= Load sharing between co-moving spheres in a tube
{title2=$F_{\mathrm{each}}\simeq F_{\mathrm{single}}/2\quad\text{in the tube-resistance regime}$}
Two identical well-separated <spheres> falling at the same speed share one laboratory <volume flux>, rather than producing twice the single-sphere piston flux. In the middle of the <three drag regimes for a nearly occluding sphere>, the same overall <Hagen-Poiseuille flow> <pressure> drop is divided equally between them, halving each <sphere>'s drag. In the local-shear and local-gap-pressure regimes each <sphere> retains its own leading resistance, so the drag per <sphere> is unchanged. This conclusion assumes nonoverlapping lubrication regions and sufficient separation from the tube ends.
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