[EDEM] Inquiry on Global Velocity Vector Access and Matrix Operations in EDEM Custom API

KJHSNU

Hello,

I am currently developing a specific physical model using the EDEM Custom API (C++).

I am utilizing the Body Force API (externalForce) and the Contact Force API (calculateForce). However, I am finding it challenging that the default API structure restricts data access to individual particles or specific contact pairs only.

My model involves a 6N * 6N global matrix (assuming 6 degrees of freedom per particle) multiplied by a 6N global velocity vector to calculate the forces for the entire system. To implement this, I need simultaneous access to the velocity information of all particles (Global Access) within a specific time step.

While I understand this could potentially be implemented indirectly through contact models, I would like to ask the following questions regarding computational efficiency and model clarity:

1. Global Data Accessibility: Is there an interface within the API that allows direct reference to an array or pointer containing the velocities of all particles currently in the simulation?
2. Calculation Workflow: Is it feasible to implement a workflow where I collect velocity data for all particles, perform the matrix multiplication, and then distribute the resulting forces back to each individual particle's force component?

I would greatly appreciate any guidance or recommended frameworks for achieving this.

Stephen Cole

Hi,

This is a challenging question for EDEM, as you have seen the Contact information is only provided by contact pair, and the Particle information only available as individual particles. There isn't a standard mechanism for providing all particle or all contact info at any given time.

You could consider chaining contact models, you can set two different contact models to run, one after another. However I've not tried this method myself so unsure if it gives you the data required.

There is also the Coupling Interface API. This is a separate type of API really designed to couple with external programs (CFD/MBD) but it does provide all particle info. It doesn't link to the Contact Model or Body Force API but maybe helpful - https://help.altair.com/edem/topics/coupling_interface_programming_guide/introducing_the_coupling_interface_programming_guide_c.htm

Regards

Stephen