Aerodynamics of a hot coffee cup

 Just for fun:



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PIVlab 3.00 released

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  I have just released PIVlab 3.00. There are several changes in the way the graphics are drawn, the way the data is exported and the way it interacts with masks / calibration and region of interest: New graphics: Transparency, masks are transparent, only ROI is opaque Colorbar is now outside the plot for much improved readability Export image data as .mp4 and as .png image Completely new mask handling, allowing much easier mask creation / modification. Mask stay editable all the time. Much easier to create holes in masks Mask operations like shrink/grow/simplify/subdivide/optimize Automatic mask generator, capable of automatic masking of bright areas / dark aread / low-contrast areas. Possibility to add more automatic mask generators in the future Mask import (of user generated masks) heavily improved Matlab Online fully supported New line extraction and area extraction interface: More straightforward and faster. Better interaction Natural file name sorting when importing image fi...
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Comparison of OpenPIV and PIVlab

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Since quite a while, I benefit from discussions with the main developer of OpenPIV (Prof. Alex Liberzon  from Tel Aviv University) and other people that contribute to OpenPIV. It is almost a bit like a cooperation, as we share thoughts on different topics, and Alex is really into practical and theoretical PIV application. I think we have a very friendly rivalry in developing useful PIV software. The results are available here:  https://github.com/alexlib/openpiv_pivlab_von_Karman_data You will notice that they are very noisy. But we intentionally decided to make the analysis very challenging for our software. The final interrogation area is e.g. only 6*6 pixels, and no smoothing is allowed. I don't really see a difference between OpenPIV and PIVlab, which is probably a good sign. It might be interesting to include commercial software too in this comparison in the future. By the way: Happy New Year to all PIVlab users (and of course all OpenPIV users too ;-D). The year 2020 has...
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High-speed low-cost PIV with the pulsed laserdiode: Examples

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Recently, I asked Prof. de Payrebrune from the University Kaiserslautern / Computational Physics in Engineering if they could lend me their Chronos 1.4 low-cost high-speed camera for some tests. She agreed to support the development of PIVlab which is very cool and kind of her!! Now I did some tests with the camera (captures data at 1.3 megapixels at 1000 Hz) and my new LD-PS pulsed laser diode. The LD-PS has a built-in synchronizer, so it triggers the Chronos and can also do frame-straddling. The Chronos has absolutely brilliant trigger characteristics, as you have complete control over the exposure timing. Now I am not limited to an interframe-time of 1/1000s anymore, but can go down to 10 µs.  When capturing data at 1000 fps, the duty cycle of the illumination becomes quite high. So I added two little fans to the LD-PS housing. Now a duty cycle of up to 50% can be reached without the laser or the driver becoming too hot. The awesome Chronos high-speed camera from krontech.ca La...
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