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By Nicole Diana, FLUENT Product Manager
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FLUENT continues to redefine the meaning of comprehensive CFD software. FLUENT 6.2 not only adds new capabilities that broaden its applicability to an even wider range of industrial problems, it also delivers important core numerical advancements that promise improved accuracy, transient efficiency, and robustness. In short, the world's best CFD code is now even better. Some of the most exciting new capabilities are described below.
A generic four valve engine, running under knocking conditions, was simulated using the autoignition model in FLUENT 6.2. The flame front (the surface shown in white) is propagating across the cylinder as the progress variable describing autoignition, shown by contours on the mid-plane, builds up in the end gas region ahead of the flame. When the ignition progress variable reaches a value of one, the remaining fuel releases its energy, causing the cylinder pressure to rise dramatically which, in turn, can lead to severe engine damage over time
Speed, Robustness and Accuracy
FLUENT 6.2 continues to enhance and improve the foundational technologies that lead to better performing CFD overall. It provides faster and more stable results for transient analyses. Numerics improvements have also resulted in better spatial accuracy, particularly on tetrahedral meshes and for complex flows. Turbulence modeling capabilities continue to set the industry standard with enhancements targeted at large eddy simulation (LES) and detached eddy simulation (DES). (See the article LES is More.)
A gerotor pump was analyzed in FLUENT 6.2. The pump consists of an inlet port (left), rotor section (middle), outlet port (right), and shaft cavity (bottom, blue). The pumping action is produced by two rotating gears. The image shows the inner gear (gray) and inner surface of the outer gear colored by static pressure. The dynamic mesh model with 2.5D meshing was used to model the rotor motion. The standard k-e turbulence model was used to model the pump oil
Courtesy of EMP Inc.
Dynamic Mesh
FLUENT 6.2 has the industry's most flexible moving and deforming (or dynamic) mesh capability. Because it is available in a fully unstructured environment, geometric fidelity does not have to be sacrificed in order to model flow around moving objects. FLUENT's general purpose dynamic meshing tools work with a wide range of physical models; they are currently helping FLUENT users model applications ranging from automotive to chemical processing to biomedical. Improvements to the dynamic mesh capability in FLUENT 6.2 include more accurate solutions with lower overall cell counts, more flexible remeshing and layering capabilities, and a built-in six-degrees-of-freedom (6-DOF) solver, which enables the accurate modeling of unconstrained motion. Parallel processing performance with the dynamic mesh capability has also been enhanced for faster time-to-solution.
Multiphase Modeling
FLUENT 6.2 is the only commercial CFD software that offers users the ability to include species transport and chemical reactions with all multiphase models in a fully unstructured environment. It is now possible to achieve more accurate simulation of historically difficult and complex multiphase flows requiring the Eulerian, mixture, DPM, or VOF formulations, along with chemical reactions. The new version also provides greater efficiency and reliability in handling freesurface flows, unsteady flows within cavities, and cases where surface tension is a factor in the analysis. Particle tracking is also more accurate and efficient.
High speed flow past an open cavity is simulated using the DES model and NITA in FLUENT 6.2, and the solution is used to predict acoustic modes. In this figure, an iso-surface of vorticity is colored by velocity magnitude inside the cavity, and the distribution of velocity magnitude on the entry plate is shown using contours
Comprehensive Acoustics Capabilities
FLUENT 6.2 provides a full range of flow-induced noise prediction tools, from approximate to highly accurate. Providing this full range of capabilities is a unique aspect of FLUENT. Improvements have been made in FLUENT 6.2 to allow the existing Ffowcs- Williams and Hawkings (FW-H) model to handle rotating surfaces, so that fan noise can be modeled. New models have also been introduced that use steady-state RANS results to provide extremely fast trend information for many types of noise simulations, including fan design. The export of FLUENT data to SYSNOISE has also been improved. Moreover, enhancements have been made to the FFT tool in FLUENT so that noise prediction results can be visualized in many useful forms.
Ozone decomposition in a fluidized bed is modeled using FLUENT 6.2. After 13 seconds of operation, the granular bed is fluidized (left), as predicted by the Eulerian granular multiphase model, and the ozone mass fraction (right) decreases as the result of a reaction catalyzed by the bed particles
Continued Reaction Modeling Advancements
FLUENT's already considerable capability for handling reacting flows has been expanded with a new stiff chemistry algorithm for laminar flows, enabling laminar finite rate chemistry problems to be solved more efficiently. Pollution prediction is improved with enhancements to the NOx model. A new ability to create custom material databases enables the re-use of material properties and reaction mechanisms from one case to another. Also, surface chemistry mechanisms can be efficiently imported in the SURFACE CHEMKIN format. The full integration of PrePDF into FLUENT 6.2 makes combustion analysis faster and easier.
For More Information Visit:
www.fluent.com/software/fluent
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