Coupling Piezoelectric and Fluid Simulations

ink jet nozzle

Ink jet nozzle

Piezoelectric devices surround us in our everyday life. Our cars and trucks contain many piezoelectric devices, including fuel level sensors, air bag deployment sensors, parking sensors and piezoelectric generators in the wheels to power the tire pressure monitoring system. Your smartphones or tablet contains piezoelectric sensors that detect the motion and orientation of the device, which my kids were using to good effect to play “Need For Speed” yesterday. Many of us have ink jet printers at home, which can use piezoelectric printer heads to eject thousands of drops per second. Continue reading

Readers Choice for Top 5 ANSYS Advantage Articles

I enjoy working on every article I coordinate for ANSYS Advantage magazine. I always learn something new while assisting ANSYS customers and staff tell their stories of excellence in engineering simulation. I have no favorites as I appreciate all of the articles. But, I decided to let our readers choose their top five, based on the power of downloading. The following are the most-read articles from the four issues (three regular issues and one special issue for oil and gas) of ANSYS Advantage published last year. All these stories have one thing in common: They feature robust and reliable design practices. Drumroll please …

Continue reading

Reshaping the Future of CFD Using Mesh Morphing

A cool title, isn’t it? Hello ANSYS blog readers! This is my first time in this blog as a guest blogger. You will notice a brief resume of mine together my photo as the author of this post, but let me introduce myself so that you can understand why I am here writing about mesh morphing to the ANSYS audience.

I am a Professor at University of Rome, with good experience in fluid structure interaction (FSI) and Fluent customization using UDF programming. Five years ago, driven by a Formula 1 Top Team, I developed a powerful mesh morphing tool crafted by tough specifications. Managing any kind of mesh, precise, fast and parallel! Nothing at that time was able to do this kind of job. We tried to go with (RBFs) Radial Basis Functions mesh morphing, one of the most promising techniques. And we made it. Continue reading

Powerfully Pragmatic Problem-Solving with CFD

The art of engineering can often be in finding pragmatic ways to use technology to solve real problems. While simulations may include an ever-increasing amount of geometric detail, it is not enough to simply generate ever finer meshes and use ever smaller time resolution. Simulations must still be solved in a reasonable time (and perhaps the one constant here has been that reasonable almost always means ‘overnight’). Therefore, until there is a dramatic breakthrough in computing power, modeling fluid flow will require engineering pragmatism in problem-solving for many years to come. But that need not be shouldered by the CFD engineer alone — ANSYS simulation software can support them in their efforts. ANSYS 15.0 contains multiple examples of how pragmatic approaches to efficient and effective simulation are contained in the software itself.

One such example is the dynamic combustion mechanism reduction capability in ANSYS Fluent. By automatically reducing the mechanisms to only the most important, dramatic reductions in simulation time can be achieved without the CFD engineer having to spend time and effort determining how to represent complex reaction mechanism in a simplified manner that models the behaviour sufficiently well. Instead, this pragmatism is built into the ANSYS software! Combined with further enhancements in ANSYS 15.0, it makes combustion simulation with even the most involved chemical reactions viable. Continue reading

Modeling Primary Atomization in ANSYS Fluent

Spray modeling has been a hot area of research especially in aerospace and automotive industries. The need to resolve the early development of sprays in the near nozzle area has grown steadily. However, this is a challenging area of modeling as resolving the liquid-gas interface is non-trivial due to complicated physical processes involved. Any modeling tool employed for this problem must be able to address the discontinuity in material properties at the interface as well as the effects of turbulence and surface tension forces at the interface.

There are some approaches that you can use currently in the context of CFD modeling. As a first approach, ANSYS Fluent’s DPM model offers something called “Atomizer” models that provide PSD based on the type of nozzle and some nozzle operational/geometrical parameters.

A second, more detailed approach is to use the VOF multiphase model to capture the liquid-gas interface at the droplet level. This requires a very fine mesh in the shear layers and hence is prohibitively expensive if entire length  of the spray needs to be captured. Continue reading

Transferring Forces from Fluent to System Coupling

A common question I hear from System Coupling users, particularly when using an operating pressure in ANSYS Fluent other than atmospheric pressure, is “Which pressure is used when transferring forces from Fluent to System Coupling and how do I change it?”.

The simple answer is that the forces passed to System Coupling are based on the gauge (or solved) pressure in Fluent by default. More accurately, the gauge pressure minus the Reference Pressure is used, but the Reference Pressure is zero by default so this is equivalent to the gauge pressure.

Before going further let’s review the Operating Pressure, Reference Pressure and gauge pressure.

The Operating Pressure in Fluent should be set to a typical absolute pressure in the system. Pressures set at boundary conditions are then specified relative to the Operating Pressure. Often the Operating Pressure is set to the absolute pressure at an outlet, and then a relative (gauge) pressure of zero is set at the outlet boundary condition(s). Continue reading

Last Minute Gift for the Holidays: How About a Robot Dragonfly Created with ANSYS Software?

Desperately searching for a gift for my nephew Dominick, I came across this article about a flying robotic Dragonfly that the Air Force has spent more than $1 million developing.

My first thought was ‘what kid wouldn’t want a flying insect that weighs less than one AA battery equipped with a camera that can be operated with an iPhone?’

My next thought was ‘Wait, a minute, I’m not shopping for myself.’

My third thought was ‘I’ve recently read about this device being created with ANSYS software.’

The Georgia Institute of Technology submitted this story and image to our 2013 Hall of Fame competition that has concluded. (Results coming, stay tuned.)

MAV Wing CFD

Here is what they told us: Continue reading

ANSYS Webinars, Events and Seminars This Week – Nov 5

image of Learning text on a keyboard ANSYS Webinars and EventsEach Monday, we like to give you a quick snapshot of the ANSYS webinars, seminars and other events of interest that are scheduled for the coming week. Today, I’d also like to take a moment to remind you that if you have missed any of our past webinars, you can find recordings in our Resource Library.

Here’s just a quick look at a few of the ANSYS webinars on tap this week. The full calendar is at the end of this post.

ANSYS Webinars – Including our Ask the Expert Series

Predicting Boiling Heat Transfer in IC Engine Cooling Jackets with ANSYS Fluent

Wednesday, November 07, 2012
4:00 pm EST, 9:00pm GMT (REGISTER)

There has been a change in the thermal management of IC engines where engineers now like to harness the superior cooling rates available when limited and controlled Nucleate Boiling is used to remove heat from high temperature zones. Any flaws in the design of such systems, such as uncontrolled heat transfer that leads to Film Boiling (Dry out condition), can have an adverse effect on the cooling performance. A detailed boiling heat transfer model for this design process would allow engineers not only to weed out flawed coolant passages early, but also to accurately predict the temperature for subsequent analysis like thermal stress analysis in solid, IC engine combustion analysis etc. Continue reading