COMSOL Blog

Heat Transfer | Posted on March 26th, 2013 by Valerio Marra

A lot of effort is put into inventing or improving existing technologies used to cool buildings, food, or any goods that need to be stored at a definite temperature. The reason is simple: adopting more efficient designs will result in achieving the same goal while consuming less energy. Both our balance sheet and the environment will benefit from these solutions. Here we will explore modeling temperature of a passive cooling design using a wine cellar as an example.

Read more on: Modeling Temperature of a Wine Cellar

Fluid | Posted on March 13th, 2013 by Valerio Marra

I love trees and my favorite is definitely the ficus, all varieties included. A few weeks ago I had the chance to admire a stately ficus microcarpa (see figure below). What struck me above all were its aerial roots. Roots are designed to absorb water and nutrients, sustaining the tree and synthesizing substances responsible for its growth. A thought crossed my mind right away: the shape of those roots and the way they coalesce have surely been optimized by Mother Nature.

Read more on: Optimal Distribution: Tree Roots and Microreactors

News | Posted on February 25th, 2013 by Valerio Marra

A while back, I bought a bag of marshmallows, indulged a bit, and then forgot about the opened bag for a few weeks. To my surprise, and disappointment, when my marshmallows cravings returned the top ones were rock-hard while the bottom ones were almost as soft as when I bought them. Why was this the case? By leaving the bag open, water had migrated from the marshmallows into the air.

Read more on: When Marshmallows Become Rock-hard

Tips & Tricks | Posted on February 13th, 2013 by Valerio Marra

As discussed in On Solvers: Multigrid Methods (referred to as “Part 1″), iterative methods eliminate oscillatory error components efficiently while leaving the smooth ones almost untouched (smoothing property). The main idea behind multigrid methods is to use the smoothing property, spatial aliasing, and the residual correction to the advantage of convergence. Before putting all the pieces of this proverbial puzzle together, we need to introduce residual correction and, even though we talked about it in the previous blog post, dig a little bit more into spatial aliasing. Let’s start with the latter.

Read more on: On Solvers: The V-Cycle Multigrid

Tips & Tricks | Posted on February 8th, 2013 by Valerio Marra

The differential equations that describe a real application admit an analytical solution only when several simplifying assumptions are made. The insights we gain from this approach are still valuable, but are not enough to confirm that our design is efficient or reduce the number of prototypes needed to reach a complete understanding of our application. This is why numerical solution methods are so important to us. They have been developed to overcome such limitations and allow us to represent our equations, on a grid obtained by partitioning the domain representing our application, in matrix form as , where is the vector solution. Once we have determined and , all we have to do is to “find” . It is important to note that the matrix form, both for stationary and transient applications, is obtained by finding a linear approximation to our equations. Nowadays, several solution methods are available. Here we will explore the ideas behind multigrid methods available in COMSOL Multiphysics.

Read more on: On Solvers: Multigrid Methods

News | Posted on January 28th, 2013 by Valerio Marra

When I first heard about Carnot’s theorem, I was impressed with its simplicity. Yet, no matter the amount of hard thinking we put into the design of everyday heat engines, we will never reach the efficiency of a Carnot engine. Still, modern-day heat engines are still effective as they get us from point A to point B by car or truck.

Read more on: What is Efficiency?

Fluid | Posted on January 22nd, 2013 by Valerio Marra

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 solid than a fluid under the percussive action of the speaker’s cone. Non-Newtonian fluids are another fascinating counter-intuitive effect to study.

Read more on: Non-Newtonian Fluids, Between Solids and Fluids

Postprocessing | Posted on January 14th, 2013 by Valerio Marra

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.

Read more on: CFD Postprocessing

Fluid | Posted on January 3rd, 2013 by Valerio Marra

Nature is full of counter-intuitive phenomena; I’m fascinated by everyday examples like the one we talked about this summer, sinking bubbles in a pint of Guinness, but I have to say that engineering has its fair share of such examples too. The concept of heat exchange in coaxial pipes struck me as a student, as it showed me the relentless tinkering attitude typical of engineers wanting to optimize their design. In this kind of heat exchanger both streams, hot and cold, may flow in the same direction (parallel-flow) but normally engineers prefer to reverse the direction of one stream (counter-flow), as they have found it to be more efficient. The simplicity of this design idea is striking; it’s not at all intuitive for a young engineer-to-be.

Read more on: Efficient Heat Exchanger, it’s all in the Pipes

Fluid | Posted on December 21st, 2012 by Valerio Marra

The winter here in Boston has been very mild so far. A few days I would even have liked to have the air conditioning back on. I checked in with one my colleagues to check if he was having an equally hard time staying cool, and to my surprise, he was not. Why? He had constructed a make-shift air conditioner (A/C).

Read more on: Make-shift Air Conditioner: How Engineers Can Stay Cool at Work (Maybe)