Trouble in measuring the viscosity using hoomd.md.update.muller_plathe_flow

[peaches liang]

Dear all,

      Now I am going to measure viscosity using hoomd.md.update.muller_plathe_flow method. My hoomd version is 2.9.7. But after simulation, I don't know how to calculate the viscosity.  Firstly, I get a velocity distribution, so I get the strain velocity, which is about 0.038 in reduced units.  My flow target is 0.004* steps, so the Jz(Px) should be 0.004/(2*Lx*Ly*dt). So I will get a viscosity to be about 1/38, which should be around 3.

       Besides, my system is a box(Lx = Ly =20, Lz =40), filled with lj particles in density of 0.85. My system is quite similar with the system used in the paper which introduce the method in 1999. 

   I think I must make a mistake, but I can't figure it out. my script and the picture of velocity distribution are attached.

[Joshua Anderson]

I answer support questions only for the latest major version of HOOMD-blue (currently 4.x).

That being said, any questions regarding the reverse perturbation flow method should be directed to the original author of that code, Ludwig Schneider.

------

Joshua A. Anderson, Ph.D.

Research Area Specialist, Chemical Engineering, University of Michigan

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<velo_distribution_0.004.png><shear.py>