Advances in Multi-scale Multi-model Simulation for Ship - PowerPoint PPT Presentation

Advances in Multi-scale Multi-model Simulation for Ship Hydrodynamics Shiqiang Yan, Qingwei Ma Research Centre for Fluid-Structure Interaction City, University of London Northampton Square, London EC1V 0HB, United Kingdom CMHL Symposium, Shanghai JiaoTong University 13 th December, 2019

Advances in Multi-scale Multi-model Simulation for Ship Hydrodynamics CMHL Symposium, SJTU, 4 th June, 2019 Harbours and breakwaters Fixed & Floating Surface & Subsea Coastal, Marine and Offshore Submarine and subsea system

Advances in Multi-scale Multi-model Simulation for Ship Hydrodynamics CMHL Symposium, SJTU, 4 th June, 2019 WSI problems: multi-scale, multi-physics problems Different spatial scales • Turbulent mixing and bubbles in centimetre • Vortex shedding in meters • Wave length in hundred meters • Change of energy spectrum in kilometres • Wind wave generation in kilometres Different temporal scales • Impacts measured by millisecond • Structural natural periods in centi-seconds • Water wave periods in a few seconds • Internal waves in minutes • Tide and tidal current in hours to days Different physical features • Viscos effect is less significant for nonbreaking waves but significant for breaking waves • Compressibility is important for impact; but not for others • Air entrapment may be considerable near free surface but not otherwise

Advances in Multi-scale Multi-model Simulation for Ship Hydrodynamics CMHL Symposium, SJTU, 4 th June, 2019 Many models available for different problems Viscous Flow Potential Theory • NS + Continuity Eqs + BCs • Laplace Eq. + BCs • May + Body Eqs • May + Body Eqs. Linear, 2 nd order, FNPT • Single or multiple phases • • FVM, FEM, FDM and meshless • BEM, FEM, HOS, SBI, SEM • VOF, Level Set… • Cannot model viscous effects, • Can model viscous/turbulent unless appropriate artificial effects damping is included • Two-phase viscous model can • Failed to model breaking deal with wave breaking waves • May suffer from undesirable • Efficient for large-domain numerical damping for large- simulation domain simulation • Less computational cost • High computational cost Hybrid models shall take advantage and overcome the difficulty of these models

Advances in Multi-scale Multi-model Simulation for Ship Hydrodynamics CMHL Symposium, SJTU, 4 th June, 2019 Multi-scale Multi-model Simulations (MMS) at City (FS) Functional splitting Hybrid (SS) domain splitting Time (TS) or space Hybrid NS potential models models Potential + NS MLPG-SPH FEM/Meshl ess (SS) Hybrid Laminar/ ESBI FEM/StarCD turbulent (TS) (SS) (FS) ESBI/ Inviscid/ QALE-FEM Turbulent FEM/OpenFoam (SS) (FS) (SS)

Advances in Multi-scale Multi-model Simulation for Ship Hydrodynamics CMHL Symposium, SJTU, 4 th June, 2019 Available Models at City Potential Theory Viscous Flow • Steady regular waves • Single- and two-phase (Linear, 2 nd order, 5 th order) MLPG-R • Enhanced Nonlinear • ISPH/SPH Schrödinger Equation • OpenFOAM (ENLSE) • StarCD/StarCCM+ • 3 rd -order Spectral Boundary Integral Method (QSBI) • Enhanced Spectral Boundary Integral Method (ESBI) • QALE-FEM One-way coupling QALE-FEM with StarCD Yan, S, Ma, QW (2010) “Numerical simulation of interaction between wind and 2D freak waves”, European Journal of Mechanics, B/Fluids , 29(1), 18-31.

Advances in Multi-scale Multi-model Simulation for Ship Hydrodynamics CMHL Symposium, SJTU, 4 th June, 2019 Available Models at City Potential Theory Viscous Flow • Steady regular waves • Single- and two-phase (Linear, 2 nd order, 5 th order) MLPG-R • Enhanced Nonlinear • ISPH/SPH Schrödinger Equation • OpenFOAM (ENLSE) • StarCD/StarCCM+ • 3 rd -order Spectral Boundary Integral Method (QSBI) • Enhanced Spectral Boundary Integral Method (ESBI) Focusing waves • QALE-FEM Two-way coupling QALE-FEM with MLPG-R Sriram, V, Ma, QW, Schlurmann, T (2014) “A hybrid method for modelling two dimensional non-breaking and breaking waves”, J ournal of Computational Physics , 272, pp. 429–454.

Advances in Multi-scale Multi-model Simulation for Ship Hydrodynamics CMHL Symposium, SJTU, 4 th June, 2019 Available Models at City Potential Theory Viscous Flow • Steady regular waves • Single- and two-phase (Linear, 2 nd order, 5 th order) MLPG-R • Enhanced Nonlinear • ISPH/SPH Schrödinger Equation • OpenFOAM (ENLSE) • StarCD/StarCCM+ • 3 rd -order Spectral Boundary Two-way coupling QALE-FEM with ISPH Integral Method (QSBI) Fourtakas, G, Stansby, PK, Rogers, BD, Lind, SJ, Yan, S, Ma, QW (2018). “On the coupling of incompressible SPH • Enhanced Spectral Boundary with a finite element potential flow solver for nonlinear free- Integral Method (ESBI) surface flows.” International Journal of Offshore and Polar • QALE-FEM Engineering , 28(3), 248–254.

Advances in Multi-scale Multi-model Simulation for Ship Hydrodynamics CMHL Symposium, SJTU, 4 th June, 2019 Available Models at City Potential Theory Viscous Flow • Steady regular waves • Single- and two-phase (Linear, 2 nd order, 5 th order) MLPG-R • Enhanced Nonlinear • ISPH/SPH Schrödinger Equation • OpenFOAM (ENLSE) • StarCD/StarCCM+ • 3 rd -order Spectral Boundary Integral Method (QSBI) • Enhanced Spectral Boundary Integral Method (ESBI) • QALE-FEM Two-way coupling QALE-FEM with SPH Zhang, NB, Yan, S, Zheng, X, Ma, QW (2019) “A 3D hybrid model coupling SPH and QALE-FEM for simulating nonlinear wave-structure interaction”, the Twenty-ninth International Ocean and Polar Engineering Conference , Honolulu, Hawaii, USA.

Advances in Multi-scale Multi-model Simulation for Ship Hydrodynamics CMHL Symposium, SJTU, 4 th June, 2019 Available Models at City Potential Theory Viscous Flow • Steady regular waves • Single- and two-phase (Linear, 2 nd order, 5 th order) MLPG-R • Enhanced Nonlinear • ISPH/ISPH Schrödinger Equation • OpenFOAM (ENLSE) • StarCD/StarCCM+ • 3 rd -order Spectral Boundary Integral Method (QSBI) • Enhanced Spectral Boundary Integral Method (ESBI) • QALE-FEM Time splitting NLSE-QSBI-ESBI Wang, J., Ma, Q.W. and Yan, S. (2016). A hybrid model for simulating rogue waves in random seas on a large temporal and spatial scale. Journal of Computational Physics, 313, pp. 279–309. doi:10.1016/j.jcp.2016.02.044. Domain size: 64L 0 � 16L 0 (~12 km � 3 km) Duration: 1000T p (~3 hours) JONSWAP spectrum ; Gaussian spreading function Intel(R) Xeon(R) CPU E5-2680 v4 @ 2.40GHz, 8-core CPU time: ESBI (52.2h), QSBI(22.6h) and ENLSE-5F(19.3h)

Advances in Multi-scale Multi-model Simulation for Ship Hydrodynamics CMHL Symposium, SJTU, 4 th June, 2019 Available Models at City Potential Theory Viscous Flow • Steady regular waves • Single- and two-phase (Linear, 2 nd order, 5 th order) MLPG-R • Enhanced Nonlinear • ISPH/SPH Schrödinger Equation • OpenFOAM (ENLSE) • StarCD/StarCCM+ • 3 rd -order Spectral Boundary Integral Method (QSBI) • Enhanced Spectral Boundary Integral Method (ESBI) • QALE-FEM Functional Splitting method using OpenFOAM

Advances in Multi-scale Multi-model Simulation for Ship Hydrodynamics CMHL Symposium, SJTU, 4 th June, 2019 Available Models at City Potential Theory Viscous Flow • Steady regular waves • Single- and two-phase (Linear, 2 nd order, 5 th order) MLPG-R • Enhanced Nonlinear • ISPH Schrödinger Equation • OpenFOAM (ENLSE) • StarCD/StarCCM+ • 3 rd -order Spectral Boundary Integral Method (QSBI) • Enhanced Spectral Boundary Integral Method (ESBI) • QALE-FEM qaleFOAM

Advances in Multi-scale Multi-model Simulation for Ship Hydrodynamics CMHL Symposium, SJTU, 4 th June, 2019 OpenFOAM QALE-FEM v Continuity equation v Governing equation ! 2 = v Two-phase Ñ f = Ñ f 0 u incompressible/compressible NS v FVM v Velocity-pressure coupling 2 v Volume of Fraction (VOF) Ñ f ¶ f r = - - - p / gz v RANS or LES for turbulent ¶ t 2 modelling Ø Time-consuming Two- phase NS solver(OpenFOAM) covers small zone near the structures Ø The majority solved by the QALE-FEM Ø Overlap area: a robust quadric interpolation scheme is developed and used

Advances in Multi-scale Multi-model Simulation for Ship Hydrodynamics CMHL Symposium, SJTU, 4 th June, 2019 Coupling Approach in qaleFOAM Ø OpenFOAM domain is placed inside the FNPT domain (Overset) 2 Ñ f ¶ f !, ∇$ , r = - - - p / gz ¶ t 2 OpenFOAM QALE-FEM %, &, '()* +,&-./01) Ø Translational zone: smooth the solution + convenience for gradient calculation + absorbing wave reflection (one-way coupling) Ø Wave outlet of NS domain: free passage of the wave into FNPT domain (two-way coupling); or smoothed from NS solver to FNPT solver(one-way coupling)

Advances in Multi-scale Multi-model Simulation for Ship Hydrodynamics CMHL Symposium, SJTU, 4 th June, 2019 Coupling Approach in qaleFOAM Ø Couple the QALE-FEM with OpenFOAM through inlet boundaries ü Improved passive wave absorber based on the feedback of the recorded wave elevation Sampling the instantaneous 4 5(#) Overall accuracy depends on • Accuracy of the data (velocity, cosh - .(#) / + 1 pressure and surface elevation) ! " # = % &(#) 5 # 6 7 " 4 sinh - .(#)1 transmit from the QALE-FEM domain (large domain) into the 8! 9 87 = 0 internal domain; • Size of the relaxation zone