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Streamwise-varying steady transpiration control in turbulent pipe flow

Streamwise-varying steady transpiration control in turbulent pipe flow
Streamwise-varying steady transpiration control in turbulent pipe flow
The effect of streamwise-varying steady transpiration on turbulent pipe flow is examined using direct numerical simulation at fixed friction Reynolds number Re?=314. The streamwise momentum equation reveals three physical mechanisms caused by transpiration acting in the flow: modification of Reynolds shear stress, steady streaming and generation of non-zero mean streamwise gradients. The influence of these mechanisms has been examined by means of a parameter sweep involving transpiration amplitude and wavelength. The observed trends have permitted identification of wall transpiration configurations able to reduce or increase the overall flow rate ?36.1% and 19.3%, respectively. Energetics associated with these modifications are presented. A novel resolvent formulation has been developed to investigate the dynamics of pipe flows with a constant cross-section but with time-mean spatial periodicity induced by changes in boundary conditions. This formulation, based on a triple decomposition, paves the way for understanding turbulence in such flows using only the mean velocity profile. Resolvent analysis based on the time-mean flow and dynamic mode decomposition based on simulation data snapshots have both been used to obtain a description of the reorganization of the flow structures caused by the transpiration. We show that the pipe flows dynamics are dominated by a critical-layer mechanism and the waviness induced in the flow structures plays a role on the streamwise momentum balance by generating additional terms.
0022-1120
588-616
Gómez, F.
094d64a4-06d9-42e0-9266-6ee783489b9b
Blackburn, H.M.
ae789033-1e30-4261-91a6-fd2e136b0ff3
Rudman, M.
1eb7fd54-c427-416e-9e5b-2f548ae0b5b5
Sharma, A.S.
cdd9deae-6f3a-40d9-864c-76baf85d8718
McKeon, B.J.
2e685015-292a-42a7-8c9e-7cc27cf2da67
Gómez, F.
094d64a4-06d9-42e0-9266-6ee783489b9b
Blackburn, H.M.
ae789033-1e30-4261-91a6-fd2e136b0ff3
Rudman, M.
1eb7fd54-c427-416e-9e5b-2f548ae0b5b5
Sharma, A.S.
cdd9deae-6f3a-40d9-864c-76baf85d8718
McKeon, B.J.
2e685015-292a-42a7-8c9e-7cc27cf2da67

Gómez, F., Blackburn, H.M., Rudman, M., Sharma, A.S. and McKeon, B.J. (2016) Streamwise-varying steady transpiration control in turbulent pipe flow. Journal of Fluid Mechanics, 796, 588-616. (doi:10.1017/jfm.2016.279).

Record type: Article

Abstract

The effect of streamwise-varying steady transpiration on turbulent pipe flow is examined using direct numerical simulation at fixed friction Reynolds number Re?=314. The streamwise momentum equation reveals three physical mechanisms caused by transpiration acting in the flow: modification of Reynolds shear stress, steady streaming and generation of non-zero mean streamwise gradients. The influence of these mechanisms has been examined by means of a parameter sweep involving transpiration amplitude and wavelength. The observed trends have permitted identification of wall transpiration configurations able to reduce or increase the overall flow rate ?36.1% and 19.3%, respectively. Energetics associated with these modifications are presented. A novel resolvent formulation has been developed to investigate the dynamics of pipe flows with a constant cross-section but with time-mean spatial periodicity induced by changes in boundary conditions. This formulation, based on a triple decomposition, paves the way for understanding turbulence in such flows using only the mean velocity profile. Resolvent analysis based on the time-mean flow and dynamic mode decomposition based on simulation data snapshots have both been used to obtain a description of the reorganization of the flow structures caused by the transpiration. We show that the pipe flows dynamics are dominated by a critical-layer mechanism and the waviness induced in the flow structures plays a role on the streamwise momentum balance by generating additional terms.

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Accepted/In Press date: 15 April 2016
e-pub ahead of print date: 19 May 2016
Published date: June 2016
Organisations: Aeronautics, Astronautics & Comp. Eng

Identifiers

Local EPrints ID: 395576
URI: https://eprints.soton.ac.uk/id/eprint/395576
ISSN: 0022-1120
PURE UUID: f690534f-a65f-45cd-a44e-246ac64f9613
ORCID for A.S. Sharma: ORCID iD orcid.org/0000-0002-7170-1627

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Date deposited: 01 Jun 2016 13:59
Last modified: 06 Jun 2018 12:25

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