Drag crisis moderation by thin air layers sustained on superhydrophobic spheres falling in water

dc.contributor.authorJetly, Aditya
dc.contributor.authorVakarelski, Ivan Uriev
dc.contributor.authorThoroddsen, Sigurdur T
dc.contributor.departmentHigh-Speed Fluids Imaging Laboratory
dc.contributor.departmentMechanical Engineering Program
dc.contributor.departmentPhysical Science and Engineering (PSE) Division
dc.date.accessioned2018-02-01T11:45:54Z
dc.date.available2018-02-01T11:45:54Z
dc.date.issued2018
dc.description.abstractWe investigate the effect of thin air layers naturally sustained on superhydrophobic surfaces on the terminal velocity and drag force of metallic spheres free falling in water. The surface of 20 mm to 60 mm steel or tungsten-carbide spheres is rendered superhydrophobic by a simple coating process that uses commercially available hydrophobic agent. By comparing the free fall of unmodified spheres and superhydrophobic spheres in a 2.5 meters tall water tank, It is demonstrated that even a very thin air layer (~ 1 – 2 μm) that covers the freshly dipped superhydrophobic sphere, can reduce the drag force on the spheres by up to 80 %, at Reynolds numbers 105 - 3×105 , owing to an early drag crisis transition. This study complements prior investigations on the drag reduction efficiency of model gas layers sustained on heated metal spheres falling in liquid by the Leidenfrost effect. The drag reduction effects are expected to have significant implication for the development of sustainable air-layer-based energy saving technologies.
dc.description.sponsorshipThis work was supported by the King Abdullah University of Science and Technology (KAUST). We acknowledge Mr. Ziqiang Yang for the assistance in the some of the experiments. The AFM imaging was performed in the KAUST Microfluidics Thrust Area Labs.
dc.eprint.versionPost-print
dc.identifier.citationJetly A, Vakarelski IU, Thoroddsen ST (2018) Drag crisis moderation by thin air layers sustained on superhydrophobic spheres falling in water. Soft Matter. Available: http://dx.doi.org/10.1039/c7sm01904a.
dc.identifier.doi10.1039/c7sm01904a
dc.identifier.issn1744-683X
dc.identifier.issn1744-6848
dc.identifier.journalSoft Matter
dc.identifier.pmid29411833
dc.identifier.urihttp://hdl.handle.net/10754/627008
dc.internal.reviewer-noteEmbargo until (dd/mm/yyyy): 22/01/2019
dc.publisherRoyal Society of Chemistry (RSC)
dc.relation.urlhttp://pubs.rsc.org/en/Content/ArticleLanding/2018/SM/C7SM01904A#!divAbstract
dc.rightsArchived with thanks to Soft Matter
dc.titleDrag crisis moderation by thin air layers sustained on superhydrophobic spheres falling in water
dc.typeArticle
display.details.left<span><h5>Type</h5>Article<br><br><h5>Authors</h5><a href="https://repository.kaust.edu.sa/search?query=orcid.id:0000-0002-7835-1527&spc.sf=dc.date.issued&spc.sd=DESC">Jetly, Aditya</a> <a href="https://orcid.org/0000-0002-7835-1527" target="_blank"><img src="https://repository.kaust.edu.sa/server/api/core/bitstreams/82a625b4-ed4b-40c8-865a-d6a5225a26a4/content" width="16" height="16"/></a><br><a href="https://repository.kaust.edu.sa/search?query=orcid.id:0000-0001-9244-9160&spc.sf=dc.date.issued&spc.sd=DESC">Vakarelski, Ivan Uriev</a> <a href="https://orcid.org/0000-0001-9244-9160" target="_blank"><img src="https://repository.kaust.edu.sa/server/api/core/bitstreams/82a625b4-ed4b-40c8-865a-d6a5225a26a4/content" width="16" height="16"/></a><br><a href="https://repository.kaust.edu.sa/search?query=orcid.id:0000-0001-6997-4311&spc.sf=dc.date.issued&spc.sd=DESC">Thoroddsen, Sigurdur T</a> <a href="https://orcid.org/0000-0001-6997-4311" target="_blank"><img src="https://repository.kaust.edu.sa/server/api/core/bitstreams/82a625b4-ed4b-40c8-865a-d6a5225a26a4/content" width="16" height="16"/></a><br><br><h5>KAUST Department</h5><a href="https://repository.kaust.edu.sa/search?spc.sf=dc.date.issued&spc.sd=DESC&f.department=High-Speed Fluids Imaging Laboratory,equals">High-Speed Fluids Imaging Laboratory</a><br><a href="https://repository.kaust.edu.sa/search?spc.sf=dc.date.issued&spc.sd=DESC&f.department=Mechanical Engineering Program,equals">Mechanical Engineering Program</a><br><a href="https://repository.kaust.edu.sa/search?spc.sf=dc.date.issued&spc.sd=DESC&f.department=Physical Science and Engineering (PSE) Division,equals">Physical Science and Engineering (PSE) Division</a><br><br><h5>Date</h5>2018</span>
display.details.right<span><h5>Abstract</h5>We investigate the effect of thin air layers naturally sustained on superhydrophobic surfaces on the terminal velocity and drag force of metallic spheres free falling in water. The surface of 20 mm to 60 mm steel or tungsten-carbide spheres is rendered superhydrophobic by a simple coating process that uses commercially available hydrophobic agent. By comparing the free fall of unmodified spheres and superhydrophobic spheres in a 2.5 meters tall water tank, It is demonstrated that even a very thin air layer (~ 1 – 2 μm) that covers the freshly dipped superhydrophobic sphere, can reduce the drag force on the spheres by up to 80 %, at Reynolds numbers 105 - 3×105 , owing to an early drag crisis transition. This study complements prior investigations on the drag reduction efficiency of model gas layers sustained on heated metal spheres falling in liquid by the Leidenfrost effect. The drag reduction effects are expected to have significant implication for the development of sustainable air-layer-based energy saving technologies.<br><br><h5>Citation</h5>Jetly A, Vakarelski IU, Thoroddsen ST (2018) Drag crisis moderation by thin air layers sustained on superhydrophobic spheres falling in water. Soft Matter. Available: http://dx.doi.org/10.1039/c7sm01904a.<br><br><h5>Acknowledgements</h5>This work was supported by the King Abdullah University of Science and Technology (KAUST). We acknowledge Mr. Ziqiang Yang for the assistance in the some of the experiments. The AFM imaging was performed in the KAUST Microfluidics Thrust Area Labs.<br><br><h5>Publisher</h5><a href="https://repository.kaust.edu.sa/search?spc.sf=dc.date.issued&spc.sd=DESC&f.publisher=Royal Society of Chemistry (RSC),equals">Royal Society of Chemistry (RSC)</a><br><br><h5>Journal</h5><a href="https://repository.kaust.edu.sa/search?spc.sf=dc.date.issued&spc.sd=DESC&f.journal=Soft Matter,equals">Soft Matter</a><br><br><h5>DOI</h5><a href="https://doi.org/10.1039/c7sm01904a">10.1039/c7sm01904a</a><br><br><h5>PubMed ID</h5><a href="https://www.ncbi.nlm.nih.gov/pubmed/29411833">29411833</a><br><br><h5>Additional Links</h5>http://pubs.rsc.org/en/Content/ArticleLanding/2018/SM/C7SM01904A#!divAbstract</span>
kaust.personJetly, Aditya
kaust.personVakarelski, Ivan Uriev
kaust.personThoroddsen, Sigurdur T.
orcid.authorJetly, Aditya::0000-0002-7835-1527
orcid.authorVakarelski, Ivan Uriev::0000-0001-9244-9160
orcid.authorThoroddsen, Sigurdur T::0000-0001-6997-4311
orcid.id0000-0001-6997-4311
orcid.id0000-0001-9244-9160
orcid.id0000-0002-7835-1527
refterms.dateFOA2019-01-22T00:00:00Z
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