Two Approaches of Substance Flow Analysis—An Inspiration from Fluid Mechanics

That flow is the common feature of substance flow and fluid flow is the viewpoint emphasized in the paper. Some notes on fluid mechanics, including the two approaches of fluid flow description, were given. The concepts of the chain and the chain group of product life cycles, which are essential for understanding the specific features of substance flow, were advanced. Taking the specific feature of substance flow into consideration, on the analogy of the two approaches in fluid mechanics, two approaches of substance flow analysis, i.e. L method and E model, were formulated. Illustrative models of steady and unsteady substance flow were sketched by both methods, and comparison between them was made in general.

FINITE ELEMENT GALERKIN APPROACH FOR A COMPUTATIONAL STUDY OF ARTERIAL FLOW

A finite element solution for the Navier_Stokes equations for steady flow through a double branched two dimensional section of three dimensional model of canine aorta is obtained. The numerical technique involves transformation of the physical coordinates to a curvilinear boundary fitted coordinate system. The shear stress at the wall is calculated for Reynolds number of 1000 with branch to main aortic flow rate ratio as a parameter. The results are compared with earlier works involving experimental data and it is observed that the results are very close to their solutions. This work in fact is an improvement of the work of Sharma and Kapoor (1995) in the sense that computations scheme is economic and Reynolds number is large.

Numerical study of equilibrium solutions for axisymmetric plasmas with toroidal flow obtained using Solovev approach

Solovev approach of finding equilibrium solutions,which was extended to include the vacuum solutions provided by Zheng,Wooton,and Solano,was found extremely useful for the purpose of shaping studies.Its extension to toroidal equilibria with a general plasma flow was examined theoretically in a companion paper by Chu,Hu and Guo.The only meaningful extension was found for plasmas with a pure toroidal rotation and with a constant Mach number.A set of functions{SOLOVEV_ZWSm}was obtained which fixed location of the magnetic axis for equilibria with quasi-constant current density profile,with toroidal flow at constant Mach number and with specific heat capacity 1.The set{Solovev_ZWSm}should have complete shaping capability for plasma shapes with positive curvature at the boundary;but not for plasmas with negative curvature boundary points,i.e.the doublets or bean shaped tokamaks.We report here extensive numerical studies showing the shaping capability of{Solovev_ZWSm}for plasmas with pure toroidal rotations,including the change in topology of the solution when the rotation mach number changes.Included plasma topology are the sphere(spheromaks);and the tokamaks(including the doublets).

A VARIATIONAL ANALYTICAL APPROACH TO TIME DEPENDENT FLOW OF OLDROYD B FLUID IN CIRCULAR TUBE

In the present investigation the time dependent flow of an Oldroyd fluid B in ahorizontal eylindrical pipe is stuided by the variational analytical approach developedby author. The tome dependent problem is mathematically reduced to a partialdifferential equation of third order. Using the improved variational approach due toKantorovich the partial differential equation can be reduced to a system of ordinarydifferential equations for different approximations. The ordinary differential equationsare solved by the method of the Laplace transform which is led to an analytical formof the solutions.

Turbulence modulation model for gas–particle flow based on probability density function approach

he paper focuses on the turbulence modulation problem in gas–particle flow with the use of probability density function（PDF） approach. By means of the PDF method, a general statistical moment turbulence modulation model without considering the trajectory difference between two phases is derived from the Navier–Stokes equations. A new turbulence production term induced by the dispersed-phase is analyzed and considered. Furthermore, the trajectory difference between two media is taken into account. Subsequently, a new k–ε turbulence modulation model in dilute particle-laden flow is successfully set up. Then, the changes to several terms, including the turbulence production, dissipation, and diffusion terms, are well described consequently. The promoted model provides a more probable explanation for the modification of particles on the turbulence. Finally, we applied the model to simulate a gas–particle turbulence flow case in a wall jet, and found that the simulation results agree well with the experimental data.

A LIMITING VISCOSITY APPROACH TO THE RIEMANN PROBLEM FOR TRANSONIC FLOW

In this paper we have obtained the existence of weak solutions of the small disturbance equations of steady two-dimension flow [GRAPHICS] with Riemann date [GRAPHICS] where v+ greater-than-or-equal-to 0, v- greater-than-or-equal-to 0 and u- less-than-or-equal-to u+ by introducing 'artificial' viscosity terms and employing Helley's theorem. The setting under our consideration is a nonstrictly hyperbolic system. our analysis in this article is quite fundamental.

A Simple Weighted Integration Method for Calculating Surface Tension Force to Suppress Parasitic Flow in the Level Set Approach

Parasitic flows may occur in the numerical simulation of incompressible multiphase flow due to errors in the calculation of surface tension terms, specifically for the curvature and unit normal vector. An improved method for calculating the surface tension based on the level set approach is proposed, in which the contribution of not only the center node but also the rest area of a control volume to the calculation of surface tension is considered in a balanced manner. The weighted integration method (WIM) is more consistent with the concept of a banded in- terface in the level set method. It is applied to the temporal evolution of a two-dimensional neutrally buoyant liquid drop and a buoyancy driven deformable bubble in an immiscible fluid for the validation of WIM. The results show that the parasitic flows are evidently suppressed by the weighted integration method. The weight factors for WIM in 3-D cases are also suggested.

求解 Flow Shop 排序问题的模拟进化法

为ＦｌｏｗＳｈｏｐ排序问题的求解构造了一类模拟进化寻优方法——基于启发式规则的有序遗传算法，并对不同规模的实例进行了计算机模拟。

Application of Stochastic Fracture Network with Numerical Fluid Flow Simulations to Groundwater Flow Modeling in Fractured Rocks

The continuum approach in fluid flow modeling is generally applied to porous geological media, but has limited applicability to fractured rocks. With the presence of a discrete fracture network relatively sparsely distributed in the matrix, it may be difficult or erroneous to use a porous medium fluid flow model with continuum assumptions to describe the fluid flow in fractured rocks at small or even large field scales. A discrete fracture fluid flow approach incorporating a stochastic fracture network with numerical fluid flow simulations could have the capability of capturing fluid flow behaviors such as inhomogeneity and anisotropy while reflecting the changes of hydraulic features at different scales. Moreover, this approach can be implemented to estimate the size of the representative elementary volume (REV) in order to find out the scales at which a porous medium flow model could be applied, and then to determine the hydraulic conductivity tensor for fractured rocks. The following topics are focused on in this study: (a) conceptual discrete fracture fluid flow modeling incorporating a stochastic fracture network with numerical flow simulations; (b) estimation of REV and hydraulic conductivity tensor for fractured rocks utilizing a stochastic fracture network with numerical fluid flow simulations; (c) investigation of the effect of fracture orientation and density on the hydraulic conductivity and REV by implementing a stochastic fracture network with numerical fluid flow simulations, and (d) fluid flow conceptual models accounting for major and minor fractures in the 2 D or 3 D flow fields incorporating a stochastic fracture network with numerical fluid flow simulations.

Characteristics of turbulence transport for momentum and heat in particle-laden turbulent vertical channel flows

The dynamic and thermal performance of particle-laden turbulent flow is investigated via direction numerical simulation combined with the Lagrangian point-particle tracking under the condition of two-way coupling, with a focus on the contributions of particle feedback effect to momentum and heat transfer of turbulence. We take into account the effects of particles on flow drag and Nusselt number and explore the possibility of drag reduction in conjunction with heat transfer enhancement in particle-laden turbulent flows. The effects of particles on momentum and heat transfer are analyzed, and the possibility of drag reduction in conjunction with heat transfer enhancement for the prototypical case of particle-laden turbulent channel flows is addressed. We present results of turbulence modification and heat transfer in turbulent particle-laden channel flow, which shows the heat transfer reduction when large inertial particles with low specific heat capacity are added to the flow. However, we also found an enhancement of the heat transfer and a small reduction of the flow drag when particles with high specific heat capacity are involved. The present results show that particles, which are active agents, interact not only with the velocity field, but also the temperature field and can cause a dissimilarity in momentum and heat transport. This demonstrates that the possibility to increase heat transfer and suppress friction drag can be achieved with addition of particles with different thermal properties.

抚河疏山水利枢纽船闸通航水流条件研究

为满足水运需求,解决船闸引航道口门区受河段地形和涉河建筑物影响而导致的通航条件困难等问题,保障船舶安全通行,以抚河疏山水利枢纽船闸工程为例,采用数值模拟方法,对枢纽船闸上游引航道口门区通航条件进行计算分析,针对不良流态问题提出优化方案措施,并对方案前后枢纽通航条件进行对比分析。研究表明,调整船闸平面布置等措施对改善设计阶段的枢纽船闸上引航道口门区通航条件是有效的。研究成果可为抚河疏山水利枢纽船闸工程通航及其他类似河段工程提供技术支持。

A simple approach for the estimation of CO_2 penetration depth into a caprock layer

Caprock is a water-saturated formation with a sufficient entry capillary pressure to prevent the upward migration of a buoyant fluid. When the entry capillary pressure of caprock is smaller than the pressure exerted by the buoyant CO2plume, CO2gradually penetrates into the caprock. The CO2penetration depth into a caprock layer can be used to measure the caprock sealing efficiency and becomes the key issue to the assessment of caprock sealing efficiency. On the other hand, our numerical simulations on a caprock layer have revealed that a square root law for time and pore pressure exists for the CO2penetration into the caprock layer. Based on this finding, this study proposes a simple approach to estimate the CO2penetration depth into a caprock layer. This simple approach is initially developed to consider the speed of CO2invading front. It explicitly expresses the penetration depth with pressuring time, pressure difference and pressure magnitude. This simple approach is then used to fit three sets of experimental data and good fittings are observed regardless of pressures, strengths of porous media, and pore fluids(water,hydrochloric acid, and carbonic acid). Finally, theoretical analyses are conducted to explore those factors affecting CO2penetration depth. The effects of capillary pressure, gas sorption induced swelling, and fluid property are then included in this simple approach. These results show that this simple approach can predict the penetration depth into a caprock layer with sufficient accuracy, even if complicated interactions in penetration process are not explicitly expressed in this simple formula.

基于遗传算法的带时间窗的多目标flow-shop调度

结合实际生产,引入机器的空闲时间建立了一个带有时间窗的flow-shop优化调度模型。通过非支配排序来进行群体虚拟适应度值的分配,引入精英解策略来保证算法的收敛性和解的多样性,运用小生境技术来避免局部收敛和早熟,维持种群多样性。通过仿真实验得到模型具有实际意义,算法具有可行性。

Numerical Study on Flow Around Modern Ship Hulls with Rudder-Propeller Interactions

Reducing the fuel consumption of ships presents both economic and environmental gains. Although in the past decades,extensive studies were carried out on the flow around ship hull, it is still difficult to calculate the flow around the hull while considering propeller interaction. In this paper, the viscous flow around modern ship hulls is computed considering propeller action. In this analysis, the numerical investigation of flow around the ship is combined with propeller theory to simulate the hull-propeller interaction. Various longitudinal positions of the rudder are also analyzed to determine the effect of rudder position on propeller efficiency. First, a numerical study was performed around a bare hull using Shipflow computational fluid dynamics(CFD) code to determine free-surface wave elevation and resistance components.A zonal approach was applied to successively incorporate Bpotential flow solver^ in the region outside the boundary layer and wake, Bboundary layer solver^ in the thin boundary layer region near the ship hull, and BNavier-Stokes solver^in the wake region. Propeller open water characteristics were determined using an open-source MATLAB code Open Prop, which is based on the lifting line theory, for the moderately loaded propeller. The obtained open water test results were specified in the flow module of Shipflow for self-propulsion tests. The velocity field behind the ship was recalculated into an effective wake and given to the propeller code that calculates the propeller load. Once the load was known, it was transferred to the Reynolds-averaged Navier-Stokes(RANS) solver to simulate the propeller action. The interaction between the hull and propeller with different rudder positions was then predicted to improve the propulsive efficiency.

Hydrological simulation approaches for BMPs and LID practices in highly urbanized area and development of hydrological performance indicator system

Urbanization causes hydrological change and increases stormwater runoff volumes, leading to flooding, erosion, and the degradation of instream ecosystem health. Best management practices （BMPs）, like detention ponds and infiltration trenches, have been widely used to control flood runoff events for the past decade. However, low impact development （LID） options have been proposed as an alternative approach to better mimic the natural flow regime by using decentralized designs to control stormwater runoff at the source, rather than at a centralized location in the watershed. For highly urbanized areas, LID stormwater management practices such as bioretention cells and porous pavements can be used to retrofit existing infrastructure and reduce runoff volumes and peak flows. This paper describes a modeling approach to incorporate these LID practices and the two BMPs of detention ponds and infiltration trenches in an existing hydrological model to estimate the impacts of BMPs and LID practices on the surface runoff. The modeling approach has been used in a parking lot located in Lenexa, Kansas, USA, to predict hydrological performance of BMPs and LID practices. A performance indicator system including the flow duration curve, peak flow frequency exceedance curve, and runoff coefficient have been developed in an attempt to represent impacts of BMPs and LID practices on the entire spectrum of the runoff regime. Results demonstrate that use of these BMPs and LID practices leads to significant stormwater control for small rainfall events and less control for flood events.

基于ARMA-AE-LSTM模型的进场交通流预测方法

为建立准确有效的空中交通短期流量预测模型,提高终端区管理效率,以进场交通流为对象进行研究。首先采用自回归移动平均(autoregressive moving average,ARMA)模型对流量时间序列进行初步线性预测,然后通过长短期记忆网络(long short term memory,LSTM)模型对线性预测后的残差序列进行非线性修正预测。考虑到冗余特征会降低LSTM模型预测精度的问题,采用自编码器(autoencoder,AE)模型对LSTM模型的天气以及流量特征输入进行自适应压缩优化,最后设置对比实验对ARMA-AE-LSTM模型的准确性、鲁棒性以及时效性进行验证。实验结果表明:预测绝对误差在1.3架以内的占比达到75%;LSTM模型的平均每轮迭代时间降低为1.014 s;与其他常用深度学习预测模型相比,ARMA-AE-LSTM模型的均方根误差(root mean square error,RMSE)、平均绝对误差(mean absolute error,MAE)以及决定系数(r-squared,R2)评价指标分别改善了45.98%~67.66%、48.56%~67.35%、5.18%~21.07%;恶劣天气影响下,ARMA-AE-LSTM模型的鲁棒性更好。由此可见,该方法能够准确有效快速的预测空中交通流量。

白河包营枢纽船闸下游口门区优化方案研究

包营枢纽下游引航道口门区流场复杂、混乱。为保障内河船舶通航安全,对枢纽下游河道整体水域进行数值模拟研究,分别对比分析扩宽河道、扩宽河道+口门区设置导流墩、扩宽河道+布置隔流堤3种优化方案前后的枢纽通航条件。结果表明,原始方案中,当流量最大时横流、纵流最大流速分别为0.95、3.60 m∕s,超出0.65、1.60 m∕s的安全限值,且延长隔流堤导致末尾处下泄主流出现较大回流、横流的不良流态。最终选定在扩宽河道的基础上设置导流墩为最佳优化方案,与其他方案相比,此方案可加强主流与口门区局部流场的动量交换,减小速度梯度以及主流与口门区夹角,显著改善口门区水流条件,保障船舶通航安全。

Theoretical Computation of Nonlinear System Equations of Heavier Pellets Movements for Two Phase Flow

This paper presents nonlinear ordinary differential equations (ODES) of the heavier pellets movement for two phase flow, which actually represent a system of equations. The usual methods of solution such as Runge -Kutta method and it's datum results are discussed. This paper solves ODES of general form using variable mesh-length, linearizing the nonlinear terms by finite analysis method, fuilding an iteration sequence, and amending the nonlinear terms by iteration . The conditions of convergent operation of iteration solution is checked. The movement orbit and velocity of the pellets are calculated. Analysis of research results and it's application examples are illustrated.

信息化背景下的医院建筑空间转型与设计应对——基于流空间视角

在信息化背景下,针对医院数字与物质空间并存互构的特点,采用流空间理论视角,以信息流、人流和物流为要素,建立医院流空间的构成与转型分析框架,并阐释了其信息化转型机制:在社会经济效益的支配下,医院流要素发生数字迁移,产生数字投影空间,并引发功能网络转型,从而在流空间逻辑下改变空间节点分布状态,使医院空间呈现出“多义化节点空间”和“分布式形态结构”等典型形态,具有去中心、碎片化和不稳定特点。在此基础上,进一步从优化功能空间组织、调整空间面积配置和保留适当的灵活性3个方面探讨了建筑设计应对思路,指出“划分并组织局部中心”将成为新的重要问题,其关键在于合理决策空间节点的分解、分散与重组、重聚,可借助中心性等网络分析来应对。