Investigation of the characteristics of complex diffractive structures based on a combined approach

The paper is devoted to the study of electrodynamic structures, which include metal and dielectric elements. Simple elements are calculated using the method of integral equations. Their solution is determined by the collocation method and scattered electromagnetic fields. The finitedifference method is required for calculating the equation. For required scattering characteristics of complex electrodynamic structures the choice of diffraction elements is carried out within the framework of a multialternative optimization approach. The individual electrodynamic components are considered first. Then, on their basis, several promising variants of more complex subsystems are formed. It is necessary to apply training information on every stage of modeling. The example of the investigated electrodynamic structure is given. The definition of its characteristics is demonstrated.

Simulation of Surfactant Oil Recovery Processes and the Role of Phase Behaviour Parameters

Chemical Enhanced Oil Recovery (cEOR) processes comprise a number of techniques whichmodify the rock/fluid properties in order to mobilize the remaining oil. Among these, surfactantflooding is one of the most used and well-known processes; it is mainly used to decrease the interfacialenergy between the phases and thus lowering the residual oil saturation. A novel two-dimensionalflooding simulator is presented for a four-component (water, petroleum, surfactant, salt), two-phase(aqueous, oleous) model in porous media. The system is then solved using a second-order finitedifference method with the IMPEC (IMplicit Pressure and Explicit Concentration) scheme. The oilrecovery efficiency evidenced a strong dependency on the chemical component properties and itsphase behaviour. In order to accurately model the latter, the simulator uses and improves a simplifiedternary diagram, introducing the dependence of the partition coefficient on the salt concentration.Results showed that the surfactant partitioning between the phases is the most important parameterduring the EOR process. Moreover, the presence of salt affects this partitioning coefficient, modifyingconsiderably the sweeping efficiency. Therefore, the control of the salinity in the injection water isdeemed fundamental for the success of EOR operations with surfactants.

Control of Groundwater Remediation Process as Distributed Parameter System

Pollution of groundwater requires the implementation of appropriate solutions which can be deployed for several years. The case of local groundwater contamination and its subsequent spread may result in contamination of drinking water sources or other disasters. This publication aims to design and demonstrate control of pumping wells for a model task of groundwater remediation. The task consists of appropriately spaced soil with input parameters, pumping wells and control system. Model of controlled system is made in the program MODFLOW using the finitedifference method as distributed parameter system. Control problem is solved by DPS Blockset for MATLAB & Simulink.

MHD Mixed Convection of Viscoelastic Fluid Over a Stretching Sheet with Ohmic Dissipation

A magnetic hydrodynamic (MHD) mixed convection of an incompressible viscoelastic fluid over a stretching sheet with ohmic dissipation is studied. The buoyant effect and the electric number E1 couple with magnetic parameter M to represent the dominance of the ohmic effect are presented in governing equations which is the main contribution by this study. The similarity transformation, the finitedifference method have been used to analyze the present problem. The numerical solutions of the flow velocity distributions, temperature profiles and the important wall unknown values of f″(0) and θ′(0) are carried out.