Semi-log plot of Nu/Ra ^0.29 as functions of Ra. 0.5d ( d / λ θ ≈ 0.5 ) and 1d ( d / λ θ ≈ 1 ) are indicated by blue solid triangle and red solid circles, respectively. nogb (Nu/Ra ^0.29 of system without partitions) are indicated by black solid rectangle. The dash lines represent the best power-law fits of corresponding cases.