Use of OpenFOAM in modeling of water on deck and dynamic stability of floating bodies in waves

Eric PatersonComputational Mechanics Division, Applied Research LabDepartment of Mechanical and Nuclear EngineeringPenn State UniversityState College, PA 16804 USAeric-paterson@psu.edu

OpenFOAM Workshop7-9 June 2007Zagreb, Croatia

OpenFOAM Usage at ARL Penn State

• Validation effort• Wigley Hull• Surface piercing NACA0024 foil• Cone with ventilated cavity• DTMB propeller P5168

• Waterjet pump cavitation breakdown• Surface ship wakes• Canine Olfaction• Water-on-Deck and Dynamic Stability of

Floating Bodies

BackgroundShip Waves, Wigley Hull

BackgroundSurface-Piercing Foil and Breaking Waves

• rasInterFoam• NACA 0024, Fr = 0.55• Validation experiment performed at the Iowa Institute of Hydraulic Research (IIHR) at The University of Iowa

BackgroundSubmerged Near-Surface Jets

Trujillo, Chahine, Peltier and Paterson, 9th International Symposium on Numerical Ship Hydrodynamics, Ann Arbor, MI, 2007

BackgroundSubmerged Near-Surface Jets

lesInterFoam, maxCo 0.8 5M cells, hex mesh generated using GRIDGEN 48 processors (METIS decomp) on 256-proc Dell woodcrest cluster Approximately 4 days for 2 seconds of real time

Objectives

• Water-on-Deck Modeling

• Role of Viscous Effects in Roll, Sway, and Roll-Sway Motions

• Dynamic Stability and Capsize

UMich Box Barge Model

C

30.48 cm

18.25 cm

38.74 cm1.12 cm

y

x φ

Obar, Lee, and Troesch, “An experimental investigation into the effects initial conditions and water on deck have on a three degree of freedom capsize mode.“

• Tank dimensions: 35m long, 0.75m wide, and 1.5m deep• Angle of vanishing stability: 11.4 degrees• Roll natural frequency: ωn=2.28 rad/s

• Wave length: λ=132.89 cm (λ/B=4.36)

• Wave height: h=2.67 cm (h/λ=1/49.8)

• Wave frequency: ωe=6.8 rad/s (ωe/ωn=3.0)

Box Barge Model

No CapsizeRelease ~120 past wave crest

CapsizeRelease ~240 past wave crest

Validation data for regular waves and fixed body

Yamasaki, Miyata, and Kanai, “Finite-difference simulation of green water impact on fixed and moving bodies” J Mar Sci Technol (2005) 10:1–10.

Progress

Flow over a submerged square

Wave modeling

Shallow-water Stokes waves over a fixed 2D square

Shallow-water Stokes waves over a 3D cube

Determination of Viscous Effects

Flow over a submerged square

Coarse Mesh Fine Mesh

Contours of volume fraction (red = water, blue = air)

u = Uwind

v = Vwind

w = Wwind

! = 0

u = gAk!

cosh k(y+h)cosh kh cos (kx! !t)

v = 0w = gAk

!sinh k(y+h)

cosh kh sin (kx! !t)" = 1

Wave Modeling, Stokes Waves

if z ≤ η

if z > η!(x, t) = H cos(kx! "t) +

12kH2 cos 2(kx! "t)

Wave Modeling, Stokes Waves

H/λ = 1/40, H/d = 0.1, Vg = 2.5, f = 0.63

H/λ = 1/20, H/d = 0.2, Vg = 2.6, f = 0.65

H/λ = 1/10, H/d = 0.4, Vg = 3.0, f = 0.74

Contours of volume fraction (red = water, blue = air)

Wave Modeling, Stokes Waves

H/λ = 1/40, H/d = 0.1, Vg = 2.5, f = 0.63

H/λ = 1/20, H/d = 0.2, Vg = 2.6, f = 0.65

H/λ = 1/10, H/d = 0.4, Vg = 3.0, f = 0.74

Contours of piezometric pressure

Wave reflections created by exit

Shallow water waves over fixed 2D square

H/λ = 1/26.7, H/d = 1/6, Vg = 3.6, f = 0.45

Diffraction waves created by body

Shallow water waves over fixed 2D square

Contours of piezometric pressure

Shallow water waves over fixed 3D cube

Shallow water waves over fixed 3D cube

Contours of piezometric pressure

Determination of Viscous Effects

NSNo slip BC, ν = 1e-6 m2/s

EulerSlip BC, ν = 1e-10 m2/s

Future Work

• Model Development

• Non-reflecting boundary conditions for OpenFOAM

• Evolve wave model for general seas

• 6DOF in OpenFOAM

• Overset Gridding for large-amplitude motion and capsize: DirtLIB and SUGGAR++ (ARL/PSU software by Ralph Noack)

• simpleInterFoam is needed for nominally steady-flow applications