COMSOL Workshops

COMSOL_Certified_Consultant

COMSOL Workshops

Over the years, our association with COMSOL has grown from one of novice user to avid user to COMSOL Certified Consultant to experts who provide Training Classes to help new and existing users maximize their use of COMSOL Multiphysics. Last fall, we had several conversations with COMSOL about a possible new association. As a result, this year we have been visiting Ohio cities with COMSOL staff members helping to conduct monthly free COMSOL Workshops.

 

Each workshop includes an overview of COMSOL in the morning during which AltaSim staff provide demonstrations of multiphysics modeling and discuss the functionality of different modules of COMSOL Multiphysics based on our real-world experience. The afternoon portion of each workshop focuses on a specific physics that changes each month as we make our way around the state. Some attendees stay for only the morning session and some stay for the entire day depending on topic and interest. So far, we have found four basic reasons people attend:

 

  1. You may be looking at COMSOL for the first time wondering if it is the kind of tool that can help
  2. You may already be a casual user needing some basic help
  3. You may be working through a free two-week trial trying to solve a specific problem
  4. You may be very adept at using COMSOL but still looking to grow your proficiency

 

In January, Kyle and Josh started our Ohio workshops in Independence focusing on Heat Transfer & Structural Mechanics. In February, Kyle and Luke were in Columbus covering Heat Transfer & Fluid Flow. In March, Kyle and Josh went to Toledo and taught on Heat Transfer & Structural Mechanics. This month, Kyle and Sergei were in Fairborn teaching about the App Builder & Aerospace Applications.

 

Below are links for the workshops we will be conducting over the next two months.

 

Cincinnati, OH May 21, 2015 – App Builder & Biomedical Workshop
http://www.comsol.com/events/id/45911

 

Independence, OH June 4, 2015 – App Builder & Biomedical Workshop

http://www.comsol.com/events/id/46351

 

As founding members of the COMSOL Certified Consultants program we combine our expertise in COMSOL Multiphysics® and our ability to extend its functionality with our in-depth knowledge of physics, mechanics, computational science and real world processes to a wide range of applications. Our desire in these free workshops is to help each attendee discover how together AltaSim and COMSOL can help them solve their challenging design problems in new ways that will have an impact on their business.

We will provide additional information about upcoming workshops through our monthly email newsletter. If you would like to receive this information directly in your email, then subscribe by entering your name and email address in the “Newsletter Registration” section on the right side of the webpage.

 

Training & Teaching Helps Us Grow

Training & Teaching Helps Us Grow

 

One of the Core Values we keep coming back to is #6 – “Courage of our Convictions.” Taking into consideration our other Core Values, we understand it is a fine line we walk when we communicate confidence in our authority to operate our business and act boldly to grow the business and serve our customers. Simply saying “we want to serve our customers” does not really mean anything unless we back it up with actions. That is precisely why we dig around and look for COMSOL Tips & Tricks to share often – monthly if possible. In case you missed them, below are several links you can use to access previously shared Tips & Tricks. Our desire is that you would benefit and grow in your ability to solve using COMSOL Multiphysics®.

Continuation

Using the Free Tetrahedral

New in v5.0-Parametric Sweeps

Built In Capabilities

Stress and Strain Variables

 

And clicking on any one of these links will give you access to our complete Archives… so help yourself.

 

But we know that Tips & Tricks is not enough, and since we use COMSOL everyday in our own consulting work, we continue to look for ways to blend our experience with our desire to see others thoroughly trained in the use of COMSOL. In fact, we want to utilize our expertise to help others become experts. As a result, we humbly share our 6-Month COMSOL Training Calendar as another option for you to go deeper and grow better skills in solving. The link below represents the Training Classes we offer over the next six months.

 

Six Month Training Calendar

 

If you have any questions whatsoever about any of these classes regarding content, instructors, desired outcomes, etc, we welcome your inquiry. You can use the “Training Inquiries” form on our COMSOL Training page, send an email to dave@altasimtechnologies.com, or call us at (614) 861-7015.

 

One thing we know – we grow when we help you grow!

 

Computational Model for Bolometer Design

Computational Model for Bolometer Design

 

Bolometers are used in a number of applications including night vision cameras, astronomy, and particle physics to measure the power of incident electromagnetic radiation. The principle of operation is shown in Figure 1: when a strip of conducting material is exposed to incident electromagnetic radiation, energy is absorbed and the temperature of the material rises. The resulting reduction in electron mobility manifests itself as a reduced electrical conductivity. If a bias current is already flowing through the strip then a reference potential is known and any change in conductivity causes a change in the reference potential which can be related to the amount of incident electromagnetic radiation. Depending on the rate of change in the material’s electrical resistance with temperature and specifics of the bolometer design, temperature changes less than 0.0001°C can be detected. To explore the effect of bolometer designs on detection of incident electromagnetic radiation, a parameterized computational model of a bolometer was developed using COMSOL Multiphysics ®. The geometry and material definitions are shown in Figure 1

 

figure1

Figure 1: Bolometer Model Geometry and Materials

 

The functioning of these devices is based on three main physical phenomena: radiation through the ambient environment, heat transfer within the solid parts and conservation of electric currents. Because of the multiphysics nature of the device, COMSOL Multiphysics is well-suited for modeling, testing, and designing these devices. When the incident electromagnetic radiation is associated with sunlight the external radiation source can be defined via the solar position option in which the direction and intensity of the sun’s incident radiation is based on the latitude and longitude position on the Earth, the date, and the time. For modeling the actual bolometer, the heat transfer and electric currents equations are coupled together and solved simultaneously because of their intimately coupled nature. The bi-directional couplings are:

 

  1. The electrical conductivity: σ, is temperature dependent
  2. The resistive heating, Q, is a function of the voltage gradient; this is also known as Joule heating

 

Figure 2 shows schematically how the equations are linked; the heating term, Q, also includes a contribution from the incident light on the top boundary of the strip which drives the functioning of the device.

 

Figure 2: Multiphysics Couplings

Figure 2: Multiphysics Couplings

 

Bolometers show greatest sensitivity when operating in a regime in which the absorbing strip material shows a strong dependence of conductivity to temperature. Depending on the material chosen for the absorbing strip, some bolometers may be more sensitive when operated at cryogenic temperatures. The results shown here are for a copper material which shows a strong dependence of conductivity to temperature in the 10-50 K range (see Figure 3). This bolometer is most sensitive when the operating temperatures are kept within this range. In contrast, specialty materials that are conductivity-sensitive at room temperatures are also available.

Figure 3:  Temperature dependent electrical conductivity of Copper

Figure 3: Temperature dependent electrical conductivity of Copper

 

Results for analysis performed here are presented below for temperature (Figure 4), current flow (Figure 5), and the change in voltage due to the sun’s heating off the top boundary of the strip (Figure 6).

Figure 4: Temperature contour plot

Figure 4: Temperature contour plot

 

Figure 5: Current Flow

Figure 5: Current Flow

 

Figure 6: Change in Voltage Due to Incident Radiation

Figure 6: Change in Voltage Due to Incident Radiation

 

An important design parameter for bolometers is sensitivity, S, defined as change in voltage divided by amount of incident light wattage absorbed.

 

equation

Good bolometer design seeks to maximize the sensitivity of these devices. Research has shown a number of design parameters can have an effect on sensitivity including the strip spacing, surface area of the strip, aspect ratio of the strip, material selection, as well as the operating temperature of the bolometer1. The loft feature available with the COMSOL Multiphysics v5.0 Design Module add-on enables the parametrization of the strip spacing parameter defined in Figure 7.

Figure 7: Geometry Side-View

Figure 7: Geometry Side-View

 

The effect of strip spacing can be seen in Figure 8, with increasing space between the mounting board and the serpentine absorber the sensitivity of the bolometer increases. This phenomenon is consistent with the operation of the device that seeks to establish the conducting absorber as a thermal isolator.

Figure 8: Strip spacing parameter study

Figure 8: Strip spacing parameter study

 

Extensions of studies of this type have been used to develop customized bolometer designs to meet the requirements of specific application.

 

Reference:
Stockhausen, Axel, “Optimization of Hot-Electron Bolometers for THz Radiation,” KIT Scientific Publishing, June 2013