Let me suggest these possible flow patterns that seem to be both logico-physically intuitive
and empirically observed:
By
stalagmatic accumulation I refer to the process slow water-carrier driven
stalagmite formation. The rust-color residue
has accumulated to a few inches in height at the base of the feed-in pipe's interface with the main vent, and
that heap of gunk is the
highest-dose spot.
Moreover, the same rust-colored stain (that I propose is
cesium-vapor residue) is also seen emanating from the interface seam. This constitutes a second unique source of rust-color staining and flow pattern versus that coming down the pipe, and both pathways would logically converge at the accumulation point. The rust-colored staining clearly appears to be associated with the
highest-dose accumulation of dark-red gunk.