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All posts by Ed Fontes

Li-Ion Battery: Heterogeneous Alternative to the Newman Model

April 13, 2016

The Newman model and its variants form the standard theory used to successfully predict the behavior of lithium-ion battery design under a range of operating conditions. In the Newman model, the geometry of the porous structure of the battery electrodes is not described in detail; instead, typical averaged dimensions are used as input to describe the electrodes as homogeneous and isotropic materials. But how accurate is this approach compared to a detailed, heterogeneous geometric model? Let’s find out.

Free Surface Computations in Mixers and Rotating Machinery

January 26, 2016

The rotation of the impellers in a mixer or stirred reactor creates ripples on the liquid surface when the agitation is moderate. If the ripples are small in comparison to the height of the fluid in the vessel, the shape and height of the free surface can be explicitly calculated from the velocity field in a separate solution step. The latest version of the Mixer Module in COMSOL Multiphysics includes a Stationary Free Surface feature for such computationally inexpensive calculations.

Simulate Three-Phase Flow with a New Phase Field Interface

December 16, 2015

In COMSOL Multiphysics version 5.2, the CFD and Microfluidics modules include a new fluid flow interface for modeling separated three-phase flow. The model behind this fluid flow interface accounts for surface tension between each pair of fluids, contact angles with the walls, as well as the density and viscosity of each of the fluids. The phase field method computes the shape of the interfaces between the three phases and also accounts for interactions with walls.

Does the Current Flow Backwards Inside a Battery?

November 25, 2015

During the discharge of a battery, the current in the circuit flows from the positive to the negative electrode. According to Ohm’s law, this means that the current is proportional to the electric field, which says that current flows from a positive to negative electric potential. But what happens inside the battery? Does the current flow from negative to positive electric potential? This blog post explains the potential profile inside a battery during discharge and recharge.

Intro to Optimizing Mixer Design by Creating an App

July 6, 2015

Since we released version 5.0 of the COMSOL Multiphysics® software, you have the ability to create simulation apps — either starting from scratch or with a demo app from the Application Library. Today, we’ll introduce you to an app that can be used for understanding and optimizing mixer design and operation for a given fluid. The exemplified app models and simulates stirred tank mixers, which are used for reactors in the fine chemical, pharmaceutical, food, and consumer products industries.

Sensing the Bio in Biosensor Design with a Simulation App

May 12, 2015

Biosensors are the workhorses of the analytical tools used for detailed mechanistic understanding at the molecular level of biological systems. The applications of these analysis tools are countless for the detection of biomolecules in the pharmaceutical, health care, and food industries; agriculture; environmental technologies; and in general for research of biological systems. The biosensor demo app is a good example of an application where non-experts can benefit from accurate multiphysics simulations.

Parallel Universes, Schrödinger, Hawking, Borges, and One Direction

May 7, 2015

What is the relation between the extremely popular band One Direction, quantum mechanics, and cosmology? Stephen Hawking may just have explained this relation in one of his recent talks at the Sydney Opera House. It has to do with the prediction of parallel universes, where we, in an infinite number of worlds, could find worlds that are almost identical to ours but with all possible permutations and differences, much like the 410-page books in The Library of Babel by Borges.

Why Car Batteries Perform Poorly in Cold Weather

February 5, 2015

Starting the car on a cold winter morning can be unpleasant if you have not been proactive the night before. When you are unable to start an engine, it is often the battery’s fault. Why is a battery more sensitive than other processes in a car? The answer lies in the battery’s ability to convert chemical energy into electrical energy, with a minimum of heat generation, and the relatively small amounts of thermal energy available at low temperatures.


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