Comparison of Lattice-Boltzmann and Brownian Dynamics Simulations of Polymer Relaxation

We have tested the accuracy of our lattice-Boltzmann polymer model [1] by detailed comparisons with Brownian dynamics. We examined the decay of the internal modes of a single polymer as measured by the Rouse mode relaxation time, τp. We use exactly the same polymer model in both simulations; FENE springs with Gaussian excluded volume, chosen to approximate a 20 μm strand of DNA. As can be seen in the figure, the Rouse times obtained with the fluctuating LB model agree well with Brownian dynamics,particularly when the resolution of the grid is sufficiently small. An account of this work has been submitted for publication.

Rouse mode relaxation times for an 11-bead FENE chain. The grid spacing is &Delta x, and the mean bond length between the beads is ~1.6 b, and the time scale t0 = 6 &pi &eta a2/kBT. The agreement is best for the finest grid resolution (right panel).

References

  1. O. B. Usta, A. J. C. Ladd and J. E. Butler, J. Chem. Phys., 122:094902, 2005.
  2. R. Kekre, A. J. C. Ladd and J. E. Butler, Phys. Rev. E, (Submitted) 2009. arXiv:0905.2434