Flow-induced heterogeneity in applications of complex fluids: causes, consequences and engineering
Lead Research Organisation:
University of Nottingham
Department Name: Sch of Chemical and Environmental Eng
Abstract
Complex fluids include emulsions, pastes, particulates, foams, polymers, grains, colloids, nanofluids, and medical fluids such as blood. Complex fluid flow is ubiquitous in everyday technologies, from food processing to minerals to ceramics to pharmaceuticals. Assumptions of homogeneous fluid response--that a fluid deforms and flows evenly throughout a flow geometry--are often violated by flow-induced heterogeneity in complex fluids, e.g. jamming of grains in hoppers, liquid/solid phase separation in food processing. Flow thus induces variations of composition and concentration across the flow geometry, as well as complicated variations of flow rate over time, leading to often serious problems with product quality and processing. This research will investigate the causes, consequences and engineering of flow-induced heterogeneity, in complex fluid flows relevant to important applications and technologies. The project has a twin focus: both solving application problems through basic experiment, measurement and understanding of key example flows; and investigating new control and design opportunities arising from control and use of flow-induced heterogeneity, by applying external fields such as ultrasound and microwaves.The research programme focuses around three flow situations that are key examples of applications: jamming in channels, in granulation (an important industrial process for turning fine powders into stable larger grains, e.g. in washing powder), and in squeeze flows (common e.g. in food processing).Direct optical measurements and observations will compare the heterogeneous response of 'model' complex fluids with controllable properties (colloids and polysaccharides, a key component of foods), to quantify the role of system properties and flow geometry as causes of flow-induced heterogeneity.The project will go on to investigate control and use of flow-induced heterogeneity, to solve process problems and generate desirable product attributes, e.g. texture in foods, by application of external fields (acoustic, microwaves). The possibilities of engineering heterogeneous response will be investigated by experimenting with the field geometry, strength, and protocol (changing field with time).Understanding the causes and consequences of flow-induced heterogeneity in complex fluids, and finding ways to use it to engineer the properties of complex fluid products, will aid a broad range of industries from foods to cosmetics to pharmaceuticals, enabling better design, testing and characterisation of products and processes. The results of this research will help turn heterogeneous flow responses such as jamming from a potentially serious and unpredictable problem, to a well-understood, predictable and useful engineering phenomenon.
People |
ORCID iD |
Mark Haw (Principal Investigator) |
Publications
Bertola V
(2015)
Impact of concentrated colloidal suspension drops on solid surfaces
in Powder Technology
Campbell A
(2010)
Jamming and unjamming of concentrated colloidal dispersions in channel flows
in Soft Matter
Haw MD
(2009)
Volume fraction variations and dilation in colloids and granulars.
in Philosophical transactions. Series A, Mathematical, physical, and engineering sciences
Jenkins MC
(2011)
Does gravity cause load-bearing bridges in colloidal and granular systems?
in Physical review letters
Description | Understanding and controlling the flow and deformation ofparticle suspensions through confined geometries is of significanttechnological importance. Soft matter materials consisting ofcolloidal particles or droplets suspended in a liquid medium arefrequently encountered in industrial products and applications.e.g. foods, paints, building materials, pharmaceuticals. Process-ing of such concentrated colloidal dispersions often involvesdriving under pressure through complex geometries, namelyconvergent and divergent pipe sections, generating extensionalcomponents of strain. Under suitably low flow rates concen-trated dispersions exhibit a constant viscosity; i.e. they behave asa Newtonian fluid. However, under higher stress or shear ratethey can also exhibit shear thickening i.e. increase in viscositywith stress. Extreme or 'discontinuous' shear thickening has beenreported where apparent viscosity increases very suddenly,accompanied by subsequent large fluctuations in viscosity andstress. Such extreme thickening has been linked with flow-induced jamming. Jamming can be defined as the transformationof a liquid system to a solid by an applied stress. Whilst therehave been some studies of concentrated colloidal systems underPoiseuille flow, the conditions under which jamming occurs arestill not properly understood. Jamming is relevant to major process problems such as uncontrolled variations in pressure which could cause significant damage; there are even indications that jamming is relevant to geological processes such as earthquakes and volcano eruptions.In this project we demonstrated experimentally a novel behav-iour of concentrated jamming suspensions, i.e. a 'self-lubrication'effect that enables a jamming suspension to revert to anunjammed simple fluid flow behaviour. Associated with this isthe creation of rotating vortex-like flow patterns, consistent witheffects seen in computer simulations of granular systems (related to geology) but not to our knowledge observed before in experiment.At the highest applied pressures the system is thus able to 'perma-nently' unjam, reverting from granular-like behaviourback to a simple hard-sphere liquid like system. In the experi-ments the important role played by the geometry in imposinga rotation on the flow pattern, thus rotating force chains andtaking advantage of the 'fragility' of the jammed system, suggestsa simple technical solution to jamming problems in processesinvolving channels: insert similar 'turns' in straight channels toenable the jamming fluid to self-lubricate and revert to simpleviscous flow. |
Description | Sponsored research- Research collaboration with MacPhie of Glenbervie (Strathclyde Links) Jan-May 2011 |
Organisation | MacPhie of Glenbervie |
Country | United Kingdom |
Sector | Private |
PI Contribution | Participant : Joint or sponsored appointments or secondments with industry or commerce : Sponsored research- Research collaboration with MacPhie of Glenbervie (Strathclyde Links) Jan-May 2011 |
Start Year | 2011 |
Description | 'Solidification of colloidal suspensions' international workshop |
Form Of Engagement Activity | Scientific meeting (conference/symposium etc.) |
Part Of Official Scheme? | No |
Primary Audience | |
Results and Impact | Chair : Organiser of major conference : Session chair, 'Solidification of colloidal suspensions' international workshop, Avignon, France, Sept 2010. |
Year(s) Of Engagement Activity | 2010 |
Description | 'Solidification of colloidal suspensions' international workshop |
Form Of Engagement Activity | Scientific meeting (conference/symposium etc.) |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Participants in your research or patient groups |
Results and Impact | Chair : Organiser of major conference : Session chair, 'Solidification of colloidal suspensions' international workshop, Avignon, France, Sept 2010. |
Year(s) Of Engagement Activity | 2010 |
Description | Invited seminar Dept of Earth sciences, University of Glasgow, July 2009 |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Primary Audience | |
Results and Impact | Visitor : Invited talk : Invited seminar Dept of Earth sciences, University of Glasgow, July 2009. |
Year(s) Of Engagement Activity | 2009 |
Description | Invited seminar Dept of Earth sciences, University of Glasgow, July 2009 |
Form Of Engagement Activity | Scientific meeting (conference/symposium etc.) |
Part Of Official Scheme? | No |
Primary Audience | |
Results and Impact | Visitor : Invited talk : Invited seminar Dept of Earth sciences, University of Glasgow, July 2009. |
Year(s) Of Engagement Activity | 2009 |
Description | Invited seminar University of Dusseldorf, February 2011 |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Primary Audience | |
Results and Impact | Visitor : Invited talk : Invited seminar University of Dusseldorf, February 2011 (postponed from Dec 2010 due to weather!). |
Year(s) Of Engagement Activity | 2011 |
Description | Invited seminar University of Dusseldorf, February 2011 |
Form Of Engagement Activity | Scientific meeting (conference/symposium etc.) |
Part Of Official Scheme? | No |
Primary Audience | |
Results and Impact | Visitor : Invited talk : Invited seminar University of Dusseldorf, February 2011 (postponed from Dec 2010 due to weather!). |
Year(s) Of Engagement Activity | 2011 |
Description | Particles and fluids |
Form Of Engagement Activity | Scientific meeting (conference/symposium etc.) |
Part Of Official Scheme? | No |
Primary Audience | Participants in your research or patient groups |
Results and Impact | Invited speaker : Participation in workshop, seminar, course : Seminar 'Particles and fluids', Biological and Soft Matter group, University of Cambridge . Particles and fluids, Cambridge |
Year(s) Of Engagement Activity | 2014 |