Body-Free Simulation of Three-Dimensional Turbulent Cylinder Wakes

TL;DR

This paper introduces a simplified, body-free simulation method for 3D turbulent cylinder wakes that accurately captures wake dynamics with reduced computational cost by using prescribed inflow conditions.

Contribution

The novel approach reconstructs wake behavior without explicitly modeling the body, relying on low-dimensional inflow data and stability analysis, enabling efficient flow studies.

Findings

Accurately reproduces wake dynamics at Reynolds numbers 500, 5000, and 11000.

Good agreement with full DNS and PIV measurements in key flow features.

Body-free simulation significantly reduces computational cost while capturing essential wake behavior.

Abstract

We present a body-free simulation framework for three-dimensional turbulent cylinder wakes, in which the upstream cylinder is not explicitly resolved. Instead, the incompressible Navier--Stokes equations are solved in a simplified rectangular domain, and the inflow is prescribed using velocity profiles extracted from experimental measurements or pre-computed direct numerical simulations (DNS). We show that, for the Reynolds numbers considered here, prescribing low-dimensional inflow information at a single downstream location is sufficient to reconstruct the principal wake dynamics, including three-dimensionality, coherent vortex shedding, Reynolds-stress distributions, and spectral content, for $Re=500$, $5{,}000$, and $11{,}000$. Comparisons with full-body DNS and particle image velocimetry (PIV) measurements show good agreement in mean velocity profiles, Reynolds stresses, and dominant shedding frequencies. A local stability analysis further shows that successful wake reconstruction is obtained when the imposed inflow is selected from the absolutely unstable near-wake region. The results support existing theory that the essential dynamics of bluff-body wakes are governed primarily by the instability of the near-wake profile rather than by the explicit presence of the body itself. The role of the onset of three-dimensionality is elucidated for first time. Relative to full DNS with the cylinder present, the proposed body-free simulation offers a substantial reduction in computational cost, providing a physically interpretable and computationally efficient route for wake reconstruction, reduced-complexity simulation, and flow-control studies.