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A Numerical Analysis of heat and fluid flow with a deformable curved free surface in a laser melting process

Title
A Numerical Analysis of heat and fluid flow with a deformable curved free surface in a laser melting process
Author
김우승
Keywords
Laser melting; Free surface flow; Thermocapillary convection; Curved free surface; Surface topography; Numerical analysis; POOL
Issue Date
2008-10
Publisher
ELSEVIER SCIENCE INC
Citation
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW, v. 29, No. 5, Page. 1481-1493
Abstract
In this study, a numerical investigation was performed to examine the effects of curved surface shapes, laser power intensity, and the thermophysical properties of a material such as Reynolds and Capillary numbers on the shape, size, and surface topography of the melt pool. This investigation was completed via two-dimensional axisymmetric thermocapillary convection analyses during laser melting processes with deformable free surfaces. In general, a bump has a deep crater at the center and a low peripheral rim, a bowl-like shape. This is caused by the surface temperature gradient-induced thermocapillary flow driving the molten material towards the cooler region, which has higher surface tension. For flat and parabolic free surfaces, surface deformations such as crater depth and rim height increase gradually with decreasing Re and increasing Ca, Bf, and especially the curvature of the free surface. In particular, it is noted that the curvature of the free surface has significantly little effect on the crater depth and rim height for a higher Re and lower Bf with fixed Ca. Its effect is considerably strengthened at a lower Re and higher Bf, indicating stronger convection. In the case of a sinusoidal wavy surface, it is noted that the crater depth and rim height increase monotonically with increasing Ca at fixed Re and Bf, while they decrease with increasing Re and Bf at fixed Ca due to the inward transfer of relatively large amounts of molten material compared to the surface tension gradient driving force, which causes the recovery of the crater center. Hence, the slope of the crater decreases significantly.
URI
https://www.sciencedirect.com/science/article/pii/S0142727X08001148http://repository.hanyang.ac.kr/handle/20.500.11754/80744
ISSN
0142-727X
DOI
10.1016/j.ijheatfluidflow.2008.06.009
Appears in Collections:
COLLEGE OF ENGINEERING SCIENCES[E](공학대학) > MECHANICAL ENGINEERING(기계공학과) > Articles
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