Flow characteristics comparison of PIV and numerical prediction results for an unmanned underwater vehicle positioned close to the free surface

A. Kilavuz, M. Ozgoren*, L. A. Kavurmacioglu, T. Durhasan, F. Sarigiguzel, B. Sahin, H. Akilli, E. Sekeroglu, B. Yaniktepe

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

In the present paper, flow characteristics of an Unmanned Underwater Vehicle (UUV) with a commonly used Myring profile were investigated numerically and experimentally using Computational Fluid Dynamics (CFD) and the Particle Image Velocimetry (PIV) technique under the influence of free surface. The 3-D and two-phase flow simulation generated using the Volume of Fluid (VOF) were carried out using the Large Eddy Simulation (LES) turbulence model for high accuracy in both near free-surface and almost uniform flow conditions. Due to the presence of the free-surface effect, dynamics and unsteady instantaneous flow characteristics such as force and moment coefficients, streamlines topology, and pressure values on the body surface along with vorticity structures were found to be very chaotic and have irregular motion in the wake while the followable variation trend of the time-averaged properties was obtained to show critical immersion ratio. The immersion ratios of 0.75≤ h/D≤3.50 were examined at Reynolds numbers Re = 2.0 × 104 and 4.0 × 104. Jet-like flow between the UUV body and the free surface of the water was detected at the immersion ratio of h/D = 0.75, which caused a substantial asymmetry in flow structures, resulting in highest drag and lift values. Increased surface disturbance at Re = 4.0 × 104 caused air introduction into via jet-like flow in h/D = 0.75, which caused positive lift. Hydrodynamic coefficients and isosurfaces shown that the free-surface effect decreased significantly up to h/D = 1.50 at constant Reynolds numbers. Further investigation of time-averaged velocity components, streamlines, vorticity and turbulence statistics revealed that h/D = 1.50 acted as a transitional immersion ratio as the flow structure changed significantly with Reynolds numbers. The utilized CFD approach yielded especially excellent agreement with the PIV measurements with the discrepancy which varies from 1% to 15% in near wake for streamwise velocity components to simulate the essential unmeasured flow features needed in the research and development process of UUVs when they move below the free surface.

Original languageEnglish
Article number103399
JournalApplied Ocean Research
Volume129
DOIs
Publication statusPublished - Dec 2022

Bibliographical note

Publisher Copyright:
© 2022 Elsevier Ltd

Funding

The authors would like to acknowledge the Scientific and Technological Research Council of Turkey (TUBITAK) under Contract No. 214M318 and the financial support of Cukurova University Scientific Research Project Coordinators (BAP) under Contract No FDK-2021-14066. The authors also thank the Advanced Fluid Mechanics PIV laboratory of Osmaniye Korkut Ata University, Turkey, for using the water channel and measurement systems and the Mechanical Engineering Department of Cukurova University for allowing usage of the CFD server cluster. The authors would like to acknowledge the Scientific and Technological Research Council of Turkey (TUBITAK) under Contract No. 214M318 and the financial support of Cukurova University Scientific Research Project Coordinators (BAP) under Contract No FDK-2021-14066. The authors also thank the Advanced Fluid Mechanics PIV laboratory of Osmaniye Korkut Ata University, Turkey, for using the water channel and measurement systems and the Mechanical Engineering Department of Cukurova University for allowing usage of the CFD server cluster.

FundersFunder number
CFD
Cukurova University Scientific Research Project Coordinators
Mechanical Engineering Department of Cukurova University
Osmaniye Korkut Ata University
Türkiye Bilimsel ve Teknolojik Araştırma Kurumu214M318
Bilimsel Araştırma Projeleri Birimi, İstanbul Teknik ÜniversitesiFDK-2021-14066

    Keywords

    • CFD
    • Free surface
    • PIV
    • Turbulent flow
    • Unmanned underwater vehicle

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