scispace - formally typeset
Search or ask a question
Author

M. M. Chen

Bio: M. M. Chen is an academic researcher from University of Illinois at Urbana–Champaign. The author has contributed to research in topics: Convection & Péclet number. The author has an hindex of 1, co-authored 1 publications receiving 281 citations.

Papers
More filters
Journal ArticleDOI
TL;DR: In this paper, a two-dimensional transient model for convective heat transfer and surface tension driven fluid flow is developed, which describes the transient behavior of the heat transfer process of a stationary band source.
Abstract: A two-dimensional transient model for convective heat transfer and surface tension driven fluid flow is developed. The model describes the transient behavior of the heat transfer process of a stationary band source. Semi-quantitative understanding of scanning is obtained by a coordinate transformation. The non-dimensional forms of the equations are derived and four dimensionless parameters are identified, namely, Peclet number (Pe), Prandtl number (Pr), surface tension number(S), and dimensionless melting temperature(@#@ Tm * @#@). Their governing characteristics and their effects on pool shape, cooling rate, velocity field, and solute redistribution are discussed. A numerical solution is obtained and presented. Quantitative effects of Prandtl number and surface tension number on surface velocity, surface temperature, pool shape, and cooling rate are presented graphically.

294 citations


Cited by
More filters
Journal ArticleDOI
TL;DR: A design criteria for a volume-of-fluid interface reconstruction algorithm to be second-order accurate is proposed, which is that it reproduce lines in two space dimensions or planes in three space dimensions exactly.

672 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present a numerical method for computing solutions of the incompressible Euler or Navier?Stokes equations when a principal feature of the flow is the presence of an interface between two fluids with different fluid properties.

503 citations

Journal ArticleDOI
TL;DR: The high-speed synchrotron hard X-ray imaging and diffraction techniques used to monitor the laser powder bed fusion (LPBF) process of Ti-6Al-4V in situ and in real time demonstrate that many scientifically and technologically significant phenomena in LPBF, including melt pool dynamics, powder ejection, rapid solidification, and phase transformation, can be probed with unprecedented spatial and temporal resolutions.
Abstract: We employ the high-speed synchrotron hard X-ray imaging and diffraction techniques to monitor the laser powder bed fusion (LPBF) process of Ti-6Al-4V in situ and in real time. We demonstrate that many scientifically and technologically significant phenomena in LPBF, including melt pool dynamics, powder ejection, rapid solidification, and phase transformation, can be probed with unprecedented spatial and temporal resolutions. In particular, the keyhole pore formation is experimentally revealed with high spatial and temporal resolutions. The solidification rate is quantitatively measured, and the slowly decrease in solidification rate during the relatively steady state could be a manifestation of the recalescence phenomenon. The high-speed diffraction enables a reasonable estimation of the cooling rate and phase transformation rate, and the diffusionless transformation from β to α ’ phase is evident. The data present here will facilitate the understanding of dynamics and kinetics in metal LPBF process, and the experiment platform established will undoubtedly become a new paradigm for future research and development of metal additive manufacturing.

490 citations

Journal ArticleDOI
TL;DR: In this paper, the authors introduce the basic concepts of macroscopic and microscopic phenomena which enter normally into any solidification process, and the latest developments in numerical techniques which are used to solve the continuity equations are briefly presented together with the advantages and inconvenience.
Abstract: Modelling of heat flow has become a standard practice in many solidification processes. Effort is currently being made to couple heat flow calculations to related macroscopic phenomena such as mould filling, fluid flow, macrosegregation, or thermal stresses. If these macroscopic aspects are important in predicting formation of macroscopic defects or optimising process conditions, then microstructural features such as phase appearance, morphology, grain size, spacings, or microdefects are certainly no less important in determining the ultimate mechanical properties of the solidified product. The aim of the present paper is to introduce the basic concepts of macroscopic and microscopic phenomena which enter normally into any solidification process. At the macroscopic level, i.e. at the scale of the whole process (casting, weldment, … ), the latest developments in numerical techniques which are used to solve the continuity equations are briefly presented together with the advantages and inconvenience...

459 citations

Journal ArticleDOI
TL;DR: In recent years, major advances have taken place in our understanding of welding processes and welded materials because of the complexity of fusion welding processes, solution of many important contemporary problems in fusion welding requires an interdisciplinary approach as mentioned in this paper.
Abstract: In recent years, major advances have taken place in our understanding of welding processes and welded materials Because of the complexity of fusion welding processes, solution of many important contemporary problems in fusion welding requires an interdisciplinary approach Current problems and issues in fusion welding are reviewed Solution of these problems, apart from being a contribution to the advancement of science, is also necessary for science-based tailoring of composition, structure, and properties of the welded materials

454 citations