Design optimization of an enzymatic assay in an electrokinetically-driven microfluidic device

Microfluidic systems are increasingly popular for rapid and cheap determinations of enzyme assays and other biochemical analysis. In this study reduced order models (ROM) were developed for the optimization of enzymatic assays performed in a microchip. The model enzyme assay used was β-galactosidase (β-Gal) that catalyzes the conversion of Resorufin β-d-galactopyranoside (RBG) to a fluorescent product as previously reported by Hadd et al. (Anal Chem 69(17): 3407–3412, 1997). The assay was implemented in a microfluidic device as a continuous flow system controlled electrokinetically and with a fluorescence detection device. The results from ROM agreed well with both computational fluid dynamic (CFD) simulations and experimental values. While the CFD model allowed for assessment of local transport phenomena, the CPU time was significantly reduced by the ROM approach. The operational parameters of the assay were optimized using the validated ROM to significantly reduce the amount of reagents consumed and the total biochip assay time. After optimization the analysis time would be reduced from 20 to 5.25 min which would also resulted in 50% reduction in reagent consumption.     

Experiences with Mathematical Modeling of Electro- Boost in Glass Furnaces

The goal of the latest strategy in glass companies is to decrease the cost of production while maintaining or increasing the glass quality. One of the perspective ways is to install the electric boosting into the existing furnace or to build the new furnace including the electric boosting. This strategy may be surprising as electric energy is generally more expensive than gas or oil （considering the cost per unit energy） but because of efficiency of use （ direct glass - melt heating by Joulean heat） it is inevitably cost effective. The use of the CFD modeling capability for electro - boost designing is presented in this contribution. The Glass Service Glass Furnace Model （ GS - GFM ） is used for investigating the optimal electrode arrangement and phasing, and moreover, for increasing the glass quality during the electro - boost applying.     

电磁流量计测量直管内速度及管长的CFD 研究

电磁流量计是一种广泛采用的流量测量仪表,测量直管长度对于保证测量管内流速轴对称分布及电磁流量计计量精度起着关键性作用.本文采用CFD数值手段对电磁流量计测量直管长度及管内流速轴对称分布特性展开研究.为了准确地研究流速分布的轴对称特性,提出了定量衡量流速分布轴对称程度的速度对称偏差度,并基于此研究了不同内径、不同过流量条件下测量管内的流速分布轴对称特性和电磁流量计对测量直管长度的要求,为电磁流量计的检定、安装、应用提供科学理论依据,为依托项目建立高精度流量计量标准装置奠定基础.     

基于CFD技术的导管螺旋桨自动优化设计技术研究

该文开发了一种基于定常计算的导管螺旋桨自动优化设计技术.该方法综合了导管桨桨叶、导管及桨毂的几何生成、网格自动划分、优化算法和CFD分析等技术,有助于将螺旋桨理论计算推广到设计阶段.文中采用该方法计算某导管螺旋桨的改造,并与试验结果进行了比较,验证了其效果.计算结果显示,优化后的导管桨可以提供更高的推力和效率.     

A physical approach of the short-term wind power prediction based on CFD pre-calculated flow fields

A physical approach of the wind power prediction based on the CFD pre-calculated flow fields is proposed in this paper. The flow fields are obtained based on a steady CFD model with the discrete inflow wind conditions as the boundary conditions, and a database is established containing the important parameters including the inflow wind conditions, the flow fields and the corresponding wind power for each wind turbine. The power is predicted via the database by taking the Numerical Weather Prediction (NWP) wind as the input data. In order to evaluate the approach, the short-term wind power prediction for an actual wind farm is conducted as an example during the period of the year 2010. Compared with the measured power, the predicted results enjoy a high accuracy with the annual Root Mean Square Error (RMSE) of 15.2% and the annual MAE of 10.80%. A good performance is shown in predicting the wind power’s changing trend. This approach is independent of the historical data and can be widely used for all kinds of wind farms including the newly-built wind farms. At the same time, it does not take much computation time while it captures the local air flows more precisely by the CFD model. So it is especially practical for engineering projects.     

基于CFD的新型结构静压油垫数值仿真技术

为了提高重载数控机床静压转台的承载能力和油膜刚度,提出了一种具有多环形流道油腔和阻尼型封油边结构的新型静压油垫,并对其性能进行了研究.在对静压油垫结构优化设计的基础上,利用CFD(computationalfluid dynamics)数值仿真技术,采用二维轴对称流动模型对新型结构静压油垫的流场特性进行了仿真分析,得到了新型静压油垫的内部流场特性,计算出油垫的承载能力和油膜刚度,并与单腔体、单平面封油边结构的静压油垫进行了对比.研究表明:新型静压油垫能通过在阻尼流道和阻尼槽内形成紊流,增加流动液阻,实现压力增益,并可在阻尼槽处产生局部静压效应,从而使新型结构静压油垫的承载能力和油膜刚度较传统结构静压油垫有所提高;此外,采用CFD技术有助于对复杂结构的静压油垫进行优化设计与性能计算,从而提高设计效率和计算准确性.     

汽车外场气动噪声仿真与计算

利用FLUENT软件,对汽车的外场远点噪声进行仿真计算：通过稳态计算,得出汽车车身的表面声功率和声源分布情况,对车身的噪声源进行定性分析;通过瞬态计算,得到车身外场某点噪声的声压频谱图。仿真结果表明：汽车外场气动噪声源主要来自车身前脸、后视镜、前风窗玻璃、前轮;远场点的声压级由前向后有增大的趋势,并且靠近尾部区域声压级较大,最大达90．4dB,直径10m弧线上接收点的声压级值比直径12m的要高,其差值最大达15．1dB。     

基于CFD的低比转速离心泵叶轮切割性能分析

根据现行的低比转速离心泵切割定律,对MH-46-100型低比转速离心泵叶轮外径进行3次切割,以分块非结构六面体网格划分计算区域。采用有限体积法对雷诺时均Navier-Stokes方程进行数值离散,选用RNGk-ε湍流模型结合SIMPLEC算法求解,对各个模型进行了叶轮和蜗壳相耦合的数值模拟。对性能预测结果与现行的低比转速离心泵切割定律进行对比,证明了切割定律的准确性和基于切割定律的各模型流动的相似性。同时得到了低比转速离心泵叶轮外径减小而效率升高的特点,并对比分析各个模型的流动状况。     

CFD方法在灯泡式贯流泵流量与压差关系预测中的应用

以南水北调东线工程金湖灯泡式贯流泵为例,应用标准k ε紊流模型和SIMPLEC算法对灯泡式贯流泵进水流道模型的水流流场进行CFD数值模拟,得到流量与进水流道上两测压点的压差数据,线性拟合后获得流量与压差的函数关系,与模型试验测得的结果相比两者差异很小,表明用CFD方法预测进水流道中流量与压差的关系精度较高。采用相同的CFD方法对模型放大10.33倍后得到的灯泡式贯流泵进水流道原型流场进行数值模拟,预测灯泡式贯流泵原型流量与压差的函数关系。结果表明,应用CFD方法预测大型灯泡式贯流泵的流量与进水流道上两测压点压差的关系是可行的,为低扬程水泵进水流道中流量与压差函数关系的确定提供了一条新途径。     

Investigation on mechanism of polymer filling in high-aspect-ratio trenches for through-silicon-via (TSV) application

Vacuum-assisted spin-coating is an effective polymer filling technology for sidewall insulating of through-silicon-via (TSV). This paper investigated the flow mechanism of the vacuum-assisted polymer filling process based on experiments and numerical simulation, and studied the effect of vacuum pressure, viscosity of polymer and aspect-ratio of trench on the filling performance. A 2D axisymmetric model, consisting of polymer partially filled into the trench and void at the bottom of trench, was developed for the computational fluid dynamics (CFD) simulation. The simulation results indicate that the vacuum-assisted polymer filling process goes through four stages, including bubble formation, bubble burst, air elimination and polymer re-filling. Moreover, the simulation results suggest that the pressure significantly affects the bubble formation and the polymer re-filling procedure, and the polymer viscosity and the trench aspect-ratio influence the duration of air elimination.