Rapid production of hollow spheres using coaxial nozzles

About the Project

Supervisory Team: Dr Ivo Peters

About the project

When gas flows from a coaxial nozzle surrounded by a liquid, it forms reproducible liquid shells useful in industries needing hollow spheres, such as pharmaceuticals and 3D printing. This project aims to understand and optimize production rates, reproducibility based on nozzle design and operating parameters.

When a gas surrounded by a liquid film flows out of a coaxial nozzle, the stream can spontaneously deform into liquid shells: bubbles of air trapped in a layer of liquid. Under the right circumstances, these liquid shells are highly reproducible and can form at a very high rate, up to thousands of liquid shells per second. This makes them highly desirable for industrial applications where hollow spherical objects need to be produced. Example application areas are encapsulation for pharmaceuticals, 3D printing of foam structures, shells for inertial confinement fusion, and even novel shower systems. Despite this vast range of applications, how these liquid shells are formed, and what conditions are required, is not fully understood.

A better understanding is needed in order to address specific application requirements. For example, the cost of a pharmaceutical product could be reduced by increasing the production rate, but this should be balanced by the potential negative impact on the reproducibility. Addressing this balance requires a thorough understanding of how the production rate influences reproducibility, and which nozzle geometry would be best suited for such a specific application.

In this project you will experimentally and/or numerically investigate the formation of liquid shells from coaxial nozzles. Nozzle can be machined and 3D-printed using different materials, and visualization will be done using state-of-the-art high-speed cameras.

Entry requirements

You must have a UK 2:1 honours degree, or its international equivalent, in one of the following:

• physical sciences
• engineering

You should have a good understanding of fluid mechanics.

Fees and funding

Full scholarships include tuition fees, a tax-free stipend at the UKRI rate for up to 3.5 years (totalling £20,780 for 2025/26, rising annually). UK, EU and Horizon Europe students are eligible for scholarships. Chinese Scholarship Council funded students are eligible for fee waivers. Funding for other international applicants is very limited and highly competitive. Overseas students who have secured or are seeking external funding are welcome to apply.

How to apply

Apply now

You need to:

• choose programme type (Research), 2026/27, Faculty of Engineering and Physical Sciences
• select Full time or Part time
• search for programme PhD Engineering & the Environment (7175)
• add name of the supervisor in section 2 of the application

Applications should include:

• your CV (resumé)
• 2 academic references
• degree transcripts and certificates to date
• English language qualification (if applicable)