PhD Position Simulations of Strongly Stratified Turbulence

Join our team at TU Delft to explore turbulent flows in strongly stratified conditions using advanced numerical simulations and contribute to new insights in theoretical fluid dynamics. 

Job description

Stratified flows, where fluid density and viscosity vary strongly, are common in both natural and industrial systems—ranging from ocean currents to advanced heat exchangers. However, conventional models like the Boussinesq approximation fail to capture the complex physics in such flows when strong stratification or non-ideal fluids are involved.

Within this PhD, you will advance our understanding of hydrodynamic stability and turbulence in strongly stratified turbulent flows, such as fluids at supercritical pressures, where extreme property variations create strong stratifications. Using linear stability analysis and direct numerical simulations of the fully compressible Navier–Stokes equations, you will explore how inertial and gravitational baroclinic mechanisms interact to trigger or suppress the transition to turbulence and how they affect the fully turbulent flow.

The work is embedded in a broader project combining theory, computation, and unique high-pressure experiments. The insights gained will inform more accurate models for a wide range of stratified shear flows and contribute to the design of efficient next-generation energy systems.

Key tasks include:

• Developing a theoretical framework for stratified shear flows that includes gravitational and inertial baroclinic instability mechanisms.

• Deriving and analyzing evolution equations for flow disturbances.

• Running DNS with advanced multi-GPU solvers using accurate real-fluid equations of state and variable properties.

• Interpreting results in close collaboration with an experimental PhD and validating findings against experimental data.

You will be embedded in a multidisciplinary team with expertise in numerical methods, compressible flows, and turbulence in non-ideal fluids, and work in synergy with an experimental PhD student studying the same flows in the laboratory.

Job requirements

We seek an enthusiastic and motivated candidate with:

• A Master’s degree (or equivalent) in mechanical engineering, applied physics, aerospace engineering, or a related field.

• A strong background in fluid mechanics, numerical methods, and thermodynamics.

• Experience with computational fluid dynamics (CFD); prior exposure to DNS or stability analysis is a strong plus.

• Solid programming skills (e.g., Python, C/C++, or Fortran); experience with GPU computing or high-performance computing is beneficial.

• The ability to work independently as well as collaboratively in an interdisciplinary environment.

• Good command of English, both written and spoken.

TU Delft (Delft University of Technology) 

Delft University of Technology is built on strong foundations. As creators of the world-famous Dutch waterworks and pioneers in biotech, TU Delft is a top international university combining science, engineering and design. It delivers world class results in education, research and innovation to address challenges in the areas of energy, climate, mobility, health and digital society. For generations, our engineers have proven to be entrepreneurial problem-solvers, both in business and in a social context. 

At TU Delft we embrace diversity as one of our core values and we actively engage to be a university where you feel at home and can flourish. We value different perspectives and qualities. We believe this makes our work more innovative, the TU Delft community more vibrant and the world more just. Together, we imagine, invent and create solutions using technology to have a positive impact on a global scale. That is why we invite you to apply. Your application will receive fair consideration. 

Challenge. Change. Impact! 

Faculty Mechanical Engineering 

From chip to ship. From machine to human being. From idea to solution. Driven by a deep-rooted desire to understand our environment and discover its underlying mechanisms, research and education at the ME faculty focusses on fundamental understanding, design, production including application and product improvement, materials, processes and (mechanical) systems. 

ME is a dynamic and innovative faculty with high-tech lab facilities and international reach. It’s a large faculty but also versatile, so we can often make unique connections by combining different disciplines. This is reflected in ME’s outstanding, state-of-the-art education, which trains students to become responsible and socially engaged engineers and scientists. We translate our knowledge and insights into solutions to societal issues, contributing to a sustainable society and to the development of prosperity and well-being. That is what unites us in pioneering research, inspiring education and (inter)national cooperation. 

Click here to go to the website of the Faculty of Mechanical Engineering. Do you want to experience working at our faculty? These videos will introduce you to some of our researchers and their work.

Conditions of employment 

Doctoral candidates will be offered a 4-year period of employment in principle, but in the form of 2 employment contracts. An initial 1,5 year contract with an official go/no go progress assessment within 15 months. Followed by an additional contract for the remaining 2,5 years assuming everything goes well and performance requirements are met. 

Salary and benefits are in accordance with the Collective Labour Agreement for Dutch Universities, increasing from €3059 per month in the first year to €3881 in the fourth year. As a PhD candidate you will be enrolled in the TU Delft Graduate School. The TU Delft Graduate School provides an inspiring research environment with an excellent team of supervisors, academic staff and a mentor. The Doctoral Education Programme is aimed at developing your transferable, discipline-related and research skills. 

The TU Delft offers a customisable compensation package, discounts on health insurance, and a monthly work costs contribution. Flexible work schedules can be arranged.  

Will you need to relocate to the Netherlands for this job? TU Delft is committed to make your move as smooth as possible! The HR unit, Coming to Delft Service, offers information on their website to help you prepare your relocation. In addition, Coming to Delft Service organises events to help you settle in the Netherlands, and expand your (social) network in Delft. A Dual Career Programme is available, to support your accompanying partner with their job search in the Netherlands.  

Additional information

For more information about this vacancy, please contact Prof. Dr. Rene Pecnik (r.pecnik@tudelft.nl) or Prof. Dr. Jerry Westerweel (J.Westerweel@tudelft.nl).

Application procedure

Are you interested in this vacancy? Please apply no later than 15 September 2025 via the application button and upload the following documents:

• CV
• Motivational letter

Doing a PhD at TU Delft requires English proficiency at a certain level to ensure that the candidate is able to communicate and interact well, participate in English-taught Doctoral Education courses, and write scientific articles and a final thesis. For more details please check the Graduate Schools Admission Requirements. 

Please note:

• You can apply online. We will not process applications sent by email and/or post. 
• A pre-employment screening can be part of the selection procedure.
• For the final candidates, a knowledge security check will be part of the application procedure. For more information on this check, please consult Chapter 8 of the National Knowledge Security Guidelines. We carry out this check on the basis of legitimate interest.
• Please do not contact us for unsolicited services.