Wetting of Elastic Fibres: A Novel Immersed Boundary-Lattice Spring-Lattice Boltzmann Simulation Approach

Lead Research Organisation: Durham University
Department Name: Physics

Abstract

Fibrous structures are versatile materials. They are abundant in nature, as observed in feathers, hairs, spider webs and adhesive pads of insects. They are also widely exploited in engineered systems, from the familiar examples of papers and textiles to high-precision micro- and nano-technologies.

For many fibrous materials, their interaction with liquids is of paramount importance. Due to the small size of the fibres, capillary action (as observed e.g. in the drawing up of liquids in plants) often plays the dominant role. Furthermore, the action of capillarity deforms the fibres, which results in an opposing force due to elasticity. This competition between elasticity and capillarity - elastocapillarity - finds its relevance in a wide range of applications, including liquid penetration in wipes and nappies, and the clumping of hairs in the tarsi of insects and of barbules in marine bird feathers.

Despite the numerous industrial applications and common occurrence in nature, our understanding of elastocapillary response of wet fibres is still very limited. Recent experiments suggest that pattern formation in nanostructures can be manipulated by elastocapillary dynamics; the capture of drops and their splashing, of relevance to the application of pesticides or herbicides among others, depend on the fibre geometry and flexibility. These are just a few of many elastocapillary phenomena ripe for investigations, especially using computer simulations, since the intricate interplay between fibre geometry, elasticity and capillarity quickly makes analytical treatments intractable. Unfortunately, simulation methods that can capture solid deformation, flow of liquids, and capillary forces are currently not available.

Thus, it is my aim in this project is to deliver a numerical platform able to tackle such a challenge. This project is rooted in my recent research advances in simulation techniques for wetting phenomena. As a proof of principle, to demonstrate that the novel method can capture wetting dynamics on soft materials, I will examine the spreading of small droplets on two elastic fibres oriented at various angles with respect to each other, and I will study the removal of these droplets under the action of a body force such as gravity. These are paradigmatic examples for understanding the arrangement and cleaning properties of natural and synthetic wet fibre assemblies.

My new simulations will be validated against experimental data provided by Procter and Gamble, where wetting of elastic fibres is relevant for many of their products, ranging from adsorbent materials (including nappies and wipes) to personal hygiene products (e.g. shampoos and laundry detergents).

If successful, my novel approach will open an unprecedented route to model static and dynamic elastocapillary phenomena embedded in complex geometries. As such, it will advance our understanding of elastocapillarity, and help channel fundamental scientific insights into design principles for practical applications.

Planned Impact

1. Knowledge and Technique
This project will produce a novel simulation method for elastocapillary phenomena, as well as new and fundamental insights into wetting dynamics on flexible fibres. In particular, the ability to simultaneously account for solid mechanics, fluid dynamics and interfacial forces is powerful and systematic future investigations will open an unprecedented modelling route to translate fundamental insight on elastocapillarity into design principles for novel and smart materials. This project will strengthen the priority themes of "Soft Matter and Biophysics" and "Complex Fluids and Rheology" as defined by EPSRC, and it aligns closely with EPSRC's "Frontier Manufacturing" research challenge under the "Manufacturing the Future" theme.

2. Economic Impact
A key priority for the UK is in high-value manufacturing. The development of a robust simulation method for elastocapillary phenomena will help us move away from empirical design process (trial and error) to "frontier manufacturing" where scientific principles are used from the start.

Indeed, elastocapillarity is a key technological driver for a wide range of industrial sectors. Here I have collaborated with the company Procter and Gamble (P&G), focussing in particular on the wetting of elastic fibres. Elastic fibres are an excellent model system for fabrics and hairs among others, and as such, this project is relevant for consumer products such as nappies and shampoos. For these two products alone, the global industrial market is forecasted at approximately $60 billion and $25 billion respectively by 2020. Wet fibres are also relevant for imbibition in filtering devices, wet lithography process in micro-electromechanical systems, and the capture of pesticides in agriculture, to list a few examples.

The link with P&G provides an excellent opportunity to deliver impact of relevance to an industrial context. The PDRA and I will sign a confidential disclosure agreement with P&G, and IP rights will be arranged with the help of Durham University Business & Innovation Services. P&G's support to this proposal includes staff time, access to their experimental data, and travel costs for two research visits.

Additionally, I will engage other industrial partners in non-competing sectors with interests on elastocapillarity through relevant academic-industrial networking events, such as the "UK Soft Matter Showcase and Industry Day" organised by the Soft Matter and Functional Interfaces Centre for Doctoral Training based in Durham and the "European Study Group with industry" meeting. I will also invite industrial representatives to a workshop on wetting phenomena I will organise as part of my "Pathways to Impact" activities.

3. Training
The development of subject specific and soft skills of the PDRA will contribute to the highly skilled workforce in the UK. The PDRA will gain expertise in cutting-edge computational modelling techniques and in the field of wetting phenomena, through close collaboration with me. The PDRA will take advantage of Durham University's Research Training Programme, which won a Times Higher Education award for Outstanding Support for Early Career Researchers. Furthermore, the industrial link with Procter and Gamble provides career development opportunity for the PDRA beyond the standard academic settings,

As PI, I will benefit from the experience in leading this EPSRC First Grant project. I will gain leadership and management skills, and I will broaden my research portfolio. The delivery of a numerical platform capable of combining solid elasticity, fluid mechanics, interfacial and wetting phenomena will distinguish my group, and allow me to strengthen and build links with leading experimentalists and industrial partners in the area of elastocapillarity. All these will help me achieve my ambition: to build a world leading research group in the field of wetting phenomena, and more generally, soft condensed matter.

Publications

10 25 50
 
Description We have two major achievements so far.

First, multiphase flows comprising of one gas and several liquid components, with high density ratio between the liquid and gas phases, are pervasive in nature and engineering applications. However, physical models suitable for addressing these phenomena are surprisingly still lacking. We have now developed a novel model that is thermodynamically rigorous and provided efficient realization using the lattice Boltzmann method.

Second, we have developed a thermodynamically consistent model for multicomponent fluids interacting with an elastic solid. To our knowledge this is the first time this is achieved using a lattice Boltzmann approach.
Exploitation Route There are a number of multiphase problems involving high density ratio that we can now simulate, which are previously not possible. Examples range from binary droplet collisions relevant for combustion engines to advanced oil recovery processes and the design of non-wetting lubricant impregnated surfaces.

We are also now in a position to study elastocapillary phenomena using lattice Boltzmann method. Examples include wetting of drops on lipid membranes, wetting of elastic fibres, and the deformation of soft capsules or colloids at a fluid interface.

In addition, we have engaged (and will continue to engage) with open-source lattice Boltzmann software developers so that our model is available to other groups.
Sectors Aerospace, Defence and Marine,Agriculture, Food and Drink,Chemicals,Digital/Communication/Information Technologies (including Software),Energy,Environment,Manufacturing, including Industrial Biotechology,Transport

 
Description The methods developed from this grant have attracted interest from two industrial companies, Procter and Gamble and ExxonMobil. With Procter and Gamble, the lattice Boltzmann method has been used to investigate new and more efficient ways of cleaning. With ExxonMobil, the method is now used to study the problem of capillary rise and capillary imbibition involving multiple fluids.
First Year Of Impact 2019
Sector Chemicals,Energy
Impact Types Economic

 
Description Funding from ExxonMobil
Amount $200,000 (USD)
Organisation ExxonMobil 
Sector Private
Country United States
Start 01/2020 
End 12/2021
 
Description Funding from P&G
Amount £30,000 (GBP)
Organisation Procter & Gamble 
Sector Private
Country United States
Start 10/2019 
End 03/2020
 
Description Industrial Funding
Amount £7,000 (GBP)
Organisation Procter & Gamble 
Sector Private
Country United States
Start 04/2017 
End 05/2018
 
Description Studentship from Soft Matter and Functional Interfaces CDT
Amount £92,000 (GBP)
Organisation Durham University 
Sector Academic/University
Country United Kingdom
Start 04/2017 
End 10/2020
 
Description UKFN Short Research Visit
Amount £800 (GBP)
Organisation UK Fluids Network 
Sector Public
Country United Kingdom
Start 10/2017 
End 12/2017
 
Description Co-leader of UKFN Special Interest Group on "Droplet and flow interactions with bio-inspired and smart surfaces" 
Organisation UK Fluids Network
Country United Kingdom 
Sector Public 
PI Contribution Together with Glen McHale (Northumbria University), I am co-leading a UKFN Special Interest Group on "Droplet and flow interactions with bio-inspired and smart surfaces". This special interest group provides a forum for scientists and engineers seeking to understand the interaction of liquids with bioinspired fluid boundaries involving texture (e.g. ribbed, super-hydrophobic, liquid-impregnated).
Collaborator Contribution As part of the SIG management team, I have co-organised several meetings to promote discussions and collaborations among scientists and engineers from academia and industry on fluid interactions with bio-inspired smart surfaces.
Impact This is a multi-displinary SIG with members from Physics, Chemistry, Mathematics, Engineering and Materials Science. Meetings organised to date: (1) Kick-off meeting, Northumbria University, 12th April 2017; (2) Joint research symposium with CSCST on "Novel Materials and Surface for Future Engineering", 23rd-24th June 2017; (3) Industry Day "Smart materials and surfaces powered future engineering solutions", Nottingham Trent University, 29th November 2017; (4) Joint Early Career Researcher Event, Northumbria University, 21st March 2018; (5) workshop on "Structural surfaces and liquid/surface interactions", Heriot-Watt University, 20th April 2018; and (5) workshop on "Multiscale modelling of wetting phenomena", Durham University, 12-13 September 2018.
Start Year 2017
 
Description Member of UK Consortium on Mesoscale Engineering Sciences (UKCOMES) 
Organisation University College London
Department UK Consortium on Mesoscale Engineering Sciences
Country United Kingdom 
Sector Academic/University 
PI Contribution UKCOMES is a UK wide consortium on mesoscale simulations funded by EPSRC. My project on modelling elastocapillarity and multiphase flow using the lattice Boltzmann method is directly relevant for the consortium's objectives. I have been invited to join UKCOMES and I have given several talks in their meetings. UKCOMES also develops several softwares. I have begun discussions with the developers of DL_MESO to incorporate our simulation model in their code.
Collaborator Contribution UKCOMES provides a platform for disseminating the simulation techniques developed during the project. UKCOMES has also provided my group access to ARCHER.
Impact This is a new collaboration so we have not any output yet.
Start Year 2017
 
Description CECAM workshop "Addressing metastability in interfacial phenomena across multiple time and length scales" 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact I co-organised a focussed workshop funded by CECAM on interfacial phenomena. The purpose of the meeting is to identify exciting problems to solve where theorists, simulators and experimentalists can collaborate together.
Year(s) Of Engagement Activity 2017
URL https://www.cecam.org/workshop-1398.html
 
Description Industry Day on Drop Coalescence 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact I co-organised an industry day on droplet coalescence at Durham University on Wednesday 25th October 2017. We had short talks both from academics and industrialists. We had representatives from 5 companies. We also had dedicated discussion sessions to promote collaborations.
Year(s) Of Engagement Activity 2017
 
Description Invitation from the Indonesian Ministry of Research, Technology and Higher Education 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Undergraduate students
Results and Impact I was invited to the "World Class Scholars Symposium" organised by the Indonesian Ministry of Research, Technology and Higher Education in December 2017. Every year they invited ~50 leading Indonesian scientists and engineers that have permanent academic positions abroad. As part of this invitation, I visited two universities in Indonesia giving talks about my research, leading a discussion panel at one university on doing teaching and research at an international level, and explore possible collaborations with Indonesian colleagues to lift their research standard. I also participated in a discussion attended by members from the Indonesian Ministry of Research, Technology and Higher Education on how to improve the quality of science in Indonesia.
Year(s) Of Engagement Activity 2017
URL http://diaspora.ristekdikti.go.id/?page_id=1230
 
Description Regular Discussion with Procter and Gamble 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact Procter and Gamble Cincinnati is a project partner. Our team discusses with the P&G team once per month to discuss the project's progress and how the results may be exploited in an industrial context.
Year(s) Of Engagement Activity 2017,2018
 
Description UKFN Industry Day 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Industry/Business
Results and Impact As part of the UKFN SIG management team, I co-organised an Industry Day "Smart materials and surfaces powered future engineering solutions" at Nottingham Trent University on 29th November 2017. We had representatives from 9 industrial companies, as well as around 50 academic participants. We had talks from the industrial participants to highlight their needs, as well as dedicated sessions to allow discussions between the industrialists and academics present.
Year(s) Of Engagement Activity 2017
URL https://www.ntu.ac.uk/about-us/events/events/2017/11/sig-industry-day
 
Description workshop "Multiscale Modelling of Wetting Phenomena" 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Postgraduate students
Results and Impact The workshop was aimed to bridge and cross-fertilise the many different theoretical approaches used to study wetting phenomena, including analytical and computational approaches, and which focus on phenomena in wide ranging length scales. We also held a dedicated career session for early career researchers, covering topics such as applying for postdocs and lectureships, writing fellowship and grant applications, and how to build a successful group.
Year(s) Of Engagement Activity 2018
URL http://ukfluids-workshop-wetting.uk