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dc.contributor.advisorThoroddsen, Sigurdur T
dc.contributor.authorMansoor, Mohammad M.
dc.date.accessioned2013-03-30T07:41:09Z
dc.date.available2015-01-01T00:00:00Z
dc.date.issued2012-12
dc.identifier.citationMansoor, M. M. (2012). Ultimate Cavity Dynamics of Hydrophobic Spheres Impacting on Free Water Surfaces. KAUST Research Repository. https://doi.org/10.25781/KAUST-0C9JC
dc.identifier.doi10.25781/KAUST-0C9JC
dc.identifier.urihttp://hdl.handle.net/10754/277455
dc.description.abstractCavity formation resulting from the water-entry of solid objects has been the subject of extensive research owing to its practical relevance in naval, military, industrial, sports and biological applications. The cavity formed by an impacting hydrophobic sphere normally seals at two places, one below (deep seal) and the other above the water surface (surface seal). For Froude numbers , the air flow into the resulting cavity is strong enough to suck the splash crown above the surface and disrupt the cavity dynamics before it deep seals. In this research work we eliminate surface seals by means of a novel practice of using cone splash-guards and examine the undisturbed transient cavity dynamics by impact of hydrophobic spheres for Froude numbers ranging . This enabled the measurement of extremely accurate pinch-off heights, pinch-off times, radial cavity collapse rates, and jet speeds in an extended range of Froude numbers compared to the previous work of Duclaux et al. (2007). Results in the extended regime were in remarkable agreement with the theoretical prediction of scaled pinch-off depth, and experimentally derived pinch-off time for . Furthermore, we investigated the influence of confinement on cavity formation by varying the cross-sectional area of the tank of liquid. In conjunction with surface seal elimination we observed the formation of multiple pinch-off points where a maximum of four deep seals were obtained in a sequential order for the Froude number range investigated. The presence of an elongated cavity beneath the first pinch-off point 5 resulted in evident "kinks" primarily related to the greatly diminished air pressure at the necking region caused by supersonic air flows (Gekle et al. 2010). Such flows passing through second pinch-offs were also found to choke the cavities beneath the first pinch- off depths causing radial expansion and hence disappearance of downward jets.
dc.language.isoen
dc.subjectCavity
dc.subjectHydrophobic
dc.subjectImpact
dc.subjectWater
dc.subjectEntry
dc.titleUltimate Cavity Dynamics of Hydrophobic Spheres Impacting on Free Water Surfaces
dc.typeThesis
dc.contributor.departmentPhysical Science and Engineering (PSE) Division
dc.rights.embargodate2015-01-01
thesis.degree.grantorKing Abdullah University of Science and Technology
dc.contributor.committeememberEl Sayed, Tamer
dc.contributor.committeememberMarston, Jeremy
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 2015-01-01.
refterms.dateFOA2015-01-01T00:00:00Z


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