Strongly correlated classical plasmas under external forcing and dissipation - an example using Molecular Dynamics

Abstract

Systems with excess of average potential energy per particle than its kinetic energy develop strong correlations. It is well known that such systems are not amenable to standard procedures of BBGKY hierarchy. This results in failure of both kinetic and fluid models. Phenomenology is the normal way out. If such a strongly correlated system is further subjected to strong drive and/or dissipation, “near first principles” computational methods such as Molecular Dynamics become necessary. Formation of Rayleigh-Bénnard convection cells (RBCC), where a liquid is under the action of external gravity and external temperature gradient, is one such phenomena. We report here, the formation of RBCC in 2-dimensional strongly coupled Yukawa liquids, characterized by coupling strength Γ (ratio of average potential energy to kinetic energy per particle) and screening parameter κ (ratio of average inter particle distance to Debye length). We observe the existence of a critical external temperature difference, beyond which RBCC are seen to emerge. Beyond this critical external temperature difference, the strength of the maximum convective flow velocity is shown to exhibit a new, linear relationship with external temperature difference and with a slope independent of (Γ, κ). The time taken for the transients to settle down (ts) is found to be 10,000 to 20,000 ωpd-1, where ωpd is dust plasma frequency. At very high values of Γ and/or low values of κ, RBCC are seen to get suppressed.