The University of Southampton
University of Southampton Institutional Repository

Wakes of wall-bounded turbulent flows past patches of circular cylinders

Wakes of wall-bounded turbulent flows past patches of circular cylinders
Wakes of wall-bounded turbulent flows past patches of circular cylinders
The properties of the wake generated by a porous body fully immersed in a turbulent boundary layer are experimentally assessed. The body consists of an array of cylinders, with diameter d, covering a circular patch of diameter D. For fixed d and D, by increasing the number of cylinders, Nc, within the patch, the wake properties are systematically tested under different levels of density (ϕ = covered planar area per total surface) and compared to the flow past a solid body of equivalent diameter and height (H). Some insights on the complex flow developing in the wake are captured: ϕ varying in the range (2−24)% results in the flow meandering among the cylinders and bleeding from the top, the sides and the trailing edge of the patch. The interplay between trailing edge and top bleeding prevents wake entrainment, locking the wake longitudinal extent to 5-7 patch diameters, regardless of the density level. Due to the finite body vertical extent, a third shear layer develops from the top of the patch. The interaction between the top shear layer and the lateral ones leads to a mutual alteration, namely a non-linear growth not captured by the classical mixing layer theory. Nevertheless, on the horizontal plane at the patch mid height, the mean flow recovers exhibiting a self-similar decay. Surprisingly, the recovery is well described by the classical planar wake theory and the characteristics scales, namely the maximum velocity deficit and the wake half width, evolve linearly as proposed by Wygnanski et al. (1986).
0022-1120
Nicolai, Claudia
8bdc34da-efe2-4dd0-b3bc-ece3bbddebff
Taddei, Sonia
d24c8712-7423-4f0a-a2df-5dab24f77a36
Manes, Costantino
7d9d5123-4d1b-4760-beff-d82fe0bd0acf
Ganapathisubramani, Bharathram
5e69099f-2f39-4fdd-8a85-3ac906827052
Nicolai, Claudia
8bdc34da-efe2-4dd0-b3bc-ece3bbddebff
Taddei, Sonia
d24c8712-7423-4f0a-a2df-5dab24f77a36
Manes, Costantino
7d9d5123-4d1b-4760-beff-d82fe0bd0acf
Ganapathisubramani, Bharathram
5e69099f-2f39-4fdd-8a85-3ac906827052

Nicolai, Claudia, Taddei, Sonia, Manes, Costantino and Ganapathisubramani, Bharathram (2020) Wakes of wall-bounded turbulent flows past patches of circular cylinders. Journal of Fluid Mechanics. (Submitted)

Record type: Article

Abstract

The properties of the wake generated by a porous body fully immersed in a turbulent boundary layer are experimentally assessed. The body consists of an array of cylinders, with diameter d, covering a circular patch of diameter D. For fixed d and D, by increasing the number of cylinders, Nc, within the patch, the wake properties are systematically tested under different levels of density (ϕ = covered planar area per total surface) and compared to the flow past a solid body of equivalent diameter and height (H). Some insights on the complex flow developing in the wake are captured: ϕ varying in the range (2−24)% results in the flow meandering among the cylinders and bleeding from the top, the sides and the trailing edge of the patch. The interplay between trailing edge and top bleeding prevents wake entrainment, locking the wake longitudinal extent to 5-7 patch diameters, regardless of the density level. Due to the finite body vertical extent, a third shear layer develops from the top of the patch. The interaction between the top shear layer and the lateral ones leads to a mutual alteration, namely a non-linear growth not captured by the classical mixing layer theory. Nevertheless, on the horizontal plane at the patch mid height, the mean flow recovers exhibiting a self-similar decay. Surprisingly, the recovery is well described by the classical planar wake theory and the characteristics scales, namely the maximum velocity deficit and the wake half width, evolve linearly as proposed by Wygnanski et al. (1986).

Text
JFM-19-S-0071.R3_Proof_hi - Author's Original
Restricted to Repository staff only
Request a copy

More information

Submitted date: 22 January 2020

Identifiers

Local EPrints ID: 439110
URI: http://eprints.soton.ac.uk/id/eprint/439110
ISSN: 0022-1120
PURE UUID: 7d3077ec-6cda-494c-8891-1f3aaa7577b1
ORCID for Bharathram Ganapathisubramani: ORCID iD orcid.org/0000-0001-9817-0486

Catalogue record

Date deposited: 03 Apr 2020 16:30
Last modified: 26 Aug 2020 01:38

Export record

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×