Vorticity in the turbulent flow above variously rough surfaces

Radka Kellnerová,Václav Uruba,Klára Jurčáková,Pavel Procházka

doi:10.1051/epjconf/201921302039

Radka Kellnerová, Václav Uruba + Show 2 more

Open Access

https://doi.org/10.1051/epjconf/201921302039

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Abstract

Highly turbulent flows above variously rough surfaces were investigated by means of Time-Resolved Particle Image Velocimetry in a wind tunnel. Proper Orthogonal Decomposition was applied to both velocity and vorticity data in order to detect dominant features in the flow based on turbulent kinetic energy and enstrophy, respectively. While both the shape and location of the POD patterns exhibited similarity with other studies, a systematic inconsistency in terms of contribution from the features to the enstrophy between the previously published papers and our results were found.

Highlights

The Proper Orthogonal Decomposition (POD) is nowadays a routine mathematical tool for an extraction of the dominant structures from the turbulent flow
It is worthy to emphasize that due to a PIV system limitation, turbulent kinetic energy (TKE) consists of two velocity components and enstrophy of one vorticity component in this paper
We evaluated the relative contributions from these particular modes with respect to the total enstrophy within the flow

Summary

Introduction

The Proper Orthogonal Decomposition (POD) is nowadays a routine mathematical tool for an extraction of the dominant structures from the turbulent flow. The wall-bounded flows is very complex and typically contain vortical features of many scales and number of non-rotational motions in a circumfluent flow In such complex flows, POD is still capable to extract merit-based structures from the redundant noise of the turbulence. Several researches documented a strong connection between the most dominant POD modes based on the velocity data and those based on the vorticity (e.g., [5, 6]). A similar percentage value of the relative contribution from the first mode can be observed with the POD applied to velocity data within the variously turbulent flows [7, 8]. We revised the POD applied to vorticity within the different categories of flow in this paper

Experimental set-up

Results

Conclusion