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.
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Abbreviations
- C :
-
constant which defines the interface
- d :
-
width of laser beam
- D :
-
thickness of workpiece
- D eff :
-
effective diffusion coefficient
- k :
-
thermal conductivity
- I :
-
length of laser beam
- L :
-
length of workpiece
- n:
-
normal vector along the interface
- p :
-
pressure
- Pe:
-
Peclet numberu o d/k
- Pr:
-
Prandtl numberv / k
- q :
-
net heat flux from laser
- Re:
-
Reynolds numberu o d/v
- r o :
-
radius of laser beam
- S :
-
surface tension number
- T :
-
temperature
- T m :
-
melting temperature
- T* m :
-
dimensionless melting temperature °K
- T∝ :
-
temperature of metal when it is not heated
- u:
-
velocity vector
- u:
-
x-component of u
- u o :
-
scanning speed of the laser beam
- u n :
-
normal velocity of the interface
- v:
-
y-component of u
- w :
-
z-component of u
- W :
-
width of workpiecex,y,z Cartesian coordinate
- p :
-
density
- k :
-
thermal diffusivity
- λ:
-
latent heat of fusion
- v :
-
kinematic viscosity
- μ :
-
viscosity
- σ :
-
surface tension
- l :
-
liquid
- s :
-
solid
- i, j :
-
indices of node for the discretization of thex,y plane
- m :
-
melting
- ∝:
-
ambient
- *:
-
dimensionless quantities
- ':
-
derivative with respect to its independent variable
- n :
-
n th time step in the finite difference equation
- ∇:
-
del operator i ∂/∂x/+j ∂/∂y
- (u ⋅ ∇ ):
-
convective operator u ∂/∂x/+v∂/∂y
- ∇ 2 :
-
Laplacian operator ∂2/∂x2+ ∂2/∂y2
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This paper is based on a presentation made at the symposium “Fluid Flow at Solid-Liquid Interfaces” held at the fall meeting of the TMS-AIME in Philadelphia, PA on October 5, 1983 under the TMS-AIME Solidification Committee.
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Chan, C., Mazumder, J. & Chen, M.M. A two-dimensional transient model for convection in laser melted pool. Metall Trans A 15, 2175–2184 (1984). https://doi.org/10.1007/BF02647100
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DOI: https://doi.org/10.1007/BF02647100