资源描述：
《Shape of a Ponytail and the Statistical Physics of Hair Fiber Bundles》由会员上传分享，免费在线阅读，更多相关内容在学术论文-天天文库。
1、weekendingPRL108,078101(2012)PHYSICALREVIEWLETTERS17FEBRUARY2012ShapeofaPonytailandtheStatisticalPhysicsofHairFiberBundles123RaymondE.Goldstein,PatrickB.Warren,andRobinC.Ball1DepartmentofAppliedMathematicsandTheoreticalPhysics,UniversityofCambridge,WilberforceRoad,Cambri
2、dgeCB30WA,UnitedKingdom2UnileverR&DPortSunlight,QuarryRoadEast,Bebington,Wirral,CH633JW,UnitedKingdom3DepartmentofPhysics,UniversityofWarwick,Coventry,CV47AL,UnitedKingdom(Received17November2011;published13February2012)Ageneralcontinuumtheoryforthedistributionofhairsinab
3、undleisdeveloped,treatingindividualfibersaselasticfilamentswithrandomintrinsiccurvatures.Applyingthisformalismtotheiconicproblemoftheponytail,thecombinedeffectsofbendingelasticity,gravity,andorientationaldisorderarerecastasadifferentialequationfortheenvelopeofthebundle,inw
4、hichthecompressibilityentersthroughan‘‘equationofstate.’’Fromthis,weidentifythebalanceofforcesinvariousregionsoftheponytail,extractaremarkablysimpleequationofstatefromlaboratorymeasurementsofhumanponytails,andrelatethepressuretothemeasuredrandomcurvaturesofindividualhair
5、s.DOI:10.1103/PhysRevLett.108.078101PACSnumbers:87.19.R,05.40.a,46.65.+gOneofthemostfamiliarfeaturesofabundleofhairsuchInparallelwiththetheoreticaldevelopment,wemea-asaponytailisits‘‘body’’or‘‘volume.’’Closeexamina-suredtheshapesofponytailsmadefromcommerciallytionrevea
6、lsthatthispropertyarisesinasubtlewayfromavailablehair‘‘switches’’[8],andoftheircomponentthestiffnessandshapesoftheindividualfibers,whosefibers.Typicalhumanhairhasanellipticalcrosssectionmeanderingpathsthroughthebundleproducemanycolli-andadistributionofmajoraxisdiameters40&
7、d&sionswithotherhairs(Fig.1).Thesemeanderingsarein140m.Wefoundd¼7916mforarandomsamplepartaconsequenceofthecontactsthemselves,buthairsfromtheswitches.Hairhasanaveragedensityof’alsohaveanintrinsicwavinessorcurliness[1,2].Such1:3g=cm3[1],andalinearmassdensity’65g=cmcur
8、vaturesmaybegeneratedduringgrowth,andvarywith(inmoreamusingunits,6:5g=km).Thoughitsinternalethnicity.Th
