On using variable molecular masses in multicomponent lattice Boltzmann simulations

Abstract

The option of varying the molecular mass in multicomponent lattice Boltzmann simulations is being explored. First, results are presented for droplet formation at an aperture in a second immiscible liquid medium in which the difference in density between the two media is achieved by introducing asymmetry in the EOS, via adding particularly intra-component interaction forces in a pseudo-potential LB model. The second application for models with variable molecular masses is a single-phase heterogeneous laminar-flow tubular chemical reactor, where the molecular masses of reactants and products differ. In this application, tuning the molecular mass requires modification of the standard equilibrium distribution function as well as the use of an extended velocity set, in our case D2Q13. The method is validated against analytical solutions for canonical 1-D diffusion-reaction cases. In both the droplet formation study and the chemical reactors, the results of the exploratory 2-D simulations look qualitatively correct.