scholarly journals The influence of convective exchanges on Coandã effect

2019 ◽  
Vol 11 (4) ◽  
pp. 191-202 ◽  
Author(s):  
Michele TRANCOSSI ◽  
Jose PASCOA
Keyword(s):  
Heat Exchange ◽  
Convective Heat ◽  
Convex Surface ◽  
Fluid Dynamic ◽  
Convective Heat Exchange ◽  
Research Direction ◽  
Effective Model ◽  
Coanda Effect ◽  
Cfd Simulations ◽  
Coandǎ Effect

Modeling Coandã effect has been a fundamental issue in fluid dynamic research in the XX century. It has lost some interest because of the improvement in CFD, even if it could be still important in the area of the preliminary design of aerodynamic devices that benefits of fluid deflection by convex surfaces. An effective model of Coandã effect has not been defined, and fundamental questions are still open. The influence of convective heat exchange on Coandã adhesion of a fluid stream on a convex surface in the presence of a temperature gradient between the fluid and the convex surface is a problem, which affects many practical cases, but it is still marginally approached by scientific literature. This paper aims to start an effective research direction on the effects of convective heat exchange on Coandã effect. It approaches the problem with a set of CFD simulations. It analyses the previous hypotheses, which are based on Prandtl number and evidences the need of a more effective model that accounts also for the Reynolds number.

scholarly journals Comparison of CFD simulations and measurements of flow affected by coanda effect

2012 ◽  
Vol 25 ◽  
pp. 01015 ◽  
Author(s):  
Jan Fišer ◽  
Jan Jedelský ◽  
Tomáš Vach ◽  
Matěj Forman ◽  
Miroslav Jícha
Keyword(s):  
Coanda Effect ◽  
Cfd Simulations ◽  
Coandǎ Effect

scholarly journals Hydrodynamics and heat exchange of crystal pulling from melts. Part I: Experimental studies of free convection mode

2019 ◽  
Vol 5 (3) ◽  
pp. 91-100
Author(s):  
Vladimir S. Berdnikov
Keyword(s):  
Heat Exchange ◽  
Convective Heat ◽  
Capillary Flow ◽  
Crystallization Front ◽  
Experimental Studies ◽  
Convective Heat Exchange ◽  
Czochralski Technique ◽  
Study Results ◽  
Front Shape ◽  
Prandtl Numbers

This work is a brief overview of experimental study results for hydrodynamics and convective heat exchange in thermal gravity capillary convection modes for the classic Czochralski technique setup obtained at the Institute of Thermophysics, Siberian Branch of the Russian Academy of Sciences. The experiments have been carried out at test benches which simulated the physics of the Czochralski technique for 80 and 295 mm diameter crucibles. Melt simulating fluids with Prandtl numbers Pr = 0.05, 16, 45.6 and 2700 have been used. Experiments with transparent fluids have been used for comparing the evolution of flow structure from laminar mode to well-developed turbulent mode. Advanced visualization and measurement methods have been used. The regularities of local and integral convective heat exchange in the crucible/melt/crystal system have been studied. The experiments have shown that there are threshold Grashof and Marangoni numbers at which the structure of the thermal gravity capillary flow undergoes qualitative changes and hence the regularities of heat exchange in the melt change. The effect of melt hydrodynamics on the crystallization front shape has been studied for Pr = 45.6. Crystallization front shapes have been determined for the 1 × 105 to 1.9 × 105 range of Grashof numbers. We show that the crystallization front shape depends largely on the spatial flow pattern and the temperature distribution in the melt.

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