Estimation of transient heat transfer and fluid flow for alloy solidification in a rectangular cavity with an isothermal sidewall

2015 ◽  
Vol 779 ◽  
pp. 53-86 ◽  
Author(s):  
A. Plotkowski ◽  
K. Fezi ◽  
M. J. M. Krane
Keyword(s):  
Fluid Flow ◽  
Energy Equation ◽  
Solidification Process ◽  
Rectangular Cavity ◽  
Scaling Analysis ◽  
Alloy Solidification ◽  
Cu Alloy ◽  
Aspect Ratios ◽  
Solidification Processes ◽  
Time Required

Transient scaling and integral analyses were performed to predict trends in alloy solidification in a rectangular cavity cooled by an isothermal sidewall. The natural convection fluid flow was approximated by a scaling analysis for a laminar boundary layer at the solidification front, and was coupled to scaling and integral analyses of the energy equation to predict the solidification behaviour of the system. These analyses predicted several relevant aspects of the solidification process, including the time required to extinguish the initial superheat and the maximum local solidification time as a function of the system parameters and material properties. These results were verified by comparison to numerical simulations for an Al–4.5 wt% Cu alloy for various initial and boundary conditions and cavity aspect ratios. The analysis was compared to previous attempts to analyse similar fluid flow and solidification processes, and the limitations of the assumptions used for this analysis were discussed.

Experimental Validation of Continuum Mixture Model for Binary Alloy Solidification

1997 ◽  
Vol 119 (4) ◽  
pp. 783-791 ◽  
Author(s):  
M. J. M. Krane ◽  
F. P. Incropera
Keyword(s):  
Mixture Model ◽  
Solidification Process ◽  
Scaling Analysis ◽  
Permeability Model ◽  
Alloy Solidification ◽  
Permeability Constant ◽  
Dendritic Array ◽  
Continuum Mixture Model ◽  
Composition Profiles ◽  
Alloy Microstructure

Experiments were performed with binary metal alloys to validate a continuum mixture model for alloy solidification. Ingots of two compositions, Pb-20%Sn and Pb-40%Sn, were cast in a permanent mold, and the solidification process was simulated. Temperature histories were measured during casting, and composition profiles were found in the solidified ingot. Dendritic arm spacings were found from optical micrographs of the alloy microstructure and used to determine a constant in the Blake-Kozeny submodel for the mushy zone permeability in the liquid-solid interaction term of the momentum equations. Scaling analysis from a previous work and a large uncertainty in the permeability constant suggested that predictions of the composition are extremely sensitive to the choice of a permeability model. Three simulations of each casting were performed using the permeability constant as a parameter, and measured temperatures and compositions were compared with predictions based on different model constants. In the region of the liquidus interface, where all of the significant advection of solute takes place, the results suggest that the Blake-Kozeny model based on measured dendritic arm spacings significantly underpredicts the resistance of the dendritic array to fluid flow.

Time-resolved x-ray imaging of aluminum alloy solidification processes

2002 ◽  
Vol 33 (4) ◽  
pp. 613-623 ◽  
Author(s):  
Ragnvald H. Mathiesen ◽  
Lars Arnberg ◽  
Kjell Ramsøskar ◽  
Timm Weitkamp ◽  
Christoph Rau ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Alloy Solidification ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Imaging ◽  
Solidification Processes

scholarly journals Solidification Process and Volume Fraction in Sn-Ag-Cu Alloy

2010 ◽  
Vol 13 (7) ◽  
pp. 521-530 ◽  
Author(s):  
Yoshiko Takamatsu ◽  
Hisao Esaka ◽  
Kei Shinozuka
Keyword(s):  
Volume Fraction ◽  
Solidification Process ◽  
Cu Alloy

Numerical Investigation of Heat Transfer in Rectangular Microchannels Under H2 Boundary Condition During Developing and Fully Developed Laminar Flow

2011 ◽  
Vol 134 (2) ◽  
Author(s):  
V. V. Dharaiya ◽  
S. G. Kandlikar
Keyword(s):  
Heat Transfer ◽  
Boundary Condition ◽  
Heat Flux ◽  
Fluid Flow ◽  
Microfluidic Devices ◽  
Transport Processes ◽  
Uniform Heat Flux ◽  
Data Set ◽  
Nusselt Numbers ◽  
Aspect Ratios

Study of fluid flow characteristics at microscale is gaining importance with shrinking device sizes. Better understanding of fluid flow and heat transfer in microchannels will have important implications in electronic chip cooling, heat exchangers, MEMS, and microfluidic devices. Due to short lengths employed in microchannels, entrance header effects can be significant and need to be investigated. In this work, three dimensional model of microchannels, with aspect ratios (α = a/b) ranging from 0.1 to 10, are numerically simulated using CFD software tool fluent. Heat transfer effects in the entrance region of microchannel are presented by plotting average Nusselt number as a function of nondimensional axial length x*. The numerical simulations with both circumferential and axial uniform heat flux (H2) boundary conditions are validated for existing data set for four wall heat flux case. Large numerical data sets are generated in this work for rectangular cross-sectional microchannels with heating on three walls, two opposing walls, one wall, and two adjacent walls under H2 boundary condition. This information can provide better understanding and insight into the transport processes in the microchannels. Although the results are seen as relevant in microscale applications, they are applicable to any sized channels. Based on the numerical results obtained for the whole range, generalized correlations for Nusselt numbers as a function of channel aspect ratio are presented for all the cases. The predicted correlations for Nusselt numbers can be very useful resource for the design and optimization of microchannel heat sinks and other microfluidic devices.

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