Hysteresis Phenomenon and Experiments of Finger Flow in Unsaturated soil
| Autor: | Kuo-Chen Ma, 馬國宸 |
|---|---|
| Rok vydání: | 2001 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 89 Wetting front instability, or gravity-driven fingering, can occur during vertical infiltration. Previous studies found that fingers persist over long periods of infiltration and in subsequent infiltration cycles. We present a physically based theory to explain finger persistence. The theory is tested using the technique in which moisture contents are visualized by the transmission of light through unsaturated sand. Theory and experiments show that hysteresis in the moisture characteristic relationship explain the persistence of fingers in time.The study is to utilize digital image to analyze soil water content, so that it can easily measure soil water content. Traditional method of measuring soil water content in laboratory does not work especially when the variation of soil water content is changing quickly, and soil sample can not be sent to laboratory as soon as possible. During the proceeding of infiltration experiment in transparent sand box, soil water content will be changing quickly, application of digital image to measure soil water content will do a good job; it’s not only reduces working time but also simplifies process. In this study, digital camera used to take picture of soil sample to get digital images continually, and the digital images are automatically saved into computer’s hard disk simultaneously, and apply the software IMAGE PRO to analyze digital images. First of all, make a comparison of the relationship between soil water content and digital image’s R,G,B value, there is a linear relationship between soil water content and digital image’s R,G,B value so that all the experimental data can be used to get a regression equation; if the soil sample is different, then there is an other different regression equation. When the infiltration experiment or fingering flow experiment is proceeding, digital camera is used get digital images of soil sample, and we can use the regression equation to obtain the soil water content easily and quickly. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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