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-   -   schlieren output (http://www.cfd-online.com/Forums/tecplot/90615-schlieren-output.html)

 wisemo July 15, 2011 13:56

schlieren output

Hi

How is it possible to get a Schlieren type image output using Tecplot? (I've checked the archives...though a few have asked this question, they have gone unanswered)

Thank you

 scott_rumage July 15, 2011 18:19

Tecplot 360 can make a “simulated” Schlieren via flooded contours of the density magnitude. Image #7 on this link gives an example: http://www.tecplot.com/Community/PlotGallery/2DPlots.aspx
BTW - a Shawdowgraph is calculated via the 360 menu bar: Analyze>>Calculate Variables>>Shawdowgraph (but I did not find the Schlieren calculation referenced in the above link).
I hope this is of some help.
Scott

 wisemo July 16, 2011 19:11

Thanks Scott, that was actually helpful. That'll be something I'll be needing too!

I'm trying to experiment with the density related variables to give me a Schlieren type image at the moment.

 wisemo July 16, 2011 19:53

Quote:
 Originally Posted by scott_rumage (Post 316297) Tecplot 360 can make a “simulated” Schlieren via flooded contours of the density magnitude.
That doesn't give me the Schlieren :(. I see only a single colour on my plot when I do that.

 AeroMike January 8, 2013 05:50

Hi,

A Sch. image is due to the density gradient if memory serves me right. Therefore you need to use the same thing in the code.

This is what I do:
1) Go to data -> alter equations
2) make two variables {rx}=ddx(V01) and {ry}=ddy(V01) where V01 is the density.
3) make a variable {sch} = ({rx}**2+{ry}**2)**0.5
4) Plot contours of {sch}

Often I find I need to change the cutoffs and ranges to bring out the detail, choose grayscale and for some reason inverting it always seems nicer but that might just be my case.

Hope this helps.
Mike

 moezzi October 6, 2014 18:19

hi,
i have recently got my schlieren type image using tecplot but my problem is here that the resolution of the created image is so low. in order to be sure that the procedure i've done to create my schlieren type image is correct, i wanted to know what kinds of variables should we use to plot a schlieren type image? and whether it should be as a contour or a shadowgraph?

thank you very much

 Durrell4 October 7, 2014 09:06

Image Resolution

Hi Moezzi,

Are you setting the contour variable to the Shadograph? Set the values to -1000 to 1000 or -100 to 100 and set the coloring to continuous and the colormap to gray-scale. This should get you to the image you are looking for if not here are two possible things going on here. It is possible that the resolution of the data is such that the contours appear jagged. If that is the case then you can try interpolation on to a finer grid which can help with the contour levels. In this case the exported image will have the same artifacts as the plot in Tecplot.

If the image output resolution is the issue you can control that from the export dialog

file>Export

From the export dialog select export format > PNG

Select: Enter width: use a value over 1500
Select: Antialiasing and accept the default.

More information available here and here

let me know how it works out

 Durrell4 October 27, 2014 14:29

Tecplot Tutorial on Shadowgraph calculations

Hi all,

I have posted a quick tutorial on using shadowgraphs in Tecplot. http://www.tecplot.com/blog/2014/10/...ity-gradients/

Hope this helps.

Durrell

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