Recent content by copria

The Russian torpedo relies upon supercavitation to produce the bubble of water vapor around it. There are relationships between cavitation and hydrophobicity. http://doc.utwente.nl/59080/1/controled_multibubble.pdf" I question whether the microcavities, which comprise of the space...

This is truly what I am getting at. This prompts me for another question. Because of the air trapped, is it appropriate to say that half of the boat hull is in contact with water (for purposes of understanding assume that the top of the asperities comprise of half of the water contact) and half...

I understand that magnetic repulsion has nothing to do with hydrophobicity. I was confused about the definition of the hydrophobic effect. Some defined it as a repulsion of water. Upon further reading, I found that, "The less surface area is exposed the fewer water molecules have to suffer the...

At a microscopic level, some superhydrophobic materials are very rough, yet water will slide off of the surface at a lesser angle than that of a very smooth, non-hydrophobic material. In trying to understand this phenomena, I imagine a boat hull (made with a superhydrophobic material)...

I am thrilled to that you have replied to my thread! Thank you! Would a boat hull made with a hydrophobic material travel faster in water than an identically shaped boat hull made of aluminum? (assuming that the displacement drag of both boats is the same)

I am confused on how Borek came to the conclusion that the contact surface does not change. I could understand if that viscous drag does not change because when the water is on top of the asperities, there is the same downward force on a smaller area (thus viscous friction is not reduced), but I...

Say we are dealing with a superhydrophobic material. Then the water is only in contact with the top of the asperities. See: http://en.wikipedia.org/wiki/Hydrophobe

By increasing the hydrophobicity of canoe hull material, will drag be reduced? Have hydrophobic materials been used on boats? My thoughts: Yes, there is less surface contact with the water. Thus less viscous (friction) forces.

Does anyone know of a pneumatic regenerative braking system (applied to any type of vehicle)?

No, I want to create cavitation (like a cavitation water heater). Sorry I did not specify earlier.

thermal energy release

If I want to optimize the energy release from cavitation would it be better to have a shallow water column (producing larger amounts of cavitation) or a deep water column (larger force collapsing the cavitation bubble)? or Would both cases yield the same energy release? assuming the...

Is there a noticable diffence in torque required to spin a marine propeller at a constant rpm (say 2000rpm) when under a different water column? (5m vs 35m)