Active force bias along negative x direction: Bug or misconfiguration?
Florian Dittrich
Dear all,
I'm currently using hoomd for simulating systems of active brownian particles. I did several big simulations where the particles form big droplets (which is intended). However, it turned out, that all the droplets drift along the negative x-axis. It is to be expected, that the droplets drift. However, there is no reason, why the direction is the same in several independent systems that were randomly initialised.
While searching for the problem, I found that there is a clear bias in the active forces’ directions. When I start the simulation, I set the directions uniformly random. The mean x and mean y components over all particles even out. Right after starting the simulations, the mean y-component fluctuates around 0, which is to be expected. The mean x-component however fluctuates around minus 0.0033. I found that this was true for several independent simulations.
Now I’m a little bit puzzled how this can happen. Is there any known bug? Or can you spot a misconfiguration in my code? I attached a minimum simulation code example. I also attached my analysis of the mean active forces’ directions.
I would be very grateful, if someone can help me along.
Best,
Florian
Joshua Anderson
Joshua A. Anderson, Ph.D.
Research Area Specialist, Chemical Engineering, University of Michigan
On Oct 7, 2021, at 10:53 AM, 'Florian Dittrich' via hoomd-users <hoomd...@googlegroups.com> wrote:
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<simulation_source.txt><Quantification of active force bias.pdf>