Suppressing the Coalescence in the LBM: Colloids Rheology

Abstract

This chapter presents a novel phenomenological approach for suppressing the coalescence in the Gunstensen multicomponent lattice Boltzmann method (LBM). The suppression of coalescence is achieved by perturbing the terminal nodes of the ambient fluid’s thin layer trapped between the approaching droplets. This additional perturbation creates a local high pressure fluid layer which eventually leads to suppressing the coalescence of the neighboring droplets while maintaining a suitable qualitative force balance representative of the physical intermolecular forces which act between them. The suppression of coalescence enables predicting the rheological properties of soft colloids, which is one of the most challenging and complicated problems in material and fluid sciences. Substantial complications in prediction of rheology arise due to the deformability and aggregation of soft colloids. Thus, a better understanding to deformation and aggregation of colloids can lead to a better understanding of the shear thinning region of colloidal solutions. This chapter provides a practical overview of the deformation and de-aggregation of droplets with change in time or increase in shear rate. Simulations performed here are used to quantify (a) relative viscosity of emulsions with change in shear rate, (b) relative viscosity of emulsions with change in time, (c) effect of deformation of droplets on the shear thinning region in emulsions, and (d) relative viscosity of emulsions with change in volume fraction.