Effects of collectively induced scattering of gas stream by impurity ensembles: Shock-wave enhancement and disorder-stimulated nonlinear screening

Abstract

We report on specific effects of collective scattering for a cloud of heavy impurities exposed to a gas stream. Formation is presented of a common density perturbation and shock waves, both generated collectively by a system of scatterers at sudden application of the stream-inducing external field. Our results demonstrate that (i) the scattering of gas stream can be essentially amplified, due to nonlinear collective effects, upon fragmentation of a solid obstacle into a cluster of impurities (heterogeneously fractured obstacle); (ii) a cluster of disordered impurities can produce considerably stronger scattering accompanied by enhanced and accelerated shock wave, as compared to a regularly ordered cluster. We also show that the final steady-state density distribution is formed as a residual perturbation left after the shock front passage. In particular, a kinklike steady distribution profile can be formed as a result of shock front stopping effect. The possibility of the onset of solitary diffusive density waves, reminiscent of precursor solitons, is shown and briefly discussed.

Bodies in an interacting active fluid: far-field influence of a single body and interaction between two bodies

“…Such a non-Newtonian nature also exists in non-equilibrium depletion forces [57][58][59][60][61]. However, these are not truly scale-free, as they are screened on scales much larger than the body size [62,63]. Interactions with similar scaling to this may be present in the strongly-interacting clustered phase of active matter, which exhibits almost-scale-free correlations [64][65][66].…”

Nonlinear dynamical screening effects and strong local fluctuations of drag forces in collective scattering of particle streams on impurity ensembles

“…Such induced correlations and dynamical friction forces on impurities are manifested most pronouncedly in the case of collective dynamical screening effect and are enhanced in the case of a nonlinear medium when strong local fluctuations of scattered field begin to act as additional scattering elements along with impurities. In addition, collective scattering effects depend on the degree of impurity cluster disorder [2]. We focus on effects provoked by the collective scattering on randomly inhomogeneous structures and by the presence of local fluctuations.…”