This work concerns to the digital treatment of the problems with strong not linearities during the resolution of the equations of Navier-Stokes in particular those due to the recirculation strong in turbulent regime. The idea developed is to use the method of subdomains: The domain in which took place the flow is decomposed several subdomains separated by imaginary boundary. In each of these subdomains, we use the best adapted digital method. The passage in all the domain is made by digital connecting. This connecting is made by covering of domain. The results are presented in the case of a jet of rejection emitted by the bottom in a rectangular canal. In this application, we divided the domain of study into two parts: Near the boundary layer, we use the finished difference method and in the outside zone the resolution is made by the method Particular. The fictitious interface between these two subdomains is processed by the method particles - meshing. A validation of this approach is made by a comparison with a direct calculation in all the domain.

The object of this work is to test two applications: Artificial destratification and Selective Racking to fight the eutrophication of lake. For this we consider a jet described by the equations of Navier stocks whose resolution is based on the finite difference method. For the first treatment (artificial Destratification), the idea is to consider a rectangular area filled with water, and start the jet from the bottom to the surface. For the second treatment (selective Racking), it considers another rectangular field full of water, but the jet will now be on the left lateral border into the hole located in the right side border.