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This paper deals with environmental policy issues related to a landfill design. The final product of numerous waste treatments should be placed on a landfill. Before waste disposal, the ground should be protected by a mineral layer with properties required by the related regulation. In order to prevent environment pollution, EU adopted the Landfill Directive 1999/31/EC. The most important technical requirements related to the characteristics of the layer material are water permeability and thickness. The performed comparative national regulatory analysis raised the question of the need for more uniform elaboration of the directive requirements over the whole European Union area (including EU candidates). The choice of the material for the impermeable mineral layer, which should be made during landfill design, is a very important decision. Methods for the determination of the permeability coefficient were analysed, showing that the Directive should define hydraulic gradient as a physical quantity and define its value through measurement of the permeability coefficient. The paper analyses whether some parts of the Directive, as landfill design BAT and base for national legislative acts, require further elaboration in order to provide sufficient information about proper protection of soil and water. Using integrated approach, seven amendments on the directive annex I were suggested related to (a) the meaning of the term artificially established geological barrier, (b) layer thickness, (c) water permeability coefficient determination, (d) mineral layer lifecycle, (e) the meaning of the term sealing and (f) leaching control of material joints. [ABSTRACT FROM AUTHOR]

The sub-laminar drag effect of microgroove surfaces was studied numerically in a steady two-dimensional channel flow at subcritical Reynolds numbers. Considerations are restricted to grooves of a few viscous length scales in depth, which are assumed not to promote the laminar to turbulent transition process. It was found that the drag reduction effect is due to the layout of grooves with respect to the flow direction and contour geometry. Results of computations show that for grooves of curved contour placed normal to the flow direction, drag arising from viscous and pressure forces is modulated due to the functional dependence of forces on the surface area projected in the flow direction. Such a groove layout leads to a large skin-friction reduction, but a comparable increase in pressure drag results in sub-laminar drag if drag over flat surface is considered as a reference. For a curved groove contour, the drag reduction increases with increasing Reynolds number and reaches about 5 % at Reynolds numbers approaching critical. [ABSTRACT FROM AUTHOR]

The concept of a micropatterned surface morphology capable of producing self-stabilization of turbulence in wall-bounded flows is considered in pipes of non-circular cross-sections which act to restructure fluctuations towards the limiting state where these must be entirely suppressed. Direct numerical simulations of turbulence in pipes of polygon-shaped cross-sections with straight and profiled sides were performed at a Reynolds number $$Re_\tau \simeq {\mathrm 300}$$ based on the wall shear velocity and the hydraulic diameter. Using the lattice Boltzmann numerical algorithm, turbulence was resolved with up to $${\mathrm 540\times 10^6}$$ grid points ( $${\mathrm 8,192\times 257 \times 256}$$ in the x, x and x directions). The DNS results show a decrease in the viscous drag around corners, resulting in a reduction of the skin-friction coefficient compared with expectations based on the well-established concept of hydraulic diameter and the use of the Blasius correlation. These findings support the conjecture that turbulence might be completely suppressed if the pipe cross-section is a polygon consisting of a sufficient number of profiled sides of the same length which intersect at right angles at the corners. [ABSTRACT FROM AUTHOR]

The stabilizing effect of microgroove surface morphology on viscous drag reduction was studied experimentally in the inlet region of a plane channel flow. The stabilization is thought to be due to the ability of a microgrooved surface pattern to suppress the velocity fluctuations in the spanwise direction on a restricted portion of the wetted surface, which prevents vorticity development at the wall and consequently across the entire flow field. This smart microflow control strategy, which works successfully only under very particular circumstances, was implemented in a microgroove-modified channel flow in which the front part has a microgrooved surface topology. The results of pressure drop measurements indicate that microgrooved surfaces can effectively stabilize laminar boundary layer development, leading to a significant reduction in the viscous drag. In the rear flat part of the microgroove-modified channel test section, a maximum drag reduction of $${\rm DR\simeq 35\%}$$ was measured. This corresponds to an overall drag reduction of $${\rm DR\simeq 16\%}$$ at a length Reynolds number of $$Re_x\simeq 10^6. $$ The drag reduction effect persisted in a narrow range of flow velocities and for the reported experimental conditions corresponds to microgroove dimensions between 1.5 and 2.5 viscous length-scales. [ABSTRACT FROM AUTHOR]

fully resolved numerical simulation of a turbulent microchannel flow, with uniformly spaced two-dimensional obstruction elements mounted at the wall and normal to the flow direction, was carried out at a very low Reynolds number of Re ≃ 970 based on the centerline velocity and the microchannel height. Employing the lattice Boltzmann numerical technique, all energetic scales of turbulence were resolved with about 19 × 10 grid points (1261 × 129 × 128 in the x, x, and x directions). The simulated results confirm the self-maintenance of turbulence at such a low Reynolds number. Turbulence persisted over more than 1,000 turnover times, which was sufficiently long to prove its self-maintenance. These findings support the conjecture that turbulence developing in microchannels having rough walls can not only be initiated but also maintained at very low Reynolds numbers. [ABSTRACT FROM AUTHOR]

Twenty-seven selected equations were tested on 162 compounds with 1958 calorimetric data for their abilities to reflect the temperature influence on the heat of vaporization of pure compounds. A new equation is recommended (overall percent deviation 0.27% and percent deviation 0.59% above 0.9T r ). [ABSTRACT FROM AUTHOR]

Spectrophotometric investigations of the reactions between cobalt(II) and cobalt(III) ions and 1,3-propanediamine- N,N′-diacetato- N,N′-di-3-propionato ligand (1,3-pddadp) in aqueous solution, demonstrate the formation of complexes [Co(1,3-pddadp)] and [Co(1,3-pddadp)]. The stability constant of [Co(1,3-pddadp)] was found to be log β = 11.07±0.03 in 0.5 M NaNO medium at 25°C. Structures for the complexes are suggested. [ABSTRACT FROM AUTHOR]