Publications of the 1999
Published in 1999
In this paper we present a strategy for grid generation for complex geomentries based on the multiblock approach. On the block level the grid is completely unstructured and may be represented by a graph. Within a block a structured grid is generated to retain both the computantional efficiency and accuracy of the finite volume approach. In order to handle extreme degrees of geometrical complexity, an object-oriented topology generation approach has been devised implemented by the Topology Input Language (TIL) to manage these objects. To this end, the configuration to be gridded is subdivided into objects (like wing, fuselage, nacelle, pylon, engine etc. for an aircraft configuration) for which individual topologies are designed. These topologies are considered to be local topologies, since they represent only a part of the solution domain. The important feature is that objects can have internal topologies that have a rich structure that is not visible from the outside. The final grid topology is constructed by combining the topologies of all objects, using their visible topology only. Thus the level of complexity can be substantially reduced. Since there is a strict separation between topology and geomentry, a topology database can be built that is fully reusable. The strategy is demonstrated for a generic X-33 configuration with the linear aerospike engine and an annular aerospike propulsion system, modeling numerious design details to demonstrate the capability of the software to model most complex geometries with relative small input from the user.
Keywords: mesh strategy, structured multiblock grid, complex geometryDownload PDF
Published in 1999
In this paper an overview is given of the "Have Java" project to attain a pure Java parallel Navier-Stokes flow solver (JParNSS) based on the thread concept and remote method invocation (RMI). The goal of this project is to produce an industrial flow solver running on an arbitrary sequential or parallel architecture, utilizing Internet, capable of handling the most complex 3D geometries as well as flow physics, and also linking to codes in other areas such as aeroelasticity etc.
Since Java is completely object oriented the code has been written in an object-oriented programming (OOP) style. The code also includes a graphics user interface (GUI) as well as interactive steering package for the parallel architecture. The Java OOP approach provides profoundly improved software productivity, robustness, and security as well as reusability and maintainability. OOP allows code construction similar to the aerodynamic design process because objects can be software coded and integrated, reflecting actual design procedures. In addition, Java is the programming language of the Internet and thus Java objects on disparate machines or even separate networks can be connected.
We explain the motivation for the design of JParNSS along with its capabilities that set it apart from other solvers. In the first two sections we present a discussion of the Java language as the programming tool for aerospace applications. In section three the objectives of the Have Java project are presented. In the next section the layer structures of JParNSS are discussed with emphasis on the parallelization and client-server (RMI) layers. JParNSS, like its predecessor ParNSS (ANCI-C), is based on the multiblock idea, and allows for arbitrary comlex topologies. Grids are accepted in GridPro or Plot3D format. Using GridPro property settings, grids of any size or block number can be directly read by JParNSS without any further modifications, requiring no additional preparation time for the solver input. In the last section, computational results are presented, with emphasis on multiprocessor Pentium and Sun parallel systems run by the Solaris operating system (OS).Download PDF