Bong-Jin Ko, Min-Hwan Kim and Bum-Jin Chung*
The Journal of Mechanical Science and Technology, vol. 26, no. 4, pp.1227-1234, 2012

Abstract : Natural convection experiments were carried out for a wide range of the Grashof number from 104 to 5 × 109 or for the Rayleigh number from 107 to 1013 in order to seek the proper transition criteria from laminar to turbulent. Using the analogy concept, heat transfer systems were simulated by corresponding mass transfer systems. The copper sulfate electroplating system was chosen as the mass transfer system. The experimental results closely reproduced the McAdams’s correlation for laminar and Fouad’s for turbulent. The Sherwood numbers obtained from the experiment were proportional to the 1/4 power of Rayleigh number or Grashof number at laminar region and the near 1/3 power at turbulent region as the well known theory. This paper concludes that the proper transition criteria of the natural convection should be the Grashof number of 109. The originality of this paper comes from the fact that the study deals with very large value of Schmidt number and that by using the analogy experiment methodology, high values of Rayleigh number and Grashof number were achieved with a relatively short test facility.

Keyword : Natural convection; Transition criteria; Boundary layer; Analogy; Electroplating system