name="Solid">
<use-mesh name="Solid_mesh" provide="yes"/>
<use-mesh name="Fluid-Mesh-Centers" from="Fluid"/>
<use-mesh name="Fluid-Mesh-Nodes" from="Fluid"/>
<read-data name="Stress" mesh="Solid_mesh"/>
<write-data name="Displacement" mesh="Solid_mesh"/>
<mapping:rbf-thin-plate-splines direction="read"
from="Fluid-Mesh-Centers" to="Solid_mesh"
constraint="consistent" />
<watch-point mesh="Solid_mesh" name="flap_tip"
coordinate="-0.05;1;0" />
</participant>
<m2n:sockets from="Fluid" to="Solid" />
<coupling-scheme:serial-implicit>
<time-window-size value="0.01"/>
<max-time value="5"/>
<participants first="Fluid" second="Solid"/>
<exchange data="Stress" mesh="Fluid-Mesh-Centers"
from="Fluid" to="Solid"/>
<exchange data="Displacement" mesh="Solid_mesh"
from="Solid" to="Fluid" initialize="0"/>
<max-iterations value="50"/>
<relative-convergence-measure limit="1e-4"
data="Stress" mesh="Fluid-Mesh-Centers"/>
<relative-convergence-measure limit="1e-4"
data="Displacement" mesh="Solid_mesh"/>
<acceleration:IQN-ILS>
<data name="Displacement" mesh="Solid_mesh"/>
<preconditioner type="residual-sum"/>
<filter type="QR1" limit="1e-6"/>
<initial-relaxation value="0.1"/>
<max-used-iterations value="50"/>
<time-windows-reused value="10"/>
</acceleration:IQN-ILS>
</coupling-scheme:serial-implicit>
</solver-interface>
</precice-configuration>
How is the tip moving?
#! /bin/bash
gnuplot -p << EOF
set grid
set title 'Displacement of the Flap Tip'
set xlabel 'Time [s]'
set ylabel 'X-Displacement [m]'
set linestyle 1 lt 2 lc 1 # red-dashed
plot "precice-Solid-watchpoint-flap_tip.log"
using 1:4
title 'Top displacemement'
with lines
EOF
See also: OpenFOAM + CalculiX
