Simulation of Hydraulic Elevations and free Surface Effects

Water surface analysis is essential to understand the operation in water and wastewater treatment plants, open channels and large hydraulic structures in general. With the use of advanced CFD techniques it is possible to study in real time hydraulic water elevations in different basins or to detect undesired water surface vortices caused by the convective flow or by mixers that are located to close to the water surface.

“Volume of Fluid” (VOF) is a CFD modelling technique to simulate free surfaces and belongs to the Eulerian multiphase methods. Using high performance computational resources, and having the required know-how to model the physics of the problem correctly, very realistic and accurate results can be achieved.

The next two images show a hydraulic structure filled with water. The water elevation, the distribution into different tanks and head loses can be analyzed in real time.

Figure 1: Water elevation and distribution in a hydraulic structure

Figure 2: Water elevation and distribution in a hydraulic structure, top view

Coarse bubble aerators, are able to induce in reactors both aeration (mass transfer) and stirring due to buoyancy forces. In order to numerically analyze such cases also a VOF modeling is used.

Figure 3: Coarse bubble aeration

Figure 4: Coarse bubble aeration

Moreover, the “Volume of Fluid” technique is mostly suitable to study water surface effects such as the formation of vortex structures that can produce air intake from the water surface.

 

Figure 5: Central vortex in the water surface in a stirred tank

To solve hydraulic problems or analyze water elevations in open structures and channels or study water surface effects, THINK Fluid Dynamix has the tools, the people and the experience to help our clients to achieve their goals.