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jdber1 / opendrop

OpenDrop pendant drop tensiometry software
GNU General Public License v3.0
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Dynamic interception #45

Open Dragon-f735 opened 1 year ago

Dragon-f735 commented 1 year ago

For low-viscosity fluids (like water), record the entire process as the droplet extrudes and becomes larger. Later, can the surface tension be calculated by intercepting the frame where the droplet is about to drop? Thanks!

eugenhu commented 1 year ago

Sure, I can consider adding this in the future. Hard to say when it will be implemented however, so unfortunately you'll need to manually do this for now (either by recording a video and extracting the frame outside of opendrop, or using opendrop's image acquisition and using a small frame interval).

Dragon-f735 commented 1 year ago

Thank you for your reply. At the moment I record video with a high-speed camera and extract a certain frame image. Afterwards, the surface tension is measured by opendrop. I am trying to determine if this method is reasonable. And the Pendant Drop method is based on the equilibrium of surface tension and gravity. The above method extrudes droplets rather than maintaining equilibrium. Does it go against the basic theory if the above method is used? Or can it be understood that for low-viscosity fluids, force equilibrium can be achieved instantaneously? This means that equilibrium is already established at any given moment (any frame).

eugenhu commented 1 year ago

I'm not really sure to be honest, I mainly work on the software side of things, sorry!

The IFT is calculated by fitting the drop profile to the axis-symmetric Young-Laplace equation, and the only pressure gradient comes from gravity. So as long as the drop is axis-symmetric and both phases have equal density (and IFT is constant along the interface), the IFT calculation will be valid. If the drop is being dilated, you might also have to consider the rearrangement of surfactants, which can occur over a different timescale. Again, not an expert unfortunately, so just my 2 cents.

Dragon-f735 commented 1 year ago

The above method is also my guess.

Therefore, I looked up relevant information to verify my ideas. I found the relevant theoretical support in the book Applied Surface Thermodynamics. The theory of the dynamic measurement of surface tension is mentioned in chapter 3.3.6.4 of this book. I hope this will help you in your software development.

Thank you again for your reply!

eugenhu commented 1 year ago

Thanks for the resource.