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Flow distortion around underwater gliders and impacts on sensor measurements: a pilot study using large-eddy simulations

Flow distortion around underwater gliders and impacts on sensor measurements: a pilot study using large-eddy simulations
Flow distortion around underwater gliders and impacts on sensor measurements: a pilot study using large-eddy simulations
The suitability of computational fluid dynamics (CFD) to numerically simulate the flow of water over autonomous underwater vehicles (AUVs) was investigated. The aim was to examine the feasibility of using large-eddy simulation to investigate; 1) the extent to which the measurements of sensors (including turbulence sensors) on an AUV are affected by the distortion of the flow around the vehicle body, and 2) the quantification of the hydrodynamic forces on AUV’s. To this end the large-eddy simulation (LES) code Gerris was used to numerically simulate the flow around underwater gliders.

Two example simulations were conducted. In both cases the flow around a Slocum Mk II glider was simulated and the second example included a MicroRider turbulence package mounted on top of the glider. The results of these studies illustrate the capability of CFD simulations but a more detailed study including further runs to examine the sensitivity of the results to model parameters and in some cases validation with experimental studies would be required before we could have full confidence in the results.

The results suggest that CFD studies may have significant value in assessing the flow distortion around glider bodies and the resulting affects upon sensor measurements. Our preliminary results suggest that the usual position of the oxygen sensor on a Slocum glider may be within a separated wake that could significantly affect the data quality. Flow distortion at the location of the shear probes on the turbulence package is low but could result in a small underestimation of the magnitude of dissipation. Lift and drag forces diagnosed from the simulations were consistent with data from gliders but a more detailed study is needed to assess the quantitative accuracy of these results.
58
National Oceanography Centre
Moat, B.I.
497dbb18-a98f-466b-b459-aa2c872ad2dc
Smeed, D.A.
79eece5a-c870-47f9-bba0-0a4ef0369490
Marcinko, C.
1fbc10e0-5c44-4cac-8a70-862ba0e47a66
Popinet, S.
e324849e-3501-458e-9487-8c4f498f8c3a
Turnock, S.
d6442f5c-d9af-4fdb-8406-7c79a92b26ce
Moat, B.I.
497dbb18-a98f-466b-b459-aa2c872ad2dc
Smeed, D.A.
79eece5a-c870-47f9-bba0-0a4ef0369490
Marcinko, C.
1fbc10e0-5c44-4cac-8a70-862ba0e47a66
Popinet, S.
e324849e-3501-458e-9487-8c4f498f8c3a
Turnock, S.
d6442f5c-d9af-4fdb-8406-7c79a92b26ce

Moat, B.I., Smeed, D.A., Marcinko, C., Popinet, S. and Turnock, S. (2016) Flow distortion around underwater gliders and impacts on sensor measurements: a pilot study using large-eddy simulations (National Oceanography Centre Research and Consultancy Report, 58) Southampton, UK. National Oceanography Centre 35pp.

Record type: Monograph (Project Report)

Abstract

The suitability of computational fluid dynamics (CFD) to numerically simulate the flow of water over autonomous underwater vehicles (AUVs) was investigated. The aim was to examine the feasibility of using large-eddy simulation to investigate; 1) the extent to which the measurements of sensors (including turbulence sensors) on an AUV are affected by the distortion of the flow around the vehicle body, and 2) the quantification of the hydrodynamic forces on AUV’s. To this end the large-eddy simulation (LES) code Gerris was used to numerically simulate the flow around underwater gliders.

Two example simulations were conducted. In both cases the flow around a Slocum Mk II glider was simulated and the second example included a MicroRider turbulence package mounted on top of the glider. The results of these studies illustrate the capability of CFD simulations but a more detailed study including further runs to examine the sensitivity of the results to model parameters and in some cases validation with experimental studies would be required before we could have full confidence in the results.

The results suggest that CFD studies may have significant value in assessing the flow distortion around glider bodies and the resulting affects upon sensor measurements. Our preliminary results suggest that the usual position of the oxygen sensor on a Slocum glider may be within a separated wake that could significantly affect the data quality. Flow distortion at the location of the shear probes on the turbulence package is low but could result in a small underestimation of the magnitude of dissipation. Lift and drag forces diagnosed from the simulations were consistent with data from gliders but a more detailed study is needed to assess the quantitative accuracy of these results.

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Published date: October 2016
Organisations: Marine Systems Modelling, Marine Biogeochemistry, Civil Maritime & Env. Eng & Sci Unit, Marine Physics and Ocean Climate

Identifiers

Local EPrints ID: 402144
URI: http://eprints.soton.ac.uk/id/eprint/402144
PURE UUID: 6af6c2f0-a1fd-4e4e-9a31-37fbc9dfff66
ORCID for C. Marcinko: ORCID iD orcid.org/0000-0002-5369-3950
ORCID for S. Turnock: ORCID iD orcid.org/0000-0001-6288-0400

Catalogue record

Date deposited: 28 Oct 2016 14:49
Last modified: 03 Nov 2023 02:32

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Contributors

Author: B.I. Moat
Author: D.A. Smeed
Author: C. Marcinko ORCID iD
Author: S. Popinet
Author: S. Turnock ORCID iD

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