Series solutions for the stagnation flow of a second-grade fluid over a shrinking sheet

This study derives the analytic solutions of boundary layer flows bounded by a shrinking sheet. With the similarity transformations, the partial differential equations are reduced into the ordinary differential equations which are then solved by the homotopy analysis method （HAM）. Two-dimensional and axisymmetric shrinking flow cases are discussed.     

Large eddy simulation of hot and cold fluids mixing in a T-junction for predicting thermal fluctuations

Temperature fluctuations in a mixing T-junction have been simulated on the FLUENT platform using the large eddy simulation （LES） turbulent flow model and a sub-grid scale Smagorinsky-Lilly model. The normalized mean and root mean square temperatures for describing time-averaged temperature and temperature fluctuation intensity, and the velocity are obtained. The power spectrum densities of temperature fluctuations, which are key parameters for thermal fatigue analysis and lifetime evaluation, are analyzed. Simulation results are consistent with experimental data published in the literature, showing that the LES is reliable. Several mixing processes under different conditions are simulated in order to analyze the effects of varying Reynolds number and Richardson number on the mixing course and thermal fluctuations.     

基于小型电磁动力驱动器的微流道混合控制研究

对于许多微流体应用系统来说,流体的混合是至关重要的.本文研究了基于电磁流体动力混合器的微流道主动混合控制方法,建立了该微流道混合系统的理论模型并进行了数值模拟.在交变Lorentz驱动下,流经混合器流道的流体及其分界面在混合器流道内往复运动,流体界面的反复折叠与流体局部流动使流体混合,流体的横向往复运动使流体分界面反复折叠从而使流体间的接触面积大大增加.对流体混合过程进行了讨论并给出了漉体混合程度评价方法.     

Analysis of shock wave reflection from fixed and moving boundaries using a stabilized particle method

In the present paper, the efficiency of an enhanced formulation of the stabilized corrective smoothed particle method （CSPM） for simulation of shock wave propagation and reflection from fixed and moving solid boundaries in compressible fluids is investigated. The Lagrangian nature and its accuracy for imposing the boundary conditions are the two main reasons for adoption of CSPM. The governing equations are further modified for imposition of moving solid boundary conditions. In addition to the traditional artificial viscosity, which can remove numerically induced abnormal jumps in the field values, a velocity field smoothing technique is introduced as an efficient method for stabilizing the solution. The method has been implemented for one- and two-dimensional shock wave propagation and reflection from fixed and moving boundaries and the results have been compared with other available solutions. The method has also been adopted for simulation of shock wave propagation and reflection from infinite and finite solid boundaries.     

Numerical investigations of asymmetric flow of a micropolar fluid between two porous disks

Numerical solution is presented for the two- dimensional flow of a micropolar fluid between two porous coaxial disks of different permeability for a range of Reynolds number Re （-300≤ Re 〈 0） and permeability parameter A （1.0≤A ≤2.0）. The main flow is superimposed by the injection at the surfaces of the two disks. Von Karman＇s similarity transformations are used to reduce the governing equations of motion to a set of non-linear coupled ordinary differential equations （ODEs） in dimensionless form. An algorithm based on the finite difference method is employed to solve these ODEs and Richardson＇s extrapolation is used to obtain higher order accuracy. The results indicate that the parameters Re and A have a strong influence on the velocity and microrotation profiles, shear stresses at the disks and the position of the viscous/shear layer. The micropolar material constants cl, c2, c3 have profound effect on microrotation as compared to their effect on streamwise and axial velocity profiles. The results of micropolar fluids are compared with the results for Newtonian fluids.     

两层液体Bénard-Marangoni对流的实验研究

采用粒子图像测速技术(PIV)对两层流体B(en)ard-Marangoni对流进行了实验研究.研究了各种不同厚度比下的临界对流模式,同时研究了在温差变大时向超临界对流模式转化过程.实验结果表明,界面张力对各种对流模式的形成和转变具有重要的作用.     

变可信度模型管理优化设计方法在气动外形设计中的应用

在信赖域最优化方法的基础上,将梯度搜索方法与近似模型管理结构相结合,结合N-S方程与Euler方程,建立了一种用于气动外形设计的梯度AMF优化设计方法.该方法在气动优化中,通过对采用不同的流体控制方程的计算结果进行组织和管理,从而可以在优化迭代过程中将主要搜索过程集中在低可信度模型的计算上,并利用高可信度模型监控优化过程,使得最终的优化解收敛到高可信度模型上.本文采用梯度AMF气动优化设计方法进行翼型设计,取得了良好的设计效果,实际结果表明本文提出的方法具有可行性和适用性.     

流体物理研究所人才需求信息

流体物理研究所组建于1970年,坐落在四川省绵阳市.现有职工700余人(其中院士1人、高级职称142人、中级职称201人),12个科研室,1个国防科技重点实验室,2个中文核心期刊.     

磁性靶向药物递送中铁磁流体的动力学建模

在所有人体内进行的药物递送技术中,磁性药物靶向递送治疗由于其非入侵性和高靶向性而成为主要的方法．磁性药物靶向递送是将药物装载到磁性纳米颗粒上,利用外部磁场使其移动并聚焦在靶部位的方法．该法能提高靶部位药物的浓度,降低药物对正常组织的毒副作用．尽管已经有不少磁性靶向药物递送的理论分析,但是很少有人研究磁流体在血管里的流体动力学模型．该文提出了一个数学模型来描述作为药物载体的铁磁流体在外磁场作用下,在血管里的流体动力学特性,并在模型中增加了磁场力以及由此产生的不对称应力,增加了磁性纳米颗粒在磁场作用下的角动量方程．由于运动方程的数学复杂性,通过保留数学模型里物理特性最显著项来获得工程近似．用计算流体力学（CFD）进行数值仿真,分析了铁磁流体在一个模拟动脉瘤血管的三维管道里的流动状况,来进一步理解铁磁流体的临床应用．仿真结果和动物实验相一致．分析结果对于磁性靶向药物递送的各种应用提供了可参考的数据．     

基于吸收分析的多属性反演技术及在油田开发中的应用

为了满足油藏开发阶段砂体内部油水识别的需求,提出了基于地层吸收分析的多属性反演流体识别技术。算法实现分三步:1利用基于广义S变换的瞬时子波吸收分析(GST_WEA)油气预测技术计算地震记录的高、低频吸收因子;2结合吸收因子和其它与流体相关的地震属性,以电阻率曲线为目标函数构建多元线性反演,利用多元逐步回归算法对包括吸收因子在内的多种地震属性进行流体敏感性排序;3进一步利用概率神经网络算法对优选的以吸收因子为主的地震属性进行多属性电阻率反演。通过模型分析验证了GST_WEA油气预测技术的抗噪性。实际应用效果表明吸收因子较其他地震属性具有更高的流体敏感性,通过多属性反演有效预测了砂体内部的含油优势区域。