Modeling of a Novel Submerged Oscillating Water Column (SOWC) Energy Harvester

Wave energy converters (WEC) are hydraulic structures that are used to harvest energy from oceans. This research explores a new concept of a WEC termed a Submerged Oscillating Water Column (SOWC). Numerical simulations using the Computational Fluid Dynamics (CFD) code Flow-3D and physical model tests were carried out at Idaho State University to assess the validity and efficiency of the proposed device. The SOWC device consists of two submerged chambers that are connected to allow airflow between the two as waves pass; ideally spaced at half a wavelength. The results of the CFD modeling for seventeen different geometries with linear waves were investigated. The model was validated with experimental tests in a flume and the efficiency of the device calculated. The influence of four parameters: water depth, wave height, period and the size of SOWC were investigated. The numerical CFD modeling indicates the ratio of water elevation movement inside the chambers can be up to 80% of wave height. The numerical and physical models indicate that the concept of the SOWC works

Resonance Raman Spectral Calculations of Organic Semiconductor Molecules

Organic semiconductors have received a great deal of attention in recent years due to their optoelectronical properties and their potential applications in industry. In this thesis, resonance Raman calculations of a family of organic semiconductor dyes: pery-lene tetracarboxylic diimides (PTCD) derivatives, are presented. Also the UV/vis, infrared and normal Raman spectra, structures and molecular orbitals, excitation ener- gies, dipole moments, (hyper) polarizabilities and charge population analyses of these molecules are calculated. The calculations in this thesis are performed using a Time- Dependent Density Functional Theory (TDDFT) method, and for that, the Amsterdam Density Functional program package (ADF2009) is used. The molecular properties cal-culated for the molecules in this thesis are then compared with experimental data and the main spectroscopic characteristics are found to be, for the most part, due to the perylene plane and therefore, the same for all of its derivatives

The effect of geometry parameters and flow characteristics on erosion and sedimentation in channels junction using finite volume method

One of the most critical problems in the river engineering field is scouring, sedimentation and morphology of a river bed. In this paper, a finite volume method FORTRAN code is provided and used. The code is able to model the sedimentation. The flow and sediment were modeled at the interception of the two channels. It is applied an experimental model to evaluate the results. Regarding the numerical model, the effects of geometry parameters such as proportion of secondary channel to main channel width and intersection angle and also hydraulic conditionals like secondary to main channel discharge ratio and inlet flow Froude number were studied on bed topographical and flow pattern. The numerical results show that the maximum height of bed increased to 32 percent as the discharge ratio reaches to 51 percent, on average. It is observed that the maximum height of sedimentation decreases by declining in main channel to secondary channel Froude number ratio. On the assessment of the channel width, velocity and final bed height variations have changed by given trend, in all the ratios. Also, increasing in the intersection angle accompanied by decreasing in flow velocity variations along the channel. The pattern of velocity and topographical bed variations are also constant in any studied angles

Effects of Geometry and Hydraulic Characteristics of Shallow Reservoirs on Sediment Entrapment

Sediment and deposition are among the main problems in dam engineering and other related fields. Because of the numerous advantages of numerical modeling, effects of different geometries of reservoirs on the flow pattern and deposition of sediments are investigated using the finite volume based Flow-3D software package. In this study, three rectangular reservoirs with different dimensional ratios are simulated using the large eddy simulation (LES) turbulence model. To validate the numerical modeling, existing experimental data is used. Results indicate that Flow-3D can accurately simulate flow and sediment deposition in the reservoirs, and the numerical data are in reasonable agreement with the experimental results. Numerical efforts showed that the amount of deposition in reservoirs is significantly dependent on the geometry. Among the modeled reservoirs, the 6 × 4 m one has the best performance. Moreover, it can be said that changing the position of the flow’s inlet and outlet of the reservoir does not have a considerable effect on increasing its efficiency

Application of Nanofluids in Thermal Performance Enhancement of Parabolic Trough Solar Collector: State-of-the-Art

The present review paper aims to document the latest developments on the applications of nanofluids as working fluid in parabolic trough collectors (PTCs). The influence of many factors such as nanoparticles and base fluid type as well as volume fraction and size of nanoparticles on the performance of PTCs has been investigated. The reviewed studies were mainly categorized into three different types of experimental, modeling (semi-analytical), and computational fluid dynamics (CFD). The main focus was to evaluate the effect of nanofluids on thermal efficiency, entropy generation, heat transfer coefficient enhancement, as well as pressure drop in PTCs. It was revealed that nanofluids not only enhance (in most of the cases) the thermal efficiency, convection heat transfer coefficient, and exergy efficiency of the system but also can decrease the entropy generation of the system. The only drawback in application of nanofluids in PTCs was found to be pressure drop increase that can be controlled by optimization in nanoparticles volume fraction and mass flow rate