The turbulent flow over the BARC rectangular cylinder: a DNS study

TL;DR

This paper presents a detailed DNS study of turbulent flow over a rectangular cylinder, providing new data and insights for turbulence modeling and benchmark validation at low Reynolds numbers.

Contribution

It offers a high-resolution DNS dataset using an in-house solver, including detailed Reynolds stress budgets and flow region analysis, advancing turbulence model verification.

Findings

Quantitative differences with previous DNS results.

Complete Reynolds stress budget terms provided.

Flow regions of production, redistribution, and dissipation identified.

Abstract

A Direct Numerical Simulation (DNS) of the incompressible flow around a rectangular cylinder with chord-to-thickness ratio 5:1 (also known as the BARC benchmark) is presented. The work replicates the first DNS of this kind recently presented by Cimarelli et al (2018), and intends to contribute to a solid numerical benchmark, albeit at a relatively low value of the Reynolds number. The study differentiates from previous work by using an in-house finite-differences solver instead of the finite-volumes toolbox OpenFOAM, and by employing finer spatial discretization and longer temporal average. The main features of the flow are described, and quantitative differences with the existing results are highlighted. The complete set of terms appearing in the budget equation for the components of the Reynolds stress tensor is provided for the first time. The different regions of the flow where production, redistribution and dissipation of each component take place are identified, and the anisotropic and inhomogeneous nature of the flow is discussed. Such information is valuable for the verification and fine-tuning of turbulence models in this complex separating and reattaching flow.