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dc.contributor.advisorThoroddsen, Sigurdur T
dc.contributor.authorAlhazmi, Mohammad A.
dc.date.accessioned2018-12-04T10:08:29Z
dc.date.available2019-12-04T00:00:00Z
dc.date.issued2018-10
dc.identifier.citationAlhazmi, M. A. (2018). Fine Jetting from Drops Impacting on a Superhydrophobic Surface. KAUST Research Repository. https://doi.org/10.25781/KAUST-754X6
dc.identifier.doi10.25781/KAUST-754X6
dc.identifier.urihttp://hdl.handle.net/10754/630142
dc.description.abstractIn this study, the associated dynamic of water droplets at low impact velocity on the Superhydrophobic surface have been investigated. The experiment is conducted on superhydrophobic surface (SH), (Contact Angel > 1500) while varying the impact velocity (V0). When the drop hits the surface, large oscillation starts, and the capillary waves travel up to the upper of the drop where a cylindrical cavity can be formed inside the drop. The cavity closes up in a self-similar way until collapse, followed by a violent singular jet which can reach up to 35 m/s. The study showed that during drop receding, the cavity can collapse in different scenarios based on the impact velocity and the surface wettability. More importantly, the collapse is observed for the first time at very high-speed video, up to 5 million fps. Furthermore, we correct the optical distortion of the cavity due to the curvature of the drop surface. This study classifies all of the 5 encountered behaviors of the cavity collapse. The jet formation and speed are strongly dependent on the specific cavity configuration. Very fast jetting behavior is observed when the collapse is pinch-off singularity which reaches zero value in the middle of the drop. Other behaviors of the collapse such the unsymmetrical closing of the cavity or bubble entrapment is discussed. The optical distortion factor is calculated through 3 different approaches. The first one is an experimental calibration technique where a small cylinder is inserted into the drop. While the other two approaches are indirect implantations of theoretical models presented in the literature to fit the instantaneous geometrical shape of the cavity inside the drop. The distortion factor (DF) gives in all cases a similar value. Therefore, the averaged distortion value is calculated, and it is a magnification of 33% increase of the actual size. The experiment results of the cavity radius are compared with power-laws and the modified Rayleigh-Plesset equation for free cylindrical flow and good agreement is shown.
dc.language.isoen
dc.subjectdrops
dc.subjectimpacting
dc.subjectSuperhydrophobic surface
dc.subjectjetting
dc.subjectcavity collapse
dc.subjectoptical distortion
dc.titleFine Jetting from Drops Impacting on a Superhydrophobic Surface
dc.typeThesis
dc.contributor.departmentPhysical Science and Engineering (PSE) Division
dc.rights.embargodate2019-12-04
thesis.degree.grantorKing Abdullah University of Science and Technology
dc.contributor.committeememberJohansson, Bengt
dc.contributor.committeememberGhaffour, NorEddine
thesis.degree.disciplineMechanical Engineering
thesis.degree.nameMaster of Science
dc.rights.accessrightsAt the time of archiving, the student author of this thesis opted to temporarily restrict access to it. The full text of this thesis became available to the public after the expiration of the embargo on 2019-12-04.
refterms.dateFOA2018-12-04T10:09:30Z


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