# COMSOL Blog

## New Accumulators Boost Particle and Ray Tracing Functionality

##### Christopher Boucher | November 26, 2014

With the release of COMSOL Multiphysics version 5.0, the Particle Tracing Module now includes a series of features called Accumulators, which can be used to couple the results of a particle tracing simulation to other physics interfaces. The accumulated variables may represent any physical quantity and can be defined either within domains or on boundaries, making them extremely flexible. Here, I will explain the different types of accumulators and their applications in particle tracing and ray optics models.

### Which Fatigue Model Should I Choose?

##### Mateusz Stec | November 25, 2014

The most frequent question we get regarding the Fatigue Module is “Which fatigue model should I use in my simulations?” There is no straight answer to this question, since fatigue is not based on an exact differential equation, but on engineering observations that lead to different physical models. The applicability of each model can depend on factors such as material and loading type. Today, I will discuss different approaches for fatigue model selection and the applicability of the different models.

### Create Geometry from an Imported Mesh

##### Andrew Griesmer | November 24, 2014

Importing meshes into COMSOL Multiphysics is often necessary when interfacing between different programs. With COMSOL Multiphysics version 5.0, these meshes can be converted into solid geometry objects for further investigation and modeling capabilities. You can also perform boolean operations on the new geometry for CFD, electromagetics, and acoustics applications.

### Apps for Teaching Mathematical Modeling of Tubular Reactors

##### Ed Fontes | November 21, 2014

The Tubular Reactor application is a tool where students can model a nonideal tubular reactor, including radial and axial variations in temperature and composition, and investigate the impact of different operating conditions. It also exemplifies how teachers can build tailored interfaces for problems that challenge the students’ imagination. The model and exercise are originally described in Scott Fogler’s book Elements of Chemical Reaction Engineering. I wish I had access to this type of tool when I was a student!

### Working with Imported CAD Designs

##### Lorant Olasz | November 20, 2014

The CAD Import Module, Design Module, and the LiveLink™ products for CAD include tools for repairing and preparing a geometry for simulation. They are powerful additions to the geometric modeling capabilities of COMSOL Multiphysics. Let’s discuss how these tools work and when to apply them.

### A Brief Introduction to the Weak Form

##### Chien Liu | November 19, 2014

This is an introduction to the weak form for those of us who didn’t grow up using finite element analysis and vector calculus in our daily lives, but are nevertheless interested in learning about the weak form, with the help of some physical intuition and basic calculus.

### Modeling Thermally Induced Focal Shift in High-Powered Laser Systems

##### Christopher Boucher | November 18, 2014

Almost all media absorb electromagnetic radiation to some extent. In high-powered laser focusing systems, a medium such as a glass lens may absorb enough energy from the laser to heat up significantly, resulting in thermal deformation and changing the material’s refractive index. These perturbations, in turn, can change the way the laser propagates. With the Ray Optics Module, it is possible to create a fully self-consistent model of laser propagation that includes thermal and structural effects.

### Analyzing Aircraft Engine Noise Through Simulation

##### Bridget Cunningham | November 17, 2014

The reduction of aircraft engine noise has been a priority in the aviation industry for many years. Minimizing sound emissions, of course, requires an understanding of engine noise — a task that can become quite challenging due to the complex nature of aircraft systems and geometries. Using a model of an aero-engine duct, we provide a more in-depth look at the acoustical field in aircraft engines.

### Introducing the Ray Optics Module

##### Walter Frei | November 14, 2014

The release of COMSOL Multiphysics version 5.0 includes a new add-on module for electromagnetics modeling: the Ray Optics Module. This optional add-on module includes the Geometrical Optics interface, which can be used to model the propagation of electromagnetic waves when the wavelength is much smaller than the smallest geometric entity in the model. The Geometrical Optics interface includes a wide variety of features and optional settings and it is fully multiphysics capable.

### Why Haven’t CPU Clock Speeds Increased in the Last Few Years?

##### Pär Persson Mattsson | November 13, 2014

The first computer I used was a real performance beast. Equipped with Intel’s 486 clocking in at 66 MHz, this machine was ready to take on whatever challenges the future would bring us. Or so I thought. The CPU clock speeds increased and soon passed 500 MHz, 1 GHz, and continued upwards. Around 2005, the top speed of the high-end processors settled around 4 GHz and hasn’t increased much since then. Why is that? I’ll explain.