EULERIAN TWO-PHASE COMPUTATIONAL FLUID DYNAMICS MODEL OF A CONCRETE SCREW MIXER

The state-of-art in computational fluid dynamics (CFD) simulations of fresh concrete mostly focuses on gravitational based physics, like Abrams cone test or L-box test. Focus of this work is the Eulerian-Eulerian two-phase CFD model of the working cycle of a continuous concrete screw mixer, useful for a simulation of the machine and a characterization of its performances. Screw mixers are used in the concrete industry to produce and convey fresh concrete directly in the moulds, starting from segregated materials put directly into the machine. The work focuses mainly on the calibration of the numerical fresh concrete fluid model, simplified as a homogenous and continuous liquid as mainly reported in scientific literature. Another task is the review of the critical in applying this simplified fluid model into a real industrial machine cycle, with centrifugal based physics applied. The calibration of the fresh concrete behaviour is obtained through a parameterization of the viscosity models. The results show how the numerical rheology of the fluid has to be corrected as a function of the simulated physics applied, and how the CFD model can be used to study the performances or compare a new design of the studied machine.