微机电糸统分析.ppt

微機電糸統分析期末報告(二) Inkjet 授課教師:李旺龍 學生:李聰瑞 Q28961038
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Inkjet Model
Inkjet printers are attractive tools for printing text and images because of their low cost, high resolution, and acceptable speed. The working principle behind inkjet technology is to eject small droplets of liquid from a nozzle onto a sheet of paper. Important properties of a printer are its speed and the resolution of the final images. Designers can vary several parameters to modify a printer’s performance. For instance, they can vary the inkjet geometry and the type of ink to create droplets of different sizes. The size and speed of the ejected droplets are also strongly dependent on the speed at which ink is injected into the nozzle. Simulations can be very useful to improve the understanding of the fluid flow and to predict the optimal design of an inkjet for a specific application.
Although initially invented to produce images on paper, the inkjet technique has since been adopted for other application areas. Instruments for the precise deposition of microdroplets often employ inkjets. These instruments are used within the life sciences for diagnosis, analysis, and drug discovery. Inkjets have also been used as 3D printers to synthesize tissue from cells and to manufacture microelectronics. For all of these applications it is important to be able to accurately control the inkjet’s performance.
This example demonstrates how to SOL Multiphysics to model the fluid flow within an inkjet. The model uses the Navier Stokes equations to describe the momentum transport and conservation of mass. Surface tension is included in the momentum equations. A reinitialized, conservative level set method represents and moves the interface between the air and ink.
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Figure 4-61 shows the geometry of the inkjet studied in this example. Because of its symmetry you can use an axisymmetric 2D model. Initially, the space between the inlet and the nozzle is filled with ink. Additional ink is injected throu