Viscoelasticity drag-reducing fluids

Yu, B., and Kawaguchi, Y, Direct numerical simulation of viscoelastic drag-reducing flow a faithful finite difference method, J. Non-Newtonian Fluid Meek, 116, 431-466 (2004). 

Earlier investigators studying the drag-reducing phenomenon in viscoelastic fluids often used Re and Reeff. The former is generally valid only for dilute polymer solutions, in which case the solution viscosity is quite close to that of the solvent. The use of Reeff seems inappropriate in the study of the drag coefficient because it does not represent any physical property of nonnewtonian fluids, although it produces a unique reference line for experimental friction data in laminar pipe flow ... 

It is noteworthy that the use of Pitot tubes and hot-film anemometry, which are applicable to newtonian fluids, is questionable for drag-reducing viscoelastic fluids. The anomalous behavior of Pitot tubes and hot-film probes in these fluids has been observed by many investigators [87-92]. 

FIGURE 10.27 Thermal entrance length for drag-reducing viscoelastic fluids. Dimensionless wall temperature versus dimensionless axial distance [93]. 

Cho and Hartnett [108,109] calculated the eddy diffusivity of heat for drag-reducing viscoelastic fluids using a successive approximation technique. The result for the minimum asymptotic case can be expressed in the following polynomial equation with respect to y ... 

Lin Z, Zheng Y, Davis H, Scriven L, Talmon Y, Zakin J (2000) Unusual effects of counterion to surfactant concentration ratio on viscoelasticity of a cationic surfactant drag reducer. J Non-Newt Fluid Mech 93 363-373... 

This chapter aims to present, in a concise way, the major elements and results from applications of computational viscoelastic fluid mechanics in numerical studies (DNS) of turbulent channel flows of homogeneous, dilute, polymer solutions under drag-reducing conditions. In the next section, we present a summary and outline of governing equations with emphasis on polymer modeling. In Section 1.3, we... 

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