Experimental investigation and modelling of foam-flow cleaning in milking systems – FOAMAT

Cleaning milking systems is essential for maintaining equipment hygiene and milk quality. Conventional cleaning-in-place (CIP) procedures require water, energy and detergents. In complex circuits, bends, junctions, vertical sections and changes in diameter can lead to uneven liquid renewal and mechanical action, allowing dairy residues and biofilms to persist.

Cleaning by foam flow offers an alternative approach, with the potential to improve contact with equipment surfaces while reducing resource consumption. Its effectiveness depends on foam formulation, liquid fraction, bubble size, drainage, stability and flow conditions. A key scientific challenge is to connect these properties to near-wall hydrodynamics, mechanical stresses and contaminant removal, and to determine how laboratory findings can be transferred to representative milking circuits.

Within the FOAMAT project, this PhD will combine foam physical chemistry, millifluidic experiments and computational fluid dynamics (CFD). The objective is to establish relationships between foam properties, flow behaviour and cleaning performance, and to support the development of operating conditions suitable for pilot-scale applications.

The doctoral researcher will undertake the following activities:

• Foam formulation and characterisation: contribute to the selection of surfactant formulations and measure foamability, bubble-size distribution, liquid fraction, drainage and stability. Characterise foam rheology and interactions with materials representative of dairy equipment.

• Experimental investigation and instrumentation: contribute to the design and instrumentation of a foam generation and circulation system. Investigate straight sections, bends, junctions and diameter changes under controlled conditions. Analyse flow-rate and pressure measurements, imaging data and, where appropriate, local shear and conductivity measurements.

• Numerical modelling: develop CFD models, particularly using COMSOL Multiphysics, incorporating an effective description of foam rheology. Compare simulations with experimental observations to identify critical flow regions and conditions favourable to cleaning.

• Cleaning assessment and pilot-scale validation: investigate the removal of dairy residues and microbial contamination. Contribute to the analysis of pilot trials conducted with ACTALIA and on the Institut de l’Élevage’s PiloTraite platform. Assess rinsing requirements and compare water, energy and chemical consumption with conventional CIP over the complete cleaning cycle.

• Scientific dissemination: analyse and interpret results, prepare scientific publications, present findings at conferences and contribute to technical recommendations for the dairy sector.

FOAMAT is coordinated by Université de Caen Normandie, in partnership with ACTALIA and Institut de l’Élevage (Idele). Kersia provides industrial support relating to detergent formulations and their use, while CNIEL contributes through advisory exchanges.

Public funding alone (i.e. government, region, European, international organization research grant)

The position is funded by the FOAMAT project under the French CASDAR programme, through the 2026 Connaissances call for proposals administered by FranceAgriMer. Contract duration: 36 months. Gross annual salary: €27,600.

The PhD will be hosted by the Aliments Bioprocédés Toxicologie Environnements research unit (ABTE, UR 4651), within the EcoTEA team at Université de Caen Normandie, France.

The doctoral researcher will be based at Campus 2, Sciences 2 building, in Caen. Research activities will combine foam formulation and characterisation, rheology, experimental fluid mechanics and numerical modelling.

The project provides a collaborative research environment linking laboratory investigations with applications in dairy equipment hygiene. Université de Caen Normandie leads the formulation, rheology, hydrodynamics and CFD activities. ACTALIA contributes expertise in cleaning assessment and pilot-loop validation. Institut de l’Élevage provides expertise in milking systems and access to the PiloTraite platform for validation and transfer to the dairy sector.

The position will involve travel for pilot-scale experiments with ACTALIA and Institut de l’Élevage.

Applicants should hold, or obtain before the start of the PhD, a Master’s degree or an equivalent engineering qualification in process engineering, fluid mechanics, physical chemistry or a closely related discipline.

The following skills and qualities are expected:

• A strong interest in experimental research, instrumentation and quantitative analysis.
• Knowledge of fluid mechanics and physical chemistry.
• Experience in rheology, multiphase systems, microfluidics or millifluidics would be an asset.
• Skills in CFD and data processing, particularly with COMSOL Multiphysics, Python or MATLAB, would be appreciated.
• Knowledge of microbiology or hygienic processing would be an additional advantage.
• Scientific rigour, autonomy and the ability to work collaboratively across disciplines and partner organisations.
• English proficiency sufficient to read scientific literature, communicate research findings and contribute to scientific publications.