simulation of droplet drawback in inkjet printing
DESCRIPTION
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) - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Simulation of Droplet Drawback in Inkjet Printing](https://reader036.vdocument.in/reader036/viewer/2022062517/568139fd550346895da1c4ac/html5/thumbnails/1.jpg)
Simulation of Droplet Drawback in Inkjet Printing
Multiphase Flow & Spray Systems Lab (MUSSL)
Ali Jafari and Nasser Ashgriz
![Page 2: Simulation of Droplet Drawback in Inkjet Printing](https://reader036.vdocument.in/reader036/viewer/2022062517/568139fd550346895da1c4ac/html5/thumbnails/2.jpg)
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)
![Page 3: Simulation of Droplet Drawback in Inkjet Printing](https://reader036.vdocument.in/reader036/viewer/2022062517/568139fd550346895da1c4ac/html5/thumbnails/3.jpg)
Overview
Basic assumptions laminar and incompressible fluid flow density constant
Involved mechanisms fluid dynamics: viscous and capillary effects Solidification is not considered
![Page 4: Simulation of Droplet Drawback in Inkjet Printing](https://reader036.vdocument.in/reader036/viewer/2022062517/568139fd550346895da1c4ac/html5/thumbnails/4.jpg)
Governing Equations
Continuity and momentum equations
Volume of Fluid (VOF)
])([
111
0
T
b
VV
FgpVVt
V
V
0)(
FVt
F
![Page 5: Simulation of Droplet Drawback in Inkjet Printing](https://reader036.vdocument.in/reader036/viewer/2022062517/568139fd550346895da1c4ac/html5/thumbnails/5.jpg)
Interface Tracking
Procedure:Surface Reconstruction
Use F-field to determine cell “normal” Determine “case” using normalPosition plane with known slope based upon volume fraction Compute plane area and vertices
Fluid AdvectionCompute flux across cell side (case dependent)Operator Split (i.e. do for x, y and z sweeps)
A sample “F” field
1
1
1 1
1 1
1 1
1
0 0 00
0 00
0
0 0
0
0
0
.85
.92
.68
.35
.09.31
.09
.42Two-fluid VOF method based on Piecewise Linear Interface Calculation (PLIC) algorithm.
![Page 6: Simulation of Droplet Drawback in Inkjet Printing](https://reader036.vdocument.in/reader036/viewer/2022062517/568139fd550346895da1c4ac/html5/thumbnails/6.jpg)
Validation: comp. with Fujimoto’s experiments
Non-Dim Time
D/D
0
0 1 2 3 4 50
0.5
1
1.5
2
2.5
3
ExperimentNum. V=2.65Num. V=2.55
Single water droplet impaction on a surface
D=0.56 mm, V=2.65 60,30 era
![Page 7: Simulation of Droplet Drawback in Inkjet Printing](https://reader036.vdocument.in/reader036/viewer/2022062517/568139fd550346895da1c4ac/html5/thumbnails/7.jpg)
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
![Page 8: Simulation of Droplet Drawback in Inkjet Printing](https://reader036.vdocument.in/reader036/viewer/2022062517/568139fd550346895da1c4ac/html5/thumbnails/8.jpg)
Non-coalesc., Δt=30 μs, Δx=58.5 μm
Times: 0, 9, 25, 30, 36, 43, 49, and 60 μs respectively
![Page 9: Simulation of Droplet Drawback in Inkjet Printing](https://reader036.vdocument.in/reader036/viewer/2022062517/568139fd550346895da1c4ac/html5/thumbnails/9.jpg)
Times: 0, 9, 25, 30, 36, 43, 49, and 60 μs respectively
Coalesc., Δt=30 μs, Δx=57.5 μm
![Page 10: Simulation of Droplet Drawback in Inkjet Printing](https://reader036.vdocument.in/reader036/viewer/2022062517/568139fd550346895da1c4ac/html5/thumbnails/10.jpg)
Non-coalesc., Δt=25 μs, Δx=56 μm
Times: 0, 9, 25, 30, 36, 43, 49, and 60 μs respectively
![Page 11: Simulation of Droplet Drawback in Inkjet Printing](https://reader036.vdocument.in/reader036/viewer/2022062517/568139fd550346895da1c4ac/html5/thumbnails/11.jpg)
Coalesc., Δt=25 μs, Δx=55 μm
Times: 0, 9, 25, 30, 36, 43, 49, and 60 μs respectively
![Page 12: Simulation of Droplet Drawback in Inkjet Printing](https://reader036.vdocument.in/reader036/viewer/2022062517/568139fd550346895da1c4ac/html5/thumbnails/12.jpg)
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
![Page 13: Simulation of Droplet Drawback in Inkjet Printing](https://reader036.vdocument.in/reader036/viewer/2022062517/568139fd550346895da1c4ac/html5/thumbnails/13.jpg)
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.
![Page 14: Simulation of Droplet Drawback in Inkjet Printing](https://reader036.vdocument.in/reader036/viewer/2022062517/568139fd550346895da1c4ac/html5/thumbnails/14.jpg)
Case 2, Δt=25 μs, Δx=55 μm at times 30, 34, 36, 38, 49, and 60 μs respectively.
Coalescence case 2: effect of timing
![Page 15: Simulation of Droplet Drawback in Inkjet Printing](https://reader036.vdocument.in/reader036/viewer/2022062517/568139fd550346895da1c4ac/html5/thumbnails/15.jpg)
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.
![Page 16: Simulation of Droplet Drawback in Inkjet Printing](https://reader036.vdocument.in/reader036/viewer/2022062517/568139fd550346895da1c4ac/html5/thumbnails/16.jpg)
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.