Scaling analyses of high-resolution dye tracer experiments
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Four unsaturated solute transport experiments with different water fluxes were conducted in a Hele-Shaw cell filled with uniform sand. The transport of the dye tracer used was recorded with a camera and the dye concentration was calculated using image analysis. The concentrations fields were analysed in terms of time moments and converted into vertical solute transport velocity V. Both mean value and standard deviation of V increased with water flux. The autocorrelation function exhibited a linear decrease for short lags. The pronounced variability of V suggested a description in terms of scaling properties, and a scaling regime was indeed found from the resolution 1.8 mm up to almost 0.1 m. The upper limit corresponds roughly to a characteristic scale of fingering structures seen in the dye concentration images. Indications of a second scaling regime at larger scales were found. In the small-scale scaling regime, the power spectrum exponent beta was generally slightly below 1 and the intermittency parameter C-1 was on average 0.00025. The moment scaling K-q functions were convex, implying a multiscaling process.
|Enheter & grupper|
Ämnesklassifikation (UKÄ) – OBLIGATORISK
|Tidskrift||Hydrological Sciences Journal|
|Status||Published - 2008|
|Peer review utförd||Ja|