SimpleMechanics

This benchmark is available as a Jupyter notebook: Mechanics/Linear/SimpleMechanics.ipynb.

The following example consists of a simple mechanics problem.

import os

out_dir = os.environ.get('OGS_TESTRUNNER_OUT_DIR', '_out')
if not os.path.exists(out_dir):
    os.makedirs(out_dir)
from ogs6py import ogs

prj_name = "SimpleMechanics"
model = ogs.OGS(PROJECT_FILE=os.path.join(out_dir, f"{prj_name}.prj"))
model.geo.add_geom(filename=f"./square_1x1.gml")
model.mesh.add_mesh(filename=f"./square_1x1_quad_1e2.vtu")
model.processes.set_process(name="SD",
                           type="SMALL_DEFORMATION",
                           integration_order="2",
                           solid_density="rho_sr",
                           specific_body_force="0 0")
model.processes.set_constitutive_relation(type="LinearElasticIsotropic",
                                        youngs_modulus="E",
                                        poissons_ratio="nu")
model.processes.add_process_variable(process_variable="process_variable",
                                   process_variable_name="displacement")
model.processes.add_process_variable(secondary_variable="sigma",
                                   output_name="sigma")
model.timeloop.add_process(process="SD",
                          nonlinear_solver_name="basic_newton",
                          convergence_type="DeltaX",
                          norm_type="NORM2",
                          abstol="1e-15",
                          time_discretization="BackwardEuler")
model.timeloop.set_stepping(process="SD", type="FixedTimeStepping",
                           t_initial="0",
                           t_end="1",
                           repeat="4",
                           delta_t="0.25")
model.timeloop.add_output(type="VTK",
                         prefix=prj_name,
                         repeat="1",
                         each_steps="4",
                         variables=["displacement", "sigma"])
model.parameters.add_parameter(name="E", type="Constant", value="1")
model.parameters.add_parameter(name="nu", type="Constant", value="0.3")
model.parameters.add_parameter(name="rho_sr", type="Constant", value="1")
model.parameters.add_parameter(name="displacement0",
                              type="Constant",
                              values="0 0")
model.parameters.add_parameter(name="dirichlet0", type="Constant", value="0")
model.parameters.add_parameter(name="dirichlet1", type="Constant", value="0.05")
model.processvars.set_ic(process_variable_name="displacement",
                        components="2",
                        order="1",
                        initial_condition="displacement0")
model.processvars.add_bc(process_variable_name="displacement",
                        geometrical_set="square_1x1_geometry",
                        geometry="left",
                        type="Dirichlet",
                        component="0",
                        parameter="dirichlet0")
model.processvars.add_bc(process_variable_name="displacement",
                        geometrical_set="square_1x1_geometry",
                        geometry="bottom",
                        type="Dirichlet",
                        component="1",
                        parameter="dirichlet0")
model.processvars.add_bc(process_variable_name="displacement",
                        geometrical_set="square_1x1_geometry",
                        geometry="top",
                        type="Dirichlet",
                        component="1",
                        parameter="dirichlet1")
model.nonlinsolvers.add_non_lin_solver(name="basic_newton",
                                    type="Newton",
                                    max_iter="4",
                                    linear_solver="general_linear_solver")
model.linsolvers.add_lin_solver(name="general_linear_solver",
                              kind="lis",
                              solver_type="cg",
                              precon_type="jacobi",
                              max_iteration_step="10000",
                              error_tolerance="1e-16")
model.linsolvers.add_lin_solver(name="general_linear_solver",
                              kind="eigen",
                              solver_type="CG",
                              precon_type="DIAGONAL",
                              max_iteration_step="10000",
                              error_tolerance="1e-16")
model.linsolvers.add_lin_solver(name="general_linear_solver",
                              kind="petsc",
                              prefix="sd",
                              solver_type="cg",
                              precon_type="bjacobi",
                              max_iteration_step="10000",
                              error_tolerance="1e-16")
try:
    model.write_input()
    model.run_model(logfile=os.path.join(out_dir, f"{prj_name}.txt"), args=f"-o {out_dir}")
except Exception as inst:
    print(f"{type(inst)}: {inst.args[0]}")

from datetime import datetime
print(datetime.now())
OGS finished with project file /var/lib/gitlab-runner/builds/e3EQ9HiK/1/ogs/build/release-all/Tests/Data/Mechanics/Linear/SimpleMechanics/SimpleMechanics.prj.
Execution took 0.8411102294921875 s
2023-01-26 18:57:33.388497
import vtuIO

pvdfile = vtuIO.PVDIO(f"{out_dir}/{prj_name}.pvd", interpolation_backend="scipy", dim=2)
time = pvdfile.timesteps
points={'pt0': (0.3,0.5,0.0), 'pt1': (0.24,0.21,0.0)}
displacement_linear = pvdfile.read_time_series("displacement", points, interpolation_method="linear")
displacement_nearest = pvdfile.read_time_series("displacement", points, interpolation_method="nearest")

import matplotlib.pyplot as plt
plt.plot(time, displacement_linear["pt0"][:,0], "b-", label="$u_x$ pt0 linear interpolated")
plt.plot(time, displacement_nearest["pt0"][:,0], "b--", label="$u_x$ pt0 closest point value")
plt.plot(time, displacement_linear["pt0"][:,1], "g-", label="$u_y$ pt0 linear interpolated")
plt.plot(time, displacement_nearest["pt0"][:,1], "g--", label="$u_y$ pt0 closest point value")
plt.plot(time, displacement_linear["pt1"][:,0], "r-", label="$u_x$ pt1 linear interpolated")
plt.plot(time, displacement_nearest["pt1"][:,0], "r--", label="$u_x$ pt1 closest point value")
plt.plot(time, displacement_linear["pt1"][:,1], "m-", label="$u_y$ pt1 linear interpolated")
plt.plot(time, displacement_nearest["pt1"][:,1], "m--", label="$u_y$ pt1 closest point value")
plt.legend()
plt.xlabel("t")
plt.ylabel("u")
Text(0, 0.5, 'u')

png


This article was written by Lars Bilke, Jörg Buchwald. If you are missing something or you find an error please let us know.
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