scholarly journals Permeability Coefficient of Unsaturated Loess and Its Gaseous and Liquid Water Migration Modeling

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Ya-lin Nan ◽  
Zai-kun Zhao ◽  
Xin Jin ◽  
Liang Zhang ◽  
Xiao-xuan Zhu ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Water Content ◽  
Soil Water ◽  
Liquid Water ◽  
Permeability Coefficient ◽  
Liquid Water Content ◽  
Engineering Properties ◽  
Water Migration ◽  
Calculation Results ◽  
Unsaturated Loess

Water migration changes the water distribution of loess and significantly affects the engineering properties of loess. However, because of the characteristics of loess such as water sensitivity and special structure, it is still difficult to understand the water migration trend of loess. The objectives of this study are to investigate the water diffusion coefficient and soil-water characteristic curve (SWCC) of loess, focusing on the effect of temperature and density, and establish a mixed migration equation for gaseous and liquid water to develop a new calculation method of loess water migration. The results show that the density of loess with larger liquid water content has a more significant effect on the diffusion coefficient than that of less liquid water content. Furthermore, the density significantly affects the matric suction of unsaturated loess, while the temperature change at normal temperature has slight effect. Based on the data obtained in this study, the soil water permeability coefficient was obtained. Moreover, considering the characteristics of mixed migration of gas and liquid water in unsaturated loess, an equation was derived for the gas-liquid water transfer in unsaturated loess. The calculation results are consistent with the experimental results of water migration experiment. Based on the calculation results of water migration, the trend of water migration and proportion of gaseous water during migration were analyzed.

A New Analytical Expression of Overall Collision Efficiency for the Water Droplet Impinging on a Cylinder

2013 ◽  
Vol 392 ◽  
pp. 90-94
Author(s):  
Ling Chen ◽  
Rui Liu ◽  
Yong Xing Cao
Keyword(s):  
Numerical Calculation ◽  
Water Content ◽  
Numerical Computation ◽  
Liquid Water ◽  
Water Droplet ◽  
Liquid Water Content ◽  
Collision Efficiency ◽  
Analytical Expression ◽  
Median Volume ◽  
Calculation Results

The ice amount accreting on the rotating multi-cylinders can be used to obtain the liquid water content (LWC) and the median volume diameter of water droplet (MVD) based on cylindrical icing model. In this model, the overall collision efficiency is usually calculated by Finstads (φ100) and Langmuirs formulations (φ<100). But this combined expression doesnt agree well with the numerical calculation in some case. This paper gives a new expression based on a large number of numerical calculation results, and this expression agrees better with the numerical computation than existing expression.

Geocryological terminology

1976 ◽  
Vol 13 (6) ◽  
pp. 862-867 ◽  
Author(s):  
R. O. van Everdingen
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Liquid Water ◽  
Water System ◽  
Liquid Water Content ◽  
System A

Ambiguity and inconsistent use of the word frozen and a number of related terms present problems in terminology describing permafrost and seasonal frost. To overcome some of these problems, the author proposes that use of the word 'frozen' be reserved exclusively for cases where at least some ice is present in the soil/water system. A new term, cryotic, is proposed to indicate that the temperature of the soil/water system is below 0 °C, without implying any phase conditions. Other terms dealt with are liquid water content, ice-rich, frost-sensitive, thaw-sensitive, frost-stable, and thaw-stable. A partially genetic terminology is proposed to describe various types of nonfrozen zones in permafrost areas.

scholarly journals Freezing experiments on unsaturated sand, loam and silt loam

2011 ◽  
Vol 52 (58) ◽  
pp. 37-43 ◽  
Author(s):  
Kunio Watanabe ◽  
Tetsuya Kito ◽  
Tomomi Wake ◽  
Masaru Sakai
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Liquid Water ◽  
Unsaturated Soils ◽  
Pressure Head ◽  
Liquid Water Content ◽  
Frozen Soil ◽  
Freezing Process ◽  
Silt Loam ◽  
Farming Soil

AbstarctEstimating soil-water flow during ground freezing is important for understanding factors affecting spring farming, soil microbial activity below the frozen soil, and permafrost thawing behavior. In this study, we performed a column freezing experiment using three different unsaturated soils (sand, loam and silt loam) to obtain a detailed dataset of temperature, water-content and pressure-head change under freezing conditions. The liquid water content and pressure head in the three soils decreased with decreasing temperature. Three soil temperature stages were found: unfrozen, stagnating near 0˚C and frozen. The temperature and duration of the stagnation stage differed among the soil types. The changes in liquid water content and pressure head during the freezing process were highly dependent on the soil-water retention curve. Water flowed through the frozen area in silt loam and sand, but no water flux was observed in the frozen loam. The freezing soil columns tended to contain more liquid water than estimated from retention curves measured at room temperature, especially at the early stage of freezing.

scholarly journals Proof of Concept: Development of Snow Liquid Water Content Profiler Using CS650 Reflectometers at Caribou, ME, USA

Sensors ◽  
2017 ◽  
Vol 17 (3) ◽  
pp. 647 ◽  
Author(s):  
Carlos Pérez Díaz ◽  
Jonathan Muñoz ◽  
Tarendra Lakhankar ◽  
Reza Khanbilvardi ◽  
Peter Romanov
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Liquid Water Content ◽  
Concept Development ◽  
Proof Of Concept

Field Measurement of the Liquid-Water Content of Snow

1981 ◽  
Vol 27 (95) ◽  
pp. 175-178 ◽  
Author(s):  
E. M. Morris
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Field Measurement ◽  
Solution Method ◽  
Liquid Water Content ◽  
Field Trials

Abstract Field trials show that the liquid-water content of snow can be determined simply and cheaply by a version of Bader’s solution method.

scholarly journals Snow dielectric properties: from DC to microwave X-band

1994 ◽  
Vol 19 ◽  
pp. 92-96 ◽  
Author(s):  
TH. Achammer ◽  
A. Denoth
Keyword(s):  
Grain Size ◽  
Dielectric Properties ◽  
Water Content ◽  
Liquid Water ◽  
Liquid Water Content ◽  
Frequency Range ◽  
Snow Density ◽  
Cold Room ◽  
X Band ◽  
Grain Size And Shape

Broadband measurements of dielectric properties of natural snow samples near or at 0°C are reported. Measurement quantities are: dielectric permittivity, loss factor and complex propagation factor for electromagnetic waves. X-band measurements were made in a cold room in the laboratory; measurements at low and intermediate frequencies were carried out both in the field (Stubai Alps, 3300 m; Hafelekar near Innsbruck, 2100 m) and in the cold room. Results show that in the different frequency ranges the relative effect on snow dielectric properties of the parameters: density, grain-size and shape, liquid water content, shape and distribution of liquid inclusions and content of impurities, varies significantly. In the low-frequency range the influence of grain-size and shape and snow density dominates; in the medium-frequency range liquid water content and density are the dominant parameters. In the microwave X-band the influence of the amount, shape and distribution of liquid inclusions and snow density is more important than that of the remaining parameters.

Comparison of Water Thickness Profiles of Compressed PEMFC GDLs

2011 ◽  
Author(s):  
Pradyumna Challa ◽  
James Hinebaugh ◽  
A. Bazylak
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Water Distribution ◽  
Polymer Electrolyte Membrane ◽  
Water Injection ◽  
Liquid Water Content ◽  
Gas Diffusion ◽  
Injection Rate ◽  
Water Levels ◽  
Ex Situ

In this paper, through-plane liquid water distribution is analyzed for two polymer electrolyte membrane fuel cell (PEMFC) gas diffusion layers (GDLs). The experiments were conducted in an ex situ flow field apparatus with 1 mm square channels at two distinct flow rates to mimic water production rates of 0.2 and 1.5 A/cm2 in a PEMFC. Synchrotron radiography, which involves high intensity monochromatic X-ray beams, was used to obtain images with a spatial and temporal resolution of 20–25 μm and 0.9 s, respectively. Freudenberg H2315 I6 exhibited significantly higher amounts of water than Toray TGP-H-090 at the instance of breakthrough, where breakthrough describes the event in which liquid water reaches the flow fields. While Freudenberg H2315 I6 exhibited a significant overall decrease in liquid water content throughout the GDL shortly after breakthrough, Toray TGP-H-090 appeared to retain breakthrough water-levels post-breakthrough. It was also observed that the amount of liquid water content in Toray TGP-H-090 (10%.wt PTFE) decreased significantly when the liquid water injection rate increased from 1 μL/min to 8 μL/min.

Sign in / Sign up

Export Citation Format

Share Document