A new adaptation of mapping method to study mixing of multiphase flows in mixers with complex geometries

The main objective of the present work is to modify the traditional mapping method for thesimulation of distributive mixing of multiphase flows in geometries involving moving parts such as,internal mixers or twin-screw extruders without a limitation on their geometrical periodicity. Theperiodicity condition, limits the results of traditional mapping method to tracking mappingmesh between specific discrete time intervals or distances for that geometry is repeated, hence, resultis only for fixed orientation of rotors. Imaginary Domain Method is introduced to track mappingmesh from one state to the next free of geometrical periodicity limitations. In this work the method isintroduced and its applicability and accuracy is discussed in details. A two-dimensional (2D)simulation of mixing of two Newtonian fluids with different viscosities in an intermeshing internalmixer is used as a test case study. In this example the key issues of ability to predict mixing state indetails for all orientations of rotors is presented. To reduce diffusion errors of mapping method in theboundaries of the rotors, mapping mesh refinement technique that relies upon one single referencemesh is also presented.