Application of computational fluid dynamics for the optimization of homogenization processes in wine tanks

Abstract

Mixing processes for modern wine-making occur repeatedly during fermentation (e.g. yeast addition, wine fermen- tation additives), as well as after fermentation (e.g. blending, dosage, sulfur additions). In large fermentation vessels or when mixing fluids of different viscosities, an inadequate mixing process can lead to considerable costs and problems (inhomogeneous product, development of layers in the tank, waste of energy, clogging of filters). Considering advancements in computational fluid dynamics (CFD) in the last few years and the computational power of computers nowadays, most large-scale wineries would be able to conduct mixing simulations using their own tank and agitator configurations in order to evaluate their efficiency and the necessary power input based on mathematical modeling. Regardless, most companies still rely on estimations and empirical values which are neither validated nor optimized. The free open-source CFD software OpenFOAM (v.2.3.1) is used to simulate flows in wine tanks. Different agitator types, different propeller geometries and rotational speeds can be modeled and compared amongst each other in the process. Moreover, fluid properties of different wine additives can be modeled. During opti- cal post-processing using the open-source software ParaView (v.4.3) the progression of homogenization can be visualized and poorly mixed regions in the tank are revealed.