University of California Water Resources Center

The effect of acoustic waves on the transport of a conservative tracer and the dissolution of dense nonaqueous phase liquids (DNAPLs) in a water saturated column packed withglass beads was investigated. It was observed from the experimental data that the addition of acoustic waves, in the frequency range between 60 to 245 Hz, to a steady background pressure gradient, enhances solute transport compared to the base case consisting of only a background pressure gradient. Furthermore, it was found that the effective velocity of the solute is approximately inversely proportional to the frequency of the acoustic wave. In addition, acoustic waves withpressure amplitudes ranging from 0 to 1625 Pa and frequencies ranging from 0 to 285 Hz were observed to increase the effluent dissolved trichloroethene (TCE) concentration, where TCE was used as the DNAPL, compared to the case where dissolution without acoustic waves was monitored. The increased effluent dissolved TCE concentration is attributed to an increase in mass flux from the dissolving TCE blobs due to increased effective pore water velocity caused by acoustic waves.