Jolanta Dziatkiewicz

Sensitivity Analysis and Inverse Problems in Microscale Heat Transfer

In the paper the selected problems related to the modeling of microscale heat transfer are presented. In particular, thermal processes occurring in thin metal films exposed to short-pulse laser are described by two-temperature hyperbolic model supplemented by appropriate boundary and initial conditions. Sensitivity analysis of electrons and phonons temperatures with respect to the microscopic parameters is discussed and also the inverse problems connected with the identification of relaxation times and coupling factor are presented. In the final part of the paper the examples of computations are shown.

Numerical analysis of laser ablation using the axisymmetric two-temperature model

Laser ablation of the axisymmetric micro-domain is analyzed. To describe the thermal processes occurring in the micro-domain the two-temperature hyperbolic model supplemented by the boundary and initial conditions is used. This model takes into account the phase changes of material (solid-liquid and liquid-vapour) and the ablation process. At the stage of numerical computations the finite difference method with staggered grid is used. In the final part the results of computations are shown.

Multicriteria identification of parameters in microscale heat transfer

Purpose The purpose of this paper is to present the multicriteria identification method used for solving the microscale heat transfer problem. The thin film exposed to ultrashort laser pulse is modeled using the finite difference method. The parameters of the model are tuned on the basis of experimental data. The multicriteria identification of the numerical model parameters is performed for subsets of experimental data. Design/methodology/approach The multicriteria identification method is used in the paper. The Pareto front for two criterions is created. The two-temperature model of heat transfer in microscale is used in the numerical model. Findings The multicriteria identification for two subsets of experimental data leads to different results. The obtained Pareto front allows to choose the most suitable set of numerical model parameters. Originality/value The multicriteria identification method was used for the first time to solve the microscale heat transfer problem.

MODELING OF PHASE CHANGES IN MICRO-DOMAIN INDUCED BY AN ULTRASHORT LASER PULSE

Abstract. An axisymmetric micro-domain subjected to the ultrashort laser pulse is considered. To describe the process of heat conduction occurring in the analyzed domain, the twotemperature hyperbolic model together with the isothermal solid-liquid and liquid-vapor phase changes is applied. This model, consisting of four equations describing the electrons and lattice temperatures and also the electrons and lattice heat fluxes, is transformed to the model consisting of only two equations describing the electrons and lattice temperatures. Derived equations together with the appropriate boundary and initial conditions, are solved using the finite difference method supplemented by additional numerical procedures which allow to take into account the phase changes. In the final part of the paper the results of computations are shown and the conclusions are formulated.