A moving least square immersed boundary method for SPH with thin-walled structures

This paper presents a novel method for smoothed particle hydrodynamics (SPH) with thin-walled structures. Inspired by the direct forcing immersed boundary method, this method employs a moving least square method to guarantee the smoothness of velocity near the structure surface. It simplifies thin-walled structure simulations by eliminating the need for multiple layers of boundary particles, and improves computational accuracy and stability in three-dimensional scenarios. Supportive three-dimensional numerical results are provided, including the impulsively started plate and the flow past a cylinder. Results of the impulsively started test demonstrate that the proposed method obtains smooth velocity and pressure in the, as well as a good match to the references results of the vortex wake development. In addition, results of the flow past cylinder test show that the proposed method avoids mutual interference on both side of the boundary, remains stable for three-dimensional simulations while accurately calculating the forces acting on structure.Comment: 15 pages,11 figure

A Comprehensive Study and Optimization of Solar and TEG based Power Systems for Outer Space Applications

The ongoing increase in the usage of non-renewable energy sources to meet the world demands has caused a massive increase in world pollution, leading to various issues such as global warming and climate change. This has motivated researchers and engineers to undertake intensive research into renewable energy sources which are clean, noise free and can be used in the long term. This thesis introduces design concepts that are aimed to aid designers in optimizing the design of renewable energy power source systems. The PV and TEG have been selected as the key examples to be studied. First, the thermodynamic modelling of the PV/TEG system and its application to outer space systems is examined where the output energy of the PV/TEG can be determined. Moreover, the model is also used as a basis for a genetic algorithm based optimization of the PV/TEG system in terms of maximizing power generation and minimizing mass. The next aspect that is covered in this thesis is the design of the associated DC/DC converter which is important for controlling or maximizing the energy that is acquired from the renewable energy source. Specifically, this thesis introduces an improved method of deriving the transfer functions that relate the inputs to the states of the DC-DC converter. Finally, two novel maximum power point tracking algorithms (MPPT) are introduced and applied to maximize the power extracted from the solar panel and the thermoelectric generator (TEG). These algorithms are known as the “Lock-On Mechanism” and a modified fuzzy logic control based MPPT algorithm. The novel MPPT algorithms are shown to track the MPP quicker and more accurately than that of conventional and previously proposed counterparts

A Parametric Study and Optimization of an Air Conditioning System for a Heat-Loaded Room

Optimization of an air conditioning system is critical in terms of the transient and steady state behavior of the air distribution along the room and the temperature of the equipment themselves. In this paper, three computational techniques, namely, the standard k-ε, RNG k-ε, and the k-ω model, are used to numerically simulate and determine the air distribution in an air-conditioned room. The simulation results for all three methods are verified via a comparison with an experiment involving a room that contains a computer server which generates up to 6 kW of heat. In doing so and by additionally performing an error analysis, it is determined that the k-ω model produces the most accurate results. The results also indicated that the direction of air supply from the air conditioners has a strong impact on the velocity field and temperature distribution along the room and on the computer server. Hence, many candidate directions of air supply options were selected for study and by conducting a performance evaluation in terms of air temperature around the server, the optimal solution was obtained

Transient Antiseepage Analysis of the Relief Well in Beijiang Dike

In this paper, the seepage finite element method (FEM) is used to simulate the transient seepage of Beijiang Dike, and antiseepage solutions are designed and discussed. By comparing the measured data of a piezometer with the steady-state calculation model, the calculated results are compatible very well with the measured data. Aiming to improve the ability to respond in extreme weather conditions, we calculate the transient seepage field after the water level suddenly rises in a short time and then select the relief well as the antiseepage measure and optimize it. The results show that when the water level is 15.78 m, the slope reaches 0.5, and the embankment is damaged. With the increase of penetration depth, the effect of drainage and decompression in the depth of 3/5 and 4/5 is relatively small due to geological strips. Due to different geological conditions, the same relief wells are placed in different positions with a wide gap in effect, the antiseepage effect is the best when the horizontal distance is 95 m, and the effect is the best when the depth is 16.5 m. The research results can be used to guide the seepage prevention and control design of Beijiang Dike

Feasibility research on a hybrid solar tower system using steam and molten salt as heat transfer fluid

As a high solar concentration technology, the solar tower power (STP) system is an appealing approach to generate high-grade thermal energy and achieve high thermal-to-electric efficiency. In this study, the authors notice the solar flux distribution characteristic of the central receiver and combine the advantages of lower average operation temperature of the direct steam generation (DSG) loop and higher efficiency of the molten salt (MS) loop. A hybrid solar tower system that involves steam and MS as the heat transfer fluids is proposed for improving the thermal efficiency of STP systems. The receiver of the hybrid system is divided into two sections, which are respectively designed for the MS and DSG loop, namely MS-DSG system. By comparing the DSG-MS system to the traditional system, the DSG-MS system demonstrates significant heat loss reduction of 31.8 GWh in Lhasa and 34.5 GWh in Tonopah, and the corresponding electricity outputs are improved by 6.22% and 5.82% with a MS receiver panel number of 8. The steam outlet quality of the DSG loop is insensitive to the overall performance of the systems. It is indicated that the steam quality can be adjusted for ensuring two-phase heat transfer stability and safe operation of the receiver. Moreover, the hybrid system also gives a flexible adjustment of thermal energy storage capacity by optimizing receiver panel number for different heat transfer fluid loop