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Subtle Agroecologies
FIGURE 25.2 Spiral vortex. (Photo courtesy of Institute of Flow Science, Wilkens et al., 2005.)
Qualitatively, this vortex form can be experienced as very open, the surface stretching widely
and also as having a contractive gesture, so that when we watch the form in fow, it draws suspended
and foating matter towards the centre. It creates a concavity which, under the right conditions, can
be many metres deep. This can be seen in Figure 25.3, both in the refections on the surface and
below it as the rope-like tube seen through the water.
This spiral vortex gesture is only part of the full picture. There is another form of fuid movement also called a vortex, the toroidal ring vortex. This is seen in air as smoke rings, often created
by smokers and less often by volcanos. It can also be generated in water. It arises not when the fuid
is being drawn under suction but when it is pushed, when it is under pressure from somewhere else.
Figure 25.4 shows such a ring vortex.
This type of vortex can also be made quite easily in a still body of water by using a short
discharge from a tube, as in Figure 25.5, which reveals both its form and its inherent layered
structure.
The ring vortex also has a path-curve geometry, but with a transformed construction that embodies asymmetric spirals. These have been termed spiroids (Blackwood, 2012). Of signifcance here
is that this ring vortex form does not have the same relation to the periphery; the movement relates
to local, not peripheral, infnity points which are in the ring and on the axis. The movement in
the form is more enclosing and relates more to itself, in that it rolls around its core. Qualitatively,
we can experience it as having an expansive gesture, both when we observe its initial appearing
(mushrooming out) and again at the end of its appearance when it meets resistance and deforms
itself. It is very convex in its inherent surfaces. Thus, we can see the toroidal ring vortex, created
with a push or a puff, as polar opposite in nature to the spiral vortex described above which was
created with a draw or a suck.
Subtle Agroecologies
FIGURE 25.2 Spiral vortex. (Photo courtesy of Institute of Flow Science, Wilkens et al., 2005.)
Qualitatively, this vortex form can be experienced as very open, the surface stretching widely
and also as having a contractive gesture, so that when we watch the form in fow, it draws suspended
and foating matter towards the centre. It creates a concavity which, under the right conditions, can
be many metres deep. This can be seen in Figure 25.3, both in the refections on the surface and
below it as the rope-like tube seen through the water.
This spiral vortex gesture is only part of the full picture. There is another form of fuid movement also called a vortex, the toroidal ring vortex. This is seen in air as smoke rings, often created
by smokers and less often by volcanos. It can also be generated in water. It arises not when the fuid
is being drawn under suction but when it is pushed, when it is under pressure from somewhere else.
Figure 25.4 shows such a ring vortex.
This type of vortex can also be made quite easily in a still body of water by using a short
discharge from a tube, as in Figure 25.5, which reveals both its form and its inherent layered
structure.
The ring vortex also has a path-curve geometry, but with a transformed construction that embodies asymmetric spirals. These have been termed spiroids (Blackwood, 2012). Of signifcance here
is that this ring vortex form does not have the same relation to the periphery; the movement relates
to local, not peripheral, infnity points which are in the ring and on the axis. The movement in
the form is more enclosing and relates more to itself, in that it rolls around its core. Qualitatively,
we can experience it as having an expansive gesture, both when we observe its initial appearing
(mushrooming out) and again at the end of its appearance when it meets resistance and deforms
itself. It is very convex in its inherent surfaces. Thus, we can see the toroidal ring vortex, created
with a push or a puff, as polar opposite in nature to the spiral vortex described above which was
created with a draw or a suck.