scholarly journals Volume-Averaged Modeling of Multiphase Flow Phenomena during Alloy Solidification

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 229 ◽  
Author(s):  
Menghuai Wu ◽  
Andreas Ludwig ◽  
Abdellah Kharicha
Keyword(s):  
Dendritic Morphology ◽  
Computer Hardware ◽  
Shrinkage Cavity ◽  
Limiting Factor ◽  
Formation Mechanisms ◽  
Solidification Model ◽  
Solidification Processes ◽  
Recent Developments ◽  
Flow Phenomena ◽  
Application Potential

The most recent developments and applications in volume-averaged modeling of solidification processes have been reviewed. Since the last reviews of this topic by Beckermann and co-workers [Applied Mech. Rev. 1993, p. 1; Annual Rev. Heat Transfer 1995, p. 115], major progress in this area has included i) the development of a mixed columnar-equiaxed solidification model; ii) further consideration of moving crystals and crystal dendritic morphology; and iii) the model applications to analyze the formation mechanisms of macrosegregation, as-cast structure, shrinkage cavity and porosity in different casting processes. The capacity of computer hardware is still a limiting factor. However, many calculation examples, as verified by the laboratory casting experiments, or even by the casting processes at a small industrial scale, show great application potential. Following the trend of developments in computer hardware (projection according to Moore’s law), a full 3D calculation of casting at the industry scale with the multiphase volume-averaged solidification models will become practically feasible in the foreseeable future.

scholarly journals Computational Approaches for Studying Slag–Matte Interactions in the Flash Smelting Furnace (FSF) Settler

Processes ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 485
Author(s):  
Jani-Petteri Jylhä ◽  
Nadir Ali Khan ◽  
Ari Jokilaakso
Keyword(s):  
Flash Smelting ◽  
Copper Production ◽  
Limiting Factor ◽  
Molten Droplet ◽  
Geometry Modeling ◽  
Droplet Behavior ◽  
Flow Phenomena ◽  
Modeling Software ◽  
Flash Smelting Furnace ◽  
Physical Phenomena

Computational methods have become reliable tools in many disciplines for research and industrial design. There are, however, an ever-increasing number of details waiting to be included in the models and software, including, e.g., chemical reactions and many physical phenomena, such as particle and droplet behavior and their interactions. The dominant method for copper production, flash smelting, has been extensively investigated, but the settler part of the furnace containing molten high temperature melts termed slag and matte, still lacks a computational modeling tool. In this paper, two commercial modeling software programs have been used for simulating slag–matte interactions in the settler, the target being first to develop a robust computational fluid dynamics (CFD) model and, second, to apply a new approach for molten droplet behavior in a continuum. The latter is based on CFD coupled with the discrete element method (DEM), which was originally developed for modeling solid particle–particle interactions and movement, and is applied here for individual droplets for the first time. The results suggest distinct settling flow phenomena and the significance of droplet coalescence for settling velocity and efficiency. The computing capacity requirement for both approaches is the main limiting factor preventing full-scale geometry modeling with detailed droplet interactions.

Porosity Formation after the Irradiation Termination of Laser

2013 ◽  
Vol 800 ◽  
pp. 201-204
Author(s):  
Wang Hong ◽  
Ling Yun Wang ◽  
Ri Sheng Li
Keyword(s):  
Surface Tension ◽  
Laser Welding ◽  
Continuous Wave ◽  
Laser Beams ◽  
Formation Mechanisms ◽  
Volume Of Fluid Method ◽  
Porosity Formation ◽  
Mode Laser ◽  
Melt Pool ◽  
Solidification Processes

Porosity is formed because of the keyhole collapse. The porosity formation is associated with the melt pool dynamics, the keyhole collapse and solidification processes. The objective of the paper is t to investigate porosity formation mechanisms and fluid flow in the melt pool using the volume of fluid method. The results indicate that the formation of porosity in continuous wave keyhole mode laser welding is associated to keyhole collapse, backfilling of liquid metal close the gas exit of the laser welding keyhole, surface tension of the gas/liquid interface play an important role in the backfilling downward to the keyhole right after laser beams left.Keywords: porosity; keyhole; collapse; welding; model

The Defects Analysis and Numerical Simulation of Automobile Brake Hydro Cylinder in Permanent Casting

2011 ◽  
Vol 704-705 ◽  
pp. 82-87
Author(s):  
Lei Rao ◽  
Lian Bing Zhu ◽  
Xiao Long Li ◽  
Qi Yao Hu
Keyword(s):  
Numerical Simulation ◽  
Shrinkage Cavity ◽  
Work Piece ◽  
Braking System ◽  
Casting Quality ◽  
Solidification Processes ◽  
Gas Entrapment ◽  
Defects Analysis ◽  
Filling And Solidification ◽  
Advanced Computer

Brake hydro cylinder is the key part of automobile hydraulic braking system, which usually works under high pressure condition. So, high safety factor of it is required to avoid accident. There are many kinds of casting defects such as shrinkage cavity, gas entrapment and slag enclosure are formed in the mold filling and solidification processes, which contribute to final casting performance. Based on the mathematical models of molding filling and solidification processes, the numerical simulation has been done. In the meanwhile, the defects forming reasons have been analyzed. According to the simulation results, two types of improved schemes have been analyzed and practiced respectively, and its work piece defects were reduced largely. It is an effective way to improve the casting quality by advanced computer technology.

scholarly journals Molecular Dynamics and Machine Learning in Catalysts

Catalysts ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1129
Author(s):  
Wenxiang Liu ◽  
Yang Zhu ◽  
Yongqiang Wu ◽  
Cen Chen ◽  
Yang Hong ◽  
...  
Keyword(s):  
Machine Learning ◽  
Molecular Dynamics ◽  
Large Scale ◽  
Reaction Force ◽  
Catalyst Design ◽  
Computer Hardware ◽  
Ab Initio Molecular Dynamics ◽  
Oxidation Reactions ◽  
Recent Developments ◽  
Promising Development

Given the importance of catalysts in the chemical industry, they have been extensively investigated by experimental and numerical methods. With the development of computational algorithms and computer hardware, large-scale simulations have enabled influential studies with more atomic details reflecting microscopic mechanisms. This review provides a comprehensive summary of recent developments in molecular dynamics, including ab initio molecular dynamics and reaction force-field molecular dynamics. Recent research on both approaches to catalyst calculations is reviewed, including growth, dehydrogenation, hydrogenation, oxidation reactions, bias, and recombination of carbon materials that can guide catalyst calculations. Machine learning has attracted increasing interest in recent years, and its combination with the field of catalysts has inspired promising development approaches. Its applications in machine learning potential, catalyst design, performance prediction, structure optimization, and classification have been summarized in detail. This review hopes to shed light and perspective on ML approaches in catalysts.

scholarly journals On More or Less Appropriate Notions of ‘Computation’

2018 ◽  
Vol 30 (1) ◽  
Author(s):  
Stefan Gruner ◽  
Andrew Gravell
Keyword(s):  
Computer Science ◽  
Academic Discipline ◽  
Natural Sciences ◽  
Computer Hardware ◽  
Classical Notion ◽  
Recent Developments ◽  
Historical Semantics ◽  
The Church

Half a century after the emergence of computer science (a.k.a. informatics) as an academic discipline, the notion of “computation” is not yet “settled”. On the contrary: recent developments in the natural sciences, in mathematics, as well as in computer hardware engineering have also shaken the belief in the sufficiency of the “classical” notion of “computation” from the tradition of the Church-Turing-Hypothesis. In this paper we review the recent discourse on what is “computation”, and we clarify our own position within this discourse. Although we present some arguments about which notions of “computation” may be considered “reasonably acceptable” for our own historic era, we also emphasize that every science-philosophical notion (including the notion of “computation”) has its own long-term historical semantics which cannot be fixed once and forever. At this point in time, however, no compelling assertion can yet be made about the possibility of “hypercomputation” as proper computation.

On the Cutting of Metals: A Mechanics Viewpoint

2020 ◽  
Vol 142 (11) ◽  
Author(s):  
Dinakar Sagapuram ◽  
Anirudh Udupa ◽  
Koushik Viswanathan ◽  
James B. Mann ◽  
Rachid M’Saoubi ◽  
...  
Keyword(s):  
Plastic Flow ◽  
Chip Formation ◽  
Metal Cutting ◽  
Large Strain ◽  
Shear Banding ◽  
Continuous Shear ◽  
Recent Developments ◽  
Flow Phenomena ◽  
The Stability

Abstract The mechanics of large-strain deformation in cutting of metals is discussed, primarily from viewpoint of recent developments in in situ analysis of plastic flow and microstructure characterization. It is shown that a broad range of deformation parameters can be accessed in chip formation—strains of 1–10, strain rates of 10–105/s, and temperatures up to 0.7Tm—and controlled. This range is far wider than achievable by any other single-stage, severe plastic deformation (SPD) process. The resulting extreme deformation conditions produce a rich variety of microstructures in the chip. Four principal types of chip formation—continuous, shear-localized, segmented, and mushroom-type—as elucidated first by Nakayama (1974, “The Formation of ‘Saw-Toothed Chip’ in Metal Cutting,” Proceedings of International Conference on Production Engineering, Tokyo, pp. 572–577) are utilized to emphasize the diverse plastic flow phenomena, especially unsteady deformation modes that prevail in cutting. These chip types are intimately connected with the underlying flow, each arising from a distinct mode and triggered by an instability phenomenon. The role of plastic flow instabilities such as shear banding, buckling, and fracture in mediating unsteady flow modes is expounded, along with consequences of the flow modes and chip types for the cutting. Sinuous flow is shown to be the reason why gummy (highly strain-hardening) metals, although relatively soft, are so difficult to cut. Synthesizing the various observations, a hypothesis is put forth that it is the stability of flow modes that determines the mechanics of cutting. This leads to a flow-stability phase diagram that could provide a framework for predicting chip types and process attributes.

scholarly journals Heat transfer and solidification processes of alloy melt with undercooling: II. Solidification model

2006 ◽  
Vol 54 (3) ◽  
pp. 765-771 ◽  
Author(s):  
Hideaki Yoshioka ◽  
Yukio Tada ◽  
Kanji Kunimine ◽  
Taira Furuichi ◽  
Yujiro Hayashi
Keyword(s):  
Heat Transfer ◽  
Solidification Model ◽  
Solidification Processes ◽  
Heat Transfer And Solidification

Simulation of Filling and Solidification Processes of Rump Pan by Procast

2013 ◽  
Vol 785-786 ◽  
pp. 1212-1215
Author(s):  
Tao Liang ◽  
Yin Hu Qu ◽  
Xin Feng Liu ◽  
Feng Wang ◽  
Min Hua Zhang
Keyword(s):  
Process Parameters ◽  
Solidification Process ◽  
Shrinkage Porosity ◽  
The Body ◽  
Shrinkage Cavity ◽  
Gating System ◽  
Optimal Process ◽  
Solidification Processes ◽  
Filling And Solidification

The rump pan is the body and the load-carry device of Scraper conveyer. the material is ZG30MnSi. In order to improve the life of the casting.this paper simulated filling and solidification process of rump pan by Procast software,and predicted the position of shrinkage cavity and shrinkage porosity in castings.Then through improving gating system and add reasonable risers, optimal process parameters scheme is got.

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