Milovan Perić CD-adapco

Use of STAR-CCM+ in Marine and Offshore

Engineering and Future Trends

CD-adapco is developing simulation capabilities in STAR-CCM+

specifically for marine and offshore applications:

– Wave models

– Motion models

– Fluid-structure interaction, etc…

This is happening in collaboration with software users in industry,

research institutions and classification societies.

The aim of this presentation is to show:

– Examples of application of STAR-CCM+ in marine and offshore

engineering by our customers,

– Trends for future development in this field.

Introduction

All major shipyards in Korea use STAR-CCM+.

One of the main topics is the automation of the simulation process:

– With previous tools, customers were able to generate 2 meshes per day;

– With automated STAR-CCM+ process, they can prepare15 simulations per day (few minutes for Excel data entry, 20 min. mesh generation)…

The automation is based on Java macros and Excel sheets.

Two templates (developed by CD-adapco Korea) are typically used:

– High Froude number (container ships)

– Low Froude number (tankers)

Advantages of automation:

– Faster process;

– Results less dependent on the user (probability for errors reduced).

Example 1: Korean Shipyards, I

Best practices captured – optimal results with minimum effort!

Example 1: Korean Shipyards, II

Automatic refinement for free surface

Automatic refinement for hull vicinity

Automatic refinement for generated waves

Automatic refinement for geometry details

Example 2: Self-Propulsion Test, I

Study by CD-adapco Korea: KRISO container ship + rotating propeller, prediction of self-propulsion point…

Trimmed grid around hull, with local refinements

Polyhedral grid around propeller, sliding cylindrical interface

Example 2: Self-Propulsion Test, II

Comparison of measured (left, B/W) and predicted (right, color) streamwise velocity contours in the plane x/LPP = 0.9911

Example 2: Self-Propulsion Test, III

Comparison of measured and predicted resistance, thrust and torque: a reasonably good agreement is obtained…

Example 3: Virtual Towing Tank, I

A validation study at Brodarski Institut, Zagreb, Croatia

Example 3: Virtual Towing Tank, II

A very good agreement between experiment and simulation is obtained. Such studies were performed for other hulls as well, with a similar success.

Example 4: Scale Effects

At Brodarski Institut, scale effects for pod-drives were investigated by comparing simulations at model and full scale. Model scale simulations are validated against experimental data.

Example 5: Lifeboat Water Entry, I

H = 33 m H = 43 m An analysis of collapse of air bubble on aft bulkhead of lifeboats was performed; the results were very close to full-scale tests (3-4%) for two drop heights. Air compressibility was very important…

Analysis by

Example 6: Oil Collector, I

The objective of this project was to find out how much oil is collected and goes through the pump in the original design, and then to optimize the design with respect to collecting capability.

Simulation by for

Example 6: Oil Collector, II

The final design that was built and used has been substantially modified relative to the original design – based on simulation results. The collection efficiency has been substantially improved through simulation…

Example 7: Wave Impact, I

Simulation of wave impact onto a platform in shallow water by DNV (will be presented at OMAE-conference 2012).

Example 7: Wave Impact, II

Wave impact on an oil platform: Coupled simulation of flow using STAR-CCM+ and deformation of platform structure using ABAQUS. Simulation by CD-adapco Engineering Services for Chevron.

Evidence of damage on a platform after it was hit by a hurricane Deformation in a simulation: good agreement with field observation…

Problems with ballast water:

– Sediment (reduces payload, restricts water flow and delays de-ballasting,

leads to increased fuel consumption due to extra weight)…

– High cost if de-ballasting cannot be completed during time slot at terminal

(less cargo can be loaded, vessel blacklisted at terminal…)

Example 8: Ballast Water Handling

Simulations performed by Germanischer Lloyd

Leakage assumed to be a small opening in the wall of a high-pressure

gas container.

Expansion to atmospheric pressure results in a high Mach number jet

flow, forming a barrel shock and Mach disk…

Example 9: Gas Dispersion due to Leakage, I

Konturplot von Machzahl- (links) und Temperatur- (rechts) verteilungen für Naturgas Leckströmung durch eine runde Lecköffnung in einer 30 Bar-Rohr

Simulations performed by Germanischer Lloyd

Objective: Assessment of risk resulting from natural gas leakage in a

closed space housing a compressor and a turbine.

The aim was to determine areas with dangerous accumulation of air-gas

mixture…

Example 9: Gas Dispersion due to Leakage, II

Low Velocity Areas Areas above 50% LEL Areas above 100% LEL

Cold

Sur

face

s

Hot S

urfa

ces

Example 10: Roll Damping

Research Project „Best Roll Damping“

University of Duisburg/Essen TU Hamburg-Harburg

Modern ship hulls form with different bilge keels

3 years research project to reduce roll motion

Simulations performed by two universities and Germanischer Lloyd using STAR-CCM+

Experiments by SVA Potsdam

Example 11: Erosion by Cavitation, I

Simulation by

Water flow at 35 m/s

3° angle of attack

75 hours duration of experiment

Simulation (DES) over several periods of shedding

Evaluation of „Erosive Potential“

Good agreement with experiment

Experiment

Simulation

Example 11: Erosion by Cavitation, II

Damage to rudder due to erosion

CFD prediction based on two fixed rudder positions (±4 deg).

One needs to perform simulations at different operating conditions to produce an estimate of cavitation erosion probability…

Simulation by

Example 12: Ship-Ice Interaction

Analysis of interaction between ice pieces and structures using DEM in STAR-CCM+ and co-simulation with ABAQUS

Objective: Assessment of risk of damage caused by impact of ice pieces on sensitive parts of structure (like propeller blades, rudder etc.).

Example 13: Ship Launching

Analysis of side-launching: - Load on structure - Ship motion

Simulation by

Exhaust dispertion

Fire simulation

Simulation of lowering of subsea equipment (which wave conditions are

allowable)

Simulation of installation of offshore equipment (wind turbines, jack-up

platforms etc.)

Vortex-induced motion

Simulation of drill ship stability (how to increase the operating window)

Optimization of vessel shape (coupled with FriendshipFramework)

Wake assessment

Shaft bending moments

Wind drag

Wave-added resistance

… etc.

Other Applications

Superposition of motions

Overset grids

Multi-component VOF with

phase change at free

surface

Recently Released New Features

Several new features which were requested by users will be implemented in STAR-CCM+ and become available in future releases:

– Additional motion models (prescribed motion and additional DOF)

– Beam models for simplified treatment of ship deformation in FSI

– Automatic set-up of standard virtual tests (PMM, zig-zag, circle…)

– Automatic local mesh refinement and coarsening (controlled by overset grid motion or flow features)

– Hydro-acoustics and vibro-acoustics

– Coupling to potential flow models for wave propagation over long distance

– … and many other improvements in collaboration with customers and research institutions.

Future Developments