Modeling Mass and Heat Transfer in Multiphase Coffee Aroma Extraction.

Instant coffee manufacture involves the aqueous extraction of soluble coffee components followed by drying to form a soluble powder. Loss of volatile aroma compounds during concentration through evaporation can lower product quality. One method of retaining aroma is to steam-strip volatiles from the coffee and add them back to a concentrated coffee solution before the final drying stage.

Toward a New Brewing Control Chart for the 21st Century.

This paper describes new results from a base model of brewing from a bed of packed coffee grains. The model solves for the diffusion of soluble species out of a distribution of particles into the flow through the bed pore space. It requires a limited set of input parameters.

Brownian dynamics simulations of aging colloidal gels.

The aging of colloidal gels is investigated using very long duration Brownian dynamics simulations. The Asakura-Oosawa description of the depletion interaction is used to model a simple colloid polymer mixture. Several regimes are identified during gel formation.

Compact model for multi-phase liquid-liquid flows in micro-fluidic devices.

We present a compact model describing the laminar flow of viscous multiphase fluids in micro-channel networks. We apply this model to the flow of 2 immiscible fluids representing typically oil and water, in a network of micro-channels comprising one inlet for each fluid splitting into 2 branches meeting at a T-junction, where the 2 phases are combined before exiting the network through two outlets. This network is akin to an electrical "Wheatstone bridge" and represents a simplified interdigital micro-reactor, where the fluids to be mixed are separated into smaller branches and later re-combined together.

Colloid flow during thickening--a particle level understanding for core-shell particles.

The flow curve of sheared concentrated colloids can show a region of shear thickening. The underlying mechanisms involved in this effect has long been an issue. Recently the author and co-workers have used Stokesian dynamics approximated for high concentrations to simulate models of polymer coated particles in the thickening regime.