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Stability in two-phase region #624

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jowr opened this issue Apr 26, 2015 · 8 comments
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Stability in two-phase region #624

jowr opened this issue Apr 26, 2015 · 8 comments
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v5.1

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@jowr
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jowr commented Apr 26, 2015

It seems like we introduced some problems lately. During the speed tests I noticed that certain areas do not get covered anymore. My code automatically removes faulty points and large blank spots thus mean that there is a stability problem because all points in that area get marked as faulty. Sorry for the colour, but magenta makes it easy to spot the empty spots. The example below shows air, but the same issues occur for (at least) n-pentane, R134a and CO2 as well. The shape of the faulty region is also similar regardless of the fluid.
@jowr jowr mentioned this issue Apr 26, 2015
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jowr commented Apr 26, 2015

Would it make sense to include the 2-phase region in the consistency plots?

jowr pushed a commit that referenced this issue Apr 26, 2015
Included a basic 2-phase consistency plot, as discussed in #624. It l…
a5baa97 
…ooks like there are some problems...
@jowr
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jowr commented Apr 26, 2015

It looks like the f(rho,T) solver does not work reliably in the two-phase region. I have no idea why, but this could be related to the "holes" in the performance plots.

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jowr commented Apr 26, 2015

Here are the other graphs

Air

timecomp-air 1x4

CO2

timecomp-co2 1x4

n-pentane

timecomp-pentane 1x4

R134a

timecomp-r134a 1x4

@jowr
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jowr commented Apr 26, 2015

The consistency plots are ready: http://www.coolprop.dreamhosters.com/binaries/sphinx/_downloads/CarbonDioxide1.pdf

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ibell commented Apr 26, 2015

:( I'll take a look, has got to be easy to fix. Thanks for finding this.

On Sun, Apr 26, 2015 at 12:55 PM, Jorrit Wronski notifications@github.com
wrote:

The consistency plots are ready:
http://www.coolprop.dreamhosters.com/binaries/sphinx/_downloads/CarbonDioxide1.pdf

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#624 (comment).

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ibell commented Apr 26, 2015

By the way, the color choice is somewhat an issue because its not possible
to differentiate between max error and missing data point. What about a
yellow background or something?

On Sun, Apr 26, 2015 at 1:03 PM, Ian Bell ian.h.bell@gmail.com wrote:

:( I'll take a look, has got to be easy to fix. Thanks for finding this.

On Sun, Apr 26, 2015 at 12:55 PM, Jorrit Wronski <notifications@github.com

wrote:

The consistency plots are ready:
http://www.coolprop.dreamhosters.com/binaries/sphinx/_downloads/CarbonDioxide1.pdf

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#624 (comment).

ibell added a commit that referenced this issue Apr 26, 2015
@ibell
Resolved issues with Dmolar,T in subcooled liquid zone without resort…
14cfd28 
…ing to saturation call; see #624

More work remains for some of other two-phase flashes
@ibell ibell added this to the v 5.1 milestone Apr 26, 2015
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ibell commented Apr 26, 2015

I think we can safely close this issue. The situation is much better than before.

@ibell ibell closed this as completed Apr 26, 2015
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jowr commented Apr 26, 2015

Indeed, I just ran some new speed tests, watch #411 for more updates.

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