Browsing by Author "Chuah C"

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    Chiral Lemniscate Formation in Magnetic Field Controlled Topological Fluid Flows
    (Wiley-VCH GmbH, 2025-04-03) Jellicoe M; Gardner Z; Alotaibi AEH; Shoemaker KE; Scott JM; Wang S; Alotaibi BM; Luo X; Chuah C; Gibson CT; He S; Vimalanathan K; Gascooke JR; Chen X; Rodger A; Huang H; Dalgarno SJ; Antunes E; Weiss GA; Li Q; Quinton JS; Raston CL
    High shear spinning top (ST) typhoon-like fluid flow in a rapidly rotating inclined tube within a vortex fluidic device (VFD) approaches homochirality throughout the liquid with toroids of bundled single-walled carbon nanotubes (SWCNTs) twisted into stable chiral lemniscates (in the shape of Figure 8s), predominantly as the R-or S-structures, for the tube rotating clockwise (CW) or counterclockwise (CCW). However, this is impacted by the Earth's magnetic field (BE). Theory predicts 1–20 MPa pressure for their formation, with their absolute chirality determined from scanning electron microscopy (SEM) and atomic force microscopy (AFM) images. Thus, the resultant lemniscate structures establish the absolute chirality of the inner and outer components of the ST flow. These chiral flows and lemniscates can be flipped to the opposite chirality by changing the orientation of the tube relative to the inclination angle of BE, by moving the geographical location. Special conditions prevail where the tangential angle of the outer and inner flow of the ST becomes periodically aligned with BE, which respectively dramatically reduce the formation of toroids (and thus lemniscates) and formation of lemniscates from the toroids formed by the double-helical (DH) flow generated by side wall Coriolis forces and Faraday waves.
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    Vortex fluidic induced mass transfer across immiscible phases
    (The Royal Society of Chemistry, 2022-03-28) Jellicoe M; Igder A; Chuah C; Jones DB; Luo X; Stubbs KA; Crawley EM; Pye SJ; Joseph N; Vimalananthan K; Gardner Z; Harvey DP; Chen X; Salvemini F; He S; Zhang W; Chalker JM; Quinton JS; Tang Y; Raston CL
    Mixing immiscible liquids typically requires the use of auxiliary substances including phase transfer catalysts, microgels, surfactants, complex polymers and nano-particles and/or micromixers. Centrifugally separated immiscible liquids of different densities in a 45° tilted rotating tube offer scope for avoiding their use. Micron to submicron size topological flow regimes in the thin films induce high inter-phase mass transfer depending on the nature of the two liquids. A hemispherical base tube creates a Coriolis force as a ‘spinning top’ (ST) topological fluid flow in the less dense liquid which penetrates the denser layer of liquid, delivering liquid from the upper layer through the lower layer to the surface of the tube with the thickness of the layers determined using neutron imaging. Similarly, double helical (DH) topological flow in the less dense liquid, arising from Faraday wave eddy currents twisted by Coriolis forces, impact through the less dense liquid onto the surface of the tube. The lateral dimensions of these topological flows have been determined using ‘molecular drilling’ impacting on a thin layer of polysulfone on the surface of the tube and self-assembly of nanoparticles at the interface of the two liquids. At high rotation speeds, DH flow also occurs in the denser layer, with a critical rotational speed reached resulting in rapid phase demixing of preformed emulsions of two immiscible liquids. ST flow is perturbed relative to double helical flow by changing the shape of the base of the tube while maintaining high mass transfer between phases as demonstrated by circumventing the need for phase transfer catalysts. The findings presented here have implications for overcoming mass transfer limitations at interfaces of liquids, and provide new methods for extractions and separation science, and avoiding the formation of emulsions.