Papers by Keyword: Finite Difference Method (FDM)

Abstract: Some research on the wave propagation in random medium with Von Karman correlation has been developed in this paper. It focuses on the seismic record of circular disturbance in random medium with Von Karman autocorrelation function. Six different kinds of random medium become the background of the dielectric object. The study of the impact to the responds of the dielectric objects can be measured by applying the FDTD to random background medium model. The numerical results show that the random media make the most obvious effect when the scale of imhomogeneity is close to the wave length.

Abstract: Considering the influence of different-shaped pans on space utilization and heat distribution, two models are established to investigate a balanced solution. In order to handle the problem of heat distribution on the outer edge, the first model establishes differential equations of heat convection in unstable state and gets definite conditions. Then we discretize the area of pans and get numerical solution by finite difference method. Having analyzed the numerical solution, our model finally concludes that the temperature field of a regular polygon can be regarded as a series of circles centering at its circumcenter and the temperature increases with the increment of the radius. As for the second model, we first calculate the maximum value of pans N in the oven by the arrangements of aligned and staggered modes. Then we normalize N by min-max method. Next, based on the rule of temperature field in the first model, the uniformity of heat distribution can be measured by the area ratio of a regular polygon to its circumcircle. After that, we use the linear weighted method to transfer the problem of multi-objective optimization into a single-objective one and draw the conclusions below: In aligned arrangement, we select round pans when p<0.3, rectangular pans when and pans in regular octagons when . In staggered arrangement, we select round pans when the value of p is small and pans in regular hexagons when the value of p is large. Eventually, through sensitivity analysis , our model proves to be stable and applicable.

Abstract: Based on the shallow water wave potential flow theory and slender ship assumption, the mathematical model is established for calculating wave caused by ship moving at supercritical speed. The wave pattern caused by ship moving at supercritical speed in shallow water was calculated by using the finite difference method. The effects of channel wall were analyzed. The computed results were compared with the ones calculated by Fourier integral transform method and experiment. A good agreement exists between the calculated with experimental results. The mathematical model and the calculation method were validated.

Abstract: Thermal transport process in copper film was numerically simulated with Two-Temperature Model, in which finite difference method was used, and the result shown the temperature change process in electron-lattice system. Some parameters were changed to carry on further simulation. The affect of film thickness on the electronic relaxation time was analyzed. The affect of pump laser beam power on the electron temperature rise was discussed. The influence of electron-lattice coupling factor G on non-equilibrium thermal process was shown in simulations.

Abstract: Rolling force is critical to realize the industrialized production of the rolled mg alloy sheets especially more than 1500 mm width which affects the mill set-up schedule, the thickness of the rolled metal, and the final product profile. An online calculation model of rolling force with high precision and high speed has also been developed with the finite difference method (FDM) in this paper which can provides a good guidance for the enhancement of product precision and the development of new products.

Abstract: In this paper, we study the finite difference solutions for two new models of phase transitions driven by configurational force. These models are recently proposed by Alber and Zhu in [2]. The first model describes the diffusionless phase transitions of solid materials, e.g., Steel. The second model describes phase transitions due to interface motion by interface diffusion, e.g., Sintering. We consider both the order-parameter-conserved case and the non-conserved one, under suitable assumptions. Also we compare the results of these two models with the corresponding ones for the Allen-Cahn and Cahn-Hilliard equations. Finally, some results about tending to zero are given.

Abstract: In this article, a model which was used to measure wood moisture content(MC) was presented. It was founded under non-uniform and asymmetric conditions and there was no any need for wood shape. It can work out the relationship between capacitance value( ) and dielectric constant( ). Compared with previous methods, it not only can greatly lessened measuring work, but also avoided the waste of media resources, such as wood. At the same time, a new kind of numerical method was given for this problem. The number of unknown variables significantly are reduced by doing this.

Abstract: Liquid sloshing inside a partially filled rectangular tank has been investigated. The fluid is assumed to be water and the tank is forced to move along x axis to simulate the actual tank excitation. The volume of fluid technique is used to track the free surface and the model solves Navier_Stokes equations by the use of the finite difference estimation. At each time step, a donar-acceptor method is used to transport the volume of fluid function and locations of the free surface. In this paper the location and transport of the free surface in the tank have been investigated using a CFD code (FLUENT) for 3D configuration. The use of a numerical tool has resulted in a detailed investigation of these characteristics, which have not been available in the literature previously.

Abstract: In order to compare the thermal sensitivity of several typical explosives, this article solved numerically one-dimensional transient heat conduction equation including thermal decomposition for explosives with finite difference method. The explicit difference equations under different boundary conditions were established, and the corresponding stability criterion was derived. The ignition times for typical explosives were calculated, which was used to evaluate thermal sensitivity of explosives.

Abstract: Thermal stress simulation is an important part in the numerical simulation of casting process. It provides engineers with insights into the evolution of displacement, strain and stress of castings in the solidification process. With thermal stress simulation, some defects of casting, i.e. hot tearing, cold cracking and large deformation can be predicted and the engineers are instructed to optimize and improve the casting process. Based on the finite difference method (FDM), this paper presents an integrated numerical method to simulate the thermal stress and deformation of casting in the solidification process. Practical examples show that the method is capable to predict stress distribution and deformation as well as the defects in the experiment.