CFD simulation Capabilities for marine / offshore Applications

CFD SIMULATION CAPABILITIES
FOR MARINE / OFFSHORE
APPLICATIONS
3/15/2017
Dr. Rafael Izarra
Burak Ozturk, PhD, CEng
Arindam Chakraborty, PhD, PE
VIAS - Virtual Integrated Analytics Solutions
1400 Broadfield Blvd. Suite 325, Houston TX 77084
Phone : +1 - 832 - 301-0881
rizarra@viascorp.com
www.viascorp.com

© 2016 Virtual Integrated Analytics Solutions Inc.
• VIAS Company Overview
• Major Design Challenges in Marine and Offshore.
• How Can CFD Help?
• Some CFD Simulation Capabilities
• State-Of-The-Art CFD Technologies
• Case Studies
• Summary
Content
CFD for Marine and Offshore - Webinar

Overview of Company
Engineering
Consultancy
Training
Hardware
Software
• Cross Industry Experience
• Expertise in Multiple Domains / Disciplines –
FEA, CFD, IM including Flaw Evaluation,
Materials & Corrosion, Data Analytics
• Houston based Consulting
• Satellite Offices in Other US Cities
(Cincinnati, San Francisco, Detroit)
• Solution Partner of Dassault Systèmes
SIMULIA Products – Abaqus, Isight,
fe-safe, Tosca, 3DX
• Provide Training, 3D Printing, and AM
Simulation Services

Our Services
1
2
5
We provide customer tailored software solutions with
complete implementations
Through our experienced consultancy services our
clients will be able to reach our global talent pool.
We transfer our experience to clients through our
software enhanced training solutions
6
Customers can optimize their investment through our
hardware solutions
4
Our design process utilizes data analytics solutions to
provide intelligent design, reduce costs and risks and
improve safety
3
Through our testing solutions we measure material
properties that are needed to design and validate product
design

CHALLENGES IN
MARINE / OFFSHORE INDUSTRY

• Fluid resistance minimization for high speed boats and ships
• Prediction of the hydrodynamic effects of wave impact on hull structure for varying
sea states (hogging and sagging)
• Slamming of hull structure on water surface causes high stresses
• Whipping and springing issues as ship sizes get ever-larger
• Propeller cavitation effects and consequent noise and pressure fluctuations on
hull
• Sloshing in ship tanks with resultant loading on structure and ship stability
considerations
• Loading due to fluid currents and vortex induced motion (VIM)
Major Design Challenges in Offshore & Marine

• Prediction and analyses of propulsion phenomenon such
as
-Propeller-ship-rudder interactions
-Hydrodynamics and cavitation effects
• Generate desired sea states and a time-accurate
simulation of wave propagation to study wave impact
• Simulate breaking waves and induced motion or
deformation of the structure
• Ship slamming, whipping and springing issues can be
simulated and addressed to optimize ship design.
• Accurately analyze hydrodynamic responses and induced
loads with methods like Dynamic Fluid-structure
interaction (DFSI) to develop the best possible design
How can CFD help in design and optimization?

CFD Simulation Capabilities
Sea State Generation
Seakeeping and
maneuverability
Prediction
/Optimization of
propulsion effects
Cavitation control
Fluid resistance
analysis on hull
Sloshing in ship tanks
Wave Impact loading
(Whipping / Springing)
Hull Slamming
VIMs on ships/offshore
structures, Springing,
Ringing
Vessel Wind Loading /
Dispersion

• Sea State Generation:
▪ Varying sea state development different wave models
➢ Linear 1st order wave theory (small amplitude
waves)
➢ Non-linear Stokes 5th order wave theory
➢ Pierson-Moskowitz and JONSWAP spectra (long-
crested irregular waves
➢ Irregular sea states: Superposition of linear waves
with arbitrary propagation direction, amplitude and
periods
• Internal wave generation:
▪ Waves generated due to mass structure motion
(radiated), sinks (injection & suction of water)
▪ Simulation of reflected waves off structures
▪ Beach simulation (resistance to vertical fluid velocity)

• Sea Keeping and Maneuverability:
▪ Vessel responses utilizing motion RAOs
▪ Motion analyses of vessels for up to 6 degrees of
freedom
➢ Displacements: Sway, Surge, Heave
➢ Rotations: Pitch, Roll, Yaw
➢ Velocities: Angular / Translational
▪ Vessel interactions with varying sea states and wave
heading directions
▪ Hydrodynamic loading on hull due to wave slap /wave
slam and stability issues with the same
➢ Pressures on hull structures
➢ Forces and overturning moments on the overall
vessel structure.
Ship hull and cargo fluid motion due to wave
interactions

• Propulsion Effects:
▪ Steady-state simulation for a single propeller or
multiple propeller blades with periodic conditions
▪ Detailed analysis of propeller- rudder interactions
and effects on vessel motion / performance
▪ Analysis of hydrodynamic loads / pressures on
blades
▪ Simulation of propulsion enhancing devices such
as water jets and design optimization to obtain
best possible performance
▪ Simulation of propeller dynamic pitch and
propulsion system wakes

• Cavitation simulation and control:
▪ Predict the onset of cavitation around the
propeller blades
▪ Cavitation analysis at varying angles of attack
of propeller blades for variable pitch design
▪ Simulation of rates of collapse of cavitation
bubbles and estimation of cavitation erosion
/ damage on propeller blades and rudder
vanes
▪ Predict cavitation-induced noise and
pressure / load fluctuations on the hull and
blades
▪ Optimize propeller blade design parameters
(hydrofoil topology, velocities, no. of blades,
angle of attack, chord length etc.)

• Fluid Resistance analysis :
▪ Prediction of fluid resistive forces in calm water and
in wavy/stormy conditions
▪ Frictional resistance analysis at varying speeds on
bare and appended hull structure.(Deep V hulls,
round bottom / flat hulls, and multi-hulls)
▪ Parametric design optimization of hull structure and
rapid assessment of hull resistance
▪ Determination and minimization of skin friction co-
efficient and pressure drag forces along hull
▪ Mean flow pattern determination around the hull
▪ Design ship/submarine hulls and remotely/ autonomous
operated underwater vehicles (ROV/AUV)
Fluid Flow over AUV hull

• Ship Tank Sloshing:
▪ Simulation of fluid motion and impact
loading in partially filled tanks during
vessel movement. This includes
➢ LNG tanks for FPSO’s and tankers
➢ Fuel tanks in ships / boats
▪ Determination of natural frequency of
fluid motion for different fillings
▪ Ship / Tank design modifications,
iterations and optimization based on
fluid motion frequency
▪ Stability and containment issues of
equipment and complete vessel due to
moving fluids
For varying filled conditions
Volume fractions

• Wave Run up and Impact Loading:
▪ Simulation of breaking waves kinetics and dynamic fluid
interaction with structure / vessel (DFSI)
▪ Wave-in-deck loads and induced motion and
deformation of structure (coupling with FEA code)
▪ Predictions of loads / forces as a wave interacts with the
structure. This includes
➢ Positive lift force (initial water entry phase)
➢ Negative downward forces (water exit phase)
➢ Added mass forces
▪ Interaction of water with wave energy converters /
turbines / wave barriers and subsequent design
optimization
▪ Hydro-elastic model development with wave interaction
for analysis of vessel whipping and springing
Water interaction with Wave Barrier
Loading on offshore platform
Whipping on hull structure due to wave
interaction (Exaggerated deformations)

• Hull Slamming:
▪ Hull penetration of vessel on flat free water
surface
▪ Analysis of structure dropping into water (e.g. .
Lifeboats)
▪ Pressure impulse and induced stress
simulation during vessel slamming
▪ Prediction of hit point effects for varying
positions of wave crests and troughs
▪ Deck water entry (due to green water, run-up)
to improve design
Slamming- Speed Boat
Life boat water entry

Vortex, Fluid motion induced vibrations:
▪ DFSI involving fluid water and ship hull structures /
offshore platforms and wind turbines
▪ Riser simulation, analysis and mitigation of
➢ In-line VIVs
➢ Cross flow VIVs
➢ Hybrid VIVs
▪ Springing and Ringing analysis of offshore
structures (mainly offshore platforms and wind
turbines)
▪ Offshore fixed structure response due to current
and wave impinging (Global Performance).
▪ Moored vessel vibration loading analysis due to
current / wave interaction

• Wind loading on Vessel and Dispersion:
▪ Air flow analysis around vessel structure
▪ Drag force analysis on ship topside structures
and design optimization to minimize wind
loading
▪ Estimate of airflow distortions over deck
structures
▪ Structure ventilation assessment
▪ Exhaust plume behavior
▪ Fire and smoke modelling
▪ Fuel / Oil leakage and dispersion

Key M&O Simulation Features:
▪ Handling of Complex Geometries
▪ Grid Adaptation to Moving Bodies
▪ Rigid Motion
▪ Mesh Morphing
▪ Overset
▪ Physics
▪ Volume of Fluid
▪ Turbulence Models
▪ Cavitation
▪ Phase Change
▪ Multiphysics and Coupling
▪ Fluid-structure interaction
▪ Wave Generation
▪ Design optimization & innovation
State-Of-The-Art CFD Technologies

Problem definition:
• CFD & FEA coupled analysis on fluid flow and structural
deformation of floating platform.
➢ Wave slamming on rigid wall by breaking wave &
water bullet.
➢ Rigid & elastic structure on wave slamming conditions.
➢ CFD for fluid domain and FEA for structural domain
Key Interest:
• Violent wave impact are very sensitive to shape of
incident wave.
• Handling different types of wave types, air entrapment
and accounting hydro-elastic effects
• Imposing spatial phase variation between hull and wave
makes the study more complex.
Case 1: Wave slamming on offshore platform

Model Details:
• Modelling of Integrated fluid and structural domain
• Scaling the model for computation simplicity.
• Modelling of sensor system
• Structured meshing.

Results:
• Instantaneous pressure before, during & after the wave impact.
• Impact pressure wave analysis on the scaled model and translation/ calibration of results to
full scale model.

Problem definition:
The ship vessel resistance plays an important role in
determining the operability of the ship with respect to
change in sea states.
• CFD analysis of vessel resistance, trim, roll and
various responses with respect to wave amplitude.
• The motion and resistance analysis is done with 6
DOF.
• Studying the Free surface change in the near vicinity
of the vessel with respect to vessel operation.
Case 2: Marine resistance prediction

Model Details:
• The ship is modeled and placed inside a bounding
box in which volume fraction of fluid is described
• The free surface effects are accounted using volume
of fluid approach.
• Trimmed hexagonal grids for the general domain with
local refinement of prism mesh in arears of interest.

Results:
• Volume distribution and free surface visualization
• Shear stress and pressure distribution imposed by
the ship’s hull on the free surface of the sea.
• Monitors for roll, trim, pressure with respect to
change in time.

Summary
• CFD can provide solutions to multiple marine associated issues as well as
answer effects from different design considerations. It includes:
➢ Hull sea keeping and maneuverability for high sea states
➢ Detailed analysis of propeller and Propeller-Rudder-Hull interactions
➢ Ship fluid (water and/or air) flow resistance analysis
➢ Hull slamming, wave run up and impact loading
➢ Vortex, fluid motion induced vibrations/springing & ringing
➢ Ship Tank Sloshing
➢ Vessel dispersion and accidental releases
• Use of state-of-the-art CFD technologies allows comprehensive geometry
description and analysis of real accurate design (+ Hardware).
• Answer many other “WHAT IF” questions.

Thank you
DR. RAFAEL IZARRA
rizarra@viascorp.com
1400 Broadfield Blvd. Suite 325, Houston, TX. 77084
Phone: +1 (832) 301-0881
www.viascorp.com

Appendix

Case Study 1: VIM of Spar platform
• Platform Vortex Induced Motion (VIM)
– Dynamic Fluid Body Interaction
– Solves 6-DOF motion
– Spar modelled as a rigid body
– All geometric details included
– Input wave based on potential flow
– Results:
› Motion of the spar
› Effect of current on spar motion
› Drag & Lift
› Green water & Run-up
› Bulwark design
› Wave slamming

• Naval Architecture
– Dynamic Fluid Body Interactions
– Up to 6 degree-of-freedom motions
– Wave Definition (1st order, 5th order, Irregular)
– Results:
› Pressures
› Forces
› Translations: Sway, Surge, Heave
› Rotations: Pitch, Roll, Yaw
› Velocities: Angular, Translational
› Wave Slap
› Wave Slam
Case Study 2: Hydrodynamic loading on ship

• Wave Run-up on a Semi-Submersible Platform
➢ Free Surface Analysis
➢ Green water and Air Gap Analysis
➢ Wave Definition: 5th Order Stokes Wave
Experiment
CFD
Case Study 3: Wave run up loading on a
Semi-submersible

• Wave Slamming on Semi-Submersible Platform
– Dynamic Fluid Body Interactions (2 degree-of-freedom motion)
– Free Surface Analysis
– Air Gap Analysis
– Wave Definition: 1st Order
– Results:
› Pressures
› Forces
› Motion: Heave
› Motion: Pitch
› Wave Slamming
› Wave Heights
Case Study 4: Wave slamming on a Semi-
submersible

CFD simulation Capabilities for marine / offshore Applications

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