Solidification Modeling: Evolution, Benchmarks, Trends in Handling Turbulence, and Future Directions
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CATION is an important phenomenon in the field of welding, casting, growth of single crystals for electronic and optoelectronic applications and many other industrial and research applications. A prediction of defects, microstructures, residual stresses, etc., in the solidified material is indispensible in these processes as these features control the final desirable characteristics, such as strengths of welded joint and cast product and electronic and optoelectronic properties of single crystals.[1] A direct observation and quantification of these features during the course of solidification is possible by highly sophisticated in situ observation techniques requiring additional elaborated setups.[2–5] Considering the fact that for the abovementioned solidification processes (welding, casting, and single crystal growth by Czochralski technique) the presence of turbulence also affects these features, and therefore, an in situ monitoring setup is required, which has extremely high resolution to capture them in a realistic manner. On the other hand, post-solidification analysis of these features provides an assessment of their values and distribution in the material, but seldom indicates the reasons for their evolution and dissemination—which is very SUDEEP VERMA, Scientist-D, is with the Solid State Physics Laboratory, Timarpur, Delhi 110054, India, and also Ph.D. Candidate, with the Department of Applied Mechanics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India. ANUPAM DEWAN, Professor, is with the Department of Applied Mechanics, Indian Institute of Technology Delhi. Contact e-mail: adewan@am. iitd.ac.in Manuscript submitted August 31, 2013. METALLURGICAL AND MATERIALS TRANSACTIONS B
important to gain a meaningful insight into the complex solidification process. Since these effects are closely coupled with the macroscopic and microscopic heat and mass transfers during the phase-change, a pragmatic way to bridge this gap is a systematic numerical modeling of the solidification phenomenon by solving the coupled fluid flow and heat- transfer equations for a given domain. Before starting a discussion on the techniques for solidification modeling, it is appropriate at this point to highlight the important issues associated with solidification modeling. First is the accurate capture of the moving solid–liquid interface, incorporation of the latent heat released at the moving solid–liquid interface, and accommodating the discontinuities in the properties of the solid and liquid phases across the interface. Further, the presence of heat-and mass-transfer effects—from the microscopic scale (morphological scale) to the macroscopic scale (overall domain scale)—adds significantly to the computational resources during the solidification modeling as the length and time scales in the models have to be chosen in such a way to capture both the microscopic and macroscopic effects. A further complication is the fact that techniques for an accurate solidification modeling of pure metal do not work effectively for an alloy. Finally
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