Thesis Work – From flow to fish: Hydraulic characterization of a new fish swimming flume

Are you a student looking to apply your knowledge to real-world solutions that support the energy transition? With us, you will have the opportunity to complete your thesis project close to the business, working alongside experienced specialists and tackling challenges where your ideas and perspectives can make a real difference. 

About the Thesis Work

To comply with the European Water Framework Directive, Sweden is currently undergoing a large-scale hydropower relicensing process under the National Plan for Modern Environmental Conditions for Hydropower (NAP) aimed at reducing the environmental impacts of hydropower production while maintaining renewable energy generation. A key challenge is the restoration of river connectivity through the implementation of effective upstream and downstream fish passage solutions. However, designing solutions that accommodate a wide range of fish species and swimming abilities requires a detailed understanding of how fish respond to hydraulic conditions such as velocity and turbulence.

To support this need, Vattenfall R&D is commissioning a new state-of-the-art flume that allows controlled investigations of fish swimming performance and behaviour under varying hydraulic and environmental conditions. Before biological experiments can be conducted, the hydraulic characteristics of the facility must be thoroughly quantified using experimental flow measurement techniques such as Acoustic Doppler Velocimetry (ADV) and Particle Image Velocimetry (PIV). The results will provide the hydraulic foundation for future research linking flow conditions to fish behaviour and swimming capacity, ultimately contributing to more effective and evidence-based fishway and bypass design.

The following tasks shall be completed as part of the thesis:

• Quantify the relationship between pump RPM, number of operating pumps, discharge, and mean flow velocity.
• Characterize the development of the flow field in streamwise and lateral direction within the swimming flume using PIV and determine where the flow becomes fully developed.
• Characterize the flow field within the outlet pool using ADV and evaluate its suitability as a potential staging area for fish.
• Validate an existing CFD model against the collected measurement data.

We are looking for a student who are about to complete their academic studies and are eager to apply their knowledge in a real-world setting through a thesis project at Vattenfall. You are someone who shares our values and identifies with our principles: Active, Open, Positive and Safety. 

• Currently pursuing studies in Environmental Engineering, Hydraulic Engineering, Civil Engineering, or a related field.
• Strong communication skills in English, both written and spoken.
• Basic understanding of hydraulics and fluid mechanics.
• Interest in conducting hands-on experimental work in a research environment.
• Strong interest in ecohydraulics and aquatic ecosystems.
• Curiosity about the relationship between hydraulic conditions and fish behaviour and performance.
• Ability to work independently and take initiative in a research project.

Scope: 30 ECTS credits (approximately 6 months).

Number of students: 1

• Start date: February/March 2027 or by agreement.
• Location: Älvkarleby, Sweden; a hybrid solution can be discussed.
• Application – Submit a single file containing your CV and a copy of your academic transcripts. Please note that only one file can be uploaded with your application, so it is important that all required information is combined into the same document.
• Application deadline: 2026-11-15.
• Contact person and supervisor at Vattenfall: Stephanie Mueller (+46 702135112, stephanie.mueller@vattenfall.com)  and Gustav Wendin (+46 761371498, gustav.wendin@vattenfall.com).

Diversity and Inclusion – In Everything We Do 

At Vattenfall, we value being Active, Positive, Open, and Safety-conscious. We are looking for employees who share our vision and can contribute to strengthening our company culture. We believe that diversity helps build a more successful and attractive company, and we strive to be role models in diversity and inclusion. Vattenfall actively works to ensure that all employees have equal opportunities and rights, regardless of age, ethnic or cultural background, gender identity, religion or belief, sexual orientation, or disability. Read more about how we work with diversity and inclusion here. 

Vattenfall is part of Sweden’s critical infrastructure, and many of our positions are therefore classified from a security perspective. If this position is security-classified, a security screening will be conducted prior to employment in accordance with the Swedish Security Protection Act.

Vattenfall is a leading European energy company serving approximately 12 million customers and employing around 21,000 people. We believe there is a way to build a future where everyone can choose fossil-free ways to move, make, and live.