Burton-Miller method, a complex linear combination of conventional boundary element method (CBIE) and hypersinglar boundary element method (HBIE), is widely used to deal with exterior acoustic problems. The difficult in implementing Burton-Miller method is computing strongly singular integrals (2D problems). Although, many weakly singular/regularization methods have been presented to evaluate these integrals, these methods are still difficult or extremely time consuming. In this paper, analytical integration of strongly singular boundary integral equations discretized with constant element for 2D Helmholtz problems is presented. All singular and strongly singular integrals are analytically evaluated in finite part sense as constant elements are applied to discretize boundary. Contour integral is used for singular and strongly integrals. Validity of formulas is demonstrated with numerical examples.

An isogeometric analysis based on a kind of local bivariate B-spline function and Burton-Miller method is introduced in boundary element method (BEM) for 3D Helmholtz problems.The method avoid efficiently computation of singular and nearly singular integrals aroud singular point of parametric surface.Numerical examples show that the algorithm has good performance in accuracy, efficiency and convergence.The algorithm performs isogeometric BEM (IBEM) with traditional global B-spline shape functions on CPU time and accuracy.The method has potential in engineering applications.

Large eddy simulation (LES) with 1.12×108 meshes was performed on three-dimensional jet in cross-flow(JICF) using lattice Boltzmann method (LBM) and multiple Graphic Processing Units (Multi-GPUs). Reynolds number based on free-stream velocity and jet diameter is 4 000, streamwise inclination angle of jet is α=30°, and jet-to-cross-flow velocity ratio is set as 0.5. Validity and feasibility of LBM-LES on simulating jet in cross-flow were verified by reasonable qualitative and quantitative results. Fine coherent structures were captured by large-scaled simulation which benefits study on mixing mechanism of jet-in-cross-flow(JICF). Moreover, 6 K20M GPUs were adopted in simulation and it took 15 402 seconds for LBM-GPU solver to simulate 71 680 LBM steps resulting in calculated performance of 521. 24 MLUPS.

A mathematical model of pulsating flow in a tapered rigid artery with an axially symmetric stenosis is established. The incompressible Navier-Stokes equation for the flow field is solved numerically and a finite difference scheme is used to implement the numerical calculation. The distributions of the wall shear stress with three stenosis severity (h/R₀=1/4,1/3,1/2) are provided and discussd.The stream function contour with h/R₀=1/3 is given. The result shows that the stenosis disturbs the flow flied in the vicinity of the stenosis, especially at the throat and in the downstream.

On the basis of analyzing the flow regime and pollution pattern of the sea area of Jiaolu Jiang Firth, the pollutant nonlinear diffusion phenomenum in the seaward firth with mixed up salt and fresh water is studied.The finite element method is used for conducting numerical analysis and the stability of the numerical solution is also investigated.Comparing the calculation data with the measured one, it is shown that the obtained result has better accuracy.This paper treats seaward firth as a dynamic system, divide the solution domain into finite elements and find the solution by a punitive function,variable size combinatorial method and non-linear optimization solution.In order to ensure solution stability,use non-dimension variables and take time-step as control condition.

This paper presents numerical solution for governing equation of flows in curvilinear coordinate system with nonstaggered grids.In order to cure the zig zag variation of pressure,the cell-face velocity interpolation method is developed for solving the pressure-velocity-coupling problem,SIMPLER algorithm is used.With the overall methods present here,the flow in a 90° square duct is calculated.The results agree well with the experiment data.

Main contents about the KENO Ⅳ interactive plotter are given such as the functions of user interface, geometry visualization (2D slices and 3D plots of a problem geometry specified in the input file), plots of K_eff results produced by KENO Ⅳ and run display.

A synthetic model of three dimensional-multilevel two dimensional diffusion is presented based on physical analysis for river current characters and boundary conditions of strong mixing seaward firth with warm sewage pollutional sources.Numerical simulation for realistic velocity and temperature fields of seaward firth shows that this model has a satisfied precision.