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Particle-Particle Interaction Verification & Validation

Particle-Particle Interaction Verification & Validation

Benchmark Lead(s)

Danny van der Haven

Bruno Chareyre

Confluence profile:

@Danny van der Haven

@Bruno Chareyre

Confirmed collaborator(s)

DEM Code name

Responsible person:

YADE

@Bruno Chareyre @Danny van der Haven

MercuryDPM

@Darius Mačiūnas

XDEM

 

LAMMPS?

 

Benchmark Type

Verification

Target Result

Agreement with analytically prescribed position, velocity, force, and/or torque solution up to a given tolerance.

Benchmark Description

This is a systemic verification benchmark of single particle-particle contact interactions, including basic principles of invariance as well as agreement with analytical solutions. To minimise the influence of the choice of numerical integration algorithm, positions and velocities will be prescribed. This will verify if the implementation of the contact response agrees with the intended response behaviour described by the mathematical formulation of the contact model.

Benchmark Geometry and Boundary Conditions

Positions and velocities will be imposed on two spheres following a prescribed set of initial parameters and analytical velocity functions.

All trajectory files are available as CSV and JSON on: https://github.com/ON-DEM/ON-DEM-WG4-testingInteractions/tree/main/output_ANA

File name

Description

Location/link

theoretical_output_test_01.*

Analytical motions for Test 1

output_ANA

…

…

….

theoretical_output_test_XX.*

Analytical motions for Test XX

output_ANA

Images to be added later.

Additional notes: Velocities and positions must be prescribed each time step. This will be the most tricky part to do for most codes.

Particle Type

Intenteded and developed for:

  • Spheres

Can be included as long as a sphere is represented:

  • Sphere clumps

  • Ellipsoidal

  • Super-quadrics

  • Level-set

  • Potential surfaces

  • Polygonal

  • Polyhedra

  • Sphero-polyhedra

  • Other (specify):

Mixture Type

  • Only two particles (not necessarily the same radius)

Particle properties

Provided by analytical script as well at https://github.com/ON-DEM/ON-DEM-WG4-testingInteractions/blob/main/scripts_PY/F_generate_analytical.py

Radii R_i and R_j

1.0

Young’s modulus E

1.0e7

Poisson’s ratio \nu

0.5

Normal stiffness k_n

1.0e7

Shear stiffness k_s

0.5e7

Rolling stiffnes k_r

0.5e7

Twisting stiffness k_t

0.5e7

Viscous damping \eta_s

t.b.d.

Viscous damping \eta_r

t.b.d.

Viscous damping \eta_t

t.b.d.

Friction coefficient \mu

0.5

Contact model and properties

The linear spring-dashpot with a Coulomb sliding limit is considered for all of normal, shear, roll, and twist. Note that for many tests, some contact model properties are set to zero. Not all of the aforementioned parameters are thus needed in every test.

ON-DEM Contact Model Database Reference:

 

 

Simulation setup

Example simulation setup for YADE can be found at https://github.com/ON-DEM/ON-DEM-WG4-testingInteractions/blob/main/scripts_DEM/yade/G_generate_forces.py

Number of time steps

1e4

Maximum time

6 pi

Data output interval

Every time step

Initial configuration

Provided by the analytical trajectories that can be found at https://github.com/ON-DEM/ON-DEM-WG4-testingInteractions/tree/main/output_ANA

Output data format

A text file in CSV format, columns are:

t x1 y1 z1 x2 y2 z2 qx1 qy1 qz1 qw1 qx2 qy2 qz2 qw2 v1x v1y v1z v2x v2y v2z w1x w1y w1z w2x w2y w2z f1x f1y f1z f2x f2y f2z t1x t1y t1z t2x t2y t2z

Where t is time, the number indicates the particle the quantity belongs to, xyz are positions, q* are quaternion orientations, v* are velocities, w* are angular velocities, f* are forces, and t* are torques. Components are provided separately.

NOTE: If your integration algorithm makes use of the half-step velocities v(t±dt), you should take the average v(t) = ( v(t-dt) + v(t+dt) )/2 to make sure that the on-step velocity is properly reported!

Examples can be found at https://github.com/ON-DEM/ON-DEM-WG4-testingInteractions/tree/main/output_DEM

Other considerations and notes

It will generally benefit participants to attempt and automate the process. Examples of automation for YADE can be found at https://github.com/ON-DEM/ON-DEM-WG4-testingInteractions/tree/main/scripts_DEM/yade

Tentative schedule

Expression of interest by:

14th of February 2026

Start date (data received from):

1st of March 2026

Submission deadline for data:

30th of March 2026

Data analysis to be completed by:

15th of May 2026

Tentative publication date for draft submission

June 2026