Cultural heritage management based on values

Cultural heritage management is perceived today as a modern system for the protection of historical monuments. However, the original meaning of heritage is intangible: with the emphasis shifted from the object (monuments) to the subject (recipients). Therefore, not only objects but also people become the area of interest. The aim of this article is to present the concept of heritage management based on values. Literature analysis indicates that numerous values are attributed to historical monuments; the article enumerates almost 130 of them. Drawing upon the experience of axiology, the values should be divided into objective (belonging to the object) and subjective (belonging to the recipient). It will allow for an even better identification of heritage resources, and for adjusting the methods of heritage protection, education and promotion. The presented concept is a starting point for the elaboration of modern methods of preserving the relicts of our past and making use of them by contemporary generations

Bubbly flow measurements in hydraulic jumps with small inflow Froude numbers

The transition from supercritical to subcritical open channel flow is characterised by a strong dissipative mechanism called a hydraulic jump. A hydraulic jump is turbulent and associated with the development of large-scale turbulence and air entrainment. In the present study, some new physical experiments were conducted to characterise the bubbly flow region of hydraulic jumps with relatively small Froude numbers (2.4 < Fr(1) < 5.1) and relatively large Reynolds numbers (6.6 x 10(4) < Re < 1.3 x 10(5)). The shape of the time-averaged free-surface profiles was well defined and the longitudinal profiles were in agreement with visual observations. The turbulent free-surface fluctuation profiles exhibited a peak of maximum intensity in the first half of the hydraulic jump roller, and the fluctuations exhibited some characteristic frequencies typically below 3 Hz. The air-water flow properties showed two characteristic regions: the shear layer region in the lower part of the flow and an upper free-surface region above. The air-water shear layer region was characterised by local maxima in terms of void fraction and bubble count rate. Other air-water flow characteristics were documented including the distributions of interfacial velocity and turbulence intensity. The probability distribution functions (PDF) of bubble chord time showed that the bubble chord times exhibited a broad spectrum, with a majority of bubble chord times between 0.5 and 2 ms. An analysis of the longitudinal air-water structure highlighted a significant proportion of bubbles travelling within a cluster structure. (C) 2011 Elsevier Ltd. All rights reserved

Froude Similitude and Scale Effects Affecting Air Entrainment in Hydraulic Jumps

A hydraulic jump is the rapid transition from a high-velocity to a low-velocity open channel flow. It is characterized by strong turbulence and air bubble entrainment. Detailed air-water flow properties were measured in hydraulic jumps with partially-developed inflow conditions. The present data set together with the earlier data of Chanson (2006) yielded similar experiments conducted with identical inflow Froude numbers but Reynolds numbers between 24,000 and 98,000. The comparative results showed some drastic scale effects in the smaller hydraulic jumps in terms of void fraction and bubble count rate distributions. The present comparative analysis demonstrated quantitatively that dynamic similarity of two-phase flows in hydraulic jumps cannot be achieved with a Froude similitude. In experimental facilities with Reynolds numbers up to 105, some viscous scale effects were observed in terms of the rate of entrained air and air-water interfacial area

Two-phase gas-liquid flow properties in the hydraulic jump: Review and perspectives

Research on multiphase flows has been strongly improved over the last decades. Because of their large fields of interests and applications for chemical, hydraulic, coastal and environmental engineers and researchers, these flows have been strongly investigated. Although they are some promising and powerful numerical models and new computing tools, computations can not always solve all actual practical problems (weather forecast, wave breaking on sandy beach…). The recent and significant developments of experimental techniques such as Particle Imagery Velocimetry (PIV) and conductivity or optical probes have particularly led scientists to physical modeling that provide series of data used to calibrate numerical models. Flows with time and length scales that were not achievable in the past are now studied leading to a better description of physical mechanisms involved in mixing, diffusion and turbulence. Nevertheless, turbulence is still not well understood, particularly in two-phase flows. In the present chapter, we focus on a classical multiphase flow, the hydraulic jump. It occurs in bedrock rivers, downstream of spillways, weirs and dams, and in industrial plants. It characterizes the transition from a supercritical open-channel flow (low-depth and high velocity) to a subcritical motion (deep flow and low velocities). Experimentally, this two-phase flow can be easily studied. Furthermore, it involves fundamental physical processes such as air/water mixing and the interaction between turbulence and free surface. This flow contributes to some dissipation of the flow kinetic energy downstream of the impingement point, in a relatively short distance making it useful to minimize flood damages. It is also associated with an increase of turbulence levels and the development of large eddies with implications in terms of scour, erosion and sediment transport. These are some of the reasons that make studies on this flow particularly relevant. Although numerical and analytical studies exist, experimental investigations are still considered as the best way to improve our knowledge. After a brief description of the hydraulic jumps, the first part of this chapter aims to review some historical developments with special regards to the experimental techniques and physical modeling (similitude). In the second part, we describe and discuss the basic properties of the two-phase flow including void fraction, bubble frequency, bubble velocity and bubble size. The free surface and turbulence properties are presented as well. In the last part, we develop some conclusions, perspectives and further measurements that should be undertaken in the future

Free-surface fluctuations in hydraulic jumps: Experimental observations

A hydraulic jump is the rapid and sudden transition from a high-velocity supercritical open channel flow to a subcritical flow. It is characterised by the dynamic interactions of the large-scale eddies with the free-surface. New series of experimental measurements were conducted in hydraulic jumps with Froude numbers between 3.1 and 8.5 to investigate these interactions. The dynamic free surface measurements were performed with a non-intrusive technique while the two-phase flow properties were recorded with a phase-detection probe. The shape of the mean free surface profile was well defined and the turbulent fluctuation profiles highlighted a distinct peak of turbulent intensity in the first part of the jump roller, with free-surface fluctuation levels increasing with increasing Froude number. The dominant free-surface fluctuation frequencies were typically between 1 and 4 Hz. A comparison between the acoustic sensor signals and conductivity probe data suggested that the air-water "free-surface" detected by the acoustic sensor corresponded to about the boundary between the turbulent shear layer and the upper free-surface layer. Simultaneous measurements of free surface and bubbly flow fluctuations for Fr = 5.1 indicated that the frequency ranges of both sensors were similar (F < 5 Hz) whatever the position downstream of the toe. The present results highlighted that the dynamic free-surface measurements can be conducted successfully using acoustic displacement meters, and the time-averaged depth measurements was a physical measure of the free-surface location in hydraulic jumps

Non intrusive measurement technique for dynamic free-surface characteristics in hydraulic jumps

This paper concerns dynamic free-surface measurements performed in hydraulic jumps with Froude numbers between 3.1 and 8.5 using non intrusive ultrasonic probes. The interest was first focused on the characteristics of mean (d) and turbulent (d’) levels of the air-water interface. Then they were coupled with phase-detection conductivity probes to assess the accuracy of the sensors. This allowed an accurate definition of the exact level detected by the ultrasonic displacement meters. The results showed a regular increase of the mean level over the jump (roller length). A peak of turbulent fluctuation was found on the roller whose amplitude depends upon the Froude number. Comparisons with previous studies showed a good agreement in terms of shapes and roller length estimation. Frequency analysis of the free-surface fluctuations revealed that highest frequencies in the jump are around 4 Hz. Based upon an autocorrelation analysis, the integral time scales of the air/water interface were found to be between 0.03 s and 0.12 s

Free Surface, Bubbly flow and Turbulence Measurements in Hydraulic Jumps

The hydraulic jump is the rapid transition from a high-velocity (supercritical regime) to a low-velocity (subcritical regime) open channel flow. It is characterized by the interaction of some strong turbulence with a free surface leading to air entrainment (bubbles, droplets, splashes) with macro-scale vortices, kinetic energy dissipation and a bubbly two-phase flow structure. The aim of this report is to present new free surface and air-water flow measurements in hydraulic jumps with partially-developed inflow conditions for a wide range of inflow Froude numbers (Fr = 3.1 to 8.5, Re= 24,000 to 62,000). New experiments were conducted in a large-size facility using ultrasonic displacement meters to describe the free surface features and a double-tip conductivity probe to study the two-phase flow properties. The mean and turbulent profiles of the air-water interface were documented. The data were processed in terms of some spectral analysis of the free surface fluctuations and compared with the frequencies of the horizontal oscillations of the toe. The free-surface measurements highlighted large fluctuations in the roller. A peak in free-surface fluctuation intensity was found in the first half of the roller reflecting the dynamic unsteady structure of the free surface in this flow region. This was followed by a gradual decrease in turbulent intensity. The normalized maximum free-surface fluctuation was found to be proportional to the inflow Froude number (Fr). Spectral analyses of the free-surface fluctuations showed dominant frequencies ranging from 0.5 to 4 Hz with decreasing frequencies when increasing Froude number. While the dominant frequencies were nearly constant in the roller, lower values were observed downstream of the roller implying that faster vortical structures developed in the roller itself. The air-water flow properties were investigated in terms of the distributions of void fraction, bubble count rate, bubble diameter, interfacial velocities, turbulent velocity fluctuations and turbulence time scales. The void fraction measurements (C) showed the presence of an advective diffusion shear layer where the air concentration vertical distributions were successfully compared with an analytical solution of the advective diffusion equation for air bubbles and compared well with earlier studies. The vertical distributions of bubble count rate (F) showed a marked peak (Fmax), with increased count rates with increasing Froude number. In the air-water shear layer, the maximum bubble count rate (Fmax) decayed with increasing distance from the jump toe as previously reported. Detailed results were presented concerning the mean bubble chord length, interfacial velocity and turbulent intensity. The vertical distributions of interfacial velocity followed closely a wall jet flow pattern. The turbulence intensity distributions exhibited large values in the jump roller with amplitude up to 400% for the largest Froude number. However the turbulence levels decreased with increasing distance from the jump toe. The probability density functions of bubble chord time exhibited a wide spectrum with a predominance of small bubble chord time for largest Froude numbers. The turbulence time scale data showed an increase with the relative elevation above the bed, as well as some decrease with increasing distance from the toe. Far downstream, nearly homogeneous profiles of turbulent time scales were observed with the smallest time scales. Simultaneous measurements of free surface and bubbly flow properties suggested some possible correlation between free surface and bubble fluctuations in terms of frequency. Some cross-correlation analysis showed large fluctuations with negative and positive correlations. Some spectral analysis of the cross-correlation function indicated predominant frequencies between 1.2 to 2.3 Hz depending on the distance to the toe. These were in agreement with free-surface fluctuations. A comparative analysis of Froude similar experiments was conducted with Reynolds numbers ranging from 25,000 to 98,000, and inflow depths of 0.012, 0.018 and 0.024 m. The results implied that the experimental data obtained with inflow Reynolds numbers up to 98,000 cannot be extrapolated to large-size prototype structures without significant scale effects in terms of void fraction, bubble count rate and bubble chord time distributions. Te result has important implications in terms of civil, environmental and sanitary engineering structures where the prototype Reynolds numbers range typically from 1E+6 to over 1E+8

Cultural quarters as a means of enhancing the creative capacity of Polish cities? Some evidence from Cracow

Culture-oriented activities conducted by diverse actors in selected urban areas may lead to the formation of unique quarters of production and consumption of cultural goods and services which function both as creative hubs and leisure spaces. Such cultural quarters may develop spontaneously or as a result of official designation and major public investment. Referring to the debate on cultural quarters in Western Europe, this article aims to examine the issue of the spatial concentration of cultural and creative activities within a selected large city in Poland. The author analyses recent transformations of two historic quarters in Cracow (Kazimierz and Podgórze) and considers the extent to which both areas can be regarded as successful cultural quarters. She describes their emergence and the changes observed in them in terms of groupings, character and number of creative-sector firms established there, pondering whether their role is limited to a function as centres of commercial cultural entertainment and night-life consumption, or whether they indeed stimulate the development of a creative economy