An efficient pressure-velocity procedure for gas-droplet two-phase flow calculations

This paper presents a non-iterative numerical technique for computing time-dependent gas-droplet flows. The method is a fully interacting combination of Eulerian fluid and Lagrangian particle calculations. The interaction calculations between the two phases are formulated on a pressure-velocity-coupling procedure based on the operator-splitting technique. This procedure eliminates the global iterations required in the conventional particle-source-in-cell (PSIC) procedure. Turbulent dispersion calculations are treated by a stochastic procedure. Numerical calculations and comparisons with available experimental data as well as efficiency assessments are given for some sprays typical of spray combustion applications.     

Multi-fidelity Gaussian process based empirical potential development for Si:H nanowires

In material modeling, the calculation speed using the empirical potentials is fast compared to the first principle calculations, but the results are not as accurate as of the first principle calculations.First principle calculations are accurate but slow and very expensive to calculate. In this work, first,the H-H binding energy and H_2-H_2 interaction energy are calculated using the first principle calculations which can be applied to the Tersoff empirical potential. Second, the H-H parameters are estimated. After fitting H-H parameters, the mechanical properties are obtained. Finally, to integrate both the low-fidelity empirical potential data and the data from the high-fidelity firstprinciple calculations, the multi-fidelity Gaussian process regression is employed to predict the HH binding energy and the H_2-H_2 interaction energy. Numerical results demonstrate the accuracy of the developed empirical potentials.     

EDQNM and DNS — Comparitive calculations

EDQNM and DNS calculations of homogenous axisymmetric turbulence in the absence of a mean flow are compared. Special care is taken in making sure that exactly equivalent initial conditions are used in the two methods. Three calculations with different degrees of anisotropy have been carried out.     

Statistical line-by-line model for atomic spectra in intermediate coupling

A statistical method to simulate detailed line accounting (DLA) calculations of complex spectra is proposed. The method is based on the recently developed partially resolved transition array model. Numerical examples show that spectrum calculations using the statistical approach are in good agreement with DLA results. In particular, the statistical method conserves systematic line coincidences across transition arrays differing only in the subshell occupation of excited spectator electrons important in opacity calculations. In addition, it is computationally efficient; hence, it can accelerate spectrum calculations without introducing significant uncertainties whenever the DLA method is considered impractical.     

Computationally efficient database and spectral interpolation for fully plastic Taylor-type crystal plasticity calculations of face-centered cubic polycrystals

A new computationally efficient database approach to fully plastic Taylor-type crystal plasticity calculations is presented in this paper. In particular, we explore strategies that circumvent the need to repeatedly solve sets of highly non-linear, extremely stiff, algebraic equations with poor convergence characteristics that are inherent to these calculations. The suggested strategies consist of computing only once all of the needed variables in crystal plasticity calculations, storing them, and retrieving the values of interest according to the need in any specific simulation. An algorithm is presented here that facilitates this approach, and involves local spectral interpolation using discrete fourier transform (DFT) methods. The approach described here results in major improvements in the computational time over both the conventional crystal plasticity calculations and our previously developed spectral approach using generalized spherical harmonics (GSH). Details of this new approach are described and validated in this paper through a few example case studies.     

穿破甲有限元的几何非线性及物理参数的确定

在现有计算程序的基础上 ,引入有限变形几何框架及大变形条件下的Bodner Partom本构模型。同时 ,利用实验数据确定了材料的物理参数。计算与实验的对比说明 ,所给出的非线性几何计算及物理参数的确定方法可用于穿破甲过程。     

Aerodynamics of an asymmetrically deformed body in nonstationary supersonic motion

A method for making numerical calculations of the stationary and nonstationary aerodynamic characteristics of bodies of variable shape is considered. The results of calculations of the aerodynamic coefficents are given [1]. The results of numerical calculations are compared with the results of Newton's theory.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 162–167, March–April, 1980.     

CALCULATION OF AIRCRAFT DYNAMIC LOADS ON SHIP-DECK AND TEST VERIFICATION

舰载飞机的舰面动载荷是结构的临界设计载荷。针对常规方法下载荷计算的设计已不能满足舰载飞机非常规工况(例如弹射拦阻、自由飞钩住、偏心着舰等)载荷计算的设计要求的问题,研究和建立了一套完整的全机动载荷计算的设计方法和流程,并以某型飞机全机落震试验为例,通过与试验数据的对比分析,验证了该设计方法和流程的合理性和可行性。     

Hydrodynamic structure of viscous flows in rotating convergent-divergent channels

The results of the numerical calculations of isothermal viscous flows in convergent-divergent channels axially rotating at a constant angular velocity are presented. With reference to the example of the calculations performed at Re = 2000 the difference in the flowfields in a fixed channel and that rotating at an angular velocity Ω₀ = 10 s^?1 in analyzed. The results of the calculations of viscous flows in convergent-divergent channels at Re = 2000 and Ω₀ = 10 s^?1 are also presented.     

Fully developed laminar flow of non-Newtonian liquids through annuli: comparison of numerical calculations with experiments

Experimental data are reported for fully developed laminar flow of a shear-thinning liquid through both a concentric and an 80% eccentric annulus with and without centrebody rotation. The working fluid was an aqueous solution of 0.1% xanthan gum and 0.1% carboxymethylcellulose for which the flow curve is well represented by the Cross model. Comparisons are reported between numerical calculations and the flow data, as well as with other laminar annular-flow data for a variety of shear-thinning liquids previously reported in the literature. In general, the calculations are in good quantitative agreement with the experimental data, even in situations where viscoelastic effects, neglected in the calculations, would be expected to play a role.