An enthalpy method based on fixed-grid for quasi-steady modeling of solidification/melting processes of pure materials

Wu, Ming; Liu, Lijun; Ding, Junling

doi:10.1016/j.ijheatmasstransfer.2017.01.018

Cited by 18 publications

(5 citation statements)

References 18 publications

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“…They can be reduced either by using a very fine grid or by using more complex finite difference schemes. [10][11][12] In this work, the melting or solidification of the germanium is not investigated in depth as most of the temperatures achieved during experiments didn't reach the melting point of germanium. In the case that a simulation does reach the melting point, the basic enthalpy method gives a reasonable estimation of the melt pool size and its effects on the temperature spread.…”

Section: Heat Propagation In Germaniummentioning

confidence: 99%

Numerical investigation of thermal effects of high-energy laser irradiation on a germanium lens

Desnijder

Vandewal²

2022

High-Power Lasers and Technologies for Optical Countermeasures

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High energy lasers (HEL) are increasingly seen as a versatile tool to counter observation systems by directly damaging or dazzling the electro-optical (EO) or infrared (IR) sensors used for detection, recognition, tracking, and targeting. The main mechanism through which high energy lasers affect their target is by heat. In the case of thermal sensors which use germanium optics, this heat is applied on the outer optical component as germanium isn’t transmissive at the typical wavelengths at which current HEL lasers operate. Germanium is a brittle material and therefore is prone to shattering due to mechanical stresses caused by local thermal expansion of the hotspot. Furthermore, germanium becomes opaque to thermal IR radiation at elevated temperatures and starts emitting radiation itself. This mechanism allows an out-of-band high-energy laser to indirectly dazzle thermal infrared sensors which is referred to as pseudo-in-band dazzling. Because this effect depends on the temperature of the germanium, the sensor can remain dazzled some time after the laser irradiation has stopped while the germanium lens is cooling down. To be able to assess the effectiveness of a laser beam to dazzle or destroy a germanium lens, one must know the evolution of the heat distribution throughout the lens. In this work a thermal simulation model is presented that takes in account several aspects that influence the propagation of heat in a realistic lens. The simulation results are compared to experimentally obtained results from an earlier measurement campaign. The potential impact of the incident radiation distribution on the heating and cooling times are discussed.

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Section: Heat Propagation In Germaniummentioning

confidence: 99%

Numerical investigation of thermal effects of high-energy laser irradiation on a germanium lens

Desnijder

Vandewal²

2022

High-Power Lasers and Technologies for Optical Countermeasures

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“…The value chosen for ξ is very large to cancel the velocity in solid region, however the value chosen for ε is very small to avoid division by zero. The values used by different authors are ξ=10 8 kg/m 3 .s and ε=0 -3 [13][14][15].…”

Section: Dimensionless Equationsmentioning

confidence: 99%

“…One of the main advantages of this method is to ensure accurate full-size integral conservation whatever the size of the mesh. It also allows a correct treatment of heterogeneous environments and facilitates the linearization of source terms [13][14][15][16][17].…”

Section: Numerical Procedures and Validationmentioning

confidence: 99%

Numerical Study of the Solidification of Phase Change Materials in a Rectangular Cavity: Effects of Convection and Aspect Ratio

Bouteldja¹,

Mezaache²,

Laouer³

2019

ACSM

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The purpose of this study is to investigate the influence of the aspect ratio and Grashof number on the convection diffusion phenomena associated with solid liquid phase transition processes during PCM solidification within a rectangular cavity. The applied two-dimensional physical model is based on the enthalpy method approach. The numerical solutions are obtained with finite volume method and validated with existing numerical and experimental studies of natural convection in phase change material. Numerical analysis are performed using water as phase change material, for an aspect ratio range 0.5 to 4. The left and right walls of the cavity are maintained at hot and cold temperatures, respectively, while the upper and lower surfaces are considered adiabatic. From this study, it is found that PCM initially liquid evolves to thermal stationary regime where solid and liquid regions are present. The solidification phase change process depends considerably on the thermal and geometrical parameters of the system. Additionally, it is demonstrated that the physical approach based on a purely conductive model remains valid to cases of low values of Grashof number and aspect ratio. The findings of this research may contribute to the elaboration of an efficient modeling of PCM heat storage systems.

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“…Due to its convenience, the enthalpy method is widely applied in the field of solidification of metals and alloys [17,18] as well as welding and additive manufacturing simulations [19][20][21][22][23][24][25][26][27]. However, in these works, the enthalpy of mixing is not considered.…”

Section: Introductionmentioning

confidence: 99%

A CALPHAD-Informed Enthalpy Method for Multicomponent Alloy Systems with Phase Transitions

Scherr,

Liepold,

Markl

et al. 2024

Modelling

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Solid–liquid phase transitions of metals and alloys play an important role in many technical processes. Therefore, corresponding numerical process simulations need adequate models. The enthalpy method is the current state-of-the-art approach for this task. However, this method has some limitations regarding multicomponent alloys as it does not consider the enthalpy of mixing, for example. In this work, we present a novel CALPHAD-informed version of the enthalpy method that removes these drawbacks. In addition, special attention is given to the handling of polymorphic as well as solid–liquid phase transitions. Efficient and robust algorithms for the conversion between enthalpy and temperature were developed. We demonstrate the capabilities of the presented method using two different implementations: a lattice Boltzmann and a finite difference solver. We proof the correct behaviour of the developed method by different validation scenarios. Finally, the model is applied to electron beam powder bed fusion—a modern additive manufacturing process for metals and alloys that allows for different powder mixtures to be alloyed in situ to produce complex engineering parts. We reveal that the enthalpy of mixing has a significant effect on the temperature and lifetime of the melt pool and thus on the part properties.

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An enthalpy method based on fixed-grid for quasi-steady modeling of solidification/melting processes of pure materials

Cited by 18 publications

References 18 publications

Numerical investigation of thermal effects of high-energy laser irradiation on a germanium lens

Numerical investigation of thermal effects of high-energy laser irradiation on a germanium lens

Numerical Study of the Solidification of Phase Change Materials in a Rectangular Cavity: Effects of Convection and Aspect Ratio

A CALPHAD-Informed Enthalpy Method for Multicomponent Alloy Systems with Phase Transitions

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