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Non-dimensional Parameter (non-dimensional + parameter)
Selected AbstractsProfile: air quality regulation policy in PortugalENVIRONMENTAL POLICY AND GOVERNANCE, Issue 1 2004João F. P. Gomes Ten years after the publication of the first air quality laws in Portugal, and seven years after the publication of the respective emission limits, it seems appropriate to analyse the degree of law enforcement by the Portuguese manufacturing industry. Therefore, based on the emission measurements made regularly by ISQ as the only officially accredited laboratory, a set of about 400 sources is analysed in terms of the compliance with the emission limits regarding total suspended particulate, sulphur dioxide, nitrogen oxides and VOCs. The compliance is evaluated through a non-dimensional parameter and plotted versus the emission flow rate to derive conclusions: it was noticed that emission limits are generally respected regarding sulphur dioxide and nitrogen oxides, which does not happen for the other pollutants considered in this study. However, the non-compliance occurs mainly for very low emission flow rates, which suggests some alterations in the emission limits' applicability, which is being revised at the moment. Copyright © 2004 John Wiley & Sons, Ltd and ERP Environment. [source] Fluid flow and heat transfer of opposing mixed convection adjacent to downward-facing, inclined heated platesHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 1 2009Kenzo Kitamura Abstract Experimental investigations were carried out for opposing mixed convective flows of air adjacent to downward-facing, inclined heated plates. The experiments covered the ranges of the Reynolds and modified Rayleigh numbers from ReL=400 to 4600 and RaL*=1.0×107 to 5.4×108, and the inclination angles from ,=15 to 75° from horizontal. The flow fields over the plates were visualized with smoke. The results showed that a separation of forced boundary layer flow occurs first at the bottom edge of the plate, and then the separation point shifts toward upstream with increasing wall heat flux, and finally, reaches the top edge of the plates. It was found that the separations at the bottom and top edges are predicted with a non-dimensional parameter (GrL,*/ReL2.5)=0.35 and 1.0, respectively. The local heat transfer coefficients of the inclined plates were also measured and the results showed that the minimum coefficients appear in the separation region. Moreover, it was revealed that forced, natural, and combined convective flows can be classified by the non-dimensional parameter (GrL,*/ReL2.5). © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res; Pub- lished online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20233 [source] Heat transfer of combined forced and natural convection from horizontal cylinder to airHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 8 2007Kenzo Kitamura Abstract Experimental investigations have been carried out for combined convective flows of air induced around uniformly heated, horizontal cylinders. Three cases of aiding, opposing, and cross flows were examined. The experiments covered the ranges of the Reynolds and modified Rayleigh numbers of Red=50 to 900 and Rad*=5×104 to 3×106. The flow fields around the cylinders were visualized with smoke. The results showed that separation points gradually shift from those of the forced convection to the top edge of the cylinder with increasing wall heat fluxes. The local heat transfer coefficients of the cylinders were also measured. Although the local coefficients show complex variations with the forced flow velocities and the wall heat fluxes, the overall coefficients become higher than those estimated from pure forced and natural convections throughout the cases of aiding, opposing, and cross flows. Moreover, it was confirmed that the overall Nusselt numbers as well as the separation points can be predicted with the non-dimensional parameter (Grd*/NudRed2). © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(8): 474,488, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20180 [source] Method to improve the mitigative effectiveness of a series of check dams against debris flowsHYDROLOGICAL PROCESSES, Issue 26 2008Rabindra Osti Abstract The advance of technology has led to more competent countermeasures, but lives and properties still continue to suffer from water-induced disasters, such as floods, landslides, and debris flows. To increase the effectiveness of counter systems, improved methods of planning and designing such systems are prerequisite. This paper describes briefly a methodological approach for predicting debris flow characteristics, and proposes techniques for evaluating and improving the mitigative effectiveness of check dams against debris flows in steep mountain torrents. Additionally, a non-dimensional parameter, namely potential storage volume, is introduced to generalize the evaluation processes. As an example, the 1999 debris-flow event in the San Julian River, Venezuela, is chosen for discussion. The paper also proposes a method of evaluating the control function of a series of check dams as well as the criteria for the selection of their sizes, numbers and locations. It is hoped that this work will help to determine which combinations of check dams will fit best together for the optimal control of debris flows and available resources in any river basin. Copyright © 2008 John Wiley & Sons, Ltd. [source] A new shallow water model with polynomial dependence on depthMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 5 2008José M. Rodríguez Abstract In this paper, we study two-dimensional Euler equations in a domain with small depth. With this aim, we introduce a small non-dimensional parameter , related to the depth and we use asymptotic analysis to study what happens when , becomes small. We obtain a model for , small that, after coming back to the original domain, gives us a shallow water model that considers the possibility of a non-constant bottom, and the horizontal velocity has a dependence on z introduced by the vorticity when it is not zero. This represents an interesting novelty with respect to shallow water models found in the literature. We stand out that we do not need to make a priori assumptions about velocity or pressure behaviour to obtain the model. The new model is able to approximate the solutions to Euler equations with dependence on z (reobtaining the same velocities profile), whereas the classic model just obtains the average velocity. Copyright © 2007 John Wiley & Sons, Ltd. [source] Modelling interactions between fold,thrust belt deformation, foreland flexure and surface mass transportBASIN RESEARCH, Issue 2 2006Guy D. H. Simpson ABSTRACT Interactions between fold and thrust belt deformation, foreland flexure and surface mass transport are investigated using a newly developed mathematical model incorporating fully dynamic coupling between mechanics and surface processes. The mechanical model is two dimensional (plane strain) and includes an elasto-visco-plastic rheology. The evolving model is flexurally compensated using an elastic beam formulation. Erosion and deposition at the surface are treated in a simple manner using a linear diffusion equation. The model is solved with the finite element method using a Lagrangian scheme with marker particles. Because the model is particle based, it enables straightforward tracking of stratigraphy and exhumation paths and it can sustain very large strain. It is thus ideally suited to study deformation, erosion and sedimentation in fold,thrust belts and foreland basins. The model is used to investigate how fold,thrust deformation and foreland basin development is influenced by the non-dimensional parameter , which can be interpreted as the ratio of the deformation time scale to the time scale for surface processes. Large values of imply that the rate of surface mass transport is significantly greater than the rate of deformation. When , the rates of surface processes are so slow that one observes a classic propagating fold,thrust belt with well-developed wedge top basins and a largely underfilled foreland flexural depression. Increasing causes (1) deposition to shift progressively from the wedge top into the foredeep, which deepens and may eventually become filled, (2) widespread exhumation of the fold,thrust belt, (3) reduced rates of frontal thrust propagation and possible attainment of a steady-state orogen width and (4) change in the style and dynamics of deformation. Together, these effects indicate that erosion and sedimentation, rather than passively responding to tectonics, play an active and dynamic role in the development of fold,thrust belts and foreland basins. Results demonstrate that regional differences in the relative rates of surface processes (e.g. because of different climatic settings) may lead to fold,thrust belts and foreland basins with markedly different characteristics. Results also imply that variations in the efficiency of surface processes through time (e.g., because of climate change or the emergence of orogens above sea level) may cause major temporal changes in orogen and basin dynamics. [source] Unsteady free convection,radiation flow over a vertical wall embedded in a porous mediumINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 11 2008Joaquín Zueco Abstract A numerical solution for the transient two-dimensional free convection flow of viscous dissipative fluid over an infinite vertical plate through a porous medium bounded, taking into account the thermal radiation, is analysed. The fluid is grey, and acts as a radiation emitting and absorbing (but non-scattering) medium. The influence of the non-dimensional parameters such as the Forchheimer coefficient (Fo), the permeability parameter (P), the Eckert number (Ec) and the radiation parameter (R) on the velocity, temperature, Nusselt number and on the time taken to reach the steady state is studied. The possibility of non-Darcy flow is also analysed. The numerical method employed, network simulation method, is based on an electro-thermal analogy and permits the direct visualization and evolution of the local and/or integrated transport variables (velocities, temperatures and fluxes) at any point or section of the medium. The numerical solutions of this work have been compared with the existing information in the literature with good agreement. Copyright © 2007 John Wiley & Sons, Ltd. [source] Orographic flow-blocking scheme characteristicsTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 603 2004A. R. Brown Abstract The characteristics of the orographic flow blocking parametrization used in the Met Office Unified Model are examined in a one-dimensional framework. This approach allows feedback of the parametrized stresses on the winds resulting, in some cases, in stresses very different from those that would be obtained without this feedback. The key controlling non-dimensional parameters are identified, and the implications of the results for the use of the scheme in climate and numerical weather-prediction models are discussed. Copyright © 2004 Royal Meteorological Society [source] | |||||||||||||