Non-circular conduits

It should be pointed out that the Lawrance equation and the Brown-DiNardo curves are true only at room temperature. Data such as those obtained by Cheng should be extended to gases other than air and water vapor, to non-circular conduits, and to temperatures encountered in vacuum metallurgy, and in freeze drying. Whether or not such work might be undertaken will, of course, depend on its commercial and technological significance. 

Scant analytical and experimental results suggest that visco-elasticity in a fluid may induce secondary motion in non-circular conduits, even rmder laminar conditions. However, measmements reported to date indicate that the friction factor - Reynolds ntrmber behavioin is little influenced by such secondary flows [Hartnett and Kostic, 1989]. 

Reynolds number based on Bingham plastic viscosity (-) Metzner-Reed definition of Reynolds number (-) generalised Reynolds number for non-circular conduits, eq. 3.90 (-). 

Since the fluid in a porous medium follows a tortuous path through channels of varying size, one method of describing the flow behaviour in the pores is to consider the flow path as a non-circular conduit . This requires an appropriate definition of the hydraulic diameter as shown in Eq. 3.15 ... 

Flow in pipes and in conduits of non-circular cross-sections... 

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