Reynolds-averaged modeling of polymer drag reduction in turbulent flows

A FENE-P k–ε turbulence model for low and intermediate regimes of polymer-induced drag reduction

“…Based on the good behaviour of the individual viscoelastic closures developed in this work, we believe that correcting the excessive underprediction of k will enable the model to achieve higher values of drag reduction and behave properly as a function of We, L 2 and b. For DR < 50% the tests demonstrated a good behaviour of the model and one comparison was against one flow case of Iaccarino et al [45], which implied the use of a higher value of L 2 . This set is characterised by Re s 0 ¼ 300, b = 0.9, L 2 = 3600 and We s 0 ¼ 36, Table 2 compares the corresponding prediction of drag reduction with that of Iaccarino et al and the DNS data and the corresponding velocity profile is plotted in Fig.…”

“…An improved relation between turbulence and the polymeric stress/conformation is required for improved modelling and there are various options. One is to make the eddy viscosity proportional to the transverse turbulence, which really decreases with We as demonstrated by Iaccarino et al [45] in the context of the k-e v 2 -f philosophy. Another is to directly work with transport equations for the Reynolds stress or to use anisotropic k-e models.…”

A Reynolds stress model for turbulent flows of viscoelastic fluids

“…Note that the viscoelastic terms related to coefficients C V 1 and C V 2 also took over some of the viscoelastic contributions, but due to a lack of information on the distribution of turbulent energy among the various terms, we chose to maximise the role of elastic contribution via the pseudo-elastic term. For this reason, the coefficient C V 1 of the viscoelastic term in Equation (22) was set to C V 1 = −1.7, keeping the same sign of the pseudo-elastic stress but with a major impact away from the wall.…”

Drag Reduction Properties of Nanofluids in Microchannels

“…The use of diverse polymers such as DRAs has been reported previously (Abubakar et al 2014;AlSarkhi 2012;Matras and Kopiczak 2015;Edomwonyi-Outu, Chinaud and Angeli 2015;Hong et al 2015;Iaccarino et al 2010;Resende et al 2011) and surfactants (Drzazga et al 2013;Li et al 2008;Różański 2011;Yu and Kawaguchi 2006;Tuan Mizunuma 2013;Qi et al 2011) depending upon the polarities and different behaviors in a turbulent flow (Tarn and Pamme 2014), while the impact of other colloidal suspensions, such as nanofluids, in reducing the pressure drop has not been widely studied. The dispersion quality of the nanoparticles in the base fluid and the stability of the suspension play a crucial role in most applications of practical interest (Rivet et al 2011;Xie et al 2003;Choi et al 2007;Ganguly et al 2009).…”