Free-surface flows are common in the design and manufacture of products used in both the home and office environment. Bottle filling is, for instance, a process which takes place on a large scale every day. Designing such a process to minimize waste while maximizing production speed can lead to significant cost savings over time. FLOW-3D can also be used to design spray nozzles, model absorptive capabilities of porous materials and many other components or capabilities of consumer goods.

Additive Manufacturing Simulation

Viscoelastic ink printing is the future of 3-D printing. It does not require added heat, instead relying on a pump to eject any number of materials with thick consistencies onto a build platform. However, like any other 3D printing method there is an issue when multiple inks are used for the same product. The use of multiple extruders comes with inherent inaccuracy associated with the transitioning of extruders. The solution is to use a single printhead in a programmable manner. In this example,  FLOW-3D is used to simulate a two-ink microfluidic printhead for printing viscoelastic inks.

The setup of the printhead is shown in Figure (a). Since the viscosity of inks is strain rate dependent, FLOW-3D allows the user to specify the fluid property in a tabular form representing the strain rate-viscosity curve. Figure (b) shows the programmable control of the incoming discharge rates of inks from the two ends of the printhead. In FLOW-3D, the exact boundary condition has been specified. FLOW-3D‘s Moving Objects model simulates the movement of the printing platform at a designated speed. In this case it is 2.65 mm/sec. Quantitatively, the research shows that for a peak discharge rate of 1600 micro-liter/min, the distance over which the fluid fraction of any ink reduces from 1 to 0, is within 1mm. It is observed that a complete transition happens around 0.5 mm of printed ink streak. This matches with experimental results1.

1This study is based on the paper from James O. Hardin, Thomas J. Ober, Alexander D. Valentine, Jennifer A. Lewis. Microfluidic Printheads for Multimaterial 3D Printing of Viscoelastic Inks, 2015. Figures (a) and (b) have been extracted from this paper.