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Numerical simulation of formation and preservation of Ningwu ice cave, Shanxi, China
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Ice caves exist in locations where annual average temperature in higher than 0 °C. An example is Ningwu ice cave, Shanxi Province, the largest ice cave in China. In order to quantitatively explain the mechanism of formation and preservation of the ice cave, we use Finite Element Method to simulate the heat transfer process at this ice cave. There are two major control factors. First, there is the seasonal asymmetric heat transfer. Heat is transferred into the ice cave from outside, very inefficiently by conduction in spring, summer and fall. In winter, thermal convection occurs that transfers heat very efficiently out of the ice cave, thus cooling it down. Secondly, ice–water phase change provides a heat barrier for heat transfer into the cave in summer. The calculation also helps to evaluate effects of global warming, tourists, etc. for sustainable development of ice cave as tourism resource. In some other ice caves in China, managers installed air-tight doors at these ice caves entrance intending to "protect" these caves, but this prevent cooling down these caves in winters and these cave ices will entirely melt within tens of years.
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... This paper is one of a number of papers discussing the possible mechanism or mechanisms explaining the existence of the Ningwu ice cave in Shanxi Province on the slopes of the mountains on the south side of the Hexi Corridor (Meng et al., 2004; Gao et al., 2005; Meng et al., 2006; Shi and Yang, 2014; Yang and Shi, 2015). This cave is also sometimes referred to as the Luyashan ice cave (State Council, 2015), and has been known to the local population for a very long time. ...
... Unfortunately, the available data provided by a magnetotelluric survey of the Ningwu ice cave (Shao et al., 2007) consists of data on the vertical cross-section of the cave, but there is no data provided on the relationship of the passage beneath the cave to the 85 m vertical chamber. The cross-section provided inFigure 1b of Yang and Shi (2015) suggests that there is also a vertical entrance above the chamber to the outside, but no detailed information is provided about its dimensions, nor whether it is open throughout the year. Enlarging the diagram, the upper entrance appears to be about 4-5 m wide and cylindrical, i.e., it is large enough to allow large quantities of summer monsoon rain and winter snow to enter the top of the cave. ...
... Accordingly, the interpretation of the authors appears to be suspect. An obvious problem is that they conclude that the area has 7 months of above-freezing mean monthly temperatures and the apparent freezing and thawing indices appear to be similar (Figure 2 in Yang and Shi, 2015). To have icy permafrost persist, it is usually necessary to have a higher mean annual freezing index than the thawing index using mean daily air temperatures. ...
Terrestrial heat indicates on the thermal process in the Earth's interior. It provides important information for geological, geophysical and geodynamical studies. Since 1988, altogether 6 compilations of heat data have been regularly performed in the continental area of China, the data from the and second compilations were reported as the 1 st and 2 nd editions, the data from the later compilations were presented no more than the statistic results. Based on the sixth heat compilation, this paper presents, as the 3 rd
Terrestrial heat flow is the direct surface indication of the thermal process in the
Earth’s interior. It provides important information for geological ,geophysical and geodynamical con2
siderations. Since 1988 ,compilation of heat flow data have been regularly performedfor 6 times in the
continental area of China. The data from the first and the second compilations were reported as the
1st and 2nd editions ,while the data from the later compilations were no more presented but the statis2
tic results. Based on the sixth compilation of heat flow ,this paper presents , as the 3rd edition ,the
450 new heat flow data since the 2nd edition. Statistical analysisof the new data set indicates that the
measured heat flow values range from 30 to 319mW/ m2with a mean of 62. 6 ±24. 2mW/ m2;if the
heat flow data related with local geothermal anomalies are excluded ,the range will be reduced to be
between 30 to 140mW/ m2with a mean of 61 ±5.5mW/ m2
The modelling of liquid-solid phase change phenomena is extremely important in many areas of science and engineering. In particular, the solidification of molten metals during various casting methods in the foundry, provides a source of important practical problems which may be resolved economically with the aid of computational models of the heat transfer processes involved. Experimental design analysis is often prohibitively expensive, and the geometries and complex boundary conditions encountered preclude any analytical solutions to the problems posed. Thus the motivation for numerical simulation and computer aided design (CAD) systems is clear, and several mathematical/computational modelling techniques have been brought to bear in this area during recent years.
This paper reports on the application of the finite element method to solidification problems, principally concerning industrial casting processes. Although convective heat transfer has been modelled, the work herein considers only heat conduction, for clarity. The heat transfer model has also been coupled with thermal stress analysis packages to predict mechanical behaviour including cracking and eventual failure, but this is reported elsewhere.
Following the introduction, the mathematical and computational modelling tools are described in detail, for completeness. A discussion on the handling of the phase change interface and latent heat effects is then presented. Some aspects of the solution procedures are examined next, together with special techniques for dealing with the mold-metal interface. Finally, some numerical examples are presented which substantiate the capabilities of the finite element model, in both two and three dimensions.
Speleothems (mineral deposits that formed in caves) are currently giving us some of the most exciting insights into environments and climates during the Pleistocene ice ages and the subsequent Holocene rise of civilizations. The book applies system science to Quaternary environments in a new and rigorous way and gives holistic explanations the relations between the properties of speleothems and the climatic and cave setting in which they are found. It is designed as the ideal companion to someone embarking on speleothem research and, since the underlying science is very broad, it will also be invaluable to a wide variety of others. Students and professional scientists interested in carbonate rocks, karst hydrogeology, climatology, aqueous geochemistry, carbonate geochemistry and the calibration of climatic proxies will find up-to-date reviews of these topics here. The book will also be valuable to Quaternary scientists who, up to now, have lacked a thorough overview of these important archives. Additional resources for this book can be found at: www.wiley.com/go/fairchild/speleothem.
A solution of the laminar boundary-layer equations has been obtained for free convection from the outer surface of a vertical cylinder. The temperature of the cylinder surface was taken to be uniform. Heat-transfer results have been found for Prandtl numbers of 0.72 and 1 (i.e., for gases) and are presented on graphs. The Nusselt numbers for the cylinder were higher than those for the flat plate. Also, the deviation of the cylinder Nusselt numbers from those for the flat plate was greater for Prandtl number of 0.72 than for Prandtl number of 1. A quantitative criterion was established for determining the conditions under which the heat transfer from a cylinder could be calculated with sufficient accuracy using the flat-plate results. An analysis based on replacing the free-convection problem by a problem in pure conduction through a fictitious layer of stagnant fluid gave good agreement with the boundary-layer solution.
Speleothems (mineral deposits that formed in caves) are currently giving us some of the most exciting insights into environments and climates during the Pleistocene ice ages and the subsequent Holocene rise of civilizations. The book applies system science to Quaternary environments in a new and rigorous way and gives holistic explanations the relations between the properties of speleothems and the climatic and cave setting in which they are found. It is designed as the ideal companion to someone embarking on speleothem research and, since the underlying science is very broad, it will also be invaluable to a wide variety of others. Students and professional scientists interested in carbonate rocks, karst hydrogeology, climatology, aqueous geochemistry, carbonate geochemistry and the calibration of climatic proxies will find up-to-date reviews of these topics here. The book will also be valuable to Quaternary scientists who, up to now, have lacked a thorough overview of these important archives.
Additional resources for this book can be found at: www.wiley.com/go/fairchild/speleothem.
The local nonsimilarity solution method has been applied to solve for natural convection on a vertical cylinder for conditions where there are large deviations from the flat plate results. To assess and insure the accuracy of the results, solutions were obtained for three levels of truncation of the governing equations. The solutions were carried out for Pr = 0.733 and for a range of cases extending from small deviations from the flat plate to a factor-of-four deviation between the local heat fluxes for the cylinder and the flat plate. The results provided by the local similarity solutions were found to be highly accurate over this range. Comparisons were made with available results for the local and surface-integrated heat transfer, and solution methods were identified which appear promising for application beyond the range studied here. A presentation of representative temperature and velocity profiles showed only small deviations between the local similarity solutions and those for the third level of truncation.
