Discrete Analog of the Burgers Equation
E. Ben-Naim and P. L. Krapivsky
We propose the set of coupled ordinary differential equations
dn_j/dt=(n_{j-1})^2-(n_j)^2 as a discrete analog of the classic Burgers
equation. We focus on traveling waves and triangular waves, and find that these
special solutions of the discrete system capture major features of their
continuous counterpart. In particular, the propagation velocity of a traveling
wave and the shape of a triangular wave match the continuous behavior. However,
there are some subtle differences. For traveling waves, the propagating front
can be extremely sharp as it exhibits double exponential decay. For triangular
waves, there is an unexpected logarithmic shift in the location of the front.
We establish these results using asymptotic analysis, heuristic arguments, and
direct numerical integration.
source,
pdf