| 1. |
- Lundin (Palmerius), Karljohan, et al.
(författare)
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Haptic Visualization of Computational Fluid Dynamics Data Using Reactive Forces
- 2005
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Ingår i: International Conference on Visualization and Data Analysis, San Jose, USA. - : SPIE. ; , s. 95-102
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Konferensbidrag (refereegranskat)abstract
- Datasets from Computational Fluid Dynamics (CFD) can be post-processed and visualized to aid understanding of the flow phenomena present. Visualization of CFD data, however, often suffers from problems such as occlusion and cluttering when methods such as glyphing and volume rendering are applied. In this paper we present a case study where new modes for haptic interaction are used to enhance the exploration of CFD data. A VR environment with interactive graphics and an integrated graphical user interface has been implemented. In contrast to previous work on haptic interaction with CFD data we employ a 'reactive' haptic scheme as opposed to direct force maping. The reactive approach not only generates more stable feedback but also provides clearer and more intuitive cues about the underlying data. Two haptic modes are used to enhance the understanding of different features in the flow data: One presents the orientation of the data and also guides the user to follow the stream as it flows around the aircraft fuselage. The other provides a haptic representation of vortex data. This mode enables the user to perceive and so follow tendencies of vorticity and vortices.
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| 2. |
- Sillén, Mattias
(författare)
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Advanced Flow Simulation Methods in Aircraft Design
- 2002
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Ingår i: Aircraft Engineering and Aerospace Technology. - : Emerald. - 0002-2667. ; 74:2, s. 138-146
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Tidskriftsartikel (refereegranskat)abstract
- The compressible Navier-Stokes equations are solved numerically for turbulent transonic aerospace applications on parallel computers. An Explicit Algebraic Reynolds Stress Model (EARSM) models the turbulence. Expressing the EARSM as an extension of an eddy-viscosity model makes the implementation straightforward in a flow solver with existing two-equation eddy-viscosity models. The k-? transport equations are used as a platform for the model. The EARSM approach significantly improves the shock position for transonic flow over wings without substantial increase in computational cost. Industrial use of advanced flow modelling requires a short turn-around time of computations. This is enabled through the use of parallel computers. To achieve good parallel performance the computational load has to be evenly distributed between the processors of the parallel computer. A heuristic algorithm is described for distributing and splitting the blocks of a structured multiblock grid for a good static load balance. Speed-up results are presented for turbulent flow around a wing on a number of parallel platforms.
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| 3. |
- Sillén, Mattias, 1966-
(författare)
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Application of Parallel Computers to Enhance the Flow Modelling Capability in Aircraft Design
- 2006
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The development process for new aircraft configurations needs to be more efficient in terms of performance, cost and time to market. The potential to influence these factors is highest in early design phases. Thus, high confidence must be established in the product earlier than today. To accomplish this, the concept of virtual product development needs to be established. This implies having a mathematical representation of the product and its associated properties and functions, often obtained through numerical simulations. Building confidence in the product early in the development process through simulations postpones expensive testing and verification to later development stages when the design is more mature.To use this in aerodynamic design will mean introducing more advanced physical modelling of the flow as well as significantly reducing the turn around time for flow solutions.This work describes the benefit of using parallel computers for flow simulations in the aircraft design process. Reduced turn around time for flow simulations is a prerequisite for non-linear flow modelling in early design stages and a condition for introducing high-end turbulence models and unsteady simulations in later stages of the aircraft design process. The outcome also demonstrates the importance of bridging the gap between the research community and industrial applications.The computer platforms are very important to reduce the turn around time for flow simulations. With the recent popularity of Linux–clusters it is now possible to design cost efficient systems for a specific application. Two flow solvers are investigated for parallelperformance on various clusters. Hardware and software factors influencing the efficiency are analyzed and recommendations are made for cost efficiency and peak performance.
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| 4. |
- Sillén, Mattias
(författare)
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Evaluation of Parallel Performance of an Unstructured CFD Code on PC–Clusters
- 2005
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Ingår i: Journal of Aerospace Computing, Information, and Communication. - 1542-9423. ; 2:1, s. 109–119-
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents an evaluation of parallel performance of a computational fluiddynamics solver on PC-clusters. The solver uses unstructured grids and is parallelized bydomain decomposition using MPI as the communication library. The influence of nodeconfiguration and type of cluster network on the parallel performance is investigated fortypical applications from an aerospace design environment. The high performance networkbecomes significant when the system scales up. More important is the node configurationwhere memory bandwidth saturation limits the performance on dual nodes.
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