Effect of Aspect Ratio on the Similarity of Developing Laminar Flows in Rectangular Ducts

A numerical study was conducted to show the effect of aspect ratio on the analogy of the developing laminar flows between in orthogonally rotating straight duct and in a stationary curved duct of rectangular cross-section. In order. to clarify the similarity of two nows, dimensionless parameters (equation omitted) and Rossby Ro= $w_{m}$$\Omega$ $d_{h}$, in a rotating straight duct were used as a set corresponding to Dean number, (equation omitted), and curvature ratio, λ=R/ $d_{h}$, in a stationary curved duct. Four. different aspect ratios A=0.25, 0.5, 2 and 4 were considered. Under the condition that the magnitudes of Ro and λ were large enough to satisfy the 'asymptotic invariance property' and the aspect ratio was larger than 1, there were strong quantitative similarities between the two flows such as flow patterns, friction factors, and maximum axial velocity magnitudes fur the same values of $K_{LR}$ and $K_{LC}$ . On the other hand, as the aspect ratio decreased below 1 (A=0.25 and 0.5), the difference of the secondary flow intensity between these two flows was enhanced and therefore the analogy of two flows was not so evident as that of the larger aspect ratio (A=2 and 4). 4).nd 4).

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