Sensitivity of Numerical Predictions to the Permeability Coefficient in Simulations of Melting and Solidification Using the Enthalpy-Porosity Method

Abstract

The high degree of uncertainty and conflicting literature data on the value of the permeability coefficient (also known as the mushy zone constant), which aims to dampen fluid velocities in the mushy zone and suppress them in solid regions, is a critical drawback when using the fixed-grid enthalpy-porosity technique for modelling non-isothermal phase-change processes. In the present study, the sensitivity of numerical predictions to the value of this coefficient was scrutinised. Using finite-volume based numerical simulations of isothermal and non-isothermal melting and solidification problems, the causes of increased sensitivity were identified. It was found that depending on the mushy-zone thickness and the velocity field, the solid–liquid interface morphology and the rate of phase-change are sensitive to the permeability coefficient. It is demonstrated that numerical predictions of an isothermal phase-change problem are independent of the permeability coefficient for sufficiently fine meshes. It is also shown that sensitivity to the choice of permeability coefficient can be assessed by means of an appropriately defined Péclet number.

Numerical study of molten metal melt pool behaviour during conduction-mode laser spot melting

“…where, C is the mushy-zone constant and is a small number to avoid division by zero as f L approaches 0. The mushy-zone constant C was set to 10 7 kg m −2 s −2 , which is large enough to dampen fluid velocities in solid regions according to the criterion defined by Ebrahimi et al [29], and was equal to 10 −3 . To capture the position of the gas-metal interface during melting, the volume-of-fluid (VOF) method developed by Hirt and Nichols [14] was utilised.…”

Numerical Investigation on Heat-Transfer and Hydromechanical Performance inside Contaminant-Insensitive Sublimators under a Vacuum Environment for Spacecraft Applications

“…The COMSOL Multiphysics software has been successfully applied to numerical studies of heat and mass transfer in various applications, which can be referred to in the literature [53][54][55][56][57]. In this paper, the setting of boundary conditions and initial conditions is consistent with or approximate to the setting of reference [20,21,23,24,26,27], which is reasonable.…”

Advances in Design, Modelling, and Applications of Heat Transfer Equipment

“…The COMSOL Multiphysics software has been successfully applied to numerical studies of heat and mass transfer in various applications, which can be referred to in the literature [53][54][55][56][57]. In this paper, the setting of boundary conditions and initial conditions is consistent with or approximate to the setting of reference [20,21,23,24,26,27], which is reasonable.…”