Modelling Natural Transition on Hydrofoils for Application in Underwater Gliders
Author Lemaire, S. , Lidtke, A.K., Vaz, G. and Turnock, S.R.
Title Modelling Natural Transition on Hydrofoils for Application in Underwater Gliders
Conference/Journal 19th Numerical Towing Tank Symposium (NuTTS), St. Pierre d'Oléron, France
Month October
Year 2016
Pages 61-66

Abstract
Underwater gliders are a class of autonomous underwater vehicles (AUV) used for long-endurance missions. They employ a buoyancy engine in order to induce vertical motion through the water column and by adopting an appropriate trim angle they propel themselves forward using hydrofoils. The velocities these vessels reach are typically less than 0.5ms-1. Efficiency of their hydrofoils is of course a key factor determining the overall system performance. Therefore, better understanding the nature of transition occurring on these foils is of significant importance for the design of next generation underwater gliders.
Standard turbulence models are known to predict transition onset too early in terms of Reynolds number, mainly because they were first developed with applications to fully turbulent flows in mind (Rosetti et al., 2016). For this reason a range of models designed to predict transition have been introduced in the literature (Van Ingen, 2008).
The aim of this paper is to assess the usefulness of the Local Correlation Transition Model (LCTM, Langtry and Menter, 2009), implemented in the finite volume solver ReFRESCO (Rosetti et al., 2016), for application to engineering problems involving laminar and transitional Reynolds number regimes. The study will be focusing on modelling the flow around 3D infinite foils and underwater glider swept hydrofoils to analyse transition to turbulence as well as the nature of the separation bubble. Development of a better understanding of these phenomena will help to achieve a more efficient design in the future.

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