Hi, my name is Fernando Zigunov, welcome to my home page! Here I share some random ideas and projects I made. I love building complex engineering systems, which I happen to do both professionally and as a hobby. Hope you find some of them interesting!
OTHER RANDOM PROJECTS AND ARTICLES:
Maybe this is happening to you at this very moment: You build a shadowgraph, spend hours or days aligning the optics and finally get the camera installed. You put a regular camera lens, used in photography, to preserve the image quality as much as possible. You start focusing the focal ring of the lens such … Continue reading I can’t focus my shadowgraph!
Just wanted to put this out as this work in progress evolves! This is something really cool that I hope will make some interesting impacts in the active flow control community. In 2020, I’ve built and tested a solenoid array driver to individually toggle individually 108 solenoids. This work was published here in the AIAA … Continue reading [WIP] Machine Learning to Active Flow Control – Supersonic Nozzle Aeroacoustics!
I’m typing this out of a frustration that I’m sure many of my colleagues have already felt when assembling a shadowgraph or a Schlieren flow visualization system: Adjusting the LED focusing lenses! Let’s look at the optics of this problem and try to see the rather unintuitive trade-offs we are making when adjusting these lenses … Continue reading Why are shadowgraph LED lenses so hard to focus?
Have you ever wanted to make a nice timelapse where you have some camera motion? If you look in the market, there’s some (rather expensive) motorized sliders that you can buy. These usually go for $300-$600, but they don’t have much travel. For example, this model has a 31.5″ (0.8m) travel and costs $258. This one is $369 and … Continue reading Transform Your Camera Tripod Into an EPIC Timelapse Panorama Slider!
Introduction For those acquainted with POD (Proper Orthogonal Decomposition), it’s very easy to throw POD at everything data analysis related. It’s such a powerful technique! For those who aren’t acquainted, I really recommend. I’ll introduce with a refresher. If you’re good, follow to the next section! We can decompose a set of N dimensional data … Continue reading Using randomized snapshot POD to overcome SVD memory issues
I’m writing this because even though it’s already 2020, this kind of stuff still cannot be found anywhere in the internet! Stacking layers of materials is something we all do in so many engineering applications! Electronic components, batteries, constructions panels, ovens, refrigerators and so many other layered materials that are inevitably under heat transfer. We … Continue reading Thermal Stacks, Transmission Lines, high power LED’s and Temperature Sensitive Paints (TSP)
So in this (last) episode of our quest to visualize sound we have to do some sound-vis experiment; right? Well, I did the experiment with an ultrasonic manipulator I was working on a couple months ago. I built a Z-Type shadowgraph (turns out I didn’t have enough space on the optical table for a knife … Continue reading Sound Visualization: The theory works! – Part IV
As discussed in Parts I and II, we established that we can use a Schlieren or a shadowgraph apparatus to visualize sound waves. The shadowgraph is not as interesting an instrument, due to its stronger high-pass behavior. Nevertheless, both instruments are viable as long as one makes it sensitive enough to see the waves. When … Continue reading Sound Visualization: Nonlinearities – Part III
This continues our saga we started at Part I (spoiler alert: you’re probably better off with a Schlieren). Thanks to a good discussion with my graduate school friend Serdar Seckin, I got curious about applying the same sensitivity criterion to a shadowgraph system. Turns out, Settles’ book also has the equations for contrast in the … Continue reading Schlieren vs Shadowgraph for Sound Visualization – Part II
Tell me: Would you be excited to see sound? Well, I sure damn was when I first attempted to see the sound produced by an ultrasonic transducer! And still am, to be honest! So let’s learn how to do it with a Schlieren apparatus and the sensitivity considerations necessary in the design of a Schlieren … Continue reading Seeing Sound Waves with your Schlieren apparatus – Part I
So you’ve probably already seen demos on Youtube showing this really weird “camera effect” where they stick a hose to a subwoofer and get the water to look like it’s being sucked back to the hose, seemingly against gravity. I personally love this effect. In the case of the subwoofer, the effect is due to … Continue reading The anti-gravity piddler: A demonstration of aliasing
So I’ve been spending quite a bit of time thinking about vortex rings. Probably more than I should! I decided I wanted something that shot vortex rings filled up with smoke, but in a way that can last for very long periods of time. I came up with this idea that if I had an … Continue reading Smoke rings to the tune of AC/DC
Mathematics in the complex plane are sometimes surprisingly difficult to understand! Well, the complex numbers definitely earned their name! Maybe you’re also studying complex analysis, or have studied it in the past and didn’t quite understand it. The fact is, it requires a lot of imagination to see the concepts. I sometimes like to compensate … Continue reading Cutting mathematical sheets
As I discussed in this past post about MIDIJets, I was attempting to make a platform for surveying microjet actuator location and parameters in aerodynamic flows for my PhD research. But I think this is something that can be quite useful in many other contexts. After working with this for a couple months now and … Continue reading Driving a hundred solenoid valves
I, and also an increasingly larger population of the world, have concerned myself and dedicated countless hours to deliberating about the unfortunate fact of life that as we grow older, we eventually might not be able to provide for ourselves due to the natural degradation of our bodies. The capitalist society, however, provides us with … Continue reading Putting an errorbar in your money
As a disclaimer, I’m applying this technique in a scientific setting, but I’m sure the same exact problem arises when doing general macro photography. So, first, what is a Scheimpff…. plug? Scheimpflug is actually the last name of Theodor Scheimpflug, who apparently described (not for the first time) a method for perspective correction in aerial … Continue reading Scheimpflug – Tilt-swing adjustment in practice
So I’m currently working on this research problem: Microjets in cross flow for disturbance-based flow control. Jets in crossflow have some promise to be a viable flow control technique in aerodynamic applications, but it’s still in its early-mid research stages, where the technology has good theoretical support (i.e. it should work) and some experimental successes … Continue reading Jet actuator arrays, turning microjets into MIDIjets
Vortex core tracking is a rather niche task in fluid mechanics that is somewhat daunting for the uninitiated in data analysis. The Matlab implementation by Sebastian Endrikat (thanks!), which can be found here, inspired me to dive a little deeper. His implementation is based on the paper “Combining PIV, POD and vortex identification algorithms for … Continue reading Finding Vortex Cores from PIV fields with Gamma 1
Yes – You can go to Amazon.com today and buy one of these gimmicky toys that float a magnet in the air. Some of which will even float a circuit that can light an LED and become a floating light bulb. A floating light bulb that powers on with wireless energy? What a time to … Continue reading The floating light bulb: Theory vs Practice
(Edit: My entry on the Gallery of Fluid Motion using this technique is online!) For the ones not introduced to the art of Schlieren photography, I can assure you it was incredibly eye-opening and fascinating to me when I learned that we can see thin air with just a few lenses (or even just one mirror … Continue reading Sub-microsecond Schlieren photography