APPLICATION OF CALCULATION REGION DECOMPOSITION IN SOLVING MAGNETOTELLURIC SOUNDING PROBLEMS

Using numerical experiments, possibilities of application the decomposition method of the calculation region in solving direct problems of the magnetotelluric sounding are considered.

Research on Flow Field and Temperature Field Characteristics of One Rocket Charge with Complicated Structure by Numerical Method

The paper researches flow field and temperature field characteristics of one rocket charge with complicated structure by numerical method. The charge, in which there exist the conduction, convection and radiation, consists of the metal shell, seven propellant columns and air gaps. For the reasons, to solve temperature field of the charge is to solve a complex heat transfer problem in a complicated calculation region. A mathematical and physical model for the flow and heat transfer process in the charge is established and unstructured meshes are applied to disperse the complicated calculation region. The SIMPLE algorithm is used to solve the partial differential equations, and the calculation results are in good agreement with the experimental data. On basis of the numerical simulation, the flow field and temperature field characteristics of the charge are researched and subsequently some valuable conclusions are gotten.

Storage Capacity of Geothermal Resources in Gaoling Group over the Eastern Half of Xi’an Depression

Weighted element method is proposed in this paper to improve the accuracy of calculating storage capacity of geothermal reservoirs. By making full use of all geothermal wells in the calculation region，this method had been proposed by the author in 2011,which is defined by every three neighboring geothermal wells. The calculation region is divided into many calculation elements. As a result, the entire calculation region of the distribution parameters is discretized into independent in each element with lumped parameters. The arithmetic mean of three-node parameters in each element is used as the lumped parameter, and the block with the same set of parameters is divided into calculation regions as small as possible. The effect of one element as well as its parameters in the entire.Calculation region depends on the weight of the area of this element in the whole calculation area. The weighted element method can be used to calculate the volumetric water storage capacity of geothermal fluids, elastic release storage capacity, geothermal storage capacity of volume water, geothermal energy storage capacity of elastic releasing water, geothermal storage capacity of geothermal reservoir rocks for each element, respectively. The storage capacities of various elements and the entire calculation regions can be calculated with superposition. The proposed approach was used to calculate the storage capacity of geothermal resources in Gaoling Formation of Xi’an Depression, in which data of 57 existing geothermal wells were available. If the geothermal energy recovery is set at 10% and the exploitation remains stable, the geothermal energy contained in the geothermal reservoir can be extracted for more than 7,000 years. Under the current conditions of exploitation technology, the actual geothermal energy that can be effectively exploited and used is 1915.6025×109kcal, which is equivalent to standard coal of 27.36575×104t.

Selection of Artificial Boundary Condition on Soil-Structure Dynamic Interaction

Numerical simulation is an important method to study the structural vibration response. And artificial boundary conditions will directly affect the reliability of numerical simulation results. While when we conduct numerical simulation of vibration, it is often assumed the input surface to be a fixed boundary. The purpose of this paper is to make a study on rationality of this method by the use of simulation on a two-dimensional homogeneous elastic half-space model and a soil-structure dynamic interaction model. The results show that: when fixed boundary used, after the wave reflected to the fixed boundary, it couldn’t leave the calculation region and will reflects back into the calculation region again; when viscous boundary used, the energy will be absorbed by the bottom boundary when the wave achieved the viscous boundary. It simulates the real situation that the wave goes through boundary surface into the infinite medium. So, when carrying out numerical simulation on structural dynamic analysis, the selection of fixed boundary is inclined to an incorrect result, while the select of viscous boundary is more accurate and reasonable.

Particle Behaviors Under Acceleration Condition in Solid-Air Two Phase Flow

This paper presents a numerical study of the particle behaviors under acceleration conditions in the solid-air two-phase flow by means of a combined two-dimensional model of computational fluid dynamics and discrete element method (CFD-DEM). The simulation model provides the information regarding the particle distribution behaviors within the calculation region and the particle run-out rate from the calculation region under different parameter conditions, such as particle size, initial particle loading and particle acceleration condition. The results demonstrate that the particle run-out rate is directly influenced by the particle size and the initial loading condition. The particle acceleration in the horizontal direction adversely affects the particle run-out rate when the initial particle loading condition is dispersed and uniform. However, this adverse effect disappears when the initial particle loading condition becomes concentrate and partial.

Overlapping Communication and Computation with OpenMP and MPI

Machines comprised of a distributed collection of shared memory or SMP nodes are becoming common for parallel computing. OpenMP can be combined with MPI on many such machines. Motivations for combing OpenMP and MPI are discussed. While OpenMP is typically used for exploiting loop-level parallelism it can also be used to enable coarse grain parallelism, potentially leading to less overhead. We show how coarse grain OpenMP parallelism can also be used to facilitate overlapping MPI communication and computation for stencil-based grid programs such as a program performing Gauss-Seidel iteration with red-black ordering. Spatial subdivision or domain decomposition is used to assign a portion of the grid to each thread. One thread is assigned a null calculation region so it was free to perform communication. Example calculations were run on an IBM SP using both the Kuck & Associates and IBM compilers.