PhD Student in Mechanisms of Laminar-Turbulent Transition

University of Bern Center for Biomedical Engineering Research

PhD Student in Mechanisms of Laminar-Turbulent Transition past Bioprosthetic Aortic Valves

The ARTORG Center for Biomedical Engineering Research is the University of Bern's transdisciplinary Center of Excellence for medical technology research. Its mission is to tackle unmet clinical needs and envision future challenges in diagnosis, monitoring and treatment to create viable healthcare technology solutions with imagination, agility and purpose. Its projects run from discovery and basic research to clinical translation.

The research group for Cardiovascular Engineering (CVE) has an open position for a PhD student (4 years).

The CVE research group focusses on the study of biomedical flow systems and cardiovascular devices. The research group operates a well-equipped cardiovascular flow lab and a computational lab for the numerical simulation of biomedical flows. The CVE group is collaborating closely with the Departments for Cardiovascular Surgery, Cardiology and Angiology of the Inselspital (Bern University Hospital).

Aortic valve replacement (AVR) is a successful treatment for moderate to severe aortic stenosis. However, aortic valve prostheses lead to unphysiological turbulent flow in the aortic root and the ascending aorta. For bioprosthetic valves, turbulent flow can be directly related to structural valve deterioration (SVD), bioprosthetic leaflet thrombosis, adverse aortic events and increased transvalvular pressure gradient. These effects are severe limitations to the positive long-term outcome of bioprosthetic AVR. We hypothesize that specific design and material properties of bioprosthetic valves may significantly reduce the level of turbulent flow. For the targeted development of such valves, it is important to precisely understand the mechanisms leading to turbulent flow (laminar-turbulent transition mechanisms) and how these mechanisms relate to valve design and material. We have recently published a study on absolute instability in mechanical heart valves (Zolfaghari & Obrist, Phys Rev Fluids, 2019). Such results are not available to date for bioprosthetic valves, and the character of the turbulent flow for different valve configurations, cardiac outputs and heart rates has not been described so far.

  • use an in-house high-order solver for fluid-structure interaction (Nestola, Becsek, et al., J Comput Phys, 2019) to study the hydrodynamic mechanisms which lead to the onset of turbulent flow past a bioprosthetic valve (laminar-turbulent transition)
  • quantitatively describe the developed turbulent flow field in the ascending aorta
  • study the effect of different valve designs and materials on the turbulent flow
  • MSc in mechanical engineering or related fields
  • Strong background in fluid mechanics with specialization on hydrodynamic stability and turbulent flow
  • Experience in programming, computational science and numerical methods for solving partial differential equations
  • Good skills in scientific writing
  • Ability to collaborate in an interdisciplinary team of medical doctors, engineers and computational scientists.
We offer
  • Creative and international environment to conduct competitive research in an interdisciplinary team
  • Strong links to the Bern University Hospital (Inselspital) to provide access to medical expertise
  • Competitive work-package and fully funded position for the whole duration of the PhD project
  • Free German courses available for those wishing to learn
The position is available immediately. Please submit your complete application (incl. motivation letter, CV) to Diana Bethge, diana.bethge(at)

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