ReFRESCO-General-Jan2015

ReFRESCO
A GENERAL MULTI-PHASE CFD CODE FOR THE MARITIME,
OFFSHORE AND RENEWABLE ENERGY INDUSTRY

ACKNOWLEDGEMENTS
• We acknowledge the work done by the following people
(developers/users) that made this presentation possible:
Guilherme Vaz, Martin Hoekstra; Chris Klaij; Luis Eca; Jaap Windt; Douwe
Rijpkema; Guilherme Rosetti; Serge Toxopeus; Maarten Kerkvliet; Bart
Schuiling; Arjen Koop; Frederick Jaouen; William Otto; Arjan Lampe; Pierre
Crepier; Xavier Quenet; Frans-Hendrik Lafeber; Chris Willemsen; Roderick
Kuin; Andre Fujarra; Nicholas Carette; Xavier Ariño; Antonio Maximiano;
Jesse Slot; Luis Rueda; Joost Sterenborg; Patrick Schrijvers; Henry Bandringa;
Xin He; James Hawkes; Filipe Pereira; Michel Make; Joao Baltazar; Thomas
Lloyd; Gerson Fernandes; Sasha Zverkhovskyi; Simon Burmester; Jan-Albert
van Ree

OVERVIEW
• Introduction
• Theoretical Formulation
• Numerical Formulation
• Relevant Features
• Quality Control
• Documentation & Support
• Applications/Portfolio...
• Current Developments & Future Plans
• Cooperation
• Conclusions

INTRODUCTION
• ReFRESCO
• It is a multiphase viscous-flow CFD code, targeted, verified and validated
exclusively for maritime-related (ships, offshore, renewables) applications.
• Started to be developed in April 2005.
• People working on ReFRESCO (NL, PT, BR, UK):
• 8 developers
• 35 users
• 4 PhD students, 4 Post-Docs
• Since 2005, >40 students (Msc and trainees)

INTRODUCTION
• ReFRESCO vs. Other codes
• Commercial codes (CFX, FLUENT, STAR-CCM, Fine-Marine): very general, robust but
not accurate enough (for us). Too expensive! No insight in algorithms. Difficult to
modify or couple with other tools. Not relevant for CFD research, like done
@MARIN.
• Open-source codes (OpenFOAM,...): not a code but a set of libraries. Needs a lot of
CFD-developer knowledge. Very general. Results severely user dependent.
Impossible to verify and validate since it is not a code. Basic CFD schemes.
• Research codes: closed for other partners, usually not using IT-state-of-the-art
features, no quality control, and not user friendly...
• ReFRESCO is an “open-usage-research commercial code”. MARIN cooperates with
Universities in its development, and with its partners in its verification&validation
(see ReFRESCO-Operation later). And “commercial” since MARIN performs
calculations for clients.

THEORETICAL FORMULATION
• What is solved inside ReFRESCO:
• Momentum equations
• Mass/pressure equation (segregated or coupled)
• Turbulence equations (1-eq, 2-eq, SAS/DES-like)
• Volume-fraction transport equations (free-surface,
cavitation, general species)
• Motion-related equations (AFM, RFM, MVG,
Interfaces, 3DOF EquationsOfMotion)
• Constitutive equations (multiphase flow
formulation)
• General transport equation is the basis.
• Important terms for discretization:
• Unsteady term
• Convection fluxes
• Diffusion fluxes
• Source terms
• Face-center vs cell-center
• Boundary conditions
THEORETICAL FORMULATION

NUMERICAL FORMULATION
• Finite Volume Approach
• Discretization of the integral eqs in the physical space. 2nd order.
• Collocated arrangement: quantities defined at cell centers. Pressure-velocity
coupling using PWI.
• Segregated method using SIMPLE. Coupled method using Krylov methods and
SIMPLE, SIMPLER as pre-conditioners.
• Face based approach:
• Permits arbitrary shape cells and unstructured grids.
• Face values calculated by interpolation based on data in only two cells.
• Discretization stencils are limited to face-neighbour cells and gradients.

• Discretization of general transport eq.
• Convection: upwind, blending, QUICK, TVD, HRIC, CICSAM, ReFRICS.
• Diffusion: 2nd order central scheme.
• Gradients: 2nd order Gauss and least-squares schemes.
• Face-interpolation: 2nd order central with excentricity correction.
• Time-discretization: (implicit) 1st order Euler, 2nd order three-time-level.
• Boundary-conditions: 2nd order.
• Domain decomposition parallelization:
• Computational domain split in sub-domains.
• Each sub-domain computed by each processor.
• Information transfer done by “ghost” cells.
• MPI (Message Passing Interface) is
used for transfer information.

• Parallelization
• Algorithm
• Solvers

• Scalability and hardware
- Tested at clusters:
256(MARCLUS2)&1600 cores(MARCLUS3)@MARIN(Nl).
2000 (TPN) @USP(Br).
2000 (Iridis4) @UoS (UK).
- ReFRESCO scales well with the number of nodes.

IT ASPECTS
• Software development:
• Targeted for Linux systems
• Scientific core in Fortran90
• Wrappers to some external libraries in C
• Object-oriented (as much as Fortran allows it ) data-structure & modules
• Usage of several open-source libraries
• OpenMPI/MPICH/IntelMPI: MPI libraries optimized
• PETSC: iterative linear-system solvers libraries (powerful!)
• MKL: direct linear-system solvers libraries (intel optimized)
• HDF5: data-storage standard, permitting also MPI-parallel operations.
• CGNS: NASA/Boeing/AIAA standard for CFD data storage
• (Par)Metis: domain decomposition algorithms.
• HYPRE/ML: other iterative preconditioners/solvers
• libXML, XSD, perl: Linux XML, perl libraries
• Doxygen: automatic documentation

IT ASPECTS
• Software development:
• Parallel Programming Eclipse version as IDE and several extra plugins
(photran, svn, XML/XSD)
• Compilation/Installation of external-libs and own-libs using (own-created)
makefiles and bash scripts. Platform dependent: code already installed at
Marclus1, Marlcus2, Marclus3, Sara-Nl, RuG-Nl, IST-Pt, USP-Br, UoS-UK.
• Tight integration with svn
• MPI programming, memory checking, debugging, profiling done using
• open-source tools: valgrind, gprof, petsc-log
• commercial tools: idb, vtune
• (others being tested… totalview, Score-p, Vampyr, tau, jumpshot,…)

IT ASPECTS
• Others:
• Input:
• XML, validation with XSD
• XSD to XML using xslt (automatic)
• XSD to Fortran code using perl
(automatic)
• CGNS for grids
• Output:
• XML
• ASCII
• CGNS for solution
• Automatic documentation of the code
using doxygen
• Automatic logging and tracing of the
code via PETSC.
• User-defined F90 routines to interact
with main code

QUALITY CONTROL
• SVN for code versioning/control (strict)!
• Automatic code control/benchmarking:
• testSuite
• automatic procedures for testing the code against developers bugs. Comparison with
previous versions and reference data (other codes).
• Easy cases and small grids. All cases run in 15 minutes.
• validationSuite
• Automatic procedure for checking differences/improvements of the code by comparing
with experimental data.
• Complex cases and medium/fine grids.
• verificationSuite
• Automatic procedure for checking differences/improvements of the code by analyzing
errors. Use of analytical solutions and MMS.
• Several grids for order of accuracy determination.
• performanceSuite
• Automatic procedure for checking code performance (cpu time, scaling, memory usage).
Compare with previous versions
• Several grids. Several cores.

QUALITY CONTROL
• Automatic code control (examples)

DOCUMENTATION & SUPPORT
• Internet:
http://www.marin.nl/refresco
http://www.marin.nl/refresco-community
• Modern software support:
• All refresco-related papers;
• MODS (general online documentation)
• Bugs & Issue tracking system (MITS);
• Mailing-list (developers an users);
• Tutorials;
• Forum (work-in-progress);
• Best-practice guidelines for typical
maritime-related problems (work-in-
progress).

CURRENT FEATURES
• Pre-processing:
• Can deal with any kind of grids and cell types!
• Accepts grids from grid-generators such as SnappyHexMesh, ICEM-CFD, Gridpro,
HEXPRESS, Pointwise, or in-house tools.
• Input : grid, in CGNS file format, plus an human-readable XML file.
ICEM-CFD
GRIDPRO
HEXPRESS
POINTWISE

CURRENT FEATURES
• Solver:
• Higher-order discretizations & boundary conditions.
• Segregated & coupled solver.
• Moving objects (RFM, AFM, MVG/ALE).
• Non-conformal and Sliding grids.
• Deforming grids.
• Automatic grid refinement.
• Turbulence models (RANS k-epsilon’s, k-omega’s, DES, SAS, PANS, LES)
• Free-surface models (surface-capturing/VOF).
• Cavitation models (Sauer, Zwart, Kunz, Singhal).
• 3/6DOF Equations-Of-Motion.
• Propeller modelling: Actuator-Disk (traditional or improved), RANS-BEM coupling or
RANS-RANS.
• Wave modelling: linear theory, 2nd, 5th order regular waves, irregular waves using wave-
flap motion.
• Post-processing:
• Output also in CGNS format and engineering data in ASCII format.
• CGNS can be visualized and processed with Tecplot (the one most used@MARIN),
Paraview, Visit, Amira, FieldView, etc.

CURRENT FEATURES
• Couplings:
• ReFRESCO-PROCAL
• Propeller modelling inside a RANS grid/calculations by using a body-force field
coming from PROCAL BEM code.
• ReFRESCO-Excalibur/FWH
• Pressure fluctuactions due to propeller simulated with RANS computed by
Excalibur BEM code.
• Or coupling with Ffowcs-William/Hawkings equations for accustics.
• ReFRESCO-Rapid/PARNASSOS
• (Fixed) Free-Surface geometry coming from Rapid/PARNASSOS used as
boundary in the RANS grid/calculation.
• ReFRESCO-XMF (work in progress)
• FreDyn, AnySim.
• Two-ways of coupling:
• 1) Hydrodynamic forces calculation by ReFRESCO and EoM solved by XMF
and send back to ReFRESCO;
• 2) All done by ReFRESCO but complex structural forces modelled by XMF.

APPLICATIONS
Continue
Complex Ships Submarines Manoeuvring Propellers
Turbines Current Loads Wind Loads VIV & VIM Thrusters
Propulsion FreeSurface&Waves Roll-Damping
Cavitation
Commercial !

APPLICATIONS – COMPLEX SHIPS
- Complex appended ships.
Experiments ReFRESCO ISIS-FIneMarine

- Complex appended ships.
Model-Scale
Full-Scale

- Energy-Saving(?)-Devices

APPLICATIONS – SUBMARINES
- DARPA SUBOFF AFF-8 (USA)

APPLICATIONS – SUBMARINES
AFF-8, 18 Deg
- “Walvis” (NL) DARPA SUBOFF (USA)
Deep water
validation
SUBOFF AFF-1
Rotating arm
validation

APPLICATIONS – SUBMARINE
- Joubert Generic Submarine / BB1 (Australia)

APPLICATIONS – SUBMARINE
- BB1 sail flow optimisation

APPLICATIONS – MANOEUVRING
• Use of CFD to improve fast-time manoeuvring predictions (HTC)
Zig-zag Turning circle
Original
Original
New
New

Black symbols: exp, Blue: CFD
• Shallow water manoeuvring (KVLCC2)

• Rudder forces (HTC)

• Towed stability and resistance optimisation
Original (Giant 4)
• Stability index -0.03
Optimised (Giant 5 III)
• Stability index +0.10; Resistance -14.2%

APPLICATIONS – PROPELLERS
- E779A propeller

- EU Project leading-Edge propeller

- Ducted propeller
J=0.3 J=1.0

APPLICATIONS – CAVITATION
Sig=1.4
Sig=1.3Sig=1.2
NACA0015
- Wings

- E779A propeller
J=0.71, Sig=4.0 J=0.71, Sig=3.0 J=0.71, Sig=2.2
J=0.71, Sig=1.76 J=0.71, Sig=1.00 J=0.71, Sig=0.63

ReFRESCO OpenFOAM Star-CCM+
Star-CCM+CFXFineMarine
PROCAL
Experiments
J=0.71, Sig=1.763

- E779A behind plates.
- J=0.897, Sig=2.5.

APPLICATIONS – CURRENT/WIND TURBINES
- Southampton Turbine

- TOCARDO (FS) Turbine

• Analysis of the flow around 5MW NREL
turbine, both model-scale and full-scale
conditions.
• Based on CFD results MARIN designed a
new model-scale MSWT (MARIN stock
wind turbine) that delivers the same
thrust as NREL at full-scale.

• MSWT Results
• Fully separated at low TSR
• Partially separated at operating condition

- MARIN Wind Stock Turbine

APPLICATIONS – CURRENT LOADS
- Current Loads of Offshore Structures

- Current Loads of Offshore Structures
Model-scale
Full-scale

- Current Loads and Blockage Effects

APPLICATIONS – WIND LOADS
- Wind Loads

APPLICATIONS – WIND LOADS
- Wind Loads - Shielding

APPLICATIONS – VIV/VIM
- Turbulence Modelling (Cylinders)
Re=1E4, K-Omega 1994
Re=1E4, K-Omega 2003 + SAS
Re=500, DNS

- Turbulence Modelling (BFS)

- Cylinders+FreeSurface

- Cylinders+FreeSurface
Re=4E4, K-Omega 1994
Cd_avg
Exp: 1.00
CFD: 0.95

- Fixed Risers

- Cylinders+Imposed Motion (XY)
Re=100
X/D=.2
Y/D=1.0
fx/fy=2.0

- Cylinders+Free-Moving (coupling with 2DOF Equations-Of-Motion)
Re=28000
X,Y free
m*ζ=0.08
Ur=4.5

- Semi+Free-Moving (coupling with 3DOF EoM)
Re=1E5
X,Y,yaw free
Ur=7.0, m*=1

- Semi+Free-Moving (coupling with 3DOF EoM)-Decay

- Semi+Free-Moving (coupling with 3DOF EoM)-VIM

- Objects+Imposed Motion

- Buoys+Imposed Motion+Deforming-Grids

APPLICATIONS – THRUSTER INTERACTIONS
- Thruster modelling vs simulation

- Thruster-Thruster Interaction

• SI (1059 rpm) x/D=1.0
Experiments
N=1059rpm
0rev 1rev 2rev
3rev 4rev 5rev
ADs (n=1059rpm)

- Thruster-Hull Interaction
Config-1 Config-2
Config-3 Config-4

- Thruster-Thruster-Hull Interaction

B1=5deg, B2=0degB1=0deg, B2=0deg
B1=10deg, B2=0deg B1=5deg, B2=5deg

0%
20%
40%
60%
80%
100%
0
330
300
270
240
210
180
150
120
90
60
30
T3
0%
20%
40%
60%
80%
100%
0
330
300
270
240
210
180
150
120
90
60
30
T1
CCW
CW
Static
CFD

APPLICATIONS – PROPULSION & INTERACTIONS
- RANS-BEM Coupling

- RANS-BEM Coupling
Nominal Self-Propulsion

- RANS-BEM Coupling
Propeller => BEM

- RANS-BEM Coupling
2.9% less Power 

- RANS-RANS (Non-Conformal Interfaces)

- RANS-RANS (Non-Conformal Interfaces)
NoDuct
D7 D1
D3 D4
D5 D6

- RANS-RANS (Sliding Interfaces)

Exps without rudder and with
free-surface!
Calcs with rudder and without
free-surface !
ReFRESCO
ISIS-FineMarine
FreSCo+

0deg 36deg 72deg

APPLICATIONS – FREE-SURFACE & WAVES
- Duncan Foil
Quick ReFRICS

- Incoming Waves (Linear Theory)
- Regular waves

- Incoming Waves (Flap-Motion Theory)
- Irregular waves created by flap motion bc.

- Transom-stern flow
Fr=2.86 Fr=2.00 Fr=1.43

- Dam-break

• L = 4 m, Fn = 0.25, no sinkage and no trim
• Domain: 5L x 1L x 0.9375L
• 3.17M cells
- Wigley Hull Damping Area
UnsteadySteady

- DTMB 5415
- Ship and basin walls
- Fn=0.28
- Unsteady calculation…

- DTMB 5415

APPLICATIONS – ROLL-DAMPING
- 2D Sections, No Free-Surface

With bilges, f influenceWith bilges, A influence
- 2D Sections, No Free-Surface

- 2D Sections, No Free-Surface + Deforming-Grids

- 2D Sections, With Free-Surface, One Cylindrical Grid

- Anti-Roll Tanks

CURRENT REFRESCO DEVELOPMENTS
- Current ReFRESCO Developments (2015-2020):
- V&V and MMS… Constant work!
- Performance, robustness … Constant work!
- Improving non-conformal/sliding grids.
- Improving deforming grids.
- Robustness and accuracy of free-surface modelling.
- Improve and Extend 6DOFs EquationsOfMotion (internal and external).
- “Unsteady” automatic-grid-refinement.
- Heterogeneous parallelization (CPU-GPU, CPU-CoProcessors, MPI+OpenMP).
- SAS/DES/PANS and LES turbulence modelling.
- Transition modelling.
- Fluid-Structure Interaction.
- Overlapping grids.
- Using also our cooperation partners and MarinAcademy.

CURRENT APPLIED RESEARCH WITH REFRESCO
- Internally using ARD.
- JIPS, EU projects:
- STREAMLINE
- GRIP
- Refit2Save
- TRUST
- DISCO
- CRS-Sharcs
- CD Propeller Series
- VIM
- Roll
- WindLoads
- Blue Mining
- MoonPool
- …
See/Check a list of all projects@:
http://www.marin.nl/web/JIPs-Networks/Public.htm

COOPERATION
- IST (PT):
- Prof. Eça (developer of PARNASSOS and now of ReFRESCO)
- Eng. F. Pereira (SAS/DES/PANS/LES)
- Prof. Falcão de Campos, Dr. Eng. Baltazar (propeller flows).
- RUG (NL):
- Prof. Verstapen, Prof. Wubs, Eng. Bandringa (SPS and LES).
- USP (BR):
- Prof. Fujarra, Eng. G. Rosetti (ReFRESCO+FSI for VIV/VIM problems).
- Eng. G. Rosetti (Turbulence, transition and roughness modelling).
- TUDelft (NL):
- Prof. C. Vuijk, Dr. Ir. Xin He (state-of-the-art solvers).
- University of Southampton (UK):
- Prof. S. Turnock, Eng. J. Hawkes (parallelization & overlapping grids).
- Dr. Ir. Thomas Lloyd (cavitation and acoustics)
- TUTwente (NL):
- Prof. H. Hoeimakers, Prof. Edwin van der Weide, Dr. Ir. Sietse Jongsma (Fluid-
Sructure-Interaction)
- Chalmers University (Se):
- Prof. R. Bensow, Dr. C.Eskilsson (Hydrodynamics)

REFRESCO-OPERATION
- We share the use of ReFRESCO, and our HPC clusters, with the Maritime
Industry within the ReFRESCO-operation consortium…
- Why?
- Our partners/clients want to do themselves CFD calculations.
- CFD packages have very “impersonal” support.
- CFD packages are expensive: prices per license, user, cores!
- Hardware (Clusters) for CFD codes is expensive, needs maintenance and peculiar
(difficult to find) expertise’s.
- Verification & Validation of commercial CFD codes has to be done by the users,
since the developers cannot test all kinds of applications.
- Dedicated CFD code needed for accurate solution of hydrodynamic problems.
- For more info see www.marin.nl/refresco-operation...

CONCLUSIONS
- ReFRESCO is a open-usage-research-commercial code.
- ReFRESCO is a CFD code targeted, verified and validated exclusively for
maritime applications.
- ReFRESCO quality control is daily business.
- ReFRESCO application, verification and validation has been for several
maritime-relevant problems.
- With the use of MARIN Internal ARD funds, JIPs, MarinAcademy and
Partners, the developments, applications and associated verification and
validation will continue. We will keep you posted…
- ReFRESCO-Operation opens the doors to the usage of ReFRESCO by external
partners: at their machines and/or at our HPC clusters.

ReFRESCO-General-Jan2015

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