Notesontheimplementationofafully-implicitnumericalschemeforatwo-phasethree-fieldflowmodelOriginalResearchArticle

Thedevelopmentofafully-implicitschemetomodelthetwo-phasethree-fieldflowandheattransferproblemispresentedhere.ThemodelwasoriginallydevelopedtosimulatethecomplexphenomenaoccurringinproximityofthequenchfrontofanuclearreactorcoreduringtherefloodphaseofapostulatedLOCA.Thefully-implicitmethodallowsrelativelargetimestepstobeusedevenonveryfinespatialgridswhichcannotbeconsideredwhenasemi-implicitschemeisappliedtosolvetheconservationequation.Theobjectiveofthispaperistocaptureasmuchaspossible,thelessonslearnedduringthedevelopmentandcodingofthefully-implicittwo-phasethree-fieldmodel.Theimplementationofthemodelisoneofthemosttimeconsumingandachallengingtask.Theliteratureonnumericalmodelsgenerallyconcentratesonthetheoreticalaspectsofthenumericalmethodbutavailableinformationontheproblemsencounteredduringtheimplementationofsuchmethodsforrealapplicationsisscarce.Thereasonisthatmanyofthesemethodsaretailoredtospecificapplicationsandsometimesareratherempirical.Thesetechniquesaretheresultofalongandtedioustrialanderrorprocessfromthedeveloper.Thearticlepresentedhereattemptstoprovidesomeinsightsandguidelinesforfuturedevelopmentofthisorsimilarmodels.