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Implicit LES for Two-Dimensional Circular Cylinder Flow by Using COMSOL Multiphysics® Software - new

M. Hashiguchi[1]
[1]Keisoku Engineering System Co.,Ltd., Tokyo, Japan

In this paper, implicit Large Eddy Simulation (LES) based on finite-element analysis is performed in order to investigate two-dimensional circular cylinder incompressible flow. Implicit LES attempts time-dependent flow computation with no explicit turbulence model. Here, two types of circular cylinder with/without surface roughness, are treated. The Reynolds number Re based of the diameter of ...

Numerical Simulation of Auto-Propulsion Mechanism of Microorganism Inside a Microchannel

S. Patra [1], A. Dalal [1], G. Biswas [1], S. Shah [2]
[1] Indian Institute of Technology Guwahati, Guwahati, Assam, India
[2] Indian Institute of Technology Bhubaneswar, Bhubaneswar, Odisha, India

The present study manifests the several ground breaking flow phenomena arising out of hydrodynamic interactions between two microorganisms swimming inside a microchannel with close proximity. The results theorized in the present investigation scrutinizes the varying behavior of the bacteria while moving inside a micro-capillary at different Reynolds number (Re). At high Re, the two swimming ...


甘政涛 [1],
[1] 中国科学院力学研究所,北京,中国

基于 Level-Set 界面跟踪方法建立了激光熔覆过程的三维瞬态数值模型,研究了瞬态熔化和凝固过程中传热传质的演化规律。该模型使用 Level-Set 方法跟踪熔池气/液界面,采用焓-多孔度(enthalpy-porosity)方法得到了固/液界面之间的糊状区,并考虑了质量添加、材料熔化/凝固、热毛细效应(Marangoni效应)、浮力效应、活性元素质量传输等对熔池流动和界面的影响。通过该模型,具体分析了质量添加、力和界面平衡条件对熔池气/液界面的影响,以及由熔池温度/浓度分布引起的热毛细效应、金属材料的熔/凝过程和熔池流动形式对熔池固/液界面的影响。结果表明:熔池的气/液界面主要由力平衡条件决定,截面近似为圆弧型,其尺寸与单位时间的质量添加量相关。熔池的固/液形态由于熔池的表面温度梯度和表面活性元素含量共同引起的熔池流动方向和速度的变化,出现三种不同的类型,分别为下凹型(熔池内流) ...

Mathematical Modeling Of Traveling-Wave Electroosmotic Micropumps By Using Of The Weak Form

J. Hrdlicka, P. Cervenka, and D. Snita
Institute of Chemical Technology Prague, Prague, Czech Republic

This contribution is devoted to the mathematical modeling of the AC electroosmotic micropumps in COMSOL Multiphysics and Matlab. The mathematical model involves the microchannel surroundings and several AC-voltage driving modes. The weak form has been used for handling singularities and other problems. The system dynamic behavior and conditions at the phase interfaces will be discussed.

Numerical Investigation of Swirl Flow in Curved Tube with Various Curvature Ratio

A. Kadyirov[1]
[1]Research Center for Power Engineering Problems of the Russian Academy of Sciences, Kazan, Russia

The influences of curvature effects and swirl intensities for Non-Newtonian viscous fluid flow in a curved tube have been numerically investigated by using COMSOL Multiphysics®. The twisted tape, which are located directly in front of the curved part, are used as swirl flow generators. The tape is twisted until it reaches an angle of 90 degrees and turns right. Swirling flow, getting into the ...

Numerical Investigation of Micronozzle Performance for Various Nozzle Geometries - new

P. A. Haris[1], T. Ramesh[1]
[1]National Institute of Technology Tiruchirappalli, Tiruchirappalli, Tamil Nadu, India

Design and manufacture of thrusters for producing very low thrust force in the range of milli or micro newtons using micronozzles has been actively developed in the last decade. The nature of propellant flow in such micronozzles differs from that of macro nozzles. In micronozzles, viscous effect dominates; hence the flow is always in laminar regime with high viscous losses. Objective of this ...

Studying PEM Fuel Cells using Equation Based Simulation

J. Blackburn [1], N. McCartney [1],
[1] National Physical Laboratory, London, UK

We present computer simulation results for PEM fuel cells using COMSOL Multiphysics® software. We have developed novel PDE equations at NPL from first principles and these are more realistic than models typically used in literature. The theory includes Maxwell-Stephan and Nernst-Planck equations for the diffusion and electrochemistry as well as equations governing electrostatic and stress/strain ...

Modeling of Silicon Transport into Germanium Using a Simplified Crystal Growth Technique

F. Mechighel[1][3], B. Pateyron[1], M. El Ganaoui[1], S. Dost[2], and M. Kadja[3]

[1]Laboratory SPCTS UMR CNRS, ENSCI, Limoges University, Limoges, France
[2]Crystal Growth Laboratory, Department of Mechanical Engineering, University of Victoria, British Columbia, Victoria, Canada
[3]Department of Mechanical Engineering, University of Constantine, Constantine, Algeria

A numerical simulation study, using COMSOL Multiphysics®, was carried out to examine the temperature and concentration fields in the dissolution process of silicon into germanium melt. This work utilized a simplified configuration which may be considered to be similar material configuration to that used in the Vertical Bridgman growth methods. The concentration profile for the SiGe sample ...

Comparing Different Approaches for Moisture Transfer Inside Constructions with Air Gaps

L. Nespoli[1], M. Bianchi Janetti[2], F. Ochs[2]
[1]Politecnico di Milano, Milan, Italy
[2]University of Innsbruck, Innsbruck, Austria

A model for the conjugate simulation of heat and moisture transfer inside porous materials and fluid domains is implemented in COMSOL Multiphysics®. The results of this model are compared with those obtained through a simplified approach: the line-source approach. The models are both validated with experimental data and with numerical results from other authors. On the one hand the conjugate ...

Numerical Calculation of Effective Density and Compressibility Tensors in Periodic Porous Media: A Multi-Scale Asymptotic Method

C. Lee[1], M. Leamy[1], and J. Nadler[2]

[1]School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
[2]Georgia Tech Research Institute (GTRI), Georgia Institute of Technology

A major issue in predicting and controlling (via design) absorption properties of rigid porous media is the determination of the frequency-dependent effective density and compressibility tensors. Unlike previous research efforts which employ in-house and, oftentimes, multiple numerical procedures for determining these two essential tensors, we formulate their solution in terms of a set of micro ...