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Department of Chemical Engineering and Biotechnology



Paste, Particle and Polymer Processing group (P4G)

Our interests lie in developing the understanding of processing of pastes, particles and polymers, and their flow behaviour in particular.  We rarely synthesize components: rather, we build from existing materials. We apply that knowledge to manufacture, at industrial scale, products with desired microstructure or function, or, equally importantly, to resolve problems encountered in processing such materials.

P4G was formed in January 2013 by the (friendly) merger of two of the groups in the Department of Chemical Engineering and Biotechnology with an interest in structured materials and processing: the Paste and Particle Processing group (P3G) and the Polymer Fluids group . The group is led by Ian Wilson, Sarah Rough and Bart Hallmark. Retired staff David Scott, John Davidson and Bob Skelton also contribute.

A substantial part of the activities led by Prof. Wilson is related to studying the formation and removal of fouling layers on heat transfer and process equipment surfaces, as well as cleaning and decontamination.  Dr Rough has a long-standing interest in particle technology, while Dr Hallmark enjoys simulating processes and flows from the meso- to the plant scale. There is much work on complex fluids, both visco-plastic and visco-elastic.

The group's activities range from fundamental theoretical, numerical and experimental investigations to applied and proof-of-concept studies. The research page gives a full listing of ongoing and past projects.



  • 10 January 2020 - Paper published: Tsai, J.-H., Hallmark, B. and Wilson, D.I. (2019) Integrated Fluid Dynamic Gauge for Measuring the Thickness of Soft Solid Layers Immersed in Opaque, Viscous, and/or Non-Newtonian Liquids in Situ, Ind. Eng. Chem. Res.58, 23124-23134.

  • End of an era The last P4G meeting of the decade took the form of a Christmas dinner held at Jesus College. Guests of Honour were members of the Mechanical and Electronics workshops, and other colleagues from the Department's Professional Support Staff, who have helped generations of P4G members through their time in the Department of Chemical Engineering and in CEB. Poignant tributes from former members were read, and gifts funded by current and past members presented. We wish all our guest well in their next adventures.
  • Wordsmith! 29th November: P4G member Saksham Sharma won one of the prizes in the Ideas Take Flight competition organised by Cambridge University Entrepreneurs.
  • Paper published: Ishiyama, E.M., Falkeman, E.S, Wilson, D.I. and S.J. Pugh, S.J. (2020) Quantifying implications of deposit aging from crude refinery preheat train data, Heat Transfer Engineering, 41(2), 115-126.
  • Paper published: Hawthorn, D. and Wilson, D.I. (2020) Calcium phosphate scale formation in power station condensers fed by cooling towers: a case of when not to use scaling indices, Heat Transfer Engineering, 41(2), 138-148.


Recent News

  • Paper published: Tsai J.-H., Cuckston, G.L, Hallmark, B. and Wilson, D.I. (2019) Fluid-dynamic gauging for studying the initial swelling of soft solid layers. AIChE J65, e16664.
  • Uncertain times: CEB is closing its mechanical and electronics workshops in early November.
  • PhD student Jamie Davidson discusses his work optimising the design of ovens as part of the podcast ‘Cooking with a Conscience’ by The Naked Scientists. Listen to the podcast here
  • Paper published: Yang, Y., Bhagat, R.K., Rosario-Fernandes, R., Nordkvist, M., Gernaey, K.V., Kruehne, U. and Wilson, D.I. (2019) Cleaning of toothpaste from vessel walls by impinging liquid jets and their falling films: Quantitative modelling of soaking effects, Chem. Eng. Sci., 208, 115148
  • 8th August - the news is back - following a period of the CEB website being down to move platform.
  • Paper published: Fernandes, R.R., Oevermann, D. and Wilson, D.I. (2019) Cleaning insoluble viscoplastic soil layers using static and moving coherent impinging water jets, Chem. Eng. Sci207, 752-768.
  • Paper publishedSargent, M.J. and Hallmark, B. (2019) Investigating the shear rheology of molten instant coffee at elevated pressures using the Cambridge multipass rheometerFood Bioproducts Proc., 115, 17-25.
    • 11 April 2019 P4G reunion in Santa Fe

      PhD student Rubens Rosario-Fernandes and Ian Wilson met up with former P4G-ers Dr Barbara Meza and Dr Juan Manuel Peralta at INTEC/UNL in Santa Fe, Argentina. Also in the picture is Prof. Susana Zorilla, one of the leaders of the Food Engineering Group at INTEC/UNL.

      Ian and Rubens' visit is part of a Royal Society/CONICET collaboration project with our Argentinian colleagues investigating the rheology and flow of bubbly liquids in food applications. Ian delivered a seminar on coupled flows of complex fluids as part of the visit.

      Juan Manuel and Barbara will visit CEB later this year.

  • 8 April 2019 - Paper published: Sargent, M.J. and Hallmark, B. (2019) Investigating the shear rheology of molten instant coffee at elevated pressures using the Cambridge multipass rheometer, Food Bioproducts Proc., 115, 17-25.
  • 28 February 2019 - Paper published: Zhang, M., Rough, S.L., Ward, R., Seiler, C. and Wilson, D.I. (2019) Non-aqueous formulations for ram and screen extrusion-spheronisation, Intl. J. Pharm, 560, 394-405. QuickLink live until 19 April 2019.
  • 14 February 2019 - Cleaning is Chemical Engineering! Ian Wilson explains this in an EHEDG webcast on LinkedIn.
  • 7 January 2019 - Paper published: Oevermann, D., Bhagat, R.K, Fernandes, R.R. and Wilson, D.I. (2019) Quantitative modelling of the erosive removal of a thin soil deposit by impinging liquid jets, Wear, 422-423, 27-34. QuickLink live until 26/2/19
  • 3 January 2019 - Paper published: Wang, S., Ke Zhou, X., Christie, G. and Wilson, D.I. (2019) Development of zero discharge net flow fluid dynamic gauging for studying biofilm and spore removal, Food Bioproducts Proc., 113, 60-67. QuickLink live until 22/2/19
  • 3 January 2019 - Paper published: Chee, M.W.L, Ahuja, T.V, Bhagat, R.K, Taesopapong, N, Wan, S.A, Wigmore, R.L, and Wilson, D.I. (2019) Effect of jet length and wall curvature on cleaning of tank walls, Food Bioproducts Proc., 113, 142–153. QuickLink live until 22/2/19
  • Paper published: Magens, O.M., Hofmans, J.F.A., Adriaenssens, Y. and Wilson, D.I. (2019) Comparison of fouling of raw milk and whey protein solution on stainless steel and fluorocarbon coated surfaces: Effects on fouling performance, deposit structure and composition, Chem. Eng. Sci., 195, 423-432.
  • Paper published: Al Ismaili, R., Lee, M.W., Wilson, D.I. and Vassiliadis, V.S. (2019) Optimisation of heat exchanger network cleaning schedules: incorporating uncertainty in fouling and cleaning model parameters, Computers & Chemical Engineering, 121, 409-421.
  • Prize Dissertation. Ole Mathis Magens received the 'bronze' prize for his PhD thesis in the 2018 Hygienic Study Award competition. This competition is held biannually and the awards are presented at the EHEDG World Congress. Ole received his award at the Congress dinner in London on 21 November.
  • Paper published: Wilson, D.I. (2018) Fouling during food processing – progress in tackling this inconvenient truth, Current Opinion in Food Science, 23, 105–112.
  • Chemeca 2018 Queenstown, New Zealand. P4G members George Cuckston, Michael Sargeant (ex) and Ian Wilson presented papers. Ian was awarded the Malcolm A Brodie Medal for the best paper presented at the conference, entitled 'Cleaning tanks by impinging liquid jets', co-authored by Rajesh Bhagat, Rubens Rosario-Fernandes, Sebastian Hunter and Francois Mace.
  • One year to go to VPF8: P4G are one of the groups organising the biannual workshop on Viscoplastic Fluids: from Theory to Application, being held in Cambridge (UK) from 16-20 September 2019.
  • Paper published: Cuckston, G.L., Alam, Z., Goodwin, J., Ward, G. and Wilson, D.I. (2019) Quantifying the effect of solution formulation on the removal of soft solid food deposits from stainless steel substrates, J. Food Eng., 243, 22-32.
  • Paper published: Bhagat, R.K., Jha, N.K., Linden, P.F. and Wilson, D.I. (2018) On the origin of the hydraulic jump in a thin liquid film, J. Fluid Mech. 851, R5. picked up by the Phys.Org website!
  • P4G at UK Fluids Network SIG 10 Conference

    Eight of of the group attended the Special Interest Group on Fluid Mechanics of Cleaning and Decontamination Conference held at the Isaac Newton Institute in Cambridge.

    George, Rajesh and Rubens gave oral presentations while Jheng-Han, Nathan, Melissa, Ian and Dirk gave poster presentations. It was good to see some recent visitors to the group there, notably Jifeng Yang (DTU, Copenhagen) , Hannes Koehler (TU Dresden) and Alistair Rogers (Leeds).

    Recordings of the conference will be available from the SIG website.

  • Paper published: Chee, M.W.L, Balaji, S, Cuckston, G.L, Davidson, J.R. and Wilson, D.I. (2018) Pendant drops shed from a liquid lens formed by liquid draining down the inner wall of a wide vertical tube, Exptl. Thermal Fluid Sci, 97, 364-374.
  • P4G at FCFP 2018

    The international conference on Fouling and Cleaning in Food Processing was held in Lund, Sweden, from 17-20 April. A P4G mini-reunion took place, with (from left) Jen-Yi Huang (Purdue University, USA), Phanida Saikhwan (Thammasat University, Thailand), Ian Wilson (still in Cambridge) and John Chew (University of Bath, UK) pictured enjoying drinks in the Hyproteck room garden with the cathedral's spires in the background. PhD students George Cuckston and Rubens Rosario-Fernandes also attended.

  • Paper published: Zhang, M., Li, X.K., Wilson, D.I., Yao, T.T. and Zhang, Y.Y. (2018) Influence of the dimensions of spheroniser plate protuberances on the production of pellets by extrusion-spheronisation, Adv. Powder Tech., 29, 1128-1141.
  • Paper published: Liu, W., Wilson, D.I, Chen, X.D and Mercadé-Prieto, R. (2018) Quantification of the local protein content in hydrogels undergoing swelling and dissolution at alkaline pH using fluorescence microscopy, Food Bioprocess Tech, 11, 572-584.
  • Congratulations to Sarah Rough, who has been awarded one of the university's Pilkington Prizes for excellence in teaching!
  • Paper published: Zhou, K.X., Ionescu, A., Wang, E., Hoa, Y.N., Barnes, H.W., Christie, G. and Wilson, D.I. (2018) Paramagnetism in Bacillus spores: opportunities for novel biotechnological application, Biotech. Bioeng, 115, 955-964.
  • Paper published: Al Ismaili, R.,  Lee, M.W., Wilson, D.I. and Vassiliadis (2018) Heat exchanger network cleaning scheduling: from optimal control to mixed-integer decision making, Comp. Chem. Eng., 111, 1-15.
  • Paper published: Zhou, X.K.,  Li, N.,  Li, N., Christie, G. and Wilson, D.I. (2017) Assessing the impact of germination and sporulation conditions on the adhesion of Bacillus spores to glass and stainless steel by fluid dynamic gauging, J. Food Sci, 82(11), 2614-2625.
  • Paper published: Patel, M.J., Blackburn, S. and Wilson, D.I. (2018) Modelling of pastes as viscous soils - lubricated squeeze flow, Powder Tech, 323, 250-268
  • Paper published: Bryan, M.P., Rough, S.L. and Wilson, D.I. (2018) Measurement of the wall slip behaviour of a solid granular soap in ram extrusion, Powder Tech, 323, 76-85.
  • Paper published: Bryan, M.P., Rough, S.L. and Wilson, D.I. (2017) Flow visualisation and modelling of solid soap extrusion, Chem. Eng. Sci., 173, 110-120.
  • Paper published: Patel, M.J., Blackburn, S. and Wilson, D.I. (2017) Modelling of paste ram extrusion subject to liquid phase migration and wall friction, Chem. Eng. Sci., 172, 487–502. Audio Slides are available.
  • Congratulations to Xu Ke Zhou and to Shiyao (Eric) Wang, who have both been approved for the PhD degree!
  • The conference flyer for the Fouling and Cleaning in Food Processing 2018 meeting, to be held in Lund, Sweden, is now available.
  • Paper published: Zhou, X.K., Wisnivesky, F., Wilson, D.I. and Christie, G. (2017) Effects of culture conditions on the size, morphology and wet density of spores of Bacillus cereus 569 and Bacillus megaterium QM B1551, Letters in Applied Microbiology, 65(1), 50–56.
  • Paper published: Markl, D., Yassin, S., Wilson, D.I., Goodwin, D.J., Anderson, A. and Zeitler, J.A. (2017) Mathematical modelling of liquid transport in swelling pharmaceutical immediate release powder compacts, Intl. J. Pharm., 526, 1-10.
  • P4G have left the building! We moved from the old Chemical Engineering building on Pembroke Street to 'new CEB' at Philippa Fawcett Drive on the West Cambridge site over the Easter break. There is daylight in the new labs!
  • Paper published:O'Neill, R., McCarthy, H.O., Montufar, E.B., Ginebra, M.-P., Wilson, D.I., Lennon, A. and Dunne, N. (2017) Critical Review: Injectability of calcium phosphate pastes and cements, Acta Biomateriala, 50, 1-19.
  • Paper published: Wilson, D.I., Polley, G.T. and Ishiyama, E.M. (2017) Twenty years of Ebert and Panchal—what next? Heat Transfer Engineering, 38(7-8), 669-680.
  • Paper published:Lister,V.Y., Davidson, J.F., Sutcliffe S.J. and Wilson, D.I. (2017) Management of acute particulate fouling in a titanium dioxide reactor system, Heat Transfer Engineering, 38(7-8), 796-804.
  • Entrepreuner Guy!

    P4G alumnus Salvatore Mascia has been awarded the Italian Ministry of Foreign Affairs 2017 prize for the best start-up company founded by an Italian entrepreneur. Salvatore is CEO of Continuus Pharmaceuticals, which he spun out of the MIT/Novartis centre for continual processing for the manufacture of pharmaceuticals. Sal did his PhD in the group and then moved to MIT to work with Prof. Bernhardt Trout. The photograph shows Sal (on the right) receiving his award from the Minister of Foreign Affairs.


Determination of quality parameters for consumer goods (baked cakes!)

News Archive

Scanning Electron Microscopy (SEM) image of a cellulose membrane, before foulingVacancies/Studentships

Extrudates of microcrystalline cellulose water-based paste (3 mm die diameter). The difference in appearance is due to the extrusion velocity - a higher velocity induces surface fractures

 Academic collaborators within other groups at Cambridge include

Active external academic collaborators

Sponsorship and funding comes from a range of sources, including the TSB, ESPRC and industry. This support is gratefully acknowledged: more information about sponsoring bodies is available on the Group Links page.

P4G also hosts the Fluid Dynamic Gauging website: this technique was developed within the P3G group.

The former P3G or Polymer Fluids Group websites can be viewed for more information.