Papers by Keyword: Moving Boundary

Abstract: A non-stationary mathematical model of desublimation UF₆ in vertical tanks considers the movement of gaseous uranium hexafluoride contains in the article. Results of calculation of time dependence of the linear velocity desublimation, the thickness of the resulting layer of the solid phase, the temperature distribution in the tank wall - desublimation layer, filling dynamics of vertical tank B-12 by solid UF₆ are presented. Calculations have shown that the 70% of B-12 tank is filled desublimation UF₆ by 250 hours, which is in good agreement with the experimental data

Abstract: Organic Rankine Cycle (ORC) is one of the most promising technologies for low-temperature energy conversion. In recent years, it has gotten more attention due to the energy crisis and environmental problems caused by the combustion of fossil fuels. In this paper, a moving boundary model is introduced to describe the transient phenomena of evaporator and condenser, which are the important components of ORC. The simulation results are given to illustrate the efficiency and feasibility of the proposed control strategy.

Abstract: The melting of the material is regarded as the moving boundary problem of the heat conduction equation. In this paper, the method of fundamental solution is extended into this kind of problem. The temperature function was expressed as a linear combination of fundamental solutions which satisfied the governing equation and the initial condition. The coefficients were gained by use of boundary condition. When the metal wire was melting, process of the moving boundary was gained through the conversation of energy and the Prediction-Correlation Method. A example was given. The numerical solutions agree well with the exact solutions. In another example, numerical solutions of the temperature distribution of the metal wire were obtained while one end was heated and melting.

Abstract: With the rapid development of social economy background, the large scale talents flow in the international and domestic have become important social phenomenon. At home and abroad, the research on talents mobility and human resources management is more and more in-depth. Through the optimal analysis of talent flow model, the flexible management applications in the flexible human resources management, to scientific analyze the coupling relationship between them that will provide human resources management talent optimize configuration, it will make positive contributions to achieve maximize the benefits.

Abstract: Dimensionless mathematical models of the fluid flow in the semi-infinite long porous media with constant production pressure on the inner boundary conditions are built, which include the effect of threshold pressure gradient (TPG). The analytical solutions of these dimensionless mathematical models are derived through new definitions of dimensionless variables. Comparison curves of the dimensionless moving boundary under different values of dimensionless TPG are plotted from the proposed analytical solutions. For the case of constant production pressure, a maximum moving boundary exists, beyond which the fluid flow will not occur. The value of maximum boundary distance decreases with increasing TPG. However, the velocity of pressure propagation decreases with time. The larger the TPG is, the steeper the curve of pressure depression cone is and the shorter the distance of the pressure propagation is.

Abstract: The paper establishes dimensionless mathematical models of the fluid flow in semi-infinite porous media with constant flow rate. Exact analytical solutions of these dimensionless mathematical models are derived by new definitions of dimensionless variables and Laplace transformation. Comparison curves of dimensionless moving boundary under different values of dimensionless Threshold Pressure Gradient (TPG) are plotted from newly proposed exact analytical solutions. An example is used to demonstrate pressure distribution in different positions with different TPG. It is shown that for the constant flow rate condition, the moving boundary extends to infinite in porous media with increasing production time. Steeper pressure curve is observed in larger TPG, which also exhibits greater pressure drop gradient and shorter pressure propagation distance at the same production time.

Abstract: Based on three-dimensional hydrodynamic model, moving boundary technique and embedded pollutant transport model, the concentration field of the soluble and conservative liquid chemicals spilled into the tidal river was calculated and the chemicals movement around a jetty at DA Liaohe was simulated. By analyzing the simulation results, the chemicals motion law with tide and their concentration field on and in water were deduced.

Abstract: A novel study of the simulations of the flow-induced noise from the moving boundary objects using the hybrid immersed boundary lattice-Boltzmann method (IB-LBM), which is the modern useful numerical method of fluid mechanics, on the Ffowcs Williams-Hawkings (FW-H) equation is carried out. The permeable surface FW-H method has been demonstrated an effective technique of the far-field noise predication, because of its complete theories and successful applications in aeroacoustics. It usually need the information of the field near sound source. Therefore, we also adopt the effective and widely used IB-LBM to treat the interaction of the moving boundaries and the fluid, in order to simulate the near-field accurately. Some simulations are shown to test the hybrid method, including the rotational cylinder. The results prove that the hybrid IB-LBM/FW-H method can simulate the large field problems of the flow-induced noise effectively and accurately.

Abstract: Traditional boundary force method of SPH applies Lennard-Jones equation to compute the virtual repulsive force by calculation of molecular force. But this method is strongly non-linear and easily leads to not convergence in calculation. In this paper, spring-damping boundary force model is utilized to solve the problem of moving boundary. Using spring-damping boundary force model, rotary moving boundary of screw channel-driven has been simulated and the result is well consistent with the simulation of Fluent. Comparing with traditional boundary force equation, this model is long-term stable and its effectiveness has been validated by case study.

Abstract: A method for nearly orthogonal grid generation is presented in this study. The generating system is based on solution of a system of partial differential equations with finite difference discretization. The influence of the number of grid points, type of boundary, and intensity of the grid quality control function and grid properties are investigated. Specification of both boundary point distribution on all sides and moving boundaries is used. The proposed method is applied to various test problems£¬which shows this method provides a good balance between controlling grid orthogonality and cell aspect ratio.