Microgravity double-helical fluid containment

Paper number

IAC-08.A2.2.1

Author

Prof. Brian Lowry, University of New Brunswick, Canada

Year

2008

Abstract

Double-helical containment is a novel approach to open containment in microgravity. In contrast to axisymmetric containers there is no length restriction on properly designed double-helical containers. Use of a double helix permits drainage to zero volume, an uncommon feature in microgravity; near-complete drainage is a key feature for any practically useful container. That double-helical containers are open and tubular makes possible a broad range of applications which rely on accessible fluids. Helical supports permit filamentary containers of infinite extent, but only double-helical containers are stable down to zero volume.

Theoretical and experimental work (recently published in Proc. Roy. Soc. A: v 464, n 2092, p 855-875) details the stability of double helical interfaces over a broad range of configurations. The base case of symmetric supports (separation angle 180 degrees) is considered in terms of symmetric volumes as well as asymmetric helicatenoid volumes.  The distinct symmetric and asymmetric cases are then related by perturbing the angle of separation between the supports. Helicatenoid volumes may combine to form a dual helicatenoid volume, which is interesting in that it permits multiphase tube-like geometries.  Double-helical behaviours such as drainability are found to vanish beyond a critical separation angle of about 246.5 degrees.  A secondary shift in behaviour occurs at 209 degrees, where separate regions of stability become more connected.  The common structures of DNA coincide with the limiting geometry at 209 degrees.  Experimental Plateau-tank results roughly verify the volume maximum for near-symmetry, and more importantly verify stability to zero volume.

This material has not previously been presented at an open conference.

Abstract document

IAC-08.A2.2.1.pdf

Manuscript document

IAC-08.A2.2.1.pdf (🔒 authorized access only).

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