| |
View the pdf of this article
The year 2004 marked the beginning
of what is hoped to become an important tradition in the CFD community: the recognition of excellence among our users. In its inaugural year, five CFD User of the Year Awards were presented to scientists and engineers for groundbreaking efforts in CFD modeling. Candidates were nominated by Fluent staff from around the world. A small committee evaluated papers and other materials and selected three finalists in each of five categories. The fifteen final papers were then reviewed by a panel of judges that included Fluent executives and outside engineers. The panel of judges chose the final five winners, whose work is described below.
Most Innovative Use of CFD Technology:
The Use of CFD in the Chase of Olympic Gold
by John Hart, Sheffield University, Sheffield, UK
The winning helmet design,
shown for two different head
positions; contours of static
pressure and pathlines are used
to illustrate the flow field
Static pressure contours on two other helmet designs tested
The panel of the judges found this work to be visionary as well as a major contribution to the application of CFD technology to the healthcare industry. The description of the CFD modeling process that was developed for understanding life-threatening intracranial aneurysms of the brain was felt to be outstanding. They found that the researchers demonstrated a practical modeling tool that could impact planned treatment and follow-up of patients after neurosurgical and endovascular interventions by neurosurgeons using 3D angiography techniques. The judges were impressed by the practical way the researchers coupled medical scan outputs with geometry and surface extraction software, and then used meshing and CFD modeling codes for predicting real world virtual blood flows.
According to the judges, Dr. Hart’s ability to model the complex curvatures associated with athletic bodies in competitive poses was very impressive. In the past, sports simulations involved generic human forms. The fact that his innovative process allowed real-world athletic forms with turnaround times of days rather than weeks or months was also felt to be a key element of the importance of this study. The judges believe that these factors would make this type of diagnostic and performance enhancement tool an ideal choice for competitive performance directors to make informed decisions about their sport and athletes. It certainly helped the UK in the Athens Olympics, where gold medals were won in both cycling and sailing!
Most Impact on Society:
Computational Replicas: Anatomic Reconstructions of Cerebral Vessels as Volume Numerical Grids at Three-Dimensional Angiography
by Tamer Hassan et al. at Tohoku University in Japan
Dr. Hassan led a team of engineers, surgeons, and radiologists from institutions in Japan and Canada in a study of blood flow in cerebral aneurysms. His team began with data from either CT or MR scans of aneurysms, some of which had ruptured and some of which had not. The geometry was processed so that 3D meshes could be built for each case. This proved to be the most challenging aspect of the project, since the geometries extracted from medical scans require a great deal of clean-up. Once the meshes were created, Dr. Hassan used either FIDAP or FLUENT to simulate the transient blood flow for each case, using ultrasound measurements for the blood flow boundary conditions. The vessel walls were assumed rigid in the FLUENT simulations, but were allowed elasticity in the FIDAP simulations, using the fluid-structure interaction capability. The CFD results were reviewed alongside angiographic scans. For the cases of ruptured aneurysms, the CFD results showed that normal or shear stresses were high in the rupture locations, suggesting a possible cause in some of the cases studied.
The surface of the tetrahedral mesh used in the simulation
Pathlines at one instant of time colored by velocity show that the entering stream of blood hits the aneurysm wall at the angiographically determined rupture area
A 2D image shows the escape of a linear stream of contrast agent
Best Industrial Study:
Simulation of Smoke Distribution and Extraction in Buildings
by Peter Vogel, Gebäude-Technik-Dresden GmbH, Germany
Dr. Vogel’s firm has been called upon to perform CFD studies of large scale structures during the early and even late stages of architectural design. Such studies are often used to test different approaches for removing or isolating smoke in the event of a fire, and the impact of these approaches on the safety of escape routes. In his award-winning study, smoke removal was the goal at Terminal 2 at Germany’s Munich Airport. A number of simulations were performed as part of the project. In addition to transient analyses for tracking the smoke plume from a single fire throughout the entire terminal, other simulations examined local flow through vents and other openings. Natural and forced smoke removal systems were compared using a highly accurate building geometry.
Dr. Vogel’s extensive CFD modeling study of the HVAC systems and equipment required for efficient smoke removal impressed the judges with both its scale and its comprehensiveness in this critical real-world CFD application. Traditionally, smoke removal systems are developed based on small-scale experimental studies. At Munich Airport, no scale model HVAC tests were carried out to design the smoke removal systems. Instead, this CFD project designed the necessary retrofit for the building. Based on the CFD recommendations, a new system was built on site and Dr. Vogel oversaw smoke machine tests that were carried out in the Terminal Hall. These tests resulted in good agreement with the CFD predictions and justified the approach used by the Airport’s management.
Velocity contours illustrate the formation of glass gobs at the feeder at the start of the forming process
Surfaces of smoke concentration were used to illustrate the differences between natural and forced smoke removal systems
The terminal under study at Munich Airport
Contours of visibility 10 minutes after the start of the fire, with blue representing the maximum distance
Smoke tests were conducted and were found to validate the CFD findings
Most Impact of CFD on a Business Process:
Simulation Saves Hundreds of Thousands by Avoiding Weeks of Glass Forming Line Downtime
by Matt Hyre, Virginia Military Institute, USA
Glass bottle manufacturing is a competitive business, with worldwide demands for increased production quantity and quality. For the past several years, Dr. Hyre has used CFD to better understand the many processes involved in glass bottle manufacturing. In his award-winning study, he focused on identifying the source of defects in glass containers being produced by a particular line. He narrowed down the origin of the defects to one step in the “press and blow” forming process. Using POLYFLOW, he determined that when the perform, or parison, was inserted into the mold, large temperature gradients occurred in certain places that later were the sites of defects. The shape of the parison mold was altered in subsequent CFD simulations until a new, problem-free shape was identified. The new mold could then be inserted in the glass forming line with virtually no lost manufacturing time.
Temperature contours and velocity vectors show the neck ring cooling process at the end of the forming line
Impact stress predictions on a glass bottle used to redesign the thickness distribution for increased bottle strength and decreased defects
The judges felt that Dr. Hyre’s work clearly demonstrated how CFD could be used to understand a complete glass bottle manufacturing process in order to solve a real glass forming process problem. Furthermore, the vast complexity of the physics and chemistry modeled in the project was impressive, including the capture of free surfaces, extrusion, combustion, radiation and thermal stresses. His simulations were used to recommend the best option for adjusting the line, and the process only had to stop for a brief period while the parison mold was switched. This retrofit saved the company weeks of downtime because they did not have to experimentally test several molds on the line. These savings were estimated to be hundreds of thousands of dollars in production costs that would otherwise have been lost.
Best Use of CFD as a Design Tool:
Delphi Cuts HVAC Development Cycle by 1.5 Years with Automated CFD Tool
by Lin-Jie Huang, Delphi Inc., USA
The customized interface, showing a 3D HVAC module
Pathlines (top) and contours of velocity magnitude (middle) and temperature (bottom) for a 3D HVAC module
Dr. Huang has long been an advocate of putting CFD into the hands of design engineers. At Delphi, he has built custom templates for the design of air handling systems for the automotive industry. By making use of similar geometries for which only a handful of parameters can be adjusted, and by exposing the user to only a limited number of modeling options, he has made CFD accessible to a wide audience at Delphi that extends beyond the CFD analyst alone. The concept has been applied to the easy, step-by-step setup of HVAC modules, powertrain cooling systems, and heat exchangers, and more applications are currently in development. The user can select a quick 2D analysis or a more comprehensive 3D analysis. In all cases, the interface limits the range of input parameters to those for which the tool has been validated. Knowledge about the anticipated flow fields is used to guide the automatic generation of the computational mesh. The setup and solution time ranges from 15 minutes to four hours, depending upon the accuracy requested.
The judges were very impressed by the scope and output of this leading-edge applied design tool that requires little or no CFD knowledge on the part of the user. It allows Delphi to use CFD in the early stages of their product design process and spread the use of CFD to 50% of their design engineers. It is estimated that the new tool has shortened Delphi’s HVAC product design cycle by 30% and reduced their model shop and testing expenses by 25% because of the consequent need for fewer prototypes to be built. This has amounted to substantial savings for the company and their product development cycle has been reduced from 4 years to 2.5 years. The success of this project has led to development efforts at Delphi to create more design tools for other items in their product line.
|
|
|
