(523b) Computational Fluid Dynamics Modeling of Heterogeneous Red Wine Fermentations

Red wine fermentations are performed in the presence of grape solids (skins and seeds) to ensure extraction phenolics. This results in a heterogeneous fermentation system, as the solids float to the top to form a porous solid-liquid “cap.” Modeling of red wine fermentations is, therefore, complex and must consider spatial heterogeneity to predict fermentation kinetics. We have developed a reactor engineering model for red wine fermentations that includes the fundamentals of fermentation kinetics, heat transfer, diffusion, and compressible fluid flow. COMSOL was used to solve all components of the model simultaneously utilizing a Finite Elements Analysis (FEA) approach.

This reactor engineering model was compared against experimental temperature profiles in red wine fermentations, to good effect. The model then permitted the simulation of difficult to measure parameters, such as spatial productivity gradients and fluid velocity profiles. This model was applied to examine the impact of vessel geometry on fermentation dynamics, and finally to investigate nontraditional fermentation vessels. Follow up work (covered in a subsequent talk) extended the reactor engineering model to the prediction of phenolic extraction during red wine fermentations.