The dynamics of hygrotactic fronts – from fundamentals of soft-matter systems to smart materials engineering applications (FAC17-R/MPEE/LEDESMA-AGUILAR)

Tactic behaviour, the ability of a system to sense and respond to external stimuli, underpins the dynamics of many complex systems, most remarkably in biology. Biological tactic behaviour consists of i) an ability to sense external stimuli (e.g., concentration or temperature gradients), and ii) a transducing mechanism to convert sensory information into large-scale motion. Bio-tactic mechanisms can increasingly inform developments in smart-materials science, from artificial swimmers (Dreyfus et al., Nature 437, 862—865 2005) inspired by bacterial magnetotaxis (Blakemore, Science 190, 377—379 1975) to self-propelling droplets on surfaces with rigidity gradients (Style et al., PNAS 110, 12541—12544 2013) motivated by cell durotaxis (Pelham & Yang, PNAS 94, 13661—13665 1997).

In this project, we will explore a transformative concept for tactic behavior in soft-matter physics and smart-materials engineering called hygrotaxis. In hygrotactic systems, evaporating or condensing liquid fronts on low-friction surfaces are capable of transducing humidity gradients into large-scale translational motion.

The main aim of the project will be an experimental-theoretical study of hygrotactic liquid fronts, supported by the following objectives:
1. Research the underpinning hydrodynamic mechanism of hygrotaxis.
2. Investigate the self-propulsion and steering of hygrotactic droplets.
3. Research fluid-structure control in confined hygrotactic fronts.

The scope of this work is experimental and theoretical, and will use a combination of experiments of evaporating droplets on low-friction SLIP surfaces, mathematical modeling, and in-house Lattice-Boltzmann simulations of a diffuse-interface hydrodynamic model (e.g., Ledesma-Aguilar, et al., Soft Matter, 10, 8267 (2014)), which can model evaporation and condensation in non-planar boundaries including rough surfaces.

Eligibility and How to Apply:

Please note eligibility requirement:
• Academic excellence of the proposed student i.e. 2:1 (or equivalent GPA from non-UK universities [preference for 1st class honours]); or a Masters (preference for Merit or above); or APEL evidence of substantial practitioner achievement.
• Appropriate IELTS score, if required.

For further details of how to apply, entry requirements and the application form, see
https://www.northumbria.ac.uk/research/postgraduate-research-degrees/how-to-apply/

Please ensure you quote the advert reference above on your application form.

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