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Center for Nonlinear Studies |
Different types of models can be found in the literature depending on the length scales associated with the type of segregation to be modeled and the castings of interest. Two of these are discussed here. The first are generally known as mushy zone models and are used to simulate segregation in castings with dimensions on the order of centimeters, where it is not possible to resolve the growth of individual dendrites, and the scale of the segregation defects is on the order of millimeters or larger. In these models the main issues involving incompressible flow of interdendritic liquid are flow in an anisotropic porous medium, the flow induced by the step change in density during phase change, and the efficiency, or lack thereof, of current computational algorithms. The second type of models attempts to describe the microscopic features in the process and simulate the growth of individual dendrites together with the associated microsegregation. Convection at this scale is also known to have strong effect in the final material properties, and although models that include convection at this level have been developed in recent years, these models are rather limited and much remains to be understood about how convection interacts with dendritic growth. In this presentation, an overview of the two types of models is given. The advantages and drawbacks of the models currently available are discussed, and an outlook into future work in the field is offered.
Host: Mikhail Shashkov