Vattenfall AB

Engineering & Technology


Importance of spillway surface roughness for discharge capacity determination, Thesis at Vattenfall AB

Expires in 3 days


Traditionally, steel plates and Plexiglas are used for construction of spillways, bottom outlets, tunnels, canals etc. in physical hydraulic modeling. After scaling, their surface finishing is equivalent to the concrete roughness in the prototype. Nowadays as a new technique, the spillways and outlets are manufactured through machine milling and 3D printing. The materials, either styrofoam (Frigolit) or polyurethane (Ureol), have another level of surface roughness/finishing, which is much rougher. The issue has never been investigated. In combination with small model dimensions, the roughened surface might have non-negligible effects on discharge determination in the model, and further in the prototype.



At the moment, there is one hydraulic model in the laboratory which provides an opportunity to numerically (CFD) answer the question raised above. To providing basis for refurbishments, the project examines the effects of material roughness and clarifies if it is a source of significant errors that affects spillway discharge determination for prototype spillways and outlets. Spillway layout is also optimized for discharge enhancement if time allows.


For the students, the benefits are as follows.

  • To get familiar with the on-going work with dam safety and dam upgrade projects.
  • To learn about hydraulic model tests.
  • To understand flow phenomena in overflow spillways.
  • To learn the fundamental knowledge of CFD modelling, including grid generation, grid convergence, model set-up, boundary conditions and numerical convergence.
  • To get familiar with turbulence models and two-phase water-air flow models.


With supervision from the laboratory, the student conducts model tests for selected flow conditions. With the same geometrical and flow data, CFD modeling is then made. In the CFD model, the spillway surface roughness is successively changed, and the resulting discharges are compared. The comparisons are made with the model tests and among the numerical results.


The project consists of the following aspects.

  1. background and literature review
  2. Data collection of the spillway and flow data
  3. Learning of the use of the Fluent program
  4. Based on the spillway geometry, generate 3D models for the waterway
  5. Model setup with phase properties and boundary conditions
  6. Modelling and Result analyses
  7. Comparison with model test results
  8. Report writing


Time frame

The project is to be completed within 4 months during 2023, ending up with a report by the diploma work student(s).



  • The project corresponds to a 30 hp diploma work
  • The applicant has a background in technical physics, mechanics or built environment
  •  It is performed with CFD (Fluent or CFX), by one or two students
  •  Proper background is civil engineering, engineering physics or similar.
  •  Knowledge of CFD modelling experiences is preferred


Your application should contain

  1. A cover letter with motivation of your application for the project and your interest in hydropower.
  2. List of courses at your university
  3. CV with complete contact information
  4. specify name of your examiner with contact information


Contact Information

The diploma work is to be carried out at Vattenfall Älvkarleby or per agreement, with James Yang as supervisor. Potential candidates should directly send in their applications to, phone 070-2723 200. Incomplete applications are not handled. The application is closed January 31, 2023.


Applications are processed on a running basis and the vacancy is filled as long a suitable candidate is found. This is the reason why you should not wait to the deadline to apply. Make up your mind and send in your application now if you are inte

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