ACADEMIC / INDUSTRIAL PARTNERSHIP FOR SAILING YACHT DESIGN

1. Nicola Parolini MOX – DipartimentodiMatematica Politecnicodi Milano ACADEMIC / INDUSTRIAL PARTNERSHIP FOR SAILING YACHT DESIGN Rencontre SMAI math-industrie Voile et Innovation Mathématique Paris, 9 December 2011

2. Flow separation behind mast Efficiency of sails Aeroelasticity of flexible sails Wave drag Viscous drag on hull Efficiency of appendages A complex physical problem Aerodynamics Free Surface Hydrodynamics

3. and numerical models A Hierarchy of physical models COMPLEXITY • FLUID MODEL • Single fluid (air or water) • Two fluids (free –surface) • Turbulence modeling • Transition modeling COMPLEXITY • FLOW CONDITION • Steady flow • Unsteady flow • Seakeeping • Maneuvering • Aero/Hydro coupling • NUMERICAL MODEL • Empirical correlations • Thin ship theory • Potential flow models • CFD (RANS) • Multi-physics (e.g. FSI) COMPLEXITY COMPLEXITY • DESIGN INTEGRATION • Parametric analysis • DOE • Shape optimization • Flow control

4. Collaboration with the Alinghi Design Team • 31st America’s Cup • Auckland (NZ), February 2003 Defender: Team New Zealand (NZ) Challenger: Alinghi (SUI) • 32nd America’s Cup • Valencia (E), July 2007 Defender: Alinghi (SUI) Challenger: Team New Zealand (TNZ) • 33rd America’s Cup • Valencia (E), February 2010 Defender: Alinghi (SUI) Challenger: BMW Oracle Racing (USA)

5. EPFL Research Team Alinghi Design Team Decision SA (Boat Builder)‏ Alinghi’s Official Scientific Advisor

6. Aero Side Force Aero Side Force Heeling Moment Heeling Moment Aero Thrust Hydro Drag Righting Moment Righting Moment Hydro Side Force Buoyancy Force Weight Hydro Side Force Equilibrium M ax = Ta(V,A) - Dh (V,A)‏ M ay = Sa (V,A) - Sh (V,A)‏ I ωhMH (V,A) - MR (V,A)‏ Ta = Dh Sa = Sh MH = MR VEQ , AEQ A Design Tool: Velocity Prediction Program (VPP)‏ Y Z X Y For each boat configuration, the VPP compute the equilibrium boat speed (VEQ) and attitude (AEQ):

7. Towing Tank Wave resistance Global forces on sail and appendages Pressure and viscous forces Pressure forces CFD Wind Tunnel Potential Flow Data Integration

8. Performance evaluation for yacht design • Objective: • prediction of aero/hydrodynamic forces • Laminar-to-turbulent transition on appendages Wave resistance and boat dynamics evaluation Optimal flying shape of sails • Modeling approach: • Multiphase RANS Equations SST k-ω turbulence model Langtry-Menter transition model Volume-of-Fluid method for interface capturing Dynamical system for 6DOF boat motion FSI for sails

9. Streamlines around appendages Streamlines around bulb and winglets Grid detail around bulb Wall-shear stress with Transition model

10. Free-surface around AC32 boat … … and around AC33 catamaran

11. What we have been working on • FLUID MODEL • Single fluid (air or water) • Two fluids (free –surface) • Turbulence modeling • Transition modeling • FLOW CONDITION • Steady flow • Unsteady flow • Seakeeping • Maneuvering • Aero/Hydro coupling • NUMERICAL MODEL • Empirical correlations • Thin ship theory • Potential flow models • CFD (RANS) • Multi-physics (e.g. FSI) • DESIGN INTEGRATION • Parametric analysis • DOE • Shape optimization • Flow control

12. Towards a unified simulation framework

13. What we are working on today • FLUID MODEL • Single fluid (air or water) • Two fluids (free –surface) • Turbulence modeling • Transition modeling • FLOW CONDITION • Steady flow • Unsteady flow • Seakeeping • Maneuvering • Aero/Hydro coupling • NUMERICAL MODEL • Empirical correlations • Thin ship theory • Potential flow models • CFD (RANS) • Multi-physics (e.g. FSI) • DESIGN INTEGRATION • Parametric analysis • DOE • Shape optimization • Flow control

14. ... and tomorrow ? Liste de souhaits et des priorités • FLUID MODEL • Single fluid (air or water) • Two fluids (free –surface) • Turbulence modeling • Transition modeling • ……………………. • FLOW CONDITION • Steady flow • Unsteady flow • Seakeeping • Maneuvering • Aero/Hydro coupling • …………………… • NUMERICAL MODEL • Empirical correlations • Thin ship theory • Potential flow models • CFD (RANS) • Multi-physics (e.g. FSI) • ……………………… • DESIGN INTEGRATION • Parametric analysis • DOE • Shape optimization • Flow control • …………………………..

15. … la discussion est ouverte !