(351a) Computational Fluid Dynamics of Viscoelastic Flow (Area 15a Plenary Lecture)

Computational fluid dynamics (CFD) provide a very effective way to probe the dynamics of a process and learn about what goes on inside the material being processed non-intrusively (Puri and Anantheswaran, 1993). Numerical simulations have a wide range of applications in equipment design, optimization, scale up and scale down in many food processing operations. The geometrical complexities of process equipments and the non- linear viscoelastic properties of food materials makes it a necessity to invest in numerical simulation if appropriate progress is to be made in improving food operations. CFD offers a powerful design and investigative tool to process engineers. It assists in a better understanding of the complex physical mechanisms that govern the operations of food processes. CFD has only recently been applied to food processing applications. The advent of powerful computers and work stations has provided the opportunity to simulate various real-world processes. Food materials are subjected to mechanical and thermal effects during processing. When simulating the processing of food products, it is necessary to take the rheological nature of a food into account as this will dictate its flow behavior. There are many CFD approaches to discretizing the equations of conservation of momentum, mass, and energy, together with the constitutive equation that defines the rheology of the fluid being modeled and the boundary and initial conditions that govern the flow behavior in particular geometries such as extruders and mixers. The most important of these are finite difference (FDM), finite volume (FVM), and finite element (FEM) methods. Others CFD techniques can be listed as spectral schemes, boundary element methods, and cellular automata, but their use is limited to special classes of problems.