Insertion with a moving mesh

In this example we show how to setup a simulation with a moving insertion face.

Name of the case: Project_Insertion_Moving_Mesh

Simulation setup

General settings

In this simulation we use particles of particle_shape command sphere:

A material with name material1 is defined:

The simulation domain is defined with x dimensions ranging from -0.055 m to 0.3 m, y dimensions ranging from -0.055 to 0.055 meters and z dimensions ranging from 0 to 0.3 meters:

Meshes and regions

We use a moving mesh as insertion face and thus start with the definition of a mesh_module of type motion:

In the next step we load the respective mesh command. Please note that the solid option is set to no and the is_planar option is set to yes.

Primitive walls are used as boundaries for the somilation domain in 5 dimensions:

	normal_axis	offset
p3	x	-0.055
p4	x	0.3
p5	y	-0.055
p6	y	0.055
p7	z	0

Altogether this simulation involves 3 geometry components: a bottom plate, a cylinder that forms the side walls and a top plate that is used to compress the particle bed. In a first step, a mesh module of type servo is defined:

Physics models

In the next step, the definition of the physics models takes place. For the particles we use the normal contact model hertz and the tangential model history.

Since we added meshes in the previous section, also a wall contact model was added automatically in this section. We use the same contact models as for the particles:

Finally also the gravity is defined:

Per default the gravity has a magnitude of 9.807 and acts into negative z-direction. These defaults can be changed by either setting the magnitude or the direction manually.

Particles

In the general settings tab we introduced two materials. Here we define the required material properties.

	material1
Density	1500
Young’s modulus	5e6
Poisson ratio	0.3
Coefficient of restitution	0.5
Coefficient of friction	0.5

In the next step the particle templates are generated. Spheres with three different diameters are used for the creation of the particle distribution:

An insertion command command of type stream is used to insert particles through the previously defined moving mesh:

Simulation control

In this tab one first choses the time step settings such as the desired simulation timestep of 1e-5 seconds and the total simulation time of 1.0 second. Per default also the check_timestep command command is enabled, which throws a warning when the time step exceeds 10 % of the Rayleigh or the Hertz timestep. These thresholds can be changed by setting an alternative value for hertz_fraction or rayleigh_fraction.

The enable_loadbalancing command command is used to ensure the highest efficiency for parallel runs.

Output settings

In this tab we first define the timestep width for the file and the terminal output:

The output_settings command command takes care that all particle information and the meshes are written to files accordingly. Furthermore it triggers the output of global quantities such as the kinetic energy of the particles or total normal and shear stresses onto meshes in the terminal. Please note that if the output of per-cell information on meshes such as wear, velocity or stress are desired, the keyword mesh_properties has to be added and the required output has to be selected.

Running the simulation

After saving the case we can change to the Simulation section. By hitting the Start button we can start running the simulation either serially or in parallel using mpi. Number of particles, kinetic energy, etc. are displayed in the line charts section.

Result

The result of the calculation can then be visualized with Paraview. The image shows the state of the simulation after 0.85 seconds, so briefly before the end.