Beschreibung:
<jats:p>We present new experiments of particle-laden turbulent fountains in a uniform horizontal crossflow, <jats:inline-formula>
<jats:alternatives>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S0022112023003427_inline1.png" />
<jats:tex-math>$u_a$</jats:tex-math>
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</jats:inline-formula>, with momentum flux, <jats:inline-formula>
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<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S0022112023003427_inline2.png" />
<jats:tex-math>$M_0$</jats:tex-math>
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</jats:inline-formula>, and buoyancy flux, <jats:inline-formula>
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<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S0022112023003427_inline3.png" />
<jats:tex-math>$B_0$</jats:tex-math>
</jats:alternatives>
</jats:inline-formula>. We use the ratio, <jats:inline-formula>
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<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S0022112023003427_inline4.png" />
<jats:tex-math>$P$</jats:tex-math>
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</jats:inline-formula>, of the crossflow speed to the characteristic fountain speed, <jats:inline-formula>
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<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S0022112023003427_inline5.png" />
<jats:tex-math>$M_0^{-1/4}|B_0|^{1/2}$</jats:tex-math>
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</jats:inline-formula>, and the ratio <jats:inline-formula>
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<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S0022112023003427_inline6.png" />
<jats:tex-math>$U$</jats:tex-math>
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</jats:inline-formula>, of the Stokes fall speed of the particles, <jats:inline-formula>
<jats:alternatives>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S0022112023003427_inline7.png" />
<jats:tex-math>$v_s$</jats:tex-math>
</jats:alternatives>
</jats:inline-formula>, to the characteristic fountain speed, to characterise the dynamics of a particle fountain in a crossflow. We find that the dynamics of these particle fountains can be categorised into three distinct regimes. In regime I when the fall speed of the particles is small in comparison with the characteristic fountain speed (<jats:inline-formula>
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<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S0022112023003427_inline8.png" />
<jats:tex-math>$U\ll 1$</jats:tex-math>
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</jats:inline-formula>), the particles remain well-coupled to the fountain fluid and the flow essentially behaves as a single-phase fountain in a crossflow. In the transitional regime II (<jats:inline-formula>
<jats:alternatives>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S0022112023003427_inline9.png" />
<jats:tex-math>$0.1< U<1$</jats:tex-math>
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</jats:inline-formula>), when the fall speed of particles is comparable to the characteristic fountain speed, we observe some particles separating from the fountain fluid during the descent of the flow which leaves some fluid neutrally buoyant. As <jats:inline-formula>
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<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S0022112023003427_inline10.png" />
<jats:tex-math>$U>1$</jats:tex-math>
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</jats:inline-formula> (regime III), we observe particles separating from the fountain as it rises from the source. We measure the average dispersal distance of the particles and the speed of the descending particles as a function of <jats:inline-formula>
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<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S0022112023003427_inline11.png" />
<jats:tex-math>$U$</jats:tex-math>
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</jats:inline-formula> and <jats:inline-formula>
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<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S0022112023003427_inline12.png" />
<jats:tex-math>$P$</jats:tex-math>
</jats:alternatives>
</jats:inline-formula> and compare these results with models of a single-phase fountain in a crossflow. We build a regime diagram to describe the effect of <jats:inline-formula>
<jats:alternatives>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S0022112023003427_inline13.png" />
<jats:tex-math>$U$</jats:tex-math>
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</jats:inline-formula> and <jats:inline-formula>
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<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S0022112023003427_inline14.png" />
<jats:tex-math>$P$</jats:tex-math>
</jats:alternatives>
</jats:inline-formula> on the flow dynamics and consider our work in the context of deep-submarine volcanic eruptions.</jats:p>