LAUSR

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. Firstly, 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 (LBM) is creatively proposed, whose effectiveness is validated by the classical Poiseuille flow. Thirdly, 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 with MATLAB and the necessary streamlines figures, cloud charts, 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, while the concave profiles are the most moderate in the proposed cases. CONCLUSION The changes of the profiles will affect the chocolate flow. The work is significant for the extrusion theory in 3D printing. This article is protected by copyright. All rights reserved.