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-   -   surface tension, contact angle of Gasoline (http://www.cfd-online.com/Forums/star-ccm/108406-surface-tension-contact-angle-gasoline.html)

devesh.baghel October 23, 2012 01:36

surface tension, contact angle of Gasoline
 
Hi

I need to perform fuel tank analysis for vapor phase model. Problem statement is: tank is partially filled with fuel and rest of the volume is occupied by vapor (gaseous phase of Gasoline).
I have to model VOF with surface tension effect for gasoline as working fluid; for this I need to include contact angle of Gasoline with plastic surface.
I tried hard but din't find appropriate data for that.

If somebody have any idea about that.......Please help me ASAP.!!!!!!:(

devesh.baghel October 25, 2012 05:45

still no response......!!!!! :(

triple_r October 25, 2012 16:35

I don't know where you can find such information other than doing the experiment yourself, but might I suggest a sensitivity analysis? You can run a few cases with different contact angles and see if the result that you are interested in changes or not, and if it changes how by how much. If you are lucky (based on the tank dimensions and characteristic velocities that occur during the simulation) you might find that the contact angle plays an insignificant role, so there is no need to loose your sleep over it.

On the other hand, if you are not so lucky, then you might be able to measure it yourself. if you put a single drop of gasoline on a horizontal plastic surface (the same plastic that the tank is made of) and then take a picture of the drop (you might need a macro lens with good magnification), then you can measure the contact angle. Make sure that the surface is clean though.

devesh.baghel October 26, 2012 06:00

Hi,

thanks for your suggestions.
I am trying trial-error method only. In some documents (Zisman plot through google) I found contact angle for Gasoline is around 20-30 degree; I run case with 20 degree it shows quit wettability on wall of tank, which is not fruitfull.

On the other way I found another doc on "lecture on contact angle" saying that Hydro-carbons (Octane - low surface energy fluid) behaves as "Hydrophobic" in nature. So I that confused me about the contact angle for gasoline ?

I do not have facility to do experiment.

Request to CFD users please through some light, if have any idea about that.

Thanks alot for your help..

abdul099 October 26, 2012 16:11

Surface tension plays only a significant role when the radius of the surface is small (e.g. when you have a lot of sloshing, small droplets etc) or you have very small gaps. But in both cases, you need to have mesh resolution appropriate for resolving this small radius elements.

When it's a more or less stationary tank just filled with gasoline and vapor, surface tension will not change much. So I suggest to spend some minutes and think if you really need surface tension. If not, you might save the time for desperately searching for contact angles.

devesh.baghel October 29, 2012 01:11

Hi Abdul

Thanking you for your post.
Sloshing is influencing parameter & I guess impact will be there into analysis.
If you do not add surface tension into analysis, fluid just hit the walls and smoothly come to the rest position. so I thought of that to take up surface tension effect into analysis along with thermal effect.

Thanks


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