MODELING THE ANTENNA INPUT IMPEDANCE BY THE METHOD OF MOMENTS

The paper presents a comparison of excitation source models when modeling antennas by the method of moments. By using a set of adjacent edges when specifying the impact, it is possible to obtain correct results when the computational grid of the antenna model is more frequent. This is shown on the example of a symmetric electric vibrator.

MODEL- AND FULL-SCALE RANS SIMULATIONS FOR A DRIFT TANKER

The flow around a full-scale (FS) ship can be simulated by means of Reynolds-Averaged Naiver-Stokes (RANS) method, which provides a way to obtain more knowledge about scale effects on ship hydrodynamics. In this work, the viscous flow around a static drift tanker in full scale is simulated by using the RANS solver based on the open source platform OpenFOAM. The k - w SST model is employed to approximate the eddy viscosity. To reduce computational time, wall function approach is applied for the FS simulation. The flow around the ship in model scale is simulated as well, but without using any wall function, i.e., using Low-Reynolds number mode. In order to verify the computations, de- tailed studies on the computational grid including investigation of the sensitivity of computed forces to y+ (dimension- less distance of first grid point to wall) and grid dependency study are carried out. The computed forces are compared with available measured data. The scale effects are analysed and discussed by comparisons.

PARAMETRIZATION OF THE HEAT AND MASS EXCHANGE PROCESS IN THE SURFACE ATMOSPHERIC LAYER

When constructing numerical models of the atmosphere and the surface atmospheric layer (PAS) interacting with it, the “parametrization” approach is used, that is, the representation of processes with scales smaller than the scale of the cells of the computational grid intended for modeling processes of larger scales.

Comparison of JET-C DD neutron rates independently predicted by the ASCOTand TRANSP Monte Carlo heating codes

Simulations of the DD neutron rates predicted by the ASCOT and TRANSP Monte Carlo heating codes for a diverse set of JET-C (JET with carbon plasma facing components) plasmas are compared. A previous study [1] of this data set using TRANSP found that the predicted neutron rates systematically exceeded the measured ones by factors ranging between 1 and 2. No single explanation for the discrepancies was found at the time despite a large number of candidates, including anomalous fast ion loss mechanisms, having been examined. The results shed doubt on our ability to correctly predict neutron rates also in the Deuterium-Tritium plasmas expected in the JET D-T campaign (DTE2). For the study presented here the calculations are independently repeated using ASCOT with different equilibria and independent mapping of the profiles of temperature and density to the computational grid. Significant differences are observed between the results from the investigations with smaller systematic differences between neutron rates measurements and predictions for the ones using ASCOT. These are traced back not to intrinsic differences between the ASCOT and TRANSP codes, but to the differences in profiles and equilibria used. These results suggest that the discrepancies reported in ref[1] do not require invoking any unidentified plasma processes responsible for the discrepancies and highlight the sensitivity of such calculations to the plasma equilibrium and the necessity of a careful mapping of the profiles of the ion and electron densities and temperatures.

Reconstruction of the 2002 tsunami at Stromboli using the Non-Hydrostatic WAVE model (NHWAVE)

In December 2002, two landslides along the Sciada del Fuoco at Stromboli triggered large tsunami waves that caused significant damage on the coast of the island up to an elevation of about 10 m above sea level. In this work, we report in detail the items and the methods used to reconstruct the 2002 tsunami at Stromboli highlighting their strengths and limits. In particular, we describe: i) the Non-Hydrostatic WAVE (NHWAVE) model used to simulate the triggering landslide, the wave propagation and the inundation/runup on the land; ii) the data and methods used to generate the topo-bathymetric computational grid; iii) the field data acquired on Stromboli after the 2002 tsunami used as ground truth for checking the simulation outputs. Our results show that the most severe damages on the coast of Stromboli could have been caused by the interaction of successive waves triggered by the same landslide. In addition, we also describe the influence that the bathymetry had on the waves propagation and interaction.

MODELING OF THE HYDRODYNAMIC REGIME OF THE VOEVOD BAY

С помощью модели Delft3D Flow выполнено численное моделирование гидродинамического режима бухты Воевода (о. Русский, залив Петра Великого, Японское море). Русловой и распределенный приток с примыкающих к акватории бухты территорий смоделирован с помощью гидрологической модели SWAT. Результаты моделирования для каждой ячейки расчетной сетки и каждого расчетного σ-слоя представлены в виде временных рядов солености и горизонтальных компонент скорости течения, на их основании построены пространственные распределения обеспеченных значений скорости течения и солености. Delft3D Flow model was applied to simulation of the hydrodynamic regime of Voevoda Bay (south Primorye, Russki Island, Peter the Great Bay, Russia). The streamflow and distributed inflow from the territories adjacent to the bay is modeled using the SWAT hydrological model. The simulation results for each the computational grid cell and each calculated σ-layer are presented in the form of time series of salinity and horizontal components of the current velocity; on their basis, the spatial distributions of the probability of exceedance for salinity and current velocity are constructed.