Investigation of effect of the profile of screw flight on chocolate flow in 3D printing using an improved lattice Boltzmann method.

BACKGROUND: 3D printing provides a new way of molding chocolate with complex geometrical structures. The screw extruder can efficiently transport the liquid chocolate, which has been adopted to investigate the effect of the profile of the screw flight on the flow. First, the rheological behavior of the liquid chocolate is measured and the Cross equation is demonstrated as the proper rheological model. Then, based on the rheological behavior, an improved lattice Boltzmann method is creatively proposed, for which the effectiveness is validated by the classical Poiseuille flow. Third, the geometrical structure of the screw extruder is analyzed and transformed. The possible changes in the profiles of the screw flights are listed. Finally, the fluid analysis is conducted and the necessary streamlines figures, cloud charts and velocity distributions are obtained. RESULTS: The large dip angle in straight cases has an obvious effect on the velocity distribution and the common flow area. The position of the convex point is the additional important factor, whereas the concave profiles are the most moderate in the proposed cases. CONCLUSION: The changes in the profiles will affect the chocolate flow. The work is significant for extrusion theory in 3D printing. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]