Three-Dimensional Effects on Slamming Loads

Three-dimensional effects on slamming loads predictions of a ship section are investigated numerically using the unsteady incompressible Reynolds-Average Navier-Stokes (RANS) equations and volume of fluid (VOF) method, which are implemented in interDyMFoam solver in open-source library OpenFoam. A convergence and uncertainty study is performed considering different resolutions and constant Courant number (CFL) following the ITTC guidelines. The numerical solutions are validated through comparisons of slamming loads and motions between the CFD simulations and the available experimental values. The total slamming force and slamming pressures on a 2D ship section and the 3D model are compared and discussed. Three-dimensional effects on the sectional force and the pressures are quantified both in transverse and longitudinal directions of the body considering various entry velocities. The non-dimensional pressure coefficient distribution on the 3D model is presented.

Dimensional Effects in Zinc Oxide Nanocomposites as Basis for Design of New Generation Gas Sensors

The possibility of using a nanocomposite based on zinc oxide ultrafine powder and polyvinyl alcohol as a sensitive element of a gas sensor is analyzed. It is shown that zinc oxide nanoparticles with a shape close to a rectangular parallelepiped can be considered as potential wells, separated by layers of polyvinyl alcohol that form potential barriers. The contribution of the tunneling component to nanocomposite current density is estimated for systems with and without oxygen chemisorptions. Results of numerical simulation are shown that a shift of the peaks in the dependence of transmittance on electron energy and a decrease of the tunneling current density are going with an increase in the concentration of oxygen atoms. Perspectives of the use of quantum-dimensional effects in the development of new generation gas sensors, which are based on conductivity modulation during sensor interaction with analyte gases, are demonstrated