A thermal fluid dynamics framework applied to multi-component substrates experiencing fusion and vaporisation state transitions

Abstract

The fluid dynamics of multi-component alloy systems subjected to high energy density sources of heat largely determines the local composition, microstructure, and material properties. In this work a multi-component thermal fluid dynamics framework is presented for the prediction of alloy system development due to melting, vaporisation, condensation and solidification phenomena. A volume dilation term is introduced into the continuity equation to account for the density jump between liquid and vapour species, conserving mass through vaporisation and condensation state changes. Mass diffusion, surface tension, the temperature dependence of surface tension, buoyancy terms and latent heat effects are incorporated. The framework is applied to describe binary vapour collapse into a heterogeneous binary liquid, and a high energy density power beam joining application; where a rigorous mathematical description of preferential element evaporation is presented.

Digital materials design by thermal-fluid science for multi-metal additive manufacturing

“…For each issue, respectively, the CLSVOF (coupled level-set and volume-of-fluid) method, the continuum surface force method, vaporisation jump conditions and species mass fraction equations are considered in this study, as described below. In most metallurgical simulations of so far, these effects have not been considered rigorously, and only very recently such an effort has begun to be pursued [7,32,33,37]. The present method enables solving AM simulation issues including vapour dynamics and multi-metal effects.…”

“…In order to understand the AM physics, these numerical formulations are considered in this study as described in Section 2. Only very recently such a modelling effort has begun to be pursued in AM simulation [7,32,33,37]. The present method is therefore a state of the art approach to tackle AM issues including vapour dynamics and multi-metal effects.…”

Magneto-hydrodynamics of multi-phase flows in heterogeneous systems with large property gradients

“…The thermal-fluid dynamics of a multi-phase mixture is fully described by the fluid velocity, pressure, chemical species fraction and temperature fields through the conservation laws for linear momentum, composition and energy transport. This results in the following one-fluid formulation of the Navier–Stokes equation for the fluid velocity, for more details see 22 , 47 , 48 : where is the velocity, is the mass density, P is the fluid pressure, and is the viscous stress tensor and is given by, …”

“…A compressive velocity field, , is instead superimposed in the vicinity of the interface to counteract numerical diffusion between the gaseous and metallic phases 51 . Additional details of the implementation can be found elsewhere 47 . The thermodynamic and transport properties of the heterogeneous mixture are computed using the mass phase fraction as a weighting factor, e.g.…”

laserbeamFoam: Laser ray-tracing and thermally induced state transition simulation toolkit

“…In the fluid state, the dynamics are dominated by the interfacial forces between the molten liquid and the vapour or gaseous phase [11]. These interfacial forces are the surface tension and its dependence on temperature, which generates strong surface shear flows, and the recoil momentum induced as portions of the metallic substrate vapourise [6,[11][12][13]. Other hydrodynamic forces, such as buoyancy, are present; however, their contribution to the momentum field is much smaller.…”