The influence of wetting dynamics on the residual air distribution

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68407700%3A21110%2F16%3A00305643" target="_blank" >RIV/68407700:21110/16:00305643 - isvavai.cz</a>

Result on the web

<a href="https://agu.confex.com/agu/fm16/meetingapp.cgi/Paper/174681" target="_blank" >https://agu.confex.com/agu/fm16/meetingapp.cgi/Paper/174681</a>

DOI - Digital Object Identifier

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Result language

angličtina

Original language name

The influence of wetting dynamics on the residual air distribution

Original language description

The amount and distribution of the residual air during the infiltration into a porous soil system has a strong influence on the infiltration rate. Concurrently, the amount of residual air is dependent on the wetting dynamics. In the presented study, two experiments were conducted on the same sample. The first experiment was performed under the constant water level condition (CWL) and the second under the constant water flux condition (CWF) at the top of the sample. The coarse sand represented a highly conductive region connected from the top to the bottom of the sample with the exception of three low (2-3 mm) separation layers made up of the medium coarse sand. Three discs of fine ceramic formed slow flow regions. Infiltration experiments were monitored by neutron radiography on two different beamlines to produce two-dimensional (2D) projections. The CWL experiment was monitored by NEUTRA station and the CWF experiment was visualized at BOA station. Both stations are located at the Paul Scherrer Institut, Switzerland. From series of corrected radiograms taken at the different angles three-dimensional (3D) image was reconstructed for steady state part of the experiment CWL and for entire experiment CWF. Then the series of 3D images mapped the wetting of the porous system over the corresponding phase of infiltration process. The results showed a faster steady state infiltration rate during the CWL. In this case, the air was mostly pushed out from the sample by moving wetting front. On the contrary, during the CWF the water infiltrated into the fine ceramics first and then into the medium coarse sand attracted by stronger capillary forces in comparison to the coarse sand. Due to this effect a significant amount of air was trapped in preferential pathways, and consequently blocking the water flow. The presence of medium coarse sand regions had a crucial impact on the water flow and amount of air trapping.

Czech name

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Czech description

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Type

O - Miscellaneous

CEP classification

DF - Pedology

OECD FORD branch

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Project

<a href="/en/project/GA14-03691S" target="_blank" >GA14-03691S: Isothermal and non-isothermal water flow and solute transport in near-saturated porous media</a><br>

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year

2016

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů