Lattice Boltzmann models (LBM) are rapidly showing their ability to simulate a lot of fluid dynamics problems that previously required very complex approaches. This study presents a LBM for simulating diffusion-advection transport of substrate in a 2-D laminar flow. The model considers the substrate influx into a set of active cells placed inside the flow field. A new innovative method was used to simulate the cells activity using the LBM by means of Michaelis-Menten kinetics. The model is validated with some numerical benchmark problems and proved highly accurate results. After validation the model was used to simulate the transport of oxygen substrates that diffuse in water to feed a set of active cartilage cells inside a new designed bioreactor.

Single droplets were dried whilst suspended from a rotating thermocouple in a horizontal wind tunnel, to study the effect of skin formation upon the retention of flavours. Native rice starch, wheat starch, or dextrin were used to encapsulate ethanol as a simulated flavour. The ethanol content of the dried droplets was measured using gas liquid chromatography and the crusts were examined using a scanning electron microecope. The effects of variations in encapsulant concentration, drying air temperature, and air flow rates upon flavour retention were determined.With the rice starch, the 'final retention' of ethanol, defined as the ethanol content of the droplet after drying for ten minutes, was largely independent of initial solids author for dl correspondence C-at 0 1% by Mareel Dckkcr. Inc, 530 SAYED. HASSAN. AND MUMFORDconcentration, air flow rate, and air temperature. No droplet expansion was observed. A comparative increase in the final ethanol retention was observed with wheat starch with increase in initial solids content and an increase in drying air temperature, provided droplet expansion did not occur. Similar reeulte were obtained with dextrin; increased air velocity also increased retention provided there was no droplet expansion It was concluded that in practice volatiles retention is a function of the mechanisms and times of skin/crust formation and their nature, and of selective diffusion, and the predominant resistance requires experimental evaluation.

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