pycbg.preprocessing.Simulation¶
- class pycbg.preprocessing.Simulation(title='Sim_title', directory='', input_filename='input_file')¶
Includes all simulation ingredients in order to create an appropriate CB-Geo MPM .json input file with the write_input_file method, after attributes definition.
- Parameters
title (str, optional) – Simulation title. Default is ‘Sim_title’.
directory (str, optional) – Path to the simulation’s directory (will be created if not existent. User-indication of a final ‘/’ is optional). Mesh, particles and entity sets files will be saved in this directory. The result folder is also set to be created by CB-Geo MPM in this directory. Default is title.
input_filename (str, optional) – Name of the input file for CB-Geo MPM, the extension .json is automatically added. Default is ‘input_file’.
- entity_sets¶
Simulation’s entity sets. Created using the init_entity_sets method.
- Type
EntitySets
object
- materials¶
Simulation’s materials. Created upon creating the Simulation object.
- Type
Materials
object
- init_stresses¶
Initial stresses for each particle, to define through the set_initial_particles_stresses method, if desired. Noting npart the number of particles, its shape is
(npart, 3)
.- Type
numpy array
- input_filename¶
Path to the CB-Geo MPM json input file to create, the extension ‘.json’ is automatically added.. If directory=’.’, the title of the simulation is automatically added before the user-specified filename. Default is ‘input_file’ in directory.
- Type
str
- title¶
Simulation title. Can be passed as an instantiation parameter.
- Type
str
- directory¶
Path to the simulation’s directory. Can be passed as an instantiation parameter.
- Type
str
- custom_params¶
Dictionary containing user-defined parameters. It will be saved in the
Simulation
object when the input file is written. Its element should be appended using the add_custom_parameters method.- Type
dict
Examples
Simulating under gravity a column made of two materials :
>>> sim = Simulation() >>> sim.create_mesh(dimensions=(1.,1.,10.), ncells=(1,1,10)) >>> sim.create_particles(npart_perdim_percell=1) >>> sim.init_entity_sets() >>> lower_particles = sim.entity_sets.create_set(lambda x,y,z: z<10, typ="particle") >>> upper_particles = sim.entity_sets.create_set(lambda x,y,z: z>=10, typ="particle") >>> sim.materials.create_MohrCoulomb3D(pset_id=lower_particles) >>> sim.materials.create_Newtonian3D(pset_id=upper_particles) >>> walls = [] >>> walls.append([sim.entity_sets.create_set(lambda x,y,z: x==lim, typ="node") for lim in [0, sim.mesh.l0]]) >>> walls.append([sim.entity_sets.create_set(lambda x,y,z: y==lim, typ="node") for lim in [0, sim.mesh.l1]]) >>> walls.append([sim.entity_sets.create_set(lambda x,y,z: z==lim, typ="node") for lim in [0, sim.mesh.l2]]) >>> for direction, sets in enumerate(walls): _ = [sim.add_velocity_condition(direction, 0., es) for es in sets] >>> sim.set_gravity([0,0,-9.81]) >>> sim.set_analysis_parameters(dt=1e-3, nsteps=1.5e8, output_step_interval=7.5e6) >>> sim.write_input_file()
- __init__(title='Sim_title', directory='', input_filename='input_file')¶
Methods
Add dict content in custom_params.
Add a force on all the elements in a entity set.
Add a friction condition on a node set.
Add a math function to the simulation.
Add a velocity condition on a node or particle set.
Create the simulation's mesh.
Create the simulation's particles.
Create the simulation's
EntitySets
object.Set the analysis parameters.
Set the value of gravity.
Set the initial stresses for each particle.
Write the input file.
- add_custom_parameters(dic)¶
Add dict content in custom_params.
- Parameters
dic (dict) – Dictionary containing the parameters to be appended in custom_params.
- add_force(dir, force, entity_set, typ='node', math_function_id=None)¶
Add a force on all the elements in a entity set.
- Parameters
dir ({0, 1, 2}) – Axis on which the force is imposed.
force (float) – Imposed force’s value (\(N\)).
entity_set (int) – Id of the entity set on which the force is imposed.
typ ({"node", "particle"}, optional) – Type of set on which the force is imposed. Default is “node”.
math_function_id (int, optional) – Id of the math function to use. Default value is None (the load is then static).
- add_friction_condition(dir, sgn_n, frict_value, node_set)¶
Add a friction condition on a node set.
- Parameters
dir ({0, 1, 2}) – Axis of the normal vector to the plane where friction is acting.
sgn_n ({-1, 1}) – Sign of the normal vector to the plane where friction is acting.
frict_value (float) – Imposed friction coefficient’s value.
node_set (int) – Id of the node set on which friction is imposed.
- add_math_function(times, values)¶
Add a math function to the simulation. The function can only be piecewise-linear.
- Parameters
times (list of floats) – Contains the times at which the values of the math function are given. The first element should always be 0. and the last should always be nsteps*dt.
values (list of floats) – Contains the values of the math function for each time given in times.
- Returns
Id of the math function just appended.
- Return type
int
- add_velocity_condition(dir, vel_value, entity_set, typ='node')¶
Add a velocity condition on a node or particle set.
- Parameters
dir ({0, 1, 2}) – Axis on which the velocity is imposed.
vel_value (float) – Imposed velocity’s value (\(m.s^{-1}\)).
entity_set (int) – Id of the entity set on which the velocity is imposed.
typ ({"node", "particle"}, optional) – Type of set on which the velocity is imposed. Default is “node”.
- create_mesh(*args, **kwargs)¶
Create the simulation’s mesh.
- Parameters
dimensions (tuple of floats) – Dimensions of the mesh. Its length should be 3, with dimensions[n] the dimension of the mesh on the axis n.
ncells (tuple of ints) – Number of cells in each direction. Its length should be 3, with ncells[n] the number of cells on the axis n.
check_duplicates (bool, optional) – See CB-Geo documentation for informations on this parameter. Default is True.
cell_type ({'ED3H8', 'ED3H20', 'ED3H64G'}, optional) – Type of cell. Only 3D Hexahedrons are supported. The number of nodes can be 8, 20 or 64. Default is ‘ED3H8’.
- create_particles(*args, **kwargs)¶
Create the simulation’s particles.
- Parameters
npart_perdim_percell (int, optional) – Number of particles for each dimension in one cell. All cells will contain
npart_perdim_percell**3
equally spaced particles. Note that particles are equally spaced within a cell, not between cells. Default is 1 .check_duplicates (bool, optional) – See CB-Geo MPM documentation for informations on this parameter. Default is True.
- init_entity_sets()¶
Create the simulation’s
EntitySets
object.Has to be called after mesh and particles creation.
- set_analysis_parameters(type='MPMExplicit3D', mpm_scheme='usl', damping=0.05, locate_particles=False, dt=1e-05, velocity_update='flip', nsteps=2000, verbosity=1000, output_step_interval=100)¶
Set the analysis parameters. Has to be called before write_input_file.
- Parameters
type ({'MPMExplicit2D', 'MPMExplicit3D'}, optional) – Analysis type. Default is ‘MPMExplicit3D’.
mpm_scheme ({'usf', 'usl', 'musl'}, optional) – MPM scheme for the stress update. The scheme can be “Update Stress First” (‘usf’), “Update Stress Last” (‘usl’) or “Modified Update Stress Last” (‘musl’).
damping (float, optional) – Cundall’s damping. Should verify :
0 <= damping < 1
. Default is 0.05 .locate_particles (bool, optional) – Stops the simulation when particles go outside the mesh if True. Default is False.
dt (float, optional) – Time step (\(s\)). Default is 1e-5 \(s\).
velocity_update ({'pic', 'flip', 'apic'}, optional) – How to compute particle’s velocity. If ‘pic’ nodal velocity is directly interpolated to particles. If ‘flip’ nodal velocity is computed from the acceleration interpolated to particles. If ‘apic’, momentum is interpolated according to Jiang, Chenfanfu, et al., 2015. Default is ‘flip’.
nsteps (int, optional) – Number of steps to be performed. Default is 2000.
verbosity (int, optional) – Number of lines to be printed in the console. Default is 1000.
output_step_interval (int, optional) – Number of steps between two data points. Default is 100.
- set_gravity(gravity)¶
Set the value of gravity. If this method isn’t called, gravity is [0,0,0].
- Parameters
gravity (list of floats) – Gravity’s value on each axis (\(m/s^2\)).
- set_initial_particles_stresses(init_stresses)¶
Set the initial stresses for each particle.
- Parameters
init_stresses (numpy array) – Initial stresses for each particle. Noting npart the number of particles, it should have the shape
(npart, 6)
.
- write_input_file()¶
Write the input file.