Comparison of Theory and Direct Numerical Simulations of Drag Reduction by Rodlike Polymers in Turbulent Channel Flows

TL;DR

This paper compares direct numerical simulations of drag reduction by rodlike polymers in turbulent channel flows with existing high- and high-e9 theories, highlighting the relationship between simulations and theoretical predictions.

Contribution

It provides a detailed comparison between DNS results and theoretical models for drag reduction by rodlike polymers in turbulent flows.

Findings

Numerical results align with theoretical predictions at certain Reynolds and Deborah numbers.

The study clarifies how to relate simulations to high- and high-e9 theories.

Insights into the limitations of current theories at moderate  and e9 levels.

Abstract

Numerical simulations of turbulent channel flows, with or without additives, are limited in the extent of the Reynolds number \Re and Deborah number \De. The comparison of such simulations to theories of drag reduction, which are usually derived for asymptotically high \Re and \De, calls for some care. In this paper we present a study of drag reduction by rodlike polymers in a turbulent channel flow using direct numerical simulation and illustrate how these numerical results should be related to the recently developed theory.