CFD analysis of the flow in an agitation bath with jets

A vessel in which particulate-laden water circulates requires stirring. The chosen solution is a passive system using the process water circulation. The incoming flow is directed in the form of lateral jets which make it possible to sweep the particles which sediment at the bottom of the tank. It is proposed here, using the numerical simulation tool in CFD Computational Fluid Dynamics to:

• Check the homogeneity of the flows in the side jets along the inlet pipe
• Check the quality of the agitation

Boundary conditions

• Input flow rate
• Pressure Output Condition

Simulation results

The flow rates through the jets along the inlet pipe are well balanced. The compromise between the pressure drop caused by the orifices of the jets and the pressure losses in the collecting pipe is clearly to the advantage of the first. The quality of the mixture can be assessed by following the development of the jets and the current lines.

The analysis of the “age of water” profiles also makes it possible to characterize the quality of the mixture. This gives the residence time of the fluid particle in the computational domain. This gives a direct indication of the rapidity of the renewal of the fluid at any point of the model.

We also propose the visualization of an isosurface. This represents a surface which is none other than the set of points for which a given quantity, here speed, has an identical value. On one side of this surface, the speeds are higher, and on the other hand, the speeds are lower. This type of rendering materializes in particular the jet (seen here with the value of 2 m / s chosen) or the zone swept by a fluid velocity defined as the sedimentation / transport limiting speed.