Getting started with
OpenFOAM-preCICE
for FSI simulations
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
participant =
precice.Participant(
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
participant =
precice.Participant(
participant_name,
config_file_name,
solver_process_index,
solver_process_size
)
# Define the coupling mesh name
mesh_name = "Generator-Mesh"
# Define the coupling mesh
vertices = [[1, y0] for y0 in y[:-1]]
vertex_ids = participant.set_mesh_vertices(mesh_name, positions)
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
participant =
precice.Participant(
participant_name,
config_file_name,
solver_process_index,
solver_process_size
)
# Define the coupling mesh name
mesh_name = "Generator-Mesh"
# Define the coupling mesh
vertices = [[1, y0] for y0 in y[:-1]]
vertex_ids = participant.set_mesh_vertices(mesh_name, vertices)
participant.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
participant.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
participant =
precice.Participant(
participant_name,
config_file_name,
solver_process_index,
solver_process_size
)
# Define the coupling mesh name
mesh_name = "Generator-Mesh"
# Define the coupling mesh
vertices = [[1, y0] for y0 in y[:-1]]
vertex_ids = participant.set_mesh_vertices(mesh_name, vertices)
participant.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
participant.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
participant =
precice.Participant(
participant_name,
config_file_name,
solver_process_index,
solver_process_size
)
# Define the coupling mesh name
mesh_name = "Generator-Mesh"
# Define the coupling mesh
vertices = [[1, y0] for y0 in y[:-1]]
vertex_ids = participant.set_mesh_vertices(mesh_name, vertices)
participant.initialize()
dt = 0.01
t = 0
while True:
print("Generating data")
u = 1 - 2 * numpy.random.rand(n)
participant.advance(dt)
t = t + dt
if(t > 0.1):
break
participant.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
participant =
precice.Participant(
participant_name,
config_file_name,
solver_process_index,
solver_process_size
)
# Define the coupling mesh name
mesh_name = "Generator-Mesh"
# Define the coupling mesh
vertices = [[1, y0] for y0 in y[:-1]]
vertex_ids = participant.set_mesh_vertices(mesh_name, vertices)
participant.initialize()
dt = 0.01
t = 0
while participant.is_coupling_ongoing():
print("Generating data")
u = 1 - 2 * numpy.random.rand(n)
participant.advance(dt)
t = t + dt
participant.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
participant =
precice.Participant(
participant_name,
config_file_name,
solver_process_index,
solver_process_size
)
# Define the coupling mesh name
mesh_name = "Generator-Mesh"
# Define the coupling mesh
vertices = [[1, y0] for y0 in y[:-1]]
vertex_ids = participant.set_mesh_vertices(mesh_name, vertices)
participant.initialize()
dt = 0.01
t = 0
while participant.is_coupling_ongoing():
print("Generating data")
u = 1 - 2 * numpy.random.rand(n)
participant.advance(dt)
precice_dt = participant.get_max_time_step_size()
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
participant =
precice.Participant(
participant_name,
config_file_name,
solver_process_index,
solver_process_size
)
# Define the coupling mesh name
mesh_name = "Generator-Mesh"
# Define the coupling mesh
vertices = [[1, y0] for y0 in y[:-1]]
vertex_ids = participant.set_mesh_vertices(mesh_name, vertices)
participant.initialize()
precice_dt = participant.get_max_time_step_size()
dt = 0.01
t = 0
while participant.is_coupling_ongoing():
print("Generating data")
u = 1 - 2 * numpy.random.rand(n)
participant.advance(dt)
precice_dt = participant.get_max_time_step_size()
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
participant =
precice.Participant(
participant_name,
config_file_name,
solver_process_index,
solver_process_size
)
# Get the preCICE mesh name
mesh_name = "Generator-Mesh"
# Define the coupling mesh
vertices = [[1, y0] for y0 in y[:-1]]
vertex_ids = participant.set_mesh_vertices(mesh_name, vertices)
participant.initialize()
precice_dt = participant.get_max_time_step_size()
dt = 0.01
t = 0
while participant.is_coupling_ongoing():
dt = np.minimum(dt, precice_dt)
print("Generating data")
u = 1 - 2 * numpy.random.rand(n)
participant.advance(dt)
precice_dt = participant.get_max_time_step_size()
t = t + dt
participant.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
participant =
precice.Participant(
participant_name,
config_file_name,
solver_process_index,
solver_process_size
)
# Get the preCICE mesh name
mesh_name = "Generator-Mesh"
# Define the coupling mesh
vertices = [[1, y0] for y0 in y[:-1]]
vertex_ids = participant.set_mesh_vertices(mesh_id, vertices)
# Get the exchanged data name
data_name = "Data"
participant.initialize()
dt = 0.01
t = 0
while participant.is_coupling_ongoing():
dt = np.minimum(dt, precice_dt)
print("Generating data")
u = 1 - 2 * numpy.random.rand(n)
participant.write_data(mesh_name, data_name, vertex_ids, u)
precice_dt = participant.advance(dt)
# u[:, -1] = participant.read_data(mesh_name, data_name, vertex_ids, dt)
t = t + dt
participant.finalize()
Data is being transfered!
preCICE configuration
Visual representation of precice-config.xml using the config visualizer.
Configure OpenFOAM
// fluid-openfoam/0/U
flap
{
type movingWallVelocity;
value uniform (0 0 0);
}
// fluid-openfoam/0/pointDisplacement
flap
{
type fixedValue;
value $internalField;
}
// fluid-openfoam/constant/dynamicMeshDict
solver displacementLaplacian;
Load the OpenFOAM adapter
// fluid-openfoam/system/controlDict
functions
{
preCICE_Adapter
{
type preciceAdapterFunctionObject;
libs ("libpreciceAdapterFunctionObject.so");
}
}
// Don't forget to build the adapter with Allwmake
Configure the OpenFOAM adapter
// fluid-openfoam/system/preciceDict
preciceConfig "../precice-config.xml";
participant Fluid;
modules (FSI);
interfaces {
Interface1 {
mesh Fluid-Mesh;
patches (flap);
locations faceCenters;
readData (Displacement);
writeData (Force);
};
};
FSI {
rho rho [1 -3 0 0 0 0 0] 1;
}
Configure the dealii adapter
// solid-dealii/parameters.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 = Force
# Name of the write data in the precice-config.xml file
set Write data name = Displacement
Configure preCICE
Configure preCICE
<data:vector name="Force" />
<data:vector name="Displacement" />
<mesh name="Fluid-Mesh" dimensions="2">
<use-data name="Force" />
<use-data name="Displacement" />
</mesh>
<mesh name="Solid-Mesh" dimensions="2">
<use-data name="Displacement" />
<use-data name="Force" />
</mesh>
<participant name="Fluid">
<export:vtk directory="results" />
<provide-mesh name="Fluid-Mesh" />
<receive-mesh name="Solid-Mesh" from="Solid" />
<write-data name="Force" mesh="Fluid-Mesh" />
<read-data name="Displacement" mesh="Fluid-Mesh" />
<mapping:rbf-thin-plate-splines
direction="write"
from="Fluid-Mesh"
to="Solid-Mesh"
constraint="conservative" />
<mapping:rbf-thin-plate-splines
direction="read"
from="Solid-Mesh"
to="Fluid-Mesh"
constraint="consistent" />
</participant>
<participant name="Solid">
<provide-mesh name="Solid-Mesh" />
<receive-data name="Displacement" mesh="Solid-Mesh" />
<read-data name="Force" mesh="Solid-Mesh" />
<watch-point mesh="Solid-Mesh" name="Flap-Tip" coordinate="0.0;1" />
</participant>
<m2n:sockets acceptor="Fluid" connector="Solid" exchange-directory=".." />
<coupling-scheme:serial-explicit>
<participants first="Fluid" second="Solid" />
<max-time value="1.5" />
<time-window-size value="0.01" />
<exchange data="Force" mesh="Solid-Mesh" from="Fluid" to="Solid" />
<exchange data="Displacement" mesh="Solid-Mesh" from="Solid" to="Fluid" />
</coupling-scheme:serial-explicit>
What we did so far: serial-explicit scheme
Let's try an implicit coupling scheme
Configure the coupling scheme
<coupling-scheme:serial-implicit>
<participants first="Fluid" second="Solid" />
<max-time value="1.5" />
<time-window-size value="0.01" />
<exchange data="Force" mesh="Solid-Mesh" from="Fluid" to="Solid" />
<exchange data="Displacement" mesh="Solid-Mesh" from="Solid" to="Fluid" />
<relative-convergence-measure limit="5e-3" data="Displacement" mesh="Solid-Mesh" />
<relative-convergence-measure limit="5e-3" data="Force" mesh="Solid-Mesh" />
<max-iterations value="50" />
</coupling-scheme:serial-implicit>
Still not enough stability for strong coupling!
Configure the coupling scheme
<coupling-scheme:serial-implicit>
<participants first="Fluid" second="Solid" />
<max-time value="1.5" />
<time-window-size value="0.01" />
<exchange data="Force" mesh="Solid-Mesh" from="Fluid" to="Solid" />
<exchange data="Displacement" mesh="Solid-Mesh" from="Solid" to="Fluid" />
<relative-convergence-measure limit="5e-3" data="Displacement" mesh="Solid-Mesh" />
<relative-convergence-measure limit="5e-3" data="Force" mesh="Solid-Mesh" />
<max-iterations value="50" />
<acceleration:constant>
<relaxation value="0.5" />
</acceleration:constant>
</coupling-scheme:serial-implicit>
Too slow! Can we do better?
Improvement 1: Aitken under-relaxation
<acceleration:aitken>
<data name="Displacement" mesh="Solid-Mesh" />
<initial-relaxation value="0.5" />
</acceleration:aitken>
Improvement 2: Anderson acceleration
<acceleration:IQN-ILS>
<data name="Displacement" mesh="Solid-Mesh" />
<initial-relaxation value="0.5" />
<preconditioner type="residual-sum" />
<filter type="QR2" limit="1e-2" />
<max-used-iterations value="100" />
<time-windows-reused value="15" />
</acceleration:IQN-ILS>
There are also parallel schemes
Improvement 3: Parallel coupling schemes
<coupling-scheme:parallel-implicit>
<time-window-size value="0.01" />
<max-time value="1.5" />
<participants first="Fluid" second="Solid" />
<exchange data="Force" mesh="Solid-Mesh" from="Fluid" to="Solid" />
<exchange data="Displacement" mesh="Solid-Mesh" from="Solid" to="Fluid" />
<max-iterations value="50" />
<relative-convergence-measure limit="5e-3" data="Displacement" mesh="Solid-Mesh" />
<relative-convergence-measure limit="5e-3" data="Force" mesh="Solid-Mesh" />
<acceleration:IQN-ILS>
<data name="Displacement" mesh="Solid-Mesh" />
<data name="Force" mesh="Solid-Mesh" />
<initial-relaxation value="0.5" />
<preconditioner type="residual-sum" />
<filter type="QR2" limit="1e-2" />
<max-used-iterations value="100" />
<time-windows-reused value="15" />
</acceleration:IQN-ILS>
</coupling-scheme:parallel-implicit>
| density = 42 | density = 1 | |
|---|---|---|
| serial-explicit | div | div |
| se-implicit | 3.41 | div |
| se-im-const | 4.48 | 5.27 |
| se-im-Aitken | 3.74 | 5.3 |
| se-im-ILS | 2.95 | 3.07 |
| parallel-im-ILS | 2.46 | 2.33 |
Beware: Configuration not fine-tuned, not rigorous comparison, application context.
Rigorous comparison from the literature
Source: Dissertation of Benjamin Uekermann (2016)
Rigorous comparison from the literature
Source: Dissertation of Benjamin Uekermann (2016)