Sampling Random Numbers from Probability Distribution Functions

Christopher Boucher September 15, 2016

In this blog series, we’ll investigate the simulation of beams of ions or electrons using particle tracking techniques. We’ll begin by providing some background information on probability distribution functions and the different ways in which you can sample random numbers from them in the COMSOL Multiphysics® software. In later installments, we’ll show how this underlying mathematics can be used to accurately simulate the propagation of ion and electron beams in real-world systems.

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Caty Fairclough July 25, 2016

Quadrupole mass filters, the key component of quadrupole mass spectrometers, filter ions by their charge-to-mass ratio, only allowing ions with a certain ratio to pass through the device. As such, a high transmission probability for a specific ion through the filter is desirable. However, fringe fields in the mass filter can affect this probability. By using multiphysics simulation, we can take a closer look at quadrupole mass filters and investigate the effect of fringe fields on these devices.

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Christopher Boucher June 8, 2016

Static mixers are well-established tools in a wide variety of engineering disciplines due to their efficiency, low cost, ease of installation, and minimal maintenance requirements. When evaluating whether a mixer can be used for a certain purpose, it is important to determine whether the resulting mixture is sufficiently uniform. In this blog post, we will discuss the setup of an app designed to quantitatively and qualitatively analyze the performance of a static mixer using the Particle Tracing Module.

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Fanny Griesmer December 2, 2015

Healthcare-associated infections (HAI) affect millions of people around the globe. While the most common cause of HAI is direct contact with the source, airborne bacteria may also play a role in patient infections. To prevent airborne infection and make hospital clean rooms safer, it’s important to design efficient ventilation systems. As an added benefit, efficient ventilation designs also lead to lower energy-related costs. The first step to a better design is CFD modeling.

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Daniel Smith November 19, 2015

Many different tools are available for counting particles. Choosing the optimal method depends on the application; specifically, whether you want to use the number of counted particles in equations or during postprocessing. The Particle Tracing interfaces in COMSOL Multiphysics feature three main particle counting options. While these approaches are versatile enough to compute quantities such as charge density and momentum flux, our focus here will be computing the number of particles on a set of domains or boundaries.

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Bjorn Sjodin January 23, 2015

How can you use an electric field to control the movement of electrically neutral particles? This may sound impossible, but in this blog entry, we will see that the phenomenon of dielectrophoresis (DEP) can do the trick. We will learn how DEP can be applied to particle separation and demonstrate a very easy-to-use biomedical simulation app that is created with the Application Builder and run with COMSOL Server™.

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Bridget Cunningham December 16, 2014

Charge exchange cells are often used as a way to obtain neutralized beams of energetic particles. In this blog post, we introduce a model of a simple charge exchange cell and analyze its neutralization efficiency.

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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.

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Alexandra Foley August 25, 2014

Hematology analysis is an important step in medical diagnoses, often determining the treatment that a patient will receive. With a patient’s life on the line, it is vital that these analyses are accurate to the highest degree possible. Researchers at HORIBA Medical, a worldwide supplier of medical diagnostic equipment, turned to simulation to develop new methods for optimizing the accuracy of their hematology analysis devices. The resulting technique is currently used in some of their best-selling equipment.

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Laura Bowen July 16, 2014

The need for a contaminant-free space to manufacture medicine has led scientists to try many creative new approaches to improve the process. At Argonne National Lab, creating a device that floats and rotates chemical compounds in thin air was just the answer they were looking for. It meant two important changes: the amount of each chemical necessary could be implemented very precisely and the risk of outside impurities disrupting the results was minimized.

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Fanny Griesmer 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 then separated out from the fluid.

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