1 / 16

Simulation of Droplet Drawback in Inkjet Printing

Simulation of Droplet Drawback in Inkjet Printing. Multiphase Flow & Spray Systems Lab (MUSSL). Ali Jafari and Nasser Ashgriz. Motivation. Investigate the interaction between two impacting droplets (drawback)

feng
Download Presentation

Simulation of Droplet Drawback in Inkjet Printing

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Simulation of Droplet Drawback in Inkjet Printing Multiphase Flow & Spray Systems Lab (MUSSL) Ali Jafari and Nasser Ashgriz

  2. Motivation • Investigate the interaction between two impacting droplets (drawback) • Investigate the effect of different parameters and liquid properties on the final droplet shapes (coalesced or not coalesced drops)

  3. Overview • Basic assumptions • laminar and incompressible fluid flow • density constant • Involved mechanisms • fluid dynamics: viscous and capillary effects • Solidification is not considered

  4. Governing Equations • Continuity and momentum equations • Volume of Fluid (VOF)

  5. Two-fluid VOF method based on Piecewise Linear Interface Calculation (PLIC) algorithm. 1 1 1 .68 0 1 1 1 .42 0 A sample “F” field .92 .09 1 1 0 1 0 0 .85 .35 .09 0 0 0 .31 0 0 0 0 0 Interface Tracking • Procedure: • Surface Reconstruction • Use F-field to determine cell “normal” • Determine “case” using normal • Position plane with known slope based upon volume fraction • Compute plane area and vertices • Fluid Advection • Compute flux across cell side (case dependent) • Operator Split (i.e. do for x, y and z sweeps)

  6. Validation: comp. with Fujimoto’s experiments Single water droplet impaction on a surface D=0.56 mm, V=2.65

  7. Simulation parameters • 20 cells per radius • ρ=997 kg/m3 • μ=.000891 kg/m.s • D=40 μm • V=5 m/s • σ=0.073 N/m • Ө=90º

  8. Non-coalesc., Δt=30 μs, Δx=58.5 μm Times: 0, 9, 25, 30, 36, 43, 49, and 60 μs respectively

  9. Coalesc., Δt=30 μs, Δx=57.5 μm Times: 0, 9, 25, 30, 36, 43, 49, and 60 μs respectively

  10. Non-coalesc., Δt=25 μs, Δx=56 μm Times: 0, 9, 25, 30, 36, 43, 49, and 60 μs respectively

  11. Coalesc., Δt=25 μs, Δx=55 μm Times: 0, 9, 25, 30, 36, 43, 49, and 60 μs respectively

  12. Velocity field (non-coalescence) Velocity distribution for case 1, Δt=30 μs, Δx=58 μm at times 36, 40, 43, 45, 49, and 60 μs respectively

  13. Velocity field (coalescence) Velocity distribution for case 1, Δt=30 μs, Δx=57.5 μm at times 36, 40, 43, 45, 49, and 60 μs respectively.

  14. Coalescence case 2: effect of timing Case 2, Δt=25 μs, Δx=55 μm at times 30, 34, 36, 38, 49, and 60 μs respectively.

  15. Non-dim. Pressure contours Δt=30 μs, Δx=57.5 μm at times 43, 45, and 60 μs respectively Δt=30 μs, Δx=58 μm at times 40, 43, and 60 μs respectively.

  16. Conclusions • Drawback is sensitive to • Drop spacing • Impact velocity • Contact angle • Inter-drop time • Small changes in any of the above parameters may result in coalescing or non-coalescing drops: e.g. for Δt=25 μs, coalescence at drop spacing of 55 m; no coalescence at 56 m • Further investigation of all important cases and parameters is planned and from these data, theoretical relations for the threshold of coalescence and non-coalescence would be developed.

More Related