坝址温度场与变物性渗流场全耦合分析

如果仅考虑流体性质受温度的影响，可得多孔介质渗透系数与温度之间存在线性关系，利用相关数据，计算得知渗流场对温度较为敏感。从温度变化引起水的密度和粘度的变化来考虑温度场对渗流场的影响，建立了温度场和变物性渗流场的瞬态全耦合数学模型，并初步探讨了这种全耦合模型的求解思路。采用FEMLAB软件，在原有模型的基础上做了二次开发，从而实现了该全耦合问题的有限元求解。结合工程实例，对所建的坝址温度场与变物性渗流场全耦合模型做了数值验证。计算结果表明，全耦合模型在求解问题时，坝址区温度升高，渗流流速普遍降低；温度场变动比较小，而渗流场变动相对大一些。     

基于FEMLAB的气浮轴承静态性能求解方法

研究了利用商用有限元软件FEMLAB进行气浮轴承静态性能分析的方法。该方法基于雷诺方程求解,既避免了其它商用流体软件进行气浮轴承性能分析时的低效率问题,又避免了手工编程计算中存在的编程困难、对轴承形式适应性差的问题;而相对于工程中常用的经验公式解析算法,该方法的计算精度很高。因此该方法在科研和工程领域都有很高的应用价值。     

磁流变减振器的电磁-流体耦合场有限元分析

根据磁流变减振器的特点,在多物理量耦合有限元分析软件包FEMLAB中建立磁流变减振器的有限元模型.对磁流变液的流变特性作适当的简化与假设,将磁场有限元计算的解转变为磁流变液流动时所受阻力的分布,采用序贯耦合法来求解磁流变减振器中的电磁-流体耦合场,并计算磁流变减振器在激励下的响应,为磁流变减振器的设计提供依据.     

坝址温度场与变物性渗流场全耦合分析

在只考虑流体性质受温度的影响条件下,根据多孔介质渗透系数与温度之间存在的线性关系,利用相关数据,分析了渗流场对温度较为敏感的敏感性。从温度变化引起水的密度和黏度的变化来考虑温度场对渗流场的影响,建立了温度场和变物性渗流场的瞬态全耦合数学模型,并初步探讨了这种全耦合模型的求解思路。采用FEMLAB软件,在原有模型的基础上做了二次开发,从而实现了该全耦合问题的有限元求解。通过工程实例,对所建的坝址温度场与变物性渗流场全耦合模型做了数值验证。计算结果表明,采用全耦合模型求解渗流问题时,坝址区温度升高,渗流流速普遍降低;温度场变动比较小,而渗流场变动相对大一些。     

Topology optimization of channel flow problems

This paper describes a topology design method for simple two-dimensional flow problems. We consider steady, incompressible laminar viscous flows at low-to-moderate Reynolds numbers. This makes the flow problem nonlinear and hence a nontrivial extension of the work of Borrvall and Petersson (2003).Further, the inclusion of inertia effects significantly alters the physics, enabling solutions of new classes of optimization problems, such as velocity-driven switches, that are not addressed by the earlier method. Specifically, we determine optimal layouts of channel flows that extremize a cost function which measures either some local aspect of the velocity field or a global quantity, such as the rate of energy dissipation. We use the finite element method to model the flow, and we solve the optimization problem with a gradient-based math-programming algorithm that is driven by analytical sensitivities. Our target application is optimal layout design of channels in fluid network systems. Using concepts borrowed from topology optimization of compliant mechanisms in solid mechanics, we introduce a method for the synthesis of fluidic components, such as switches, diodes, etc.     

Numerical analysis of temperature distribution of plasma arc with molten pool in plasma arc melting

The relationships among the parameters that govern the plasma arc MR (melting and refining) process and the quality of the alloy melts are complicated. Only a simulation of the process can enable the process to be properly controlled and the right compositions to be achieved. The main purpose of this paper is to simulate the temperature distribution in the molten pool using the software FEMLAB. Numerical calculations were based on finite element analysis and the coupling of heat transfer, fluid flow and electromagnetic modules. The results of simulations are verified with the meniscus shape of liquid isothermal line in the solid ingot.     

A high‐level programming‐language implementation of topology optimization applied to steady‐state Navier–Stokes flow

We present a versatile high‐level programming‐language implementation of non‐linear topology optimization. Our implementation is based on the commercial software package FEMLAB, and it allows a wide range of optimization objectives to be dealt with easily. We exemplify our method by studies of steady‐state Navier–Stokes flow problems, thus extending the work by Borrvall and Petersson on topology optimization of fluids in Stokes flow (Int. J. Num. Meth. Fluids 2003; 41 :77–107). We analyse the physical aspects of the solutions and how they are affected by different parameters of the optimization algorithm. A complete example of our implementation is included as FEMLAB code in an appendix. Copyright © 2005 John Wiley & Sons, Ltd.     

Structure topology optimization: fully coupled level set method via FEMLAB

This paper presents a procedure which can easily implement the 2D compliance minimization structure topology optimization by the level set method using the FEMLAB package. Instead of a finite difference solver for the level set equation, as is usually the case, a finite element solver for the reaction–diffusion equation is used to evolve the material boundaries. All of the optimization procedures are implemented in a user-friendly manner. A FEMLAB code can be downloaded from the homepage www.imtek.de/simulation and is free for educational purposes.     

超磁致伸缩执行器的三维非线性动态有限元模型

超磁致伸缩执行器工作时超磁致伸缩材料的磁导率会随着应力变化而变化,并存在磁滞损失和涡流损失等非线性问题,同时磁场、电场、温度场及机械应力场之间存在耦合.建立了超磁致伸缩执行器电场、磁场和机械应力场3场耦合的三维非线性动态有限元模型,考虑了超磁致伸缩执行器Terfenol D棒质量、预压应力、偏置磁场、磁滞和涡流损失.使用Jile-Autherton磁化模型计算磁滞损失,在商业有限元软件FEMLAB中实现了有限元模型.模型仿真结果和实验结果相一致,验证了所建立模型的正确性.     

基于 FEMLAB 的钻井过程中流固热耦合响应分析

在石油开采等行业中,钻井过程中的渗流-变形-温度多场耦合作用非常复杂,它对井壁稳定分析具有重要意义。该文将在有关文献的基础上,首先建立一组饱和多孔岩体介质瞬态的流、固、热三场耦合方程组(其中包括固体变形、能量传输、流体流动三个相互耦合的过程,多物理场之间的交叉耦合还包括材料性质与独立变量之间的耦合关系);然后给出了该方程组在FEMLAB软件(基于偏微分方程组的多物理过程模拟工具)中的详细数学表达;最后以FEMLAB作为平台,着重分析了钻井过程中的流固热耦合作用过程,讨论了井壁温度发生突然降低后,井壁附近围岩的孔隙水压力、温度、应力的变化过程,为井壁稳定分析提出更为准确的应力分布。计算结果反映了耦合作用对井壁围岩应力的重要影响。该文的计算结果与解析解进行了比较,结果非常吻合,证明了耦合模型及求解方法的正确性。