A UV reactor consists of a reaction vessel containing a number of UV lamps. The UV lamps are protected against the water by quartz sleeves surrounding them. Water enters the reactor and flows around the quartz sleeves. Pathogens present in the water will travel with the water flow through the reactor and will be irradiated by the UV light. The UV intensity, also called fluence rate, depends on the relative position of the particle and the lamp. Inactivation of pathogens is directly related to the total UV dose (i.e., UV intensity multiplied by contact
time) received by the microorganisms.
To calculate the UV dose received by particles or pathogens, their trajectories through the reactor and residence time distribution have to be known, as well as the distribution of the UV light intensity inside the reactor. However, both processes are characterized by complexity and high variability of the operative conditions; hence, the use of a proper simulation tool allows better controlling of processes, and can be exploited for achieving both technical and economical optimization (Georgi Kalitzin et al. 2005).
This paper shows a step forward in the development of a stabilized method for solving the Reynolds equations (RANSE) including free surface effects. The starting point of this method is the modified governing differential equations for an incompressible turbulent viscous flow and the free surface condition, incorporating necessary stabilization terms via a Finite Increment Calculus (FIC) procedure. Time integration scheme of the method is based on an implicit monolithic second order method. Implementation of the algorithm, based on the Finite Element Method (FEM) using unstructured grids of linear tetrahedra, allows us to take into account dynamic sinkage and trim. This paper also presents a validation study of numerical results obtained for America’s Cup boats.
This paper presents a step forward in the formulation for incompressible fluid flow analysis using the Finite Element Method (FEM) for naval hydrodynamics problems. The necessary stabilization of convective character and incompressibility restriction are introduced via the finite increment calculus (FIC) technique. A second order implicit monolithic method, based on projection schemes, to solve Navier Stokes equations is also presented. The fluid flow equations are written in an Arbitrary Lagrangian Eulerian way, useful to treat fluid-structure interaction problems, both using the standard ALE approach or the fully Lagrangian one. Finally, some examples of application of this formulation in practical naval problems are presented.
A stabilized semi-implicit fractional step algorithm based on the finite element method for solving ship wave problems using unstructured meshes is presented. The stabilized governing equations for the viscous incompressible fluid and the free surface are derived at a differential level via a finite calculus procedure. This allows us to obtain a stabilized numerical solution scheme. Some particular aspects of the problem solution, such as the mesh updating procedure and the transom stern treatment, are presented. Examples of the efficiency of the semi-implicit algorithm for the analysis of ship hydrodynamics problems are presented.
We present a general formulation for incompressible fluid flow analysis using the finite element method. The necessary stabilization for dealing with convective effects and the incompressibility condition are introduced via the Finite Calculus method using a matrix form of the stabilization parameters. This allows to model a wide range of fluid flow problems for low and high Reynolds numbers flows without introducing a turbulence model. Examples of application to the analysis of incompressible flows with moderate and large Reynolds numbers are presented.
