Influence of a transverse magnetic field on solidification structure during directional solidification

International audienceThree alloys were directionally solidified at low growth speeds under a transverse magnetic field. The results show that the application of the transverse magnetic field significantly modified the solidification structure. Indeed, we found that along with the refinement of cells/dendrites, the magnetic field caused the deformation of liquid-solid interfaces, extensive segregations (i.e., freckles and channels) in the mushy zone. Moreover, we observed that dendrite fragments and equiaxed grains were moved approximately along the direction perpendicular to the magnetic field. Modification of the solidification structure under a weak magnetic field is attributed to a TEMC-driven heat transfer and interdendritic solute transport and a TEMF-driven motion of dendrite fragments

Modeling of the effect of a thermoelectric magnetic force onto conducting particles immersed in the liquid metal

International audienceSimulation of a thermo-electromagnetic force which acts on a conducting particle immersed into liquid metal is performed using multi-gird multi-physics software AEQUATIO. To verify numerical solutions a model thermoelectric problem is solved using two methods. In the first one a phase function is used to indicate the phase transition whereas in the second the solid particle is described with a real frontier of a simplified shape. Numerical and analytical solutions for a model problem qualitatively agree but strong oscillations are observed in a numerical solution with a phase function. Further AEQUQTIO is applied for calculation of the velocity of a dendrite fragment observed in-situ in experiment of solidification of AlCu alloy. Numerical solution gives a good agreement with the experimental observation

Three-Dimensional Integral Method for Modeling Electromagnetic Inductive Processes

International audienceThis paper describes a three-dimensional integral method that models electromagnetic phenomena taking place during inductive melting. The method is well suited to inductive systems undergoing sinusoidal excitation at midrange or high frequencies. Under these conditions, only the surfaces of the conductors need to be meshed. The unknowns of the model are current density and scalar electrical potential. Power density, electromagnetic forces, and electrical impedance can easily be derived. Comparison's between numerical results and measurements confirm the accuracy of the model

MHD in cold crucible

International audienc

Physical analysis and modelization of phenomena in electromagnetic levitation in conical inductor

International audienceLevitation melting offers many advantages in metallurgy compared with classical techniques ; the main advantages are cleanness and superheating. Today levitation melting is not a widespread technique because of bad understanding of the physical mechanisms involved. The aim of this paper is to analyse the interaction between the equilibrium shape of the melt and the magnetic field distribution. The configuration is supposed to be axisymmetric and the frequency to be high enough to ensure an electromagnetic skin depth smaller than the size of the levitated sample. In this case the problem to be solved is only concerned with magnetostatics: internal fluid motion does not influence the free surface shape and can be ignored

Free boundary problems in electromagnetic levitation melting and continuous casting

International audienceTwo applications of the melting in cold crucibles are presented: continuous casting and levitation melting. These processes are typical examples of coupled phenomena. A free boundary problem has to be solved to determine the equilibrium shape of molten metal with respect to the electrical and geometrical parameters of the system. The magnetic field distribution is calculated by using a boundary integral method. The free surface can be deduced from a global analysis, that is based on the minimization of the total energy of the system. The derivation with respect to the domain leads to a rapid convergence toward the solution

3D Numerical Modelling of Coupled Phenomena in Induced Processes of Heat Treatment with Malice

International audienc

Modelling of coupled phenomena in electromagnetic levitation

International audienceThe process of levitation melting of metals has some important advantages like cleanliness and superheating. In order to optimize this fusion process we present here a model of the coupled aspects of the magnetic field and of the equilibrium geometry of the liquid metal. In a rather simple configuration of a levitated charge in a conic wire we determine the equilibrium form of the charge by minimizing the energy of the system with an iterative variational method. In each step the crucial point is the calculation of magnetic values which is facilitated by simple discretization of the free surface. The resolution of the linear system with no discretization of all space reduces computer memory requirement

Numerical simulations of turbulent flow in an electromagnetically levitated metallic droplet using k-Ω SST and Reynolds stress models

International audienceElectromagnetic levitation of a metallic droplet in the microgravity conditions is modelled accounting for the droplet shape variation, its displacement and turbulent character of the flow in the system. Three different models are applied for description of turbulent flow in the droplet: k − ω SST model and two models based on Reynolds stresses (RSM), all of them resulted in a qualitatively similar flow inside a droplet. Use of RSM-based models leads to a sharper interface of a droplet in volume-of-fluid calculations compared to the k − ω SST model. Two RSM models predict value of the surface tension close to a theoretical one, yet, both fail in predicting of viscosity of the droplet's material

NUMERICAL SIMULATIONS OF TURBULENT FLOW IN THE ELECTROMAGNETICALLY LEVITATED METALLIC DROPLET

International audienc