Direct numerical simulation of polymer-induced drag reduction in turbulent boundary layer flow

Abstract

We describe a method for direct numerical simulation of polymer-induced friction drag reduction in turbulent boundary layers. The effect of the polymer additives that induce spatial variations of skin-friction drag is included in the momentum equation through a continuum constitutive model for the viscoelastic stress, which is based on the evolution of a parameter describing the fluid microstructure. We demonstrate that the turbulence structure and polymer microstructure evolve asynchronously as one moves in the streamwise direction. We observe an initial development length, which is followed by a quasisteady region where variations in drag reduction are weak. High drag reduction behavior can be present at short downstream distances from the inflow plane.

Investigating the Drag Reduction Performance of Rigid Polymer–Carbon Nanotubes Complexes

“…While Considering the dependence of the complex on time and the effects of CNT on the polymer used, it was realized that DR does not relate exclusively to molecular degradation, in that, time taken for the polymer alone and that of the complex mixture before breaking down was different, upon deformation, their rearrangement as well exhibit similar trend, although (Dimitropoulos et al 2005) suggested that, it takes a period of time for turbulent structures rearrangement after such deformation, as such DR ultimate level is not achieved by DR immediately, therefore making DR a complicated function with respect to time.…”

A Short Review on Drag-Reduced Turbulent Flow of Inhomogeneous Polymer Solutions

“…The measured profile affected by the wall roughness slightly moves down relative to the profile of the case with smooth wall. For the case with polymer injection, although the upward shift of the mean velocity profile in the logarithmic region is very evident, the slope of the logarithmic region is lower than that of the flow with homogeneous polymer solution [22,37,38]. When the polymer drag-reduced flow with low DR transforms to the flow with high DR, the logarithmic region representing the inertial effects vanishes gradually.…”

“…In more recent work, a large number of numerical simulations based on the constitutive equations of polymer solution including the most often used finitely extensible nonlinear elastic with Peterlin approximation (FENE-P) constitutive equation [18] have also been developed for investigating Toms effect with homogeneous polymer solutions [19][20][21][22][23][24][25]. Den Toonder et al [26] posited that viscous anisotropic stress was the main reason for drag reduction by using two different constitutive equations.…”

“…Dimitropoulos et al [22,40] used DNS to simulate the development of drag reduction associated with some flow characteristics for TBL. It was observed that the turbulence structures and polymer microstructures evolve asynchronously, and the drag-reducing phenomenon is sustained primarily in the vicinity of the low-speed streaks where the injected polymers are most effective.…”

Modifications to a Turbulent Inflow Generation Method for Boundary-Layer Flows

“…This method used recycling of the downstream data to provide the inlet boundary condition on the inflow simulation (illustrated in Figure 1). It has been successfully applied in both incompressible and compressible boundary layer simulations [3][4][5]. Despite the wealth of publications that have successfully applied this method, a number of studies [5][6][7][8][9][10] have indicated that some aspects of LWS method can prove difficult to implement.…”