- J.S.Kowalik, An Introduction to High Performance Computing: Technology, Tools and Applications | abstract
- R.Puzyrewski and P.Flaszynski, Qualitative Comparison of 2D and 3D Computation of Flow Field in the Cone Shaped Turbine Nozzle | abstract
- A.Tyliszczak and A.Boguslawski, Pseudospectral Approximation Compared with Control Volume Formulation and Finite Differences- Some Test Cases | abstract
- T.Koronowicz, T.Tuszkowska and L.Wilczynski, Numerical Investigation of the Flow Around Wing Tips | abstract
- M.Banaszkiewicz and J.Badur, Gradient Theory for the Description of Interfacial Phenomena in Flashing Water Flows | abstract
- W.Lubaszewski, A Grammar for the Polish Inflection Lexicon | abstract
From the History of Science and Technology in Ancient Gdansk:
- A.Januszajtis, The Gdansk Clocks and Their Creators
h J.S.Kowalik, An Introduction to High Performance Computing: Technology, Tools and Applications
Traditionally High Performance was applied to very computationally demanding poblems in science and engineering. They were known as the Grand Challenge Problems that required supercomputers equiped with very large computer memories and capable of high rates of computation measured by Megaflops (Million Floating Point Operations per second). In the last two decades the world of business and industry has recognized the enormous potential of large distributed computer systems for their business enterprise applications. Today most of the existng high performance computers are employed in the enterprise environments. A typical system has three layers of servers: user interface, applications and database. These Client /Server architectures are the working horse of the large enterprise information processing. This introductory paper describes both areas of High Performance Computing applications that differ in the nature of workload, performance objectives, design methodology and scientific focus.
h R.Puzyrewski and P.Flaszynski, Qualitative Comparison of 2D and 3D Computation of Flow Field in the Cone Shaped Turbine Nozzle
The paper presents qualitative comparison of 2D and 3D computation of flow field in the cone shaped turbine nozzle. The calculation yields surface S2 for a given conical stream surfaces S1. S2 stream surface represents curvature of blading passages. This formulation is typical for the inverse problem. Basing on such obtained surface S2 it is possible to design shape of the blade. Results of 3D computation by means of FLUENT have been presented and compared with assumptions in 2D model.
h A.Tyliszczak and A.Boguslawski, Pseudospectral Approximation Compared with Control Volume Formulation and Finite Differences- Some Test Cases
The paper presents comparison of the pseudospectral method with low-order approximation for two test cases. The first test case is quasi one-dimensional supersonic flow through converging-diverging nozzle for which exact solution exists. The comparison of the error of pseudospectral approximation and upwind finite-differences using Steger-Warming flux splitting method shows high accuracy of the pseudospectral method even for few collocation points. The same conclusion is formulated for the second test case, namely incompressible flow in two-dimensional driven cavity solved by control volume formulation with modified QUICK upwinding scheme and SIMPLEC algorithm for pressure correction. As usually conclusions concerning accuracy of numerical methods are flow case dependent, but the two examples shown give some idea about the accuracy and resolution of spectral approximation versus standard CFD schemes.
h T.Koronowicz, T.Tuszkowska and L.Wilczynski, Numerical Investigation of the Flow Around Wing Tips
The paper deals with the problems of modelling of flow around wing tip and tip vortex cavitation. Theoretical bases of vorticity method and vorticity calculation models for design and estimation of hydrodynamic characteristics of the hydrofoil are presented. Basic assumptions of double layer lifting surface model are described. Double layer lifting surface model enables proper modelling of the phenomena occurring in the flow around a hydrofoil tip and especially generation of free vortices system.
h M.Banaszkiewicz and J.Badur, Gradient Theory for the Description of Interfacial Phenomena in Flashing Water Flows
The present work concerns the description of phenomena taking place within interfacial regions during a flow of water, which is accompanied by heterogeneous flashing. The main aim of the work is to present a unified approach to first order phase transitions with the inclusion of capillary effects and to built on this basis a mathematical model describing nonequilibrium two-phase flows, in which the properties of the mixture include capillary components. The analysis of the problem was started with a discussion of physical aspects of flashing, which are the contents of Chapter 2. On the basis of the experimental data analysis a physical model of the phenomenon was formulated. In Chapter 3 a gradient description of first order heterogeneous phase transitions was given. The analysis was begun with a discussion of the properties and structure of interfacial areas. On the basis of the analysis constitutive equations for reversible stress tensor and free energy of a two-phase system treated as a homogeneous medium were formulated. The constitutive equations include capillary components modelled by means of the dryness fraction gradients and resulting from the nonuniformity of the system caused by the existence of two phases and interfacial surfaces. On the basis of the proposed theory a homogeneous model of two-phase flow with capillary effects was derived, which is a subject of Chapter 4. Taking into consideration the assumptions of the homogeneous model, one-dimensional balance equations for mass, momentum and energy of the mixture and mass of vapour were derived. A constitutive equation for the source term appearing in the last equation was obtained on the basis of the theory of internal parameters with the usage of the proposed form of free energy including a gradient term known from the second gradient theory. The remaining constitutive equations for the density of the two-phase system, wall shearing stresses and capillary pressure were also given. The proposed mathematical model was investigated from the point of view of wave properties, which were discussed in Chapter 5. The analysis of small disturbations was conducted, as a result of which a dispersion equation was obtained giving a relation between the velocity of disturbations, attenuation coefficient and frequency. This dispersive model was then applied for the prediction of critical mass flux in a channel flow using PIF method. On the basis of the comparison of the model predictions with experimental measurements a reasonably good agreement was found. In Chapter 6 the results of numerical calculations of flashing flow in channel were presented. Since the proposed mathematical model contains several phenomenological coefficients, a parametric analysis was performed in order to determine their value and the influence on solutions. For the sake of the analysis the classical benchmark experiment known as the Moby Dick was used. After fitting the solution of the model into the experimental measurements new calculations for other runs and other experiments were carried out. As a result of the analysis a good agreement of the model with reality was found, as well as its usefulness for the calculations of pressure and void fraction distributions in channels and for the determination of mass flow rate of two-phase systems. It constitutes a confirmation of the correctness of the proposed model as well as the theory on the basis of which it was built.
h Invited paper: W.Lubaszewski, A Grammar for the Polish Inflection Lexicon
The inflection dictionary of Polish language available on the web: www.icsr.agh.edu.pl/fleksbaz was generated automatically. The paper is intended to explain this generation process.