Primary Investigators

Fred Stern, Pablo Carrica, Bob Wilson, Joe Longo

Sponsors

Dr. L.P. Purtell, Office of Naval Research

Project Duration

October 1, 2003 - September 30, 2006

Overview

The proposal has three primary objectives: (1) extend CFDSHIP-IOWA including modeling and numerical methods for large amplitude motions and maneuvering simulations; (2) development advanced towing tank measurement systems and acquisition EFD benchmark data for CFD validations; and (3) development/application EFD and CFD UA methodology and procedures.

An integrated CFD, EFD, and UA building block approach is used whereby successive steps based on previous knowledge.  Both idealized (surface-piercing flat plate and NACA 0024 foil) and practical (DTMB 5512) geometries are used for physics and model development and benchmarking for practical applications, respectively.  Surface-piercing flat plate geometry used for research on effects of wave-induced pressure gradient and free surface on turbulence and on contact line phenomena.  Surface-piercing NACA 0024 foil used for research on wave-induced separation, including naturally unsteady free surface vortex flow and separation, unsteady pressure, turbulence, free surface waves and wave breaking and air entrainment.  DTMB model 5512 used for research on large amplitude motions and maneuvering, unsteady boundary layer and wake, vortex flow and separation, and free surface waves and wave breaking.

Research is divided into 7 tasks: (1) physics and model development; (2) code development and high performance computing; (3) CFD simulations; (4) transition; (5) development/application advanced towing tank measurement systems; (6) towing tank experiments; and (7) development/application CFD and EFD UA methodology and procedures.  Subtasks and schedule are given under Task and Schedule sections.  Priority will be given to practical geometries.

Primary Investigators

Fred Stern, Bob Wilson

Sponsors

Dr. L.P. Purtell, Office of Naval Research

Project Duration

April 1, 2002 - March 31, 2005

Overview

Previous ONR sponsored IIHR and UOP collaborative project [1] was successful in demonstrating capability of CFD-based optimization for naval surface combatant 5415.  Optimization modules were developed and coupled with CFDSHIP-IOWA.   The 5415 sonar dome was optimized for minimum wave heights and axial vortices and the transom stern was optimized for minimum stern waves [2].  Based on this success, an expanded three-year project is proposed.

General formulation CFD-Based optimization modules will be developed, including CAD-based hull form modification, high-performance optimization (HPO), and multiple-objective optimization.  Modules will be coupled with the unsteady RANS method CFDSHIP-IOWA and exercised for multi-disciplinary applications such as combined resistance and propulsion, seakeeping, or maneuvering.  The work will be done in collaboration with UOP and INSEAN through their respective NICOP projects, including towing tank validation experiments at INSEAN.

A CAD-based hull form modification method will be developed using a commercial CAD system suitable for ship design.  The previous successive quadratic programming (SQP), parallel computing HPO optimization modules will be extended for modified sensitivity analysis based on adjoint variable methods and scaleable message passing interface (MPI).  Non-deterministic approaches such as genetic algorithms will also be investigated.  Interfaces with CFDSHIP-IOWA will be developed for the CAD-based hull form modification method and the HPO modules.  The modules will be implemented for multiple-objective optimization using Pareto optimal set and decision maker theories.  The overall approach will be validated through towing tank tests conducted for combined discipline optimization such as resistance and propulsion, seakeeping, or maneuvering.

The collaboration with UOP and INSEAN is based on annual meetings at UOP and INSEAN and extended summer visits of UOP and INSEAN principal investigators at IIHR.

Towing-tank maneuvering flow-map measurement system

Primary Investigators

Fred Stern, Joe Longo

Sponsors

Dr. L.P. Purtell, Office of Naval Research, IIHR - Hydroscience & Engineering, The University of Iowa

Project Duration

April 1, 2004 - April 1, 2006

Overview

A maneuvering test flow-map measurement system is requested for the IIHR Hydroscience and Engineering (IIHR) towing tank in support of its internationally recognized research and research-related educational program in complementary computational fluid dynamics (CFD), experimental fluid dynamics (EFD) and uncertainty analysis (UA) for 6DOF viscous ship hydrodynamics.  The measurement system features a custom design comprised of a planar motion mechanism (PMM) for captive model testing with an integrated three-dimensional particle image velocimetry (3DPIV) for procuring instantaneous and phase-averaged flow maps.  The PMM consists of a main PMM sway/yaw motion mechanism unit, roll/pitch/heave free/fixed mount, and three component load cell; and sub PMM sway/yaw motion mechanism unit, 3DPIV traverse, and linked motion mechanism.  The 3DPIV consists of laser and light delivery system, high/low resolution volume map camera systems, and underwater housing and struts for cameras and light delivery system.  Computers and software for data acquisition and reduction and on-site installation and training are included.  Commissioning tests will be conducted for pure and combined sway/yaw motions.  The requested instrumentation comprise the most advanced maneuvering test flow-map measurement system of its kind in the world, which along with IIHR 6DOF contact-less motion tracker will maintain the IIHR towing tank as a unique asset for basic science and technology naval research.

The requested instrumentation will augment the current ONR Grant N00014110073 “6DOF Viscous Ship Hydrodynamics” and is essential for development of new research capabilities for future focus on large-amplitude motions and maneuvering.  Complementary CFD, EFD, and UA provides engine for realization of simulation design technology for naval hydromechanics, which merges traditional fields of resistance and propulsion, seakeeping, and maneuvering and with inclusion of power systems and open-ocean and littoral environmental effects offers the possibility of completely innovative out-of-the box concepts for future naval ships to meet the challenges of the 21^st century Navy.