NWO - 1 PhD experimental positions - Tailoring large-scale turbulence with bespoke small-scale fibers

The Physics of Fluids group works on a variety of aspects in Fluid Mechanics. The focus of our work is the fundamental understanding the phenomena of the physics of fluids. Present research areas include turbulence and multiphase flow, micro- and nanofluidics, biomedical flow, and granular flow. Both fundamental science and more applied science — then often in close collaboration with industrial partners — is done in the group and both experimental, theoretical, and numerical methods are used. The group presently has 10 scientific staff members, 7 part-time professors, 4 supporting technicians, and typically 10 postdocs, 45 PhD students, and 10–15 master students. Numerous natural phenomena and industrial applications involve turbulence with complex-shaped particles. However, most experimental and numerical studies into particle-laden turbulence have been carried out for low volume fractions of particles (ϕ<1%) with simple rigid geometries (spheres and fibers). The bottlenecks for experimental investigation of soft or anisotropic particles in turbulence are the lack of powerful equipment for turbulence generation including sophisticated measurement techniques, and the low throughput of processes that enable fabrication of complex-shaped particles with controlled stiffness. The objective of this project is to open up and investigate unexplored parameter spaces of particle-laden turbulence. In collaboration with another research group we will design and fabricate tailored particles via in-air photopolymerization, a new platform for particle fabrication. The connection between the in-air process and the particle properties will be opened for the first time, by high-speed imaging of the flow and solidification dynamics during particle formation. Particles with controlled shape, flexibility, and local composition will be fabricated and placed in turbulent flows.

Left:Sample particles created using in-air photopolymerization. Right: Schematic of a Taylor–Couette facility.

We will systematically vary these particle properties, the Reynolds number, and the particle volume fraction to assess their influence on the flow characteristics of highly turbulent Taylor-Couette flows, including turbulent drag, turbulence intensity, and local particle dynamics (position, velocity, orientation, rotation etc.). We will use the Twente Turbulent Taylor–Couette facilities (see here) for these experiments, which allows flows with Reynolds numbers up to 2*106 and allows to rotate both cylinders independently. The curvature and density of particles may affect entanglement and clustering in turbulence, respectively, providing insight in the efficiency of particle transport and opportunities for drag reduction. This understanding would enable predictions and control of large-scale particle-laden flows as observed in nature, chemical reactors, wastewater treatment, and food processing and many more.

Your profile:

You have a strong background in (applied) physics, aerospace engineering, or mechanical engineering, or in a closely related discipline. You have strong communication skills, including fluency in written and spoken English. You are enthusiastic and highly motivated to do a PhD. Experimental experience, extended knowledge on fluid mechanics, and experience in image and data analysis are required.

Our offer:

Applicants should be in the possession of a master degree in (applied) physics, aerospace engineering, mechanical engineering, or closely related field. Applications should provide:
  1. A motivational letter (1 page max) describing why you want to apply for this precise position including how your research interests/experience connect to this position.
  2. A detailed CV.
  3. Academic transcripts from your Bachelor’s and Master’s degrees.
  4. Name and email addresses of at least two visible references who are willing to send a letter of recommendation on your behalf.
  5. An interview with a scientific presentation on your previous work will be part of the interview process.
Deadline: March 15th

Contact: Assoc. Prof. Dr. Sander Huisman (PoF)

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