Our department has been using and developing CFD models for hydraulic and sedimentation engineering since 1990. Initial work was focused on sediment problems with regards to hydropower intakes, primarily due to the difficulties of modelling fine sediment in physical models. Since then the scope of our CFD research has expanded to other hydraulic and environmental topics.

Computer Programs

Most of our CFD work has been carried out using the SSIIM program. The program is based on the solution of the Navier-Stokes equations on a non-orthogonal 2D or 3D grid. Both structured and unstructured grid versions are used. The SIMPLE method is used for computing the pressure and the the k-epsilon model is used to calculate turbulence. The sediment transport is calculated by solving the convection-diffusion equation for sediment concentration. Changes in bed elevation over time are computed, and algorithms for wetting and drying enables the prediction of lateral channel movements.

More information and download instructions for SSIIM

Publications

• International publications
• External publications where SSIIM has been used

On-line books

We have made some CFD books publically available on the PDF format. A short description and download links are given below.

CFD class notes (593 kB)
"Computational Fluid Dynamics for Hydraulic and Sedimentation Engineering" was made for the CFD part in our class "Withdrawal of water from sediment-carrying rivers". The class notes provides a simple introduction to the basics of CFD. The latest version was made 16. June 1999.

User's manual for SSIIM (1.3 MB)
The user's manual for SSIIM provides standard information about the SSIIM program, like user interface, data format for input and result files etc. The latest version was made 31. May 2010.

Numerical modelling and hydraulics (1.7 MB)
The class notes for a course with the same name, given for the first time in the spring 2001. It is an undergraduate course in the 4th year of the Civil Engineering study at NTNU. This is the version from October 2009.

CFD Algorithms for Hydraulic Engineering (678 kB)
The book is a more detailed documentation of general and special hydraulic engineering CFD algorithms. It is intended to be used as a textbook for graduate courses in CFD, and also to provide assistance for people writing CFD codes. The present version is from 14. December 2000, and before this date it has not been checked by anyone but the author.

CFD for Hydraulic Structures (535 kB)
The book is about experiences using the SSIIM model to compute flow in/around hydraulic structures. The following cases are discussed: Vegetation, spillways, local scour and intakes. The present version is from 8. May 2001.

Projects

Several examples from our research are listed below. Much of the work has been carried out in cooperation with other institutions, so many of the examples are located on other web servers.
The numbers in brackets indicate size of graphics files in kB. The date indicate latest update.

Sediment transport

• Steady water and sediment flow in Garita Hydropower Reservoir, Costa Rica. 4. January 2011. (In Norwegian)
• Sediment deposition in a sand trap. 13. June 2015.
• Bed changes in a sand trap
• Local scour around a circular cylinder
• Turbidity current in a laboratory flume
• 3D reservoir flushing using a dynamic unstructured grid, 14. May 1999
• Turbidity currents in Cachi Reservoir, Costa Rica (100)
• Modelling the sand traps in Khimti Hydropower Plant, Nepal. 6. June 2000 
• Formation of a meandering channel from an initial upstream pertubation. 13. August 2001 
• Sediment depositon in habitat improvmenet structures at Oyvollen, Norway. 15. March 2003 
• Formation of a meandering channel without initial pertubations. 13. July 2015 
• Modelling sediment flow in Agno intake. 12 May 2003.
• Bed changes in a 90 degree bend. 2004 
• Bed changes in sine-shaped channels. 2006 
• Sediment transport and bed changes in a 180 degree bend. 2006 
• Water and sediment flow in the delta of Lake Øyern. 2011 
• Sediment flow in the Angostura Reservoir in Costa Rica. 24. December 2011
• Bed changes in an S-shaped channel. 14. March 2011
• Final report from the delta project (in Norwegian). 3. June 2011
• Final report from the reservoir sedimentation project (in Norwegian). 18. April 2013
• Sediment slide in water reservoir. 30. December 2013 
• Sediment flow in the Iffezheim reservoir. 2. December 2014

General hydraulics

• Flood wave hitting a construction. 20. March 2003.
• Velocity field in river with large roughness. 24. June 2011.
• Himalayan headworks/intake (165)
• Flow visualization by particle animation (380)
• Vortex shedding behind a circular cylinder
• Head loss in a gate plug
• Flow around a groyne in a channel, 6. June 2000 
• Water velocities in Colombia River downstream Wanapum Dam, August 2000 
• Finding coefficient of discharge for a spillway. 28. January 1997.
• Flow over dunes, March 2007
• The river Nidelva. 11. December 2007
• Flow over a rough bed. 19. October 2010
• Broad-crested spillway with an unstructured grid. 5. March 2012
• The Sarpfossen reservoir and spillway. 14. April 2011
• The Sysen Dam spillway system. 8. August 2011
• The spillway system of the Innerdalen Dam. 8. August 2011
• Spillway modelling using OpenFOAM. 12. March 2012
• V-shaped weir. 29. July 2015

Water quality

• Radioactive spill in Lake Tyrifjorden, Norway. 2000 (Norwegian only) 
• Water quality in Lake Mjosa, Norway, during a flood (280) 2 Dec. 1998
• Circulation and algae modelling of Eglwys Nynydd water reservoir, Wales, UK, 21. Sept. 1999
• Circulation and algae modelling of Estwaithe Water, UK, 21. Sept. 1999
• Water currents and temperatures in Lake Sperillen, Norway. 2000

Habitat hydraulics

• Habitat modelling in Gurobekken laboratory flume at SINTEF, Norway, 15. Nov. 2000
• Sea trout spawning habitat in Gråelva, Norway, 31. Oct. 2001

CFD links

Hydroelectric power is the technology of generating electric power from the movement of water through rivers, streams, and tides thanks to the potential energy of the elevation of waters. Water is fed via a channel to a turbine where it strikes the turbine blades and causes the shaft to rotate. To generate electricity the rotating shaft is connected to a generator which converts the motion of the shaft into electrical energy.

Hydroelectric power now supplies about 715,000 MW or 19% of world electricity and large dams are still being designed. Apart from a few countries with an abundance of it, hydro power is normally applied to peak-load demand, because it is so readily stopped and started. Nevertheless, hydroelectric power is probably not a major option for the future of energy production in the developed nations because most major sites within these nations with the potential for harnessing gravity in this way are either already being exploited or are unavailable for other reasons such as environmental considerations.

Hydroelectric power can be far less expensive than electricity generated from fossil fuel or nuclear energy. Areas with abundant hydroelectric power attract industry with low cost electricity. Recently, increased environmental concerns surrounding hydroelectric power, have begun to outweigh cheap electricity in some countries.

The chief advantage of hydroelectric dams is their ability to handle seasonal (as well as daily) high peak loads. When the electricity demands drop, the dam simply stores more water. Some electricity generators use water dams to store excess energy (often during the night), by using the electricity to pump water up into a basin. The electricity can be re-generated when demand increases. In practice the utilization of stored water in river dams is sometimes complicated by demands for irrigation which may occur out of phase with peak electrical demands.

Small hydro is the application of hydroelectric power on a commercial scale serving a small community or medium sized industry. A generating capacity of up to 10 MW is becoming generally accepted as the upper limit of what can be termed small hydro. Small hydro can be further subdivided into mini hydro, usually defined as less than 1,000 kW, and micro hydro which is less than 100 kW. Micro hydro is usually the application of hydroelectric power sized for small communities, single families or small enterprise.

Small scale hydro or micro-hydro power has been increasingly used as an alternative energy source, especially in remote areas other power sources are not viable. Small scale hydro power systems can be installed in small rivers or streams with little environmental effect on things such as fish migration.

There are some major factors to consider when installing a micro-hydro system. First, the amount of water flow available on a consistent basis. Periods of little or no rain can greatly affect power output. Second is what is known as head, this is the amount of drop the water has between the intake and the exit of the system. The more head, the larger amount of power can be generated. Third, there can be legal and regulatory issues that must be researched. Most counties, cities, and states have their own regulations about water rights and easements.

Norway has a very large hydropower potential and has developed it to great extend so that today hydropower covers over 99% of the electricity consumption of the country. Since most of the main sites have already been developed, the focus is now on the development of small hydropower plants. NVE (Norwegian Water Resources and Energy Directorate) has assessed the small hydropower potential and found that 18 TWh could be developed for less than 3 NOK/kWh. NVE estimates that 5 TWh out of 18 TWh could be developed within the next 10 years, which would be an increase of 4.5 % from today’s hydropower production. 5 TWh represent 1000 small hydropower plants with an installed capacity of 1 MW and an investment of 10 to 15 billions NOK.