# Mix of oil and water under pressure

I'm not a physicist so please ignore my ignorance. I'm wondering what would happen if: Imagine a mug with hollow handle. Now, one half of that mug is filled with water, another half with oil (of some kind). If i seal that mug and apply a lot of pressure on top (where the opening is), taking into account oil and water have different characteristics would oil start flowing through handle and back to the surface or simply nothing would happen?

EDIT: Basically, my idea was without high temperatures - would high pressure cause oil to perhaps heat a bit, expand a bit and start flowing through handle to the bottom of the mug (literally, a mug shaped container) and then back to the surface? Would a high static pressure be enough to create a motion of oil through the water taking into account different properties (and possibly different reactions to pressure) of those different liquids?

• If true, wouldn't that be a perpetual motion device? Commented Sep 29, 2016 at 20:16

EDIT

This is not an answer suitable for the question above, but I will leave it here for reference in case anybody else reads the question incorrectly, as I did.

END EDIT

Under standard conditions, hydrocarbons and water do not mix; however, at high temperatures and high pressures near the critical point of water, they freely mix. You need a lot of pressure

Oil and water are not miscible but can form emulsions in which tiny droplets of one component are dispersed in the other. Milk and face creams, are examples of oil/water emulsions.

Image Source: Wikipedia Critical Point of Water

When water is heated under pressure it reaches its critical point at 374 °C and 22.1 MPa. (3191 psi) At this point there is no longer a difference between the liquid and gas phases. The water no longer dissociates and no clusters of water molecules can form. At this point, the properties of the water are like those of an oil and the two can be freely mixed together.

I don't fully follow your mug description, but whereever water flows, this mixture should flow also.

• Thanks for your response. Basically, my idea was without high temperatures - would high pressure cause oil to perhaps heat a bit, expand a bit and start flowing through handle to the bottom of the mug (literally, a mug shaped container) and then back to the surface? Would a high static pressure be enough to create a motion of oil through the water taking into account different properties (and possibly different reactions to pressure) of those different liquids? Commented Sep 23, 2016 at 20:36
• I searched the Internet and 2 possible results came up, both industrial rather than domestic. 1. High temperatures do seem required to change the water phase 2. Researchers found that taking all of the dissolved air out of the water greatly increased the mixing action. But hopefully someone more expert than I will give you an answer that may not involve temperatures. If you like, as you have phrased your question more clearly in your comment above, I would suggest that you edit it into your post and I can delete my answer as not appropriate to your question.
– user108787
Commented Sep 23, 2016 at 20:45
• Done. Basically i'm interested in (potential) exploiting differences in materials to produce a dynamic "system" from static conditions. Like having oil constantly flow through water under static pressure. Lame idea, and i'm not very sure if that's (static conditions producing constant motion) possible in applied physics :\ Commented Sep 23, 2016 at 20:50

I worked with a wide range of drilling fluids in the past and at the time they were water mud with oil in them and lessor times oil mud with water in it. Daily, multiple times a battery of tests were run and analyzed by sometimes multiple people. Pressures and heat were all part of the testing usually to do the opposite of the question. We had to picture what was happening down hole and believe me at times there is plenty of pressure on an emulsion that is breaking down. In the testing we found ALWAYS we needed to keep the pumps running and the pressure on so as not to go back to two phase which is just the opposite of what you hope can happen. There was motion before or flow even. It was just that the emulsion was always too strong to break and the added pressure from the flow just made that emulsion so much stronger. I just do not see any way your premise could work. It is imaginative and had me pondering it for some time this night.

• Of course motion and shear helped that emulsion but very much so did the added pressure. Commented Sep 24, 2016 at 11:37
• In every case when the emulsion broke down pressure or not the fluid went back to its relative natural position relative to the other fluid. Commented Sep 24, 2016 at 11:58
• So, pressure would force those two liquids to mix instead of forcing them to move relative to each other? I assumed that if water is not compressible and oil might be somewhat compressible certain amount of pressure might induce spontaneous movement of oil before certain point that would induce mixing... Commented Sep 24, 2016 at 12:39
• Another good question. I know for sure that pressure helps keep the emulsion in tact as for actually making an emulsion? I do not suspect so but do not know for sure. What I do know for sure is as an emulsion breaks it will revert to it's natural position. I know for sure it takes flow to move oil through water or water through oil. Thus I don't see the original question working out as hoped. Commented Sep 24, 2016 at 13:09
• Possibly at the interface a wee bit. Commented Sep 24, 2016 at 13:16

Guest86 I understand what you are trying to do. I can get you part of the way there. As I stated before the testing I did in the past closely did the opposite of what you are looking for. Just applying pressure and hoping a mixture would get through would never happen. Now add a surfactant to help facilitate an emulsion. Then quickly add your pressure and relieve it multiple times, many multiples. An emulsion would definitely start near the meniscus between the two liquids and possibly create an emulsion deep enough to get to the bottom of the underlying liquid. To get it to break out at the bottom to get the separated oil or water "depending on the weight of oil used" into the handle would be another matter but you may be on to something. I'm not sure of any useful application a success would have but it is your question and you may have one. Just figure out how to break it out in a direction that is not the natural state. Good luck with that one.

• Possibly with multiple weights of oil one heavier and one lighter than water you could get the unnatural weighted oil to hold tension enough to break out the "wrong" way. Commented Sep 29, 2016 at 14:08
• Well it's just an idea, without any actual tests or calculations done. Applications? Possibility to create a motion of oil through the handle using just a static pressure might be useful. Also, i'm not 100% sure of pressure distribution - if applied on top how would it be distributed inside of side-handle that has much smaller diameter. Maybe having a "mug" that's not perfectly cylindrical would distribute the pressure differently and help the cause. I'm not sure. Commented Sep 29, 2016 at 20:16
• My hopes were that water-oil barrier would hold firmly (until some extreme pressure and temperatures) :) I hope that water and oil would repel each other strong enough. The way i see it, in nature fluids of different temperatures may create a motion (water currents, tornado) - why fluids that react differently to pressure (compressability) won't? :) Commented Sep 29, 2016 at 20:23
• Regarding your comment on pressure distribution the size of the handle will not matter unless one side or the other has a restricted orifice "then size would matter" so for a period of time the pressure is different but eventually the same. I'm assuming an even, one point entry of the pressure. I know of no pressure or temperature or a combination of the two that would do that with water and oil. We had plenty of both with what we did on the rigs and in the lab too. I am not a man of theory just a guy who did plenty of real life application. Commented Sep 30, 2016 at 1:42
• I dealt a great deal on Pneumatic applications too during my 35 years with the oil and gas industry, a now nearly extinct discipline. Once again real life. Commented Sep 30, 2016 at 1:50