Modification of the LSMPS Method for the conservation of the thermal energy in laser irradiation processes

Abstract

In this work, new least-square moving particle semi-implicit (LSMPS) formulations for the modeling of the heat conduction in laser irradiation processes for both thick blocks and thin plates are developed. These new LSMPS formulations guarantee the conservation of the total thermal energy during the heatexchangebetweenparticles.Theconservationofthethermalenergyinthe LSMPSmethodwasimplementedtogetherwithmultiresolutiontechniquesfor thediscretizationofthedomainwithparticlesofdifferentsizessothatabetter characterization of the thermal gradients in the vicinity of the laser beam can beobtained.Thesimulationoflaserirradiationprocessesforthinplatesisstill verychallengingforparticlemethodswithsphericalparticlesandthisisessentially because it is difficult to accommodate a minimum number of particles alongthethicknessdirectionwithoutincreasingconsiderablytheresolutionor thenumberofparticlesintheentireplate.Inordertoovercomethisdifficulty,a newmultiresolutionmethodbasedonparticleswithellipsoidalshapeswasalso developed for a more efficient modeling of the laser irradiation in thin plates. Byconductingtheheatconductionsimulations,inwhichthestandardLSMPS method can provide accurate temperature distribution and by comparing the resultswithananalyticalsolution,itwasconfirmedthattheproposedmethodis asaccurateasthestandardLSMPSmethod.Moreover,theheatconductionwith anexternalheatsource,inwhichthetotalthermalenergyisnotconservedby usingthestandardLSMPSmethod,wassuccessfullysimulatedbyusingtheproposed method. The simulations of laser irradiations were also conducted, and thevalidityoftheproposedmethodhasbeenconfirmedbycomparingnumerical resultswithexperimentaldata.