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 […]

The fact that oil and water don’t mix is something that you are probably all familiar with. At one point or another, you’ve most likely noticed what happens when you shake a bottle of say, Italian salad dressing, and the liquids mix momentarily, only to become separated again within seconds as oil bubbles rise to the surface. Creating a simulation describing how these two immiscible fluids interact is a great way to introduce computational fluid dynamics (CFD) applied to two-phase […]

Water purification is the process by which chemicals, contaminants, and sediments are removed from dirty water to make it clean, and there are many processes through which this can be done. What you might not know, is that ozone molecules can be used as a means of disinfection in the purification process. “Ozonation” has been used to purify water, kill germs and bacteria in food, and even get rid of bad smells. Not only does ozonation provide clean water without […]

Ultra-precise optical components require blemish-free surfaces that often cannot be achieved by the machining processes that grind these components. Fluid jet polishing (FJP) is a new technology being developed by Zeeko Ltd to replace the hand polishing that was often required. With the help of COMSOL, Zeeko was able to create a product that polishes the optical components in only ten minutes instead of an entire day, and without waveforms.

One of my favorite sitcoms is “The Big Bang Theory”, thanks to its focus on physics. From time to time they run funny experiments that can be easily arranged at home, causing me to wonder if I know the physics that are at work. One of my favorite episodes is when they fill the cone of a speaker with a suspension of starch in water. Instead of spattering around, the suspension starts to dance because it behaves more like a […]

Of all boats, I find sailboats to be the most fascinating, especially when sails are their only means of propulsion. Kinetic energy is transferred from the wind to the sails, which results in a lift force that balances drag forces and allows the sailboat to move through the water. We are all familiar with the parts of a boat above the waterline: deck, spars, sails, and the rudder used to turn the boat (figure 1c). Not everyone pays attention to […]

If you enjoy ketchup with your food, there’s a good chance you’ve experienced what we’ll call here the all-or-nothing ketchup quandary. You know, that moment when you reach for a new glass bottle of ketchup, remove the cap, and turn the bottle practically upside down — and then nothing happens. Intuitively, you shake or tap the bottle, and then suddenly your food is completely coated in ketchup (unless your reflexes are really good, of course). In this blog post, we […]

The use of acoustic waves to manipulate suspensions of particles, such as cells, has inspired the work of many researchers, paving the way for the field of ultrasound acoustofluidics. The manipulation is achieved in many ways, including using bulk acoustic waves (BAW) and surface acoustic waves (SAW), as well as acoustic radiation forces and acoustic streaming-induced drag. The latter two combine to produce the acoustophoretic motion of the suspended particles; i.e., movement by means of sound, and the methods provide […]

Microbubbles filled with oxygen can be injected into contaminated lakes to restore the water quality. Typically, water is purified via water-treatment plants, but this microbubble technique is both inexpensive and more environmentally-friendly in comparison. As seen in a COMSOL News 2011 article, oxygen microbubbles are a researcher’s way of copying nature’s own self-restoration mechanism for cleaning contaminated lakes.

We have written several blog posts on postprocessing already, but none detailing postprocessing for CFD. Postprocessing has always been an important part of my teachings, as you learn how to use COMSOL Multiphysics while also gaining insight into the physics at hand. I would like to share with you part of the classwork I proposed when teaching a CFD training course not long ago.