Computational Fluid Dynamics
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.
The picture above shows the grid of a self-forming meandering channel. The colours show the bed levels. More information.
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.
We have made some CFD books publically available on the PDF format. A short description and download links are given below.
"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.
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.
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.
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.
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.
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.
Steady water and sediment flow in Garita Hydropower Reservoir, Costa Rica. 4. January 2011. (In Norwegian)
Sediment deposition in a sand trap. 13. January 2011.
Bed changes in a sand trap
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
Morphological changes around habitat improvmenet structures at Nesheim, Norway. 13. November 2002
Formation of a meandering channel without initial pertubations. 9. December 2002
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. 2007-2010
Sediment flow in the Angostura Reservoir in Costa Rica. 3. January 2011
Flood wave hitting a construction. 20. March 2003.
Velocity field in river with large roughness (218)
Himalayan headworks/intake (165)
Flow visualization by particle animation (380)
Vortex shedding behind a circular cylinder
Head loss in a gate plug
Density currents in a lock (131)
Compound meandering channel (400)
Embretsfoss Hydropower Reservoir, Norway. 30. May 2000
Flow around a groyne in a channel, 6. June 2000
Modelling vegetation in a laboratory channel
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. 14. November 2009
Modelling water flow in the Sarpfossen reservoir and spillway. 19. May 2010
Radioactive spill in Lake Tyrifjorden, Norway. 2000 (Norwegian only)
Water quality in Lake Mjosa, Norway, during a flood (280) 2 Dec. 1998
Spatial distribution of algae in Loch Leven, Scotland (107)
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 in Lake Sperillen, Norway. 2000