In the area of re-engineering or re-purposing of existing software, model driven methodologies are hard to adopt because of lack of the central asset: models for the existing source code. Large companies and organizations that maintain a large code basis over long periods of time have recognized this issue, and are looking for ways to turn that code basis into models understandable under a business purposes point of view. In this paper, we introduce a technique that address this issue for C/C++ code. It delivers code-models, a representation of source code close to control flow graphs, by means of tool-supported analysis and transformations from legacy source code. Code models extend usual control flow graphs with rich information on both nodes and edges. They are immediately analyzable and verifiable in the jABC MDD framework, thus adequate for a model driven design, development, and evolution process.

Model driven analysis and design are increasingly recognized as powerful methodologies for software development and evolution. Model driven approaches in particular can be also combined with formal methods, offering advantages for verification, analysis, and testing. In order to use model driven methods for re-designing existing software, however, one needs additional facilities to transform the existing source code into adequate models. We examine in this paper a large number of existing tools for the analysis and processing of C/C++ source code, and evaluate them with respect to their usefulness in the model driven development process of software re-design projects. Our goal is to identify tools suitable to convert C or C++ code into a code-level model. Preferably, we want to use existing compilers, adequate system tools or other research and commercial programs to automate the process of deriving code-level models of large software applications.

The detection of vortical phenomena in vector data is one of the key issues in many technical applications, in particular in flow visualization. Many existing approaches rely on purely local evaluation of the vector data. In order to overcome the limits of a local approach, we choose to combine a local method with a correlation of a pre-defined generic vortex with the data in a medium-scale region. Two different concepts of generic vortices were tested on various sets of flow velocity vector data. The approach is not limited to the two generic patterns suggested here. The method was found to successfully detect vortices in cases were other methods fail.

Vortices are important features in many research and engineering fields. Visualization is an important step in gaining more understanding and control of vortices. Vortex detection criteria fall into two categories: point based scalar quantities, calculated at single points, and curve based geometric criteria, calculated for, e.g., streamlines. The first category is easy to compute, but does not work in all cases. The second category is more intuitive and should work in all cases, but currently only works in 2D (or 3D projected) flows. We show applications of both approaches in hydrodynamic flows.

Comparative visualization has successfully been applied to a variety of fluid dynamic problems. Most applications rely on image level comparison such as experimental flow visualization versus computational flow imagery (CFI) which tries to simulate optical image acquisition in flow testing. When differences become difficult to distinguish or once a quantitative result is required, data level comparison provides powerful means to visualize data from multiple sources. Data level comparison and visualization turns out to be an essential tool in modern aircraft design projects. It is already successfully applied in the geometric preprocessing stage and the CFD analysis and will serve for comparison with experimental data as well.

A recent study of a flow detail of an engine intake of future ground to orbit transport systems provided extremely complex data from numerical flow simulation and experimental flow visualization. The data posed a challenging problem to flow visualization, computational flow imaging (CFI), and the comparison of experimental imaging techniques versus computational imaging techniques. Some new visualization techniques have been implemented to provide compact representations of the complex features in the data. It turned out to be most useful to combine various specialized techniques for an icon-like representation of phenomena in a single image in order to study interaction of flow features. Some lessons were learned by simulating experimental visualization techniques on the numerical data.

In computational fluid dynamics, visualization is a frequently used tool for data evaluation, understanding of flow characteristics, and qualitative comparison with flow visualizations originating from experiments. Building on an existing visualization software system that allows for a careful selection of state-of-the-art visualization techniques and some extensions, it became possible to present various features of the data in a single image. The visualization shows vortex position and rotation as well as skin-friction lines, experimental oil-flow traces, shock-wave positions, and time surfaces. Animation provides a natural perception of flow in combination with an abstract representation of phenomena. By adding experimental flow visualization, a comparison between numerical simulation and wind-tunnel flow becomes possible up to a high level of detail. Since some of the underlying algorithms are not yet described in detail in the visualization literature, some experiences gained from the implementation are illustrated. The dedicated techniques which are illustrated in this paper address specific properties of vector quantities in the flow field, such as the velocity vector or the friction vector. Image complexity is reduced by employing complex visualization methods. Thus, the room is created which is necessary to study the interaction of various phenomena.>

In computational fluid dynamics visualization is a frequently used tool for data evaluation, understanding of flow characteristics, and qualitative comparison to flow visualizations originating from experiments. Building on an existing visualization software system, that allows for a careful selection of state-of-the-art visualization techniques and some extensions, it became possible to present various features of the data in a single image. The visualizations show vortex position and rotation as well as skin-friction lines, experimental oil-flow traces, and shock-wave positions. By adding experimental flow visualization a comparison between numerical simulation and wind-tunnel flow becomes possible up to a high level of detail. Since some of the underlying algorithms are not yet described in detail in the visualization literature, some experiences gained from the implementation are illustrated.>

Some techniques developed recently at DLR's Institute of Theoretical Fluid Mechanics in order to cope with the demands arising from today's work in aerodynamics are illustrated. Such new demands arise from new aerodynamical problems like the hypersonic flow field around re-entry vehicles, the study of unsteady phenomena which comes more and more within reach due to the increased availability of computing power and the tendency towards enhanced international cooperation especially within Europe which calls for the use of co-operative systems on wide area networks.>

Abstract Several feasibility studies for cooperative visualization were performed based on an existing modular visualization system. Two different architectures for the implementation of a cooperative system were identified, implemented and tested. One architectural model, the broadcast model, assumes either one single visualization system running on a central facility driving multiple displays or in case of cooperative work it assumes that each visualization module drives multiple displays. The second model, the synchronized visualization systems, features distributed visualization tools with synchronization mechanisms. The synchronization ensures that all partners create identical images from identical data. This model requires special control features to avoid conflicts created by user‐interaction. Both architectures are complete by adding bi‐directional video connection and audio communication over the network plus offering remote cursor functionality. Two prototype implementations were produced to compare the two architectures and to evaluate the feasibility of cooperative visualization on existing hardware. Because of the poor access to wide‐area networks, the prototypes were tested in a local area network. Visualization protocols, data communication, video and audio ran on a standard Ethernet based on TCP/IP communications. The tests were done using typical data from aerodynamics or numerical flow simulations. In spite of the limits due to low network bandwidth and slow performance of some hardware components the second architecture using the synchronized systems seems to be useful and feasible even under today's circumstances. There are no additional features identified which would be needed to run the cooperative visualization on a wide area network but a higher network throughput would be required.