Hydraulics CFD Validations & Studies
- Sump Intake Design
- Batch Sedimentation
- Fishway Optimization
- Waterways Experiment Station (WES) Spillway
- Rough Ramps & Slides
- Hydrodynamic Screws
- Grit Chamber Modeling
- Spillway & Stilling Basin Design
Vortex formation with FLOW-3D
One of the most critical aspects of sump pump design is to ensure its unhindered performance. A good design requires knowledge of the level of submergence of the pump’s suction pipe necessary to prevent the formation of vortices (submerged or free surface) near the pipe. Over the years, studies have been conducted to find out the critical submergence levels of suction pipes. FLOW-3D can predict the conditions under which there would be probable formation of vortices and to evaluate the efficiency of preventive measures to prevent them. Read the full validation: Pump Performance at Sump Intakes.
Batch Sedimentation: CFD Validation
Batch sedimentation consisting of solid particles settling out in a column of liquid is an example of a two-phase flow that can be well simulated using the drift-flux model in FLOW-3D. In the example shown here the column is 0.5m high and is filled with water. At the beginning of the flow a packed bed of solid glass spheres of diameter 0.008m (8mm) extends from a height of 0.32m above the bottom of the column to 0.42m. The initial volume fraction of the packed spheres is 0.6, their density is 2.6kg/m3.
Read the full validation: Batch Sedimentation: A Two-phase Flow Validation Example
Image courtesy Tecsult, Inc.
Contributed by Jean-François Mercier, eng., Tecsult Inc., Montreal, Qc, Canada
A fishway was built in 2005-2006 by SEBJ on the Eastmain River in James Bay, Quebec, Canada. Follow-up studies conducted in 2006 and 2007 showed no successful use of the fishway by sturgeon, while other species of fish climbed the ladder.
Two problems were identified: the low attraction of fish to the fishway and high water velocities.
Read the full case study: Eastmain-1 Fishway Optimization: A Numerical Modeling Study
An experimental validation shows a close match between simulation and reality
Many existing spillway structures are under-sized to cope with the amended probable maximum flood levels. Formation of lifting pressure and cavitations over spillway crest under flood condition can be encountered. Early dam structures were designed with limited hydrological information. The US Army Corps of Engineering scaled physical models which were expensive and time consuming.
View the full validation: Examination of A Standard Waterways Experiment Station (WES) Spillway Under Various Flood Conditions
Simulating rough ramps and slides with FLOW-3D
To analyze the effects of boulders on the water surface levels and flow velocities, as well as the resistant coefficients of the boulders a physical model was built at the University of Wuppertal’s Hydraulic Laboratory. State-of-the-art measurement techniques were used to give information about flow characteristics and forces on the boulders. The physical model allowed variations of boulder arrangements and discharges. All model runs were compared with 3-D simulations using FLOW-3D.
Read the full study: Physical and numerical modeling of rough ramps and slides
Reducing hydrodynamic noise with FLOW-3D
In addition to the laboratory tests, several very complex simulations were carried out with FLOW-3D. The three-dimensional modeling of rotating geometries placed huge demands on both FLOW-3D and the hardware used. The General Moving Objects (GMO) model enables the user to compute complex moving or rotating geometry like turbines or screws without adaption of the mesh and therefore without changes in the memory allocation. The GMO model was necessary to compute the fluid/solid interaction, and FLOW-3D’sTruVOF™ algorithm was vital for calculating the water surface elevations.
Read the full study: Reducing noise in hydrodynamic screws
Modeling grit chambers with FLOW-3D
Computational fluid dynamics simulations of the flow going into the aerated grit tank were prepared using FLOW-3D. It was observed that for higher pumping rates (Q ≥ 225 mgd) the flow in the distribution system became unsymmetrical with relatively lower velocities on the southern side of the distribution system (where the 6th grit tank is located). Because a lower velocity of water entering the grit chamber produces higher grit deposition, the results gives an initial idea about the origin of the problem. A continuous input of suspended sediment at the chamber inlet tunnel is being investigated with the help of FLOW-3D for different pumping rates and the results show that asymmetry in the sediment diverted to chamber 6 is more pronounced as flow discharge increases.
Read the full study: Modeling of flow into the aerated grit chamber of a water reclamation plant
Sliced view of simulated flow velocity for chute
basin option 2 - 15ft wide basin at Q = 1133 cfs with
tailwater. Elev. 5292 ft.
Computational fluid dynamics modeling was conducted by applying FLOW-3D to assist the design of spillway rehabilitation as well as the stilling basin for the lower outlet for a dam in the mid-west of USA. The purpose of the project was to evaluate various new spillway and outlet alternatives to meet updated hydrology requirements.
Read the full study: CFD Assisted Spillway and Stilling Basin Design