ABSTRACT
LECHMUSZYNSKI/·*DIOGOBAPTISTA2andDOUGLASJ.GARDNER2 1DepartmentofWoodScience&Engineering,119RichardsonHall,OregonStateUniversity, Corvallis,OR97331-5751,USA 2AdvancedEngineeredWoodCompositesCenter,UniversityofMaine,Orono,ME04469-5793, USA
Abstract-Asimplemodeltopredicttheevaporativebehaviorofsphericalsessiledropletsonimpermeablesurfacesispresented.Themodeliscapableofpredictingchangesinshapeandvolumeof sphericaldropletsresultingfromevaporationfromthedroplet'scaparea.Itisdemonstratedthatat anymomentallgeometricalparametersofasphericaldropletonasurface(volume,contactangle, contactradiusandarea,capradiusandarea,dropletheight)canbeeasilycalculatedfrombasic geometricalrelationsifanytwoofthemareknown(e.g.,initialdropletvolumeandinitialcontact angle,ordropletcapradiusandheight).Dropletdynamicbehaviorduetoevaporationisfurtherdeterminedusingtheknownvalueoftheevaporationintensityfromaunitareaofthedropletcap(or evaporationflux).Thebulkevaporationratefromthedropletcapdecreasesproportionallytothe shrinkingcaparea.Morecomplexdropletbehaviorcanbesimulatedifarecedingcontactangle valueisknown.Thismodelwasusedtosimulateexperimentsperformedbytheauthorsaswellas reportedbyotherresearchers.Itisdemonstratedthatthesimplegeometricalrelationsactuallyaccountformanyfeaturesofthesessiledropletdynamicbehaviorreportedintheliterature.Itisalso demonstratedthattheoftenreportedbulkevaporationrate,notadjustedforchangingdropletcap area,shouldnotbeusedasameaningfulindicatorofdropletdynamics.
