8/3/2019 Hydroelastisitas Kapal Menggunakan RANS CFD_Marine Transport_Querard_Aymeric

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Numerical Modelling

Hydroelasticity studies the structural response generated by the water forces

Classical approach involves in-vacuo analysis to study the modal response of thestructure and strip theory to assess the fluid forces :

Hydroelasticity

Strip theory offers a mean of simplifying a complex 3D problem into several 2D

simpler ones. The hydrodynamic coefficients (added mass/inertia and viscousdamping) are calculated for each slice and then integrated over the whole shiplength.

A. Qurard

LR UTC, University of Southampton, UK

Hydroelasticity of Ships Using RANS CFD

Fluid Structure Interactions

Research Group,

Lloyds Register

University Technical Centre

AcknowledgementsThis project is funded by

Lloyds Register of Shipping

Until now, the hydrodynamic coefficients of the slices were determined from potential

flow. But Reynolds Averaged Navier-Stokes offers a more accurate representation ofthe fluid :

Reynolds Averaged Navier-Stokes

Potential flow R.A.N.S.

Navier Stokes equation simplified by assuming :

inviscid, incompressible and irrotational flow

Navier Stokes equation averaged in time, assuming :

Turbulence can be modelled

Non-linear, viscous phenomena can be simulated

(large amplitude, roll, shallow waters)

Simple to use. Quick to solve

FreeFree--slip Wallslip Wall

SymmetrySymmetry

NoNo--slipslip

WallWall

OpeningOpening

FreeFree--slip Wallslip Wall

OpeningOpening

One of the roles of classification societies is to makesure that ships are safe to operate with anadequate structure. The ability to predict accurately

the dynamic forces and stresses on a ship at sea isthus of prime interest.

The meshes need to capture free-surface,boundary layer and the eventual sharpcorners.

Hydrodynamic coefficients

The sections are forced to oscillate harmonically.

To obtain the hydrodynamic coefficients, a force approach is preferred to anenergy one. Fourier analysis is thus applied to the forces and moments timehistories to get added mass/inertia and viscous damping:

Aims Investigate the feasibility of using a commercial RANS solver to model the dynamic

loads in the frequency and time domain

Validate the method against experimental results and potential flow analysis

Study the symmetric and antisymmetric dynamic behaviour of different hull shapes

Objectives Obtain added mass and fluid damping for standard 2D-sections and compare topotential flow

Get rigid motion of standard ships, such as S-175

Obtain structural response through the use of hydroelasticity

Investigate different cases : bilge keels, catamarans and crafts in shallow water

For sway : dtetFA

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And for roll : dtetMii Tt

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