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[sprayFoam] strange spray formation behaviour

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Old   March 23, 2015, 12:41
Default [sprayFoam] strange spray formation behaviour
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Pascal Balz
Join Date: Feb 2015
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Dear FOAMers,

I want to simulate the injection of liquefied propellant into ambient air using sprayFoam. For some simple tests I started off with the aachenBomb tutorial and some major simplifications.
So at the moment I'm investigating an isothermal case without any breakup/reactions/combustion, etc. The problem I'm facing right now is some really strange spray behaviour which shows up as soon as I change ambient pressure to 1e5 Pa. During the solution process I get some fluctuations in ambient temperature reaching from around 330K to 350K (initial). These are directly related to the spray fluctuations I think.

This has to be some sort of numerical issue I guess. The boundary conditions should be fine as well as the spraycloudproperties. But I'm not getting the error I'm doing here because the spray behaviour is solely dependent on the ambient pressure in my 0-folder.

As soon as I turn on the phaseChangeModel, the spray behaves like it should and forms a nice plume although the evaporation rate is to high and therefore quickly reduces the droplets size.
Thats another task as I'm using the thermophysical properties from the aachenBomb tutorial which are obviously not correct as I need R134a and not heptane. But that shouldn't be the reason for my problem.

So, if anybody has an idea on how to improve the spray formation behaviour to a more phyiscal level... I would be really greatful!

Please let me know if you need any case files.
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File Type: jpg strange-spray.jpg (27.7 KB, 15 views)
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Pascal
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