Fluid

Jennifer Segui | January 9, 2014

Spectroscopic imaging has been used for decades to map the chemical composition of material surfaces with atomic-scale resolution. In order to achieve adequate chemical specificity and spatial resolution during imaging, both the material sample and the imaging system are placed under high or ultra-high vacuum (UHV). In practice, materials are often used outside of vacuum environments and therefore it is also necessary to evaluate their surface properties at higher or ambient pressure. Differential pumping is the key to designing vacuum […]

Read more ⇢

Article Categories

Fanny Littmarck | January 3, 2014

Before conducting certain blood sample analyses, researchers need to separate the red blood cell particles from the blood plasma. Using lab-on-a-chip (LOC) technology, red blood cell separation can be achieved via magnetophoresis, i.e. motion induced by magnetic fields. Since the magnetic permeability of the particles is different from the blood plasma, their trajectory can be controlled within the flow channel of the LOC device and thereby separated out from the fluid.

Read more ⇢
Alexandra Foley | December 19, 2013

A while back, I had the opportunity to speak with Steven Conrad, a critical care physician at the Louisiana State University (LSU) Health Science Center in New Orleans. Not only is Dr. Conrad a physician as well as a professor at LSU, he’s also a biomedical engineer who uses finite element analysis (FEA) to conduct research on the design of dialyzers. Dr. Conrad uses COMSOL Multiphysics to gain a deeper understanding of the physics behind these devices, and to create […]

Read more ⇢

Article Categories

David Kan | December 18, 2013

A prospective user of COMSOL approached me about modeling viscous fingering, which is an effect seen in porous media flow. He hadn’t found a satisfying solution elsewhere, so he turned to COMSOL. I’d like to share with you some of my insight on how to go from idea to model to simulation by taking a “do-it-yourself approach” and utilizing the equation-based modeling capabilities of COMSOL Multiphysics.

Read more ⇢

Article Categories

Phil Kinnane | December 6, 2013

The Mixer Module provides ready-made interfaces for describing the difficult problem of laminar and turbulent flows in rotating machinery with free liquid surfaces. COMSOL has been developing different techniques for modeling CFD, moving geometries, and free surfaces during the past few years for a number of different applications. This has now culminated in the new Mixer Module that was released with version 4.4, and it clearly showcases the improved CFD capabilities of COMSOL.

Read more ⇢

Article Categories

Andrew Griesmer | November 13, 2013

The International Temperature Scale of 1990 (ITS-90) is the industry calibration standard for measuring temperatures throughout the world. The National Physical Laboratory (NPL) works to establish and maintain the ITS-90 through experiments, most notably, thermometer calibration. To better understand and overcome the shortcomings of the experimental process, Jonathan Pearce, at the UK’s National Physics Laboratory, turned to simulation. His results yielded fascinating results about the microscopic behavior of the liquid-solid interface during the freezing process.

Read more ⇢
Alexandra Foley | November 7, 2013

Until recently, simulation had not been widely used by vacuum system designers because of an absence of commercial simulation tools. Last October, my colleague James Ransley held a webinar about how to model vacuum systems using COMSOL Multiphysics. The webinar was a great success, and it inspired us to produce a dedicated product for modeling vacuum applications: the Molecular Flow Module (new with version 4.3b). This year, on November 21st, James will be giving a webinar explaining the new features […]

Read more ⇢

Article Categories

Fabrice Schlegel | October 28, 2013

Microfluidic devices are so small that the micropumps and micromixers that control and mix the fluid inside the device cannot involve any moving components. Instead, they must take advantage of electroosmotic flow. Here, I will describe the concept of electroosmosis and the electrical double layer (EDL), and how to model these in COMSOL, walking you through two example models.

Read more ⇢

Article Categories

Alexandra Foley | October 1, 2013

Laminar static mixers are used for the accurate mixing of fluids (both liquid and gas). Unlike a mixer containing moving blades, a static mixer contains twisted stationary blades that are positioned at different angles throughout the cylindrical flow channel of the mixer. When a fluid is pumped through the channel, the alternating directions of the cross-sectional blades cause the fluid to become mixed as it passes along the length of the channel. This mixing technique allows for precise control over […]

Read more ⇢
Walter Frei | September 16, 2013

COMSOL Multiphysics offers several different formulations for solving turbulent flow problems: the Spalart-Allmaras, k-epsilon, k-omega, Low Reynolds number k-epsilon, and SST models. All of these formulations are available in the CFD Module, and the k-epsilon and Low Reynolds number k-epsilon are available in the Heat Transfer Module. This posting outlines the reasons why we want to use these various turbulence models, how to choose between them, and how to use them effectively. Throughout the post, you’ll find links to relevant […]

Read more ⇢

Article Categories

Andrew Griesmer | September 13, 2013

Starting the design process by testing on a small scale is often the best way to tackle issues affecting large objects, like a ship. Detailed in COMSOL News 2013, researchers at INSEAN, The Italian Ship Model Basin, used small-scale testing and then simulation to analyze the effect of placing a sonar system within the bulbous bow at the hull of a ship. Using a small-scale model of a bulbous bow, the researchers at INSEAN performed fluid-structure interaction experiments, and subsequently […]

Read more ⇢
1 2 3 4 5 8