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Two buildings differing in height in tandem configuration are subjected to a turbulent boundary layer flow. The physical modelling in a wind tunnel has been performed, Particle Image Velocimetry in horizontal planes has been applied. The time-mean flow-field is dominated by the contrarotating vortex pair in the near-wake of the upstream building forming strong back-flow in this wake. Dynamical activity is located close to the bigger downstream building below the level of the smaller building roof. The dynamical structures in the space between them are studied using advanced analytical methods, Oscillation Pattern Decomposition (OPD). The 3 important OPD modes were detected differing by topology and frequency. The 2 OPD modes are characterized by vortical structures formed within the wake of the smaller upstream building and moving downstream towards the bigger building. The last OPD mode shows strong pulsation transversal flow in front of the bigger building. Typical frequency of the cyclo-stationary behaviour could be characterized by the Strouhal number in the range from 0.09 up to 0.15.

Lamb waves, as one of the types of guided waves, are extensively used for inspecting large structures as well as for structure health monitoring applications. One of the biggest benefits of guided waves is their ability to travel over long distances without much attenuation. Lamb waves are often used for inspection of piping systems and similar geometries where the dimension in the third direction is significantly smaller than the other two. No wonder that the study of the interaction of Lamb waves with particular types of geometric discontinuities is a frequent topic of research. The main aim of the proposed paper is to present the findings related to the numerical study of the interaction between low-order Lamb wave modes and surface breaking crack oriented at different angles relative to the free surface.

The paper presents the numerical results obtained with the use of the ANSYS FLUENT commercial code for analysing the flow structure around a two rectangles in line surface-mounted bluff bodies immersed in a boundary layer. The simulation of a configuration with a flow around objects has been done using both the steady and unsteady approaches. Effects of the inflow boundary layer thickness on the flow field, wall-shear stress and the grid resolution accuracy in predicting periodic vortex shedding from two tandem arrangement bodies are examined. It has been observed that the periodic vortex shedding is considerably reduced with an increase in the δ/H parameter.

The paper presents the results of experimental and numerical research focused on the reduction of fuel consumption of vehicles driving one after another in a so-called platoon arrangement. The aerodynamic parameters and safety issues were analyzed in order to determine the optimal distance between the vehicles in traffic conditions. The experimental research delivered the results concerning the drag and was performed for simplified model of two vehicles positioned in wind tunnel equipped with aerodynamic balance. The additional numerical analysis allowed investigating the pressure and velocity fields as well as other aerodynamics parameters of the test case.

Computational methods have been widely applied in conjugate heat transfer analysis. The very first and crucial step in such research is the meshing process which consists in dividing the analysed geometry into numerous small control volumes (cells). In Computational Fluid Dynamics (CFD) applications it is desirable to use the hexahedral cells as the resulting mesh is characterized by low numerical diffusion. Unfortunately generating such mesh can be a very time-consuming task and in case of complicated geometry - it may not be possible to generate cells of good quality. Therefore tetrahedral cells have been implemented into commercial pre-processors. Their advantage is the ease of its generation even in case of very complex geometry. On the other hand tetrahedrons cannot be stretched excessively without decreasing the mesh quality factor, so significantly larger number of cells has to be used in comparison to hexahedral mesh in order to achieve a reasonable accuracy. Moreover the numerical diffusion of tetrahedral elements is significantly higher. Therefore the polyhedral cells are proposed within the paper in order to combine the advantages of hexahedrons (low numerical diffusion resulting in accurate solution) and tetrahedrons (rapid semi-automatic generation) as well as to overcome the disadvantages of both the above mentioned mesh types. The major benefit of polyhedral mesh is that each individual cell has many neighbours, so gradients can be well approximated. Polyhedrons are also less sensitive to stretching than tetrahedrons which results in better mesh quality leading to improved numerical stability of the model. In addition, numerical diffusion is reduced due to mass exchange over numerous faces. This leads to a more accurate solution achieved with a lower cell count. Therefore detailed comparison of numerical modelling results concerning conjugate heat transfer using tetrahedral and polyhedral meshes is presented in the paper.

The flow-field in the vicinity of tandem building model in a wind tunnel will be subjected to analysis of dynamics. The model is 3D consisting of the two blocks of different sizes arranged in a streamwise direction. Experiments were performed using time-resolved PIV technique in several measuring planes to capture both spatial and dynamical features.

Wind power generation is the most dynamically developing branch of renewable energy sector in Poland. The high price of coal and its negative environmental impact result in ever growing support for the renewable energy in the energy sector. Wind power industry produces clean energy, but costs of investments are very high. Process of creating a wind farm is very long and complicated. It requires the knowledge of many disciplines such as law, economics, energetic. The aim of this paper was study the state and the development of the wind power sector, especially wind farm in Poland. The economic analysis on investment in wind farm in Poland according to a new act on renewable energy sources was presented. The subject of this analysis was to estimate profitability of wind farm project 40 MW capacity. The analysis includes the comparison of various support systems - the system of green certificates and the new - auction model on the profitability of investment in wind farm. This aims to show how important is appropriate government support for producers of green energy words.

The problem of flow field in the urban boundary-layer (UBL) in aspects of wind comfort around buildings and pollutant dispersion has grown in importance since human activity has become so intense that it started to have considerable impact on environment. The issue of wind comfort in urban areas is the result of complex interactions of many flow phenomena and for a long time it arouses a great interest of the research centres. The aim of article is to study urban atmospheric flow at the local scale, which allows for both a detailed reproduction of the flow phenomena and the development of wind comfort criteria. The proposed methodology involves the use of PIV wind tunnel experiments as well as numerical simulations (Computational Fluid Dynamics, CFD) in order to enhance understanding of the flow phenomena at this particular scale in urban environments. The analysis has been performed for the 3D case of two surface-mounted buildings arranged in tandem, which were placed with one face normal to the oncoming flow. The local characteristics of flow were obtained by the use of commercial CFD code (ANSYS Fluent). The validation was carried out with reference to the PIV results.

Chemical Looping Combustion (CLC) is a technology that allows the separation of CO2, which is generated by the combustion of fossil fuels. The majority of process designs currently under investigation are systems of coupled fluidized beds. Advances in the development of power generation system using CLC cannot be introduced without using numerical modelling as a research tool. The primary and critical activity in numerical modelling is the computational domain discretization. It influences the numerical diffusion as well as convergence of the model and therefore the overall accuracy of the obtained results. Hence an innovative approach of computational domain discretization using polyhedral (POLY) mesh is proposed in the paper. This method reduces both the numerical diffusion of the mesh as well as the time cost of preparing the model for subsequent calculation. The major advantage of POLY mesh is that each individual cell has many neighbours, so gradients can be much better approximated in comparison to commonly-used tetrahedral (TET) mesh. POLYs are also less sensitive to stretching than TETs which results in better numerical stability of the model. Therefore detailed comparison of numerical modelling results concerning subsection of CLC system using tetrahedral and polyhedral mesh is covered in the paper.

This paper presents results that show the effect of hydrothermal carbonization and subsequent cold plasma jet treatment with helium and argon on the structure and sorption properties of a material—spent brewery grain. Treatment of activated carbon, with a cold atmospheric plasma jet, was used comparatively. The effect of activation on the pore structure of the materials was carried out by the volumetric method at low pressure (N2, 77 K). The specific surface area as well as the total pore volume, average pore size, and pore size distribution were determined using different theoretical models. A high improvement in the sorption capacity parameter was obtained for hydrochars after cold atmospheric plasma jet treatment with an increase of 7.5 times (using He) and 11.6 times (using Ar) compared with hydrochars before cold atmospheric plasma jet treatment. The increase in specific surface area was five-fold (He) and fifteen-fold (Ar). For activated carbon, such a large change was not obtained after plasma activation. Regardless of the gas used, the increase in structural parameter values was 1.1–1.3. [ABSTRACT FROM AUTHOR]

This paper considers the coupled kinematic and dynamic models of a mobile crane. A full description of boom and load movement has been provided as a response of the system to the influence of kinematic forces. The linear system model was treated as rigid, and the carried load as a nondeformed static body. To describe the position of said load, Bryant angles were used. The dynamic model includes the impact of external forces (wind pressure) while load carrying and positioning. Algorithm and calculation software were developed to enable dynamic phenomena analysis during both a work cycle and free movement of said load. The initial problem was solved by means of the ode45 calculation procedure in the Matlab software based on the Runge–Kutta 4th Order Method. The work presents exemplary results of load movement simulation with respect to various wind velocities, selected on the basis of guidelines from Poland's standards regarding safe operation of mechanical equipment. [ABSTRACT FROM AUTHOR]