Fatemeh Behrouzi

Electrical Generation Using Renewable Technology for Remote Area: A Review

This paper is a review about process, progress and operation principle of renewable technology using water current as a clean, green and renewable energy to generate electricity for areas especially remote site that access to water but they are poor in electricity.

Hydrodynamic Resistance Reduction of Multi-Purpose Amphibious Vehicle due to Air Bubble Effect

Multipurpose Amphibious Vehicles (MAV) and other blunt shaped floating vehicles encounter the problem of a large bow wave forming and hydrodynamic resistance at high speeds. This wave formation is accompanied by higher resistance and at a critical speed results in bow submerging or swamping. Three new shapes of hull bow design for the multipurpose amphibious vehicle were conducted at several speeds to investigate the hydrodynamic phenomena using Computational Fluid Dynamics (CFD, RANS code), which is applied by Ansys-CFX14.0 and Maxsurf. The vehicle’s hydrodynamic bow shapes were able to break up induced waves and avoid swamping. Comparative results with the vehicle fitted with U-shape, V-shape and Flat-shape of hull bow, showed that the U-shape of the hull bow has reduced the total resistance to 20.3% and 13.6% compared with the V-shape and flat shape respectively. Though, the U-shape of hull bow is capable to increase the amphibious operating life and speed of vehicle. Also it has ability to reduce the vehicle’s required power, fossil fuel consumption and wetted hull surface. On the other hand, the use of air cushions to support marine vehicles, heavy floating structures and in other operation is well known. The main problem in Multi-purpose Amphibious Vehicles (MAV) is the amount of power needed in order to overcome the hydrodynamic resistance acting on the hull which is included the frictional and pressure resistances. Therefore, more power is needed to move the MAV forward. In this respect, more fuel will be required to operate the amphibious vehicles. This problem could be effectively reduced by the introduction of the air cushion concept. With the air being drawn from top of craft to the cavity below the hull will produce some cushioning effect and also help to reduce skin friction drag. In this paper, air cushion effect will be studied in rigid surface cavity instead of using flexible skirts. This would avoid the problem of high maintenance due to replacement of damaged skirts. Finally, the MAV will be supported using air cavity and bubbles generated by an air pump (compressor and air pressure vessel) to pushes the hull of multi-purpose amphibious vehicle up and reduce the frictional resistance due to draft and wetted surface reduction and layer of air between hull surface and water. This research would be done via CFD (ANSYS-CFX 14.0) and analyzed the hydrodynamic resistance

Propeller Effect on 3D Flow at the Stern Hull of a LNG Carrier Using Finite Volume Method

Numerical study and RANS simulations have been applied to investigate the incompressible free surface flow around the stern hull of Liquefied Natural Gas (LNG) ship affected by working propeller behind of her. Experimental works are carried out using LNG ship model in Marine Teknologi Center (MTC) of Univrsiti Teknologi Malaysia (UTM) to verify the computational fluid dynamic (CFD) results. Ansys-CFX 14.0 based on viscous flow finite volume code using the two-phase Eulerian–Eulerian fluid approach and shear stress transport (SST) turbulence model have been used in this study. A tetrahedral unstructured combined with prism grid were used with the viscous flow code for meshing the computational domain of water surface around it. CFD simulation has been verified using available experimental results. Finally, the flow structure, streamlines, velocity and pressure distribution around stern hull and propeller zone are discussed and analysed.

Numerical Prediction of Thermal Effect on Flow Field around a High-Rise Building Model

Recently, CFD (Computational Fluid Dynamics) is being more and more used in the investigation of the flow and thermal around high-rise buildings. In this study, prediction of thermal effect on flow pattern around high-rise buildings model located in the surface boundary layer was carried out using k-e turbulence model. Investigation of thermal effect on flow pattern behind the building and comparison between isothermal and non-isothermal building using standard k-e showed that the surface temperature of building wall led to a strong upward motion close to heating wall and decreased the reattachment length behind it. The model sittings of validation study was accomplished by comparing the simulation of wind flow around building models with the experimental data of Architectural Institute of Japan (AIJ) that results showed in weak wind region, standard k-e has good agreement with experimental.

Prediction of wind flow around high-rise buildings using RANS models

Recently, CFD (Computational Fluid Dynamics) is being increasingly used to investigation of the flow around high-rise buildings. In this study, prediction of wind flow around two cases high-rise buildings model placed within the surface boundary layer were carried out using various turbulence models. The accuracy of two-equation turbulence models were compared with experimental data of Architectural Institute of Japan (AIJ).as a result, all two-equation models are shown overestimation the reattachment length behind the buildings.

Numerical Study on Hydrodynamic Resistance of New Hull Design for Multipurpose Amphibious Vehicle

Multipurpose Amphibious V ehicles ( MAV ) and other blunt-shaped floating vehicles encounter the problem of a large bow wave forming at high speeds. This wave formation is accompanied by higher resistance and at a critical speed results in bow submergence or swamping. Three new shapes of hull bow design for the multipurpose amphibious vehicle were conducted at several speeds to investigate the hydrodynamic phenomena using Computational Fluid Dynamics (CFD, RANS code) which is applied by Ansys-CFX14.0 and Maxsurf. The vehicle’s hydrodynamic bow shapes were able to break up induced waves and avoid swamping. Comparative results with the vehicle fitted with U-shape, V-shape and Flat-shape of hull bow, showed that the U-shape of the hull bow has reduced the total resistance to 20.3% and 13.6% compared with the V-shape and flat shape respectively. Though, the U-shape of hull bow is capable to increase the amphibious operating life and speed of vehicle. Also it has ability to reduce the vehicle’s required power, fossil fuel consumption and wetted hull surface.

Arm Effect on Performance of Vertical Axis Current Turbine Using RANS Simulation

Climate changing, electrical demands, rising diesel fuel prices, as well as fossil fuel-based energy is limited and in fact is depleting ,are subjects to use of renewable technologies. Among the different renewable energy technologies, hydro power generation (large and small scale) is the prime choice in terms of contribution to the worlds electricity generation by using water current turbines.CFD simulation using two equations turbulence model was carried out to compare performance of conventional savonius turnine and new consept of vertical axis turbine. This study was coducted to reach suitable desigh of vertical axis turbines for capturing more kineticenergy of current via of others esspecially,low current speed.

Numerical analysis of three dimensional flow around marine propellers in restricted water

Marine propeller blades have complicated geometries and as a consequence, the flow pattern around these propellers is very complex. The efficiency of the marine propeller is strongly dependent on propeller performance, thrust force and torque of propeller. In channels, canals, harbors and other types of restricted waters, flow inlet to the propellers is asymmetric and non-uniform, therefore hydrodynamic characteristics of the propeller is affected greatly by the presence of lateral restrictions of the navigation area, such as banks, quay walls and bottom. This research has approached the propeller hydrodynamic performance related to study on wake pattern behind of propeller affected by bank via numerical modeling using a finite volume code. Finally, the results of simulation the propellers wake pattern and 3D flow around the propeller, with and without bank are compared. The influence of these parameter changings in the working propeller performance are carefully considered and analyzed.