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CFD
Nye metoder og værktøjer
Grundfos A/S, Poul Due Jensen Academy, Bjerringbro
Onsdag den 6. oktober 2004, kl. 9.00 - 16.00
Det er dagens mål at give deltagerne et samlet overblik over væsentlige aspekter ved anvendelse af CFD. Lige fra anvendte koder og logistikken omkring koderne så som pre- og postprocessering, hardware platforme, og til kvalitetskontrol af beregningerne.
09.00 Registrering
09.15 Velkomst
Dr. Peter Elvekjær, Forskningsdirektør, Grundfos Management
09.30 "Latest Advances in Grid Generation"
Dr. Andreas Kolms, ICEM CFD Engineering, Hannover, Germany
Creating an adequate discretization of the geometry is an integral part of CFD and FEA, and this apparently simple task has proved to be rather challenging. Advanced meshing includes model diagnosis, geometry cleanup, and feature detection in a common environment. ANSYS ICEM CFD traditionally provides structured and unstructured grid generation for more than hundred CFD codes. CAD surface models to be analyzed by the Finite Element Method are often characterized by general n-sided, strongly curved boundaries, as well as by holes. Hybrid meshing, i.e. composition of different types of grids as well as automatic volume filling, requires an "outside-inside" approach. In addition, prescribed curves and points within the structure need to be taken into account. A recursive meshing scheme based on the "looping" algorithm satisfying the listed constraints will be presented. Finally, multiple automatic and semi-automatic pathways from CAD geometry to high quality meshes will be discussed.
10.00 Pause
10.15 "Power Flow, Lattice-Boltzman Approach to Fluid Dynamics"
Mr. G. Lang, EXA Power Flow, Europe, Germany
11.00 "Status and Progress in CFD Simulation Methods and Applications"
Dr. Georg Scheuerer, Managing Dir. ANSYS Germany, Otterfing
Computational Fluid Dynamics (CFD) has become an increasingly important technology for the improvement of existing and the design of new products and processes. The increased use of CFD software has been promoted by rapid advances in computer hardware and by improvements in the mathematical models and solution algorithms in the CFD software. These new developments permit much more reliable simulations of industrial flow problems in much shorter turn-around times. Recent developments in the field of numerical methods were: 1) High-resolution discretisation schemes, which permit accurate and bounded solutions. 2) Implicit coupled solution of the conservation equations describing single and multi-phase flows (as contrasted with the traditional sequential solution of the equations); this technology provides increased robustness and faster convergence of the equation set. 3) Use of acceleration techniques such as algebraic multi-grid methods, which lead to reduced calculation times and a linear increase of calculation times with the number of grid points. 4) Scalable parallelisation of the solution algorithms on shared and distributed memory computers, including PC clusters and network configurations. These modern techniques, combined with advanced statistical turbulence models, like the SST turbulence model, define the current state-of-the-art in industrial CFD. They will be briefly reviewed in the presentation. Currently, most industrial CFD applications are for steady-state flow. However, in the future there will be an increasing demand for predicting the unsteady-state behavior of components efficiently. Examples of such unsteady-state flows are start-up and operational transients, and prediction of instabilities or component hysteresis. Also, some processes like acoustics, cavitation, and many multi-phase flows are inherently unsteady-state. The efficient prediction of unsteady-state phenomena poses new challenges for CFD methods. On the numerical methods side, techniques like grid and time-step adaptation, coupled with error estimation, will become more important. On the mathematical model side, the currently used statistical turbulence models have to be extended to predict unsteady-state phenomena accurately. This will require more than just running steady-state turbulence models in an unsteady-state mode (URANS). A suitable technology from an accuracy point of view for predicting unsteady-state, three-dimensional flows are Large Eddy Simulations (LES). However, performing LES for industrial flows at high Reynolds numbers can be computationally prohibitive. There are, however, recent developments to blend URANS and LES models, thus exploiting the advantages of both. One of the most promising techniques in this area are the so-called ‘Scale Adaptive Simulations’ which will be discussed in the presentation.
11.45 "Discrete Vortex Simulation"
Dr. Jens H. Walther, Research Associate, ETH, Zurich, Switzerland
12.15 Frokost
13.00 Rundvisning i Grundfos cirkulationspumpe-produktion
Her ses Grundfos produktion af UP-pumper. Cirkulationspumperne finder anvendelse til opvarmning, ventilation og aircondition i beboelseshuse, kontorbygninger osv. Produktionen har en kapacitet på 20.000 stk dagligt og har en høj grad af automatisering, der sikrer både kapaciteten og lønsomheden ved produktion her i landet. Grundfos er i dag verdens største producent af cirkulationspumper og dækker omkring 50% af verdensmarkedet for disse. Det er ikke tilladt at tage billeder under rundvisningen.
14.00 "CFD complete vehicle simulations at Volvo Car Corporation - today and in the future"
Dr. Hans Envald, Volvo Cars, Sweden
Volvo Car Corporation has a long tradition of using Computational Fluid Dynamics for product development, driven by the need to produce more different cars with a drastically reduced product development time. In order to achieve a controlled accuracy of the simulations the CFD processes for aerodynamics, thermo&cooling, climate comfort have been validated versus experimental data and documented in computational procedures. The short-term strategy is to reduce the turn-around time of the simulations and to widen the range of applications of CFD to aero-acoustics and two-phase flow applications such as dirt deposition. The next step is to introduce more accurate turbulence models (LES/DES) for critical applications.
14.45 Pause
15.00 "Virtuel Reality and CFD"
Dr. Michael Grønager, Konsulent UNI·C, Lyngby
One of the visions for the Center Contract: “MaskinAkustik” is to be able view and interact with a tree dimensional fluid dynamics field in real time, however, traditional CFD solvers usually have no or poor support for geometry changes during a transient calculation, and hence steering becomes cumbersome. On the other hand a 3D Lattice Boltzmann solver with support for geometry changes can be written quite easily, and besides for supporting interaction the Lattice Boltzmann algorithm is famous for its linear scalability when running on even a high number of CPUs. In the talk I will demonstrate our experimental OpenLB solver coupled to an interactive 3D interface enabling geometry changes while the actual computation is done in parallel on the Nordic production grid facility NorduGRID.’
15:45 Afslutning
DANSIS - The Danish Society for Industrial Fluid Dynamics     Email: dansis@dansis.dk