COMSOL Day: Simulation in Engineering Education and Research

Simulating the Effects of Brief Periods of Eye Closure on the Dynamics of pO2 Underneath a Contact Lens Using COMSOL Multiphysics^®

Restriction of corneal oxygen supply from the external environment can lead to a number of corneal disorders. The overall goal was to quantify the microenvironment based on noninvasive fluorescence spectroscopy so that one may initiate strategies to alleviate the problems secondary to contact lens wear. The specific objective of this study was to simulate unsteady-state diffusion of oxygen in the human cornea. A frequency-domain approach was employed to measure the lifetime for enabling extremely rapid pO2 measurements. In this study, we developed an unsteady-state reactive-diffusion model and gave attention to corneal oxygen diffusivity and solubility. We also adopted nonlinear Monod kinetics to describe the physiological dependence of the oxygen consumption rate on oxygen tension. The model was simulated in COMSOL Multiphysics^® by defining the boundary conditions and necessary parameters. The parameters on which the oxygen consumption depends were also determined.

Multiphysics Analysis of MEMS Devices

COMSOL Multiphysics^® is used extensively at the National MEMS Design Centre at NIT Silchar to design and optimize the performance of different RF MEMS switches. After the calculation of electrical characteristics of the device is made, researchers revisit the structure and modify it to suit the present trend. COMSOL Multiphysics^® allows for simpler results analysis and graphic extraction while the compatibility of MPH-files with other tools enables direct importing of the model into these tools. At NIT Silchar, researchers have created a kidney-on-chip model using the Microfluidics Module, which supports various kinds of biostudies, such as particle tracing and solute reaction. The design includes a sophisticated structure that goes through critical studies and performance simulations before it is fabricated. On simulation and analysis, the structure has shown satisfactory performance and is currently under fabrication. The flexibility to incorporate different structural changes and different multiphysics phenomena makes the design more realistic and therefore reliable. A micropump with nozzles has also been developed for a microdrug delivery system, wherein the required flow and pressure analysis is done using simulation.

Plasmonics for Structural Color and Image Processing Applications

Light-matter interactions at the nanoscale underpin the massive growth of recent interest in applications of nano-optics where incident visible light is modified on transmission through, or reflection from, tailored nanostructures. Supporting experimental research, COMSOL Multiphysics^® is an invaluable tool in optimizing device design prior to potentially time-intensive and costly nanofabrication processes as well as providing insights into the fundamental science underpinning performance. Furthermore, it provides support for theoretical research into rapid, quasi-analytic approaches to probing the physics of these structures. Specific examples from ongoing research into plasmonic structural color and all-optical image processing will be presented.

Modeling and Simulation of Electrochemical Energy Conversion and Storage Devices

Electrochemical energy conversion and storage systems play a significant role in a wide range of applications. These devices are critical, enabling electric transportation, the transition to renewable energy, energy management, conservation, and storage. Modeling, simulation, and optimization of these electrochemical energy devices provides much-needed insight for improvement in cost, lifetime, and performance, leading to continued expansion into existing and emerging market sectors. These technologies will have a substantial impact on the environment and the way we produce and utilize energy. COMSOL Multiphysics^® is a well-established tool for modeling and simulation of different electrochemical energy technologies such as lithium-ion batteries, proton exchange membrane fuel cells (PEMFCs), and vanadium redox flow batteries. This talk will present the work done in modeling the different components of a PEMFC, namely the flow channel, gas diffusion layer, catalyst layer, and membrane. Species transport phenomena, electrochemical reactions, current distribution, and the flux transfer taking place at each layer are modeled. The model developed provides significant insight into the voltage-current relation and power output under varying design and operating parameters, some of which will be presented. A brief overview of the use of COMSOL Multiphysics^® in other electrochemical systems, including lithium-ion batteries and redox flow batteries, will be presented.

Design and Analysis of Resonant Microsensors and Piezoelectric Energy Harvesters

Resonant sensing has become a very popular method for measuring physical, chemical, and biological phenomena and has been implemented in numerous devices for the measurement of acceleration, biological detection, density, flow, force (AFM cantilevers), gas detection, humidity, mass, magnetic field, temperature, and viscosity. Energy harvesting from ambient vibrations has been actively undertaken using smart materials such as piezoelectric materials. One of the most significant issues in energy harvesting using piezoelectric materials is to achieve high output voltage (power) in a broad operating frequency range. This talk will cover resonant pressure sensors; resonant magnetic field sensors; vibrational energy harvesters including broadband; and how they are designed, analyzed, and optimized using COMSOL Multiphysics^®. The experimental results are demonstrated to be in close agreement with the simulation results obtained from COMSOL Multiphysics^®.

Modeling of Food Processing Operations Using COMSOL Multiphysics^®

Food processing operations are complex and associated with intricate changes in terms of biochemical, physical, microbiological, nutritional, and sensory quality. While the focus here remains on food structuring, food science also considers the destructuring component — food digestion and absorption. Overall, this explains a series of operations from farm to fork and the body wherein food is utilized. With the potential of COMSOL Multiphysics^® spanning across several sectors, its application range in the food industry is also vast. Research, academia, and industry have used simulation as a powerful tool to optimize various food processing unit operations, improve equipment design, and understand process capabilities, which contributes to overall process control. Accordingly, the focus of this talk will be on detailing the wide range of applications where multiphysics simulation can complement existing tools and techniques. Interesting applications include understanding the hydration behavior of a different variety of paddy at different soaking temperatures, describing the volume expansion, crust formation, and evaporation during the bread baking process, and studying the shrinkage and porosity variations on potato slices during drying. Another area of exploration involving the peristalsis of the stomach during digestion was modeled by considering the real stomach shape and its movement. The action of physical forces experienced inside the stomach was used to predict pressure distribution and velocity fields with different changeable viscosities of ingested meals. Similarly, the intestinal peristaltic movement during the digestion process and the absorption of vitamin E was modeled. An investigation on the effect of glycemic response showed that depending on proximate contents of the food, the glycemic response also varied. Overall, the talk will provide insights into the need for interdisciplinary research and cast light on the capabilities of COMSOL Multiphysics^® for the food industry, with an emphasis on current challenges and research needs.

Modeling and Simulation of Ultrasound-Assisted Additive Manufacturing

Advances in additive manufacturing techniques have enabled the development of novel and structural composite materials, such as those that possess multilevel hierarchical microstructures. These structures can be designed to have good strength-to-weight ratio, sometimes mimicking those found in nature. The ability to control and tune such microstructures bottom-up, starting from the microstructure, is critical to fabricate such composites. In this talk, the use of an ultrasound-assisted additive manufacturing process will be presented. An ultrasound field is used as a force field within a 3D printing setup to enable the self-assembly of particles or filler materials with a fluid resin. A COMSOL^® model is presented to describe the setting up of an ultrasound field and the tracking motion of particles under the acoustic radiation force. The simulation involves multiple physical phenomena that are coupled together, including the piezoelectric actuator, structure of the vat container, ultrasound field, and the particle-fluid drag. Simulation results from this model show the filler particles agglomerating at the pressure nodal lines, forming desired patterns under the influence of the ultrasound field. The simulation results are comparable and similar to observations in our preliminary experiment setup. The validation of this model provides us with a design tool to study the effect of various parameters in the 3D printing process.

Hyperloop Technologies: Modeling and Optimization Using COMSOL Multiphysics^®

Hyperloop is an upcoming mode of transportation envisioned for high-speed travel in low transit times. At team Avishkar Hyperloop, we aim to research and develop Hyperloop technologies ranging from contactless propulsion and levitation to eddy current and regenerative braking. Through the course of our presentation, we will take you through the linear induction motor, circular levitator machine, and eddy current braking mechanism, all of which have been designed, modeled, and optimized using COMSOL Multiphysics^®.