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Re: Hydrodynamic forces analysis
From: |
Jean-Noël Grad |
Subject: |
Re: Hydrodynamic forces analysis |
Date: |
Tue, 31 Oct 2023 18:00:19 +0100 |
User-agent: |
Mozilla Thunderbird |
Hi,
To the best of my knowledge, there isn't a way to calculate this
quantity from the Python interface, because the particle coupling code
that updates particle forces also updates the LB grid and thermostat as
a side-effect.
If you are familiar with C++ programming, it would be a fun exercise to
update the particle coupling code to also update a dictionary of
particle forces. To do so, one would adapt `ParticleCoupling::kernel()`
to write forces to a `std::unordered_map<int,Utils::Vector3d> obs` using
particle ids as key.
The particle forces from the LB grid are calculated here:
https://github.com/espressomd/espresso/blob/b70d9e8/src/core/lb/particle_coupling.cpp#L279
One can then accumulate forces with `obs[p.id()] += force_on_particle;`
and reset all forces to zero as the first step of `couple_particles()`
with `for(auto &[k,v] : obs){v=Utils::Vector3d{};}`.
Hope this helps,
JN
On 10/30/23 15:18, Ahmad Reza Motezakker wrote:
Dear EspressoMD Community,
I hope this email finds you well. I am working on a project involving
nanoparticles and polymers in a cubic box, simulated with LB fluid
dynamics and Lennard-Jones forces.
I am particularly interested in analyzing the hydrodynamic forces acting
on the nanoparticles. Could you share any tips or tools in EspressoMD
that would help me isolate and accurately calculate these forces and the
net force?
Thank you in advance for your assistance.
Best,
ARM