Fluid

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 […]

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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 […]

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Alexandra Foley | September 11, 2013

Shell and tube heat exchangers are one of the most widely used type of heat exchanger in the processing industries (65% of the market according to H. S. Lee’s book, Thermal Design) and are commonly found in oil refineries, nuclear power plants, and other large-scale chemical processes. Additionally, they can be found in many engines and are used to cool hydraulic fluid and oil. There are a variety of different configurations for these heat exchangers, but their basic concept can […]

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Nagi Elabbasi | September 6, 2013

Today we have the pleasure of welcoming Nagi Elabbasi of Veryst Engineering as a guest blogger. Read on to see what this COMSOL Certified Consultant has to say about fluid-structure interaction. Two weeks ago I led a webinar on fluid-structure interaction (FSI) using COMSOL Multiphysics. FSI involves coupling between a deformable or moving structure and a surrounding or internal fluid flow. There is a growing number of engineering and scientific problems where a purely structural or purely CFD analysis just […]

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Laura Bowen | August 29, 2013

When it comes to recreational water sports, simulation can make a dramatic difference in performance. Skimboards are a perfect example of this. These short, thin boards are similar to surfboards without fins and they allow riders to float on the water’s surface and glide. In order to improve the design of the board, one group of researchers relied on hydrodynamics to understand the interaction between water and skimboards.

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Fanny Littmarck | August 27, 2013

Plate heat exchangers have a larger surface with respect to their volume as compared to a conventional shell and tube design, making for an efficient temperature regulation device. As the name infers, these types of heat exchangers consist of layers of corrugated metal forming channels in between. In order to optimize their performance, you need the flow through the channels to be well-distributed. As you can imagine, the flow is very detailed and modeling it can be computationally demanding, if […]

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Alexandra Foley | August 22, 2013

There are many different routes through which drugs and other medications can be delivered into a patient’s body during treatment. These include topographical ointments, pills, vaporizers, and injection systems, among others. Many of these drug delivery systems require an enormous amount of precision when it comes to the location, timing, concentration, and amount of the drug to be administered. This is where simulation can be a big help, as it can allow for the modeling of each of these aspects […]

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Alexandra Foley | August 21, 2013

Solar photovoltaic (PV) cells are semiconductor devices that directly convert solar energy into electricity or voltage using the photovoltaic effect. These PV cells are more commonly known as solar cells, or solar panels, and in 2012 they produced roughly 93 terawatt-hours (TWh) of electricity — enough energy to power over 20 million homes. Because the cells must be directly exposed to the sun’s rays, they are housed outdoors where the panels are affected by the elements. Therefore, the cells must […]

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Matheus Fernandes | August 9, 2013

Suppose we have a rectangular microchannel containing a laminar flow with Reynolds number Re = 1. Next, let’s randomly distribute suspended particles at the channel’s inlet. Given that there are no external forces acting on these particles, you would intuitively expect that the particles would trace the fluid streamline. However, scientists from Massachusetts General Hospital (MGH) and Veryst Engineering would disagree, and their research findings suggest a completely different pattern than what would be expected. The researchers claim that depending […]

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Alexandra Foley | August 8, 2013

When pesticides are used in crops to control pests, their effects on the environment continue even after they have served their purpose. Pesticides can leach into the soil and water sources that both humans and animals depend on, spreading harmful chemicals to the surrounding ecosystem. Over time, their active ingredients are detoxified through different reactions that occur after their release, eventually degrading them into harmless products. Understanding the pesticide runoff patterns and mobility of various pesticides before and after they […]

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Matheus Fernandes | July 31, 2013

When you think of a valve, what is the first thing that comes to mind? Electromagnetic waves, or perhaps, Stokes flow separating charged chemicals in a microchannel system? Maybe neither. The truth is, when researchers try to separate small (in the picoliters region), well-defined sample volumes of chemicals, the dispensing accuracy provided by a mechanical regulator probably won’t suffice. An electrokinetic valve, a type of microfluidic valve, on the other hand, provides the perfect solution by giving researchers the flow […]

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