<abstract xmlns="http://www.w3.org/1999/xhtml"> Progressive urban development of the human environment requires new methods of rain water treatment. Recently, there has been a growing interest in the improvement of gravitational suspension separation, and especially in the application of the centrifugal force. This important factor can be induced in two ways; by the circulation of the reservoir containing the fluid (centrifugal separators), or by a tangent supply of this reservoir (circulative separators). In addition to the centrifugal force, another essential transversal force is at work in this case, resulting from the local variability of the pressure. In the literature, this force is derived for centrifuge conditions, but applied also to circulative separators, which is questionable, as in the latter devices velocity and pressure fields are clearly different. The paper is devoted to the determination of the transversal pressure effect in circulative separators. First, a model of tangent and radial velocity profiles is introduced. The radial pressure distribution, calculated on this basis and verified experimentally, leads to the final result, that is, a technical formula describing the force in question</abstract>

Transversal Pressure Effect in Circulative Separators

<abstract xmlns="http://www.w3.org/1999/xhtml">An incremental model is proposed to describe pre-failure behaviour of granular soils in plane strain conditions. The model has been derived from an approach applied in the analysis of triaxial tests. We have applied the methods of tensor algebra to transfer our triaxial results to a 2D case. The model describes the pre-failure deformations of fully drained sands and phenomena associated with undrained response such as static liquefaction. This model has a simple structure in the form of incremental equations. For some simple loading paths, these equations can be integrated analytically. For more complex loading paths a simple numerical algorithms will be sufficient. The model takes into account an initial anisotropy of soil which is ignored in most models. It also takes into account the initial state of soil, defined as rather contractive or dilative, in addition to classical geotechnical division into loose and dense sands. The proposed constitutive equations allow the study of pre-failure instabilities of sand, and some examples are presented.We have also derived analytically the equation for an instability line.</abstract>

Institute of Hydro-Engineering Polish Academy of Sciences, ul. Koscierska 7, 80-382 Gdańsk, Poland

Institute of Hydro-Engineering Polish Academy of Sciences, ul. Kościerska 7, 80-382 Gdańsk, Poland

Deformations and liquefaction of granular soils in plane strain conditions

<abstract xmlns="http://www.w3.org/1999/xhtml"> A two-dimensional numerical model was used for a simulation of vertical average longshore currents generated by both wind friction and wind-wave action in the nearshore zone. The modelling domain includes the southern part of the Baltic Proper (all boundaries were closed). Wind, uniform in space and varying in time, was the only forcing in the model. The correlation coefficient higher than 0.8 was obtained by model calibration versus the field measurements of currents conducted at the Lubiatowo field station (southern Baltic) during about 1.5 months in 2006. Comparative simulations of total currents including both wind-induced drift and wave components, and of total currents including only a wind-induced drift component, showed that the input of the drift component into currents in the nearshore zone is greater than commonly believed.Wind-induced drift strongly dominates outside the zone of wave transformation, and its input into the total resulting currents remains noticeable even in a zone between the shoreline and the depth of the first wave breaking. Thus, wind-induced drift constitutes up to 50% of the resulting longshore currents for longshore winds and no less than 20% of the longshore component of currents for winds at 45 degrees to the longshore direction.</abstract>

Wind Influence on the Formation of Nearshore Currents in the Southern Baltic: Numerical Modelling Results

<abstract xmlns="http://www.w3.org/1999/xhtml"> Today, intensive urban development calls for new technologies in the field of environmental engineering. Extensive infrastructure requires more roads and motorways, as well as larger areas covered with concrete, which altogether leads to greater volumes ofwater creating surface run-off. Rotational separators, besides lamella and coalescence units, may provide a highly efficient method for treatment of storm water running off roads and motorways. This paper is focused on two important aspects of the operation of rotational separators: forces acting on a particle in liquid flow, and pressure distribution in the chamber. The resulting relations constitute crucial elements in the future method of designing such devices.</abstract>

Specification of forces in rotational separator

<abstract xmlns="http://www.w3.org/1999/xhtml"> The article concentrates on the identification of geotechnical parameters of alluvial soil represented by silts found near Poznan and Elblag. Strength and deformation parameters of the subsoil tested were identified by the CPTU (static penetration) and SDMT (dilatometric) methods, as well as by the vane test (VT). Geotechnical parameters of the subsoil were analysed with a view to using the soil as an earth construction material and as a foundation for buildings constructed on the grounds tested. The article includes an analysis of the overconsolidation process of the soil tested and a formula for the identification of the overconsolidation ratio OCR. Equation 9 reflects the relation between the undrained shear strength and plasticity of the silts analyzed and the OCR value. The analysis resulted in the determination of the Nkt coefficient, which might be used to identify the undrained shear strength of both sediments tested. On the basis of a detailed analysis of changes in terms of the constrained oedometric modulus M0, the relations between the said modulus, the liquidity index and the OCR value were identified. Mayne’s formula (1995) was used to determine the M0 modulus from the CPTU test. The usefullness of the sediments found near Poznan as an earth construction material was analysed after their structure had been destroyed and compacted with a Proctor apparatus. In cases of samples characterised by different water content and soil particle density, the analysis of changes in terms of cohesion and the internal friction angle proved that these parameters are influenced by the soil phase composition (Fig. 18 and 19). On the basis of the tests, it was concluded that the most desirable shear strength parameters are achieved when the silt is compacted below the optimum water content.</abstract>

Geotechnical Parameters of Alluvial Soils from in-situ Tests

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Archives of Hydro-Engineering and Environmental Mechanics

 Archives of Hydro-Engineering and Environmental Mechanics (formerly Archives of Hydro-Engineering and Archiwum Hydrotechniki) cover the broad range of research disciplines related to hydro-engineering, including: hydrodynamics and hydraulics of inlands and sea waters, hydrology, hydroelasticity, ground-water hydraulics, water contamination, coastal engineering, geotechnical engineering, geomechanics and structural mechanics.  The main objective of Archives of Hydro-Engineering and Environmental Mechanics is to provide an up-to-date reference for civil engineers and scientists involved in the applications of mechanics to the analysis of various phenomena encountered in the natural environment, those occurring due to human activities, as well as to the problems arising from the influence of the environment on man-made structures and objects. Theoretical, experimental and practice-oriented papers on various topics, such as those mentioned above, are welcomed. Review papers are also invited. Occasionally, special issues containing papers presented at international conferences and other scientific meetings may be published.  All papers (in regular and special issues) are selected for publication through a peer review process, based on their significance and research originality.  Archiving  Sciendo archives the contents of this journal in Portico - digital long-term preservation service of scholarly books, journals and collections.  Plagiarism Policy  The editorial board is participating in a growing community of Similarity Check System's users in order to ensure that the content published is original and trustworthy. Similarity Check is a medium that allows for comprehensive manuscripts screening, aimed to eliminate plagiarism and provide a high standard and quality peer-review process. 