High Prandtl number boundary layers with mass injection.

AIAA Journal ◽  
1969 ◽  
Vol 7 (3) ◽  
pp. 547-548 ◽  
Author(s):  
E. R. THOMPSON
Keyword(s):  
Prandtl Number ◽  
Boundary Layers ◽  
Mass Injection ◽  
High Prandtl Number

Scale Analysis of Thermocapillary Weld Pool Shape With High Prandtl Number

2011 ◽  
Author(s):  
P. S. Wei ◽  
C. L. Lin ◽  
H. J. Liu
Keyword(s):  
Prandtl Number ◽  
Boundary Layers ◽  
Molten Pool ◽  
Surface Flow ◽  
Transport Processes ◽  
Surface Boundary ◽  
Scale Analysis ◽  
Melting Front ◽  
Pool Shape ◽  
High Prandtl Number

The molten pool shape and thermocapillary convection during melting or welding of metals or alloys are self-consistently predicted from parametric scale analysis for the first time. Determination of the molten pool shape is crucial due to its close relationship with the strength and properties of the fusion zone. In this work, surface tension coefficient is considered to be negative values, indicating an outward surface flow, whereas high Prandtl number represents the thermal boundary layer thickness to be less than that of momentum. Since Marangoni number is usually very high, the scaling of transport processes is divided into the hot, intermediate and cold corner regions on the flat free surface, boundary layers on the solid-liquid interface and ahead of the melting front. Coupling among distinct regions and thermal and momentum boundary layers, the results find that the width and depth of the pool can be determined as functions of Marangoni, Prandtl, Peclet, Stefan, and beam power numbers. The predictions agree with numerical computations and available experimental data.

scholarly journals Boundary layers in turbulent vertical convection at high Prandtl number

2021 ◽  
Vol 930 ◽  
Author(s):  
Christopher J. Howland ◽  
Chong Shen Ng ◽  
Roberto Verzicco ◽  
Detlef Lohse
Keyword(s):  
Heat Flux ◽  
Prandtl Number ◽  
Boundary Layers ◽  
Environmental Flows ◽  
Three Dimensional ◽  
Vertical Channel ◽  
Vertical Surface ◽  
Wide Range ◽  
High Prandtl Number ◽  
Prandtl Numbers

Many environmental flows arise due to natural convection at a vertical surface, from flows in buildings to dissolving ice faces at marine-terminating glaciers. We use three-dimensional direct numerical simulations of a vertical channel with differentially heated walls to investigate such convective, turbulent boundary layers. Through the implementation of a multiple-resolution technique, we are able to perform simulations at a wide range of Prandtl numbers ${Pr}$ . This allows us to distinguish the parameter dependences of the horizontal heat flux and the boundary layer widths in terms of the Rayleigh number $\mbox {{Ra}}$ and Prandtl number ${Pr}$ . For the considered parameter range $1\leq {Pr} \leq 100$ , $10^{6} \leq \mbox {{Ra}} \leq 10^{9}$ , we find the flow to be consistent with a ‘buoyancy-controlled’ regime where the heat flux is independent of the wall separation. For given ${Pr}$ , the heat flux is found to scale linearly with the friction velocity $V_\ast$ . Finally, we discuss the implications of our results for the parameterisation of heat and salt fluxes at vertical ice–ocean interfaces.

Onset of temporal aperiodicity in high Prandtl number liquid bridge under terrestrial conditions

2004 ◽  
Vol 16 (5) ◽  
pp. 1746-1757 ◽  
Author(s):  
D. E. Melnikov ◽  
V. M. Shevtsova ◽  
J. C. Legros
Keyword(s):  
Prandtl Number ◽  
Liquid Bridge ◽  
High Prandtl Number
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