[M-IS22] Geophysical fluid dynamics-Transfield approach to geoscience

[MIS22-05] A phenomenological model for convective cell size in a fluid layer with internal heat generation at low Rayleigh numbers

*Ichiro KUMAGAI¹, Ryuta ABE², Yuji TASAKA², Anne Davaille³, Yuichi MURAI², Takatoshi YANAGISAWA⁴ (1.School of Science and Engineering, Meisei University, 2.Faculty of Engineering, Hokkaido University, 3.Laboratoire FAST, CNRS, Universite Pairs-Sud, 4.Department of Deep Earth Structure and Dynamics Research, JAMSTEC)

The convective behavior of a fluid layer with internal heat generation at low Rayleigh number (6 ≤ RaI/RaIc ≤ 12) was experimentally investigated. The horizontal fluid layer of 0.5 wt% KCl water solution was internally heated by Joule heating using the electric current. We quantitatively measured 2-D temperature and velocity fields by seeding the micro-encapsulated thermo-chromic liquid crystals in the fluid layer. We experimentally obtained the fluid dynamic scaling on non-dimensional temperature and the maximum downwelling velocity as a function of the Rayleigh number, and also refined the experimental data obtained by the previous studies. The scaling relations were combined with a phenomenological model based on the stability of the top thermal boundary layer. This phenomenological model consistently explained the increase in convective wavelength with increasing the Rayleigh number.