Competition of coarsening and shredding of clusters in a driven diffusive lattice gas

We investigate a driven diffusive lattice gas model with two oppositely moving species of particle. The model is motivated by bidirectional traffic of ants on a pre-existing trail. A third species, corresponding to pheromones used by the ants for communication, is not conserved and mediates interactions between the particles. Here we study the spatio-temporal organization of the particles. In the unidirectional variant of this model it is known to be determined by the formation and coarsening of 'loose clusters'. For our bidirectional model, we show that the interaction of oppositely moving clusters is essential. In the late stages of evolution the cluster size oscillates because of a competition between their 'shredding' during encounters with oppositely moving counterparts and subsequent 'coarsening' during collision-free evolution. We also establish a nontrivial dependence of the spatio-temporal organization on the system size.