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| CFX Announces New Release |
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| Application: CFD for Ship and Yacht Design |
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Posted Fri October 19, 2001 @04:48PM
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Ship and yacht designers are increasingly turning to CFD to help in the design of hulls and propellers. Recent advances in fluid modeling allow designers to tackle tough problems such as wake prediction, propeller-hull interaction, and acoustics.
Military applications include reducing acoustic and non-acoustic signatures (such as the wake field observed by synthetic aperture radar).
The naval and commercial ship design communities have long needed a predictive capability to address the complex interaction between a ship's boundary layer, the nonlinear free-surface, and the propulsor. In commercial ship design, the prediction of near-field flows is central to the problems of unsteady propeller loads, cavitation, and propeller-induced hull vibrations. The solution to these problems requires detailed knowledge of the turbulent stern flow (including thick and perhaps separated boundary layers), bilge vorticity, and propeller/hull interaction.
Another interesting application is the prediction of ship hydrodynamic response, how the ship pitches and rolls, in heavy seas.
There are several CFD codes available which are tailored for hydraulic analysis.
The use of CFD in the ship building industry has been spured by
the expense and time-consuming nature of hydrodynamic tank testing.
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| Team NZ Using SGI for Boat Design |
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Posted Thu October 18, 2001 @05:21PM
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SGI has supplied defending America's Cup champion Team New Zealand with UNIX workstations to be used for CFD analysis of the boat's hull, keel, wings and sails.
Although many boat parts are now totally computer designed, for some key parts, such as the hull, there is still no substitute for the traditional method of physically building models and testing them in tow tanks.
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Posted Thu October 18, 2001 @08:59AM
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CFX-ProMixus is a software tool for optimising mixing and reaction vessels. CFX is organising seminars with "hands-on" sessions during October and November at the following venues:
31 October - Ware, UK;
2 November - Cork, Ireland;
5 November - Brussels, Belgium;
7 November - Amsterdam, Netherlands;
8 November - Barcelona, Spain;
9 November - Tarragona, Spain.
For a registration form please contact Lin Hall on +44 1235 448018 e-mail: lin.hall@cfx.aeat.com or visit our web-site www.cfx.aeat.com
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| A Novel Approach to Fluid-Structure Interaction |
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Posted Wed October 17, 2001 @04:37PM
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CD adapco Group has released EZ-FSI a software tool for analyzing fluid-structure interaction problems. A brochure is available which describes the product and its novel approach to coupling structural analysis with CFD.
Typical fluid-structure interation (FSI) simulations attempt to couple the full structural analysis FEA code with the CFD solver and compute the structural stresses and deformations after each iteration. The approach taken in the EZ_FSI product takes advantage of a lumped-mass model of the solid part to simplify the analysis.
First, the solid part is meshed and the fluid-structure interaction points (the "wetted" points) are identified. The solid part is then analyzed to determine lumped mass, damping, and stiffness values for the wetted points. The lumped system will behave exactly as the full system for linear systems with small deformations.
Next, the fluid portion of the domain is meshed and the fluid structure interaction points are identified as a special moving boundary. As the transient, CFD solution progresses, the pressure on the wetted points is used as a forcing function on the lumped mass system to determine the new location at the current time. The boundary is moved to the new location, the CFD mesh is updated, and the process repeats. This is all done within the CFD solver -- eliminating the need to communicate with an external structural analysis package every iteration.
Finally, after completing the CFD analysis, the transient pressure data can be imported into the structural analysis package to determine dynamic stresses within the solid.
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| CFDRC to Develop Urban Dispersion Tool |
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Posted Tue October 16, 2001 @10:20AM
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At a time when it is unfortunately very topical, CFDRC has been awarded a contract to develop simulation tools to model the dispersal of nuclear, chemical, biological, and radiological (NCBR) substances in urban areas.
The tool, dubbed the Urban Dispersion Simulator (UDS), must overcome such modeling obstacles as geometry acquisition, meshing, and attaining a solution on building to city blocks scale. Additionally, prevailing wind and turbulence fields, buoyancy, solar radiation, tree-induced flow losses, HVAC effects, and the dispersal of gas-phase agents as well as solid and liquid dispersants must be considered.
To facilitate rapid modeling of such large-scale structures, CFDRC has hit upon an image based approach to model generation. By analyzing an image representing a height map of the area of interest, a voxel-based solid model is created. The solid model is then used to create a CFD mesh using a 2N tree-based mesh generator.
The UDS development is being funded under a Small Business Innovation Research contract through the Defense Threat Reduction Agency.
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