![]() ![]() The liquid phase is probably the least well understood of all the states of matter. At ordinary temperatures, glasses are as solid as true solids. Since the process is not as well defined as true freezing, some believe that glass may still flow even after it has completely cooled, which is not the case. Molten glass is extremely viscous and approaches infinite viscosity as it solidifies. Some fats like butter or margarine are so viscous that they seem more like soft solids than like flowing liquids. Pastes, gels, emulsions, and other complex liquids are harder to summarize. Most ordinary liquids have viscosities on the order of 1 to 1,000 mPa s, while gasses have viscosities on the order of 1 to 10 μPa s. The viscosity of water at 20☌ is 1.0020 millipascal seconds (which is conveniently close to one by coincidence alone). Viscosity is first and foremost a function of the material. Simple models of molecular interactions won't work to explain this behaviour. Since liquids are normally incompressible, an increase in pressure doesn't bring the molecules significantly closer together. Viscosity is normally independent of pressure, but liquids under extreme pressure experience an increase in viscosity. That external force (F) is proportional to Shear rate (SR), Dynamic Viscosity (η), and Surface area (A). The internal resistance of a liquid flow suggests an external force applied in the movement of a liquid. Kinematic viscosity is a more fundamental property.Īpart from the difference between dynamic viscosity and kinematic viscosity, a few relations of this concept should be cleared. It is utilized when inertia and viscous force are dominant.ĭynamic force is utilized only when viscous force is dominant. ![]() This represents the ratio between shear stress to shear strain. This represents the ratio between dynamic viscosities to density. The symbol of the kinematic viscosity is V. Whereas, dynamic viscosity represents the viscous force of the liquid. It represents the inertia as well as the viscous force of the fluid. It gives more information about the force required to make the liquid flow at a specific rate. To be precise, it explains how fast the liquid is moving when a certain amount of external force is applied. Walking with 5 km/h would have the same sense of drag like running with 40 km/h.This is defined as the diffusivity of momentum. The main problem is not the viscosity, but the super-high drag due to the extreme density of the atmosphere (compared to the Earth).ĭrag is quadratically proportional to the speed, thus the $\approx 65$ times higher density would cause the drag what we would feel on the Earth with $\approx$ 8 times higher speed. It is still a lot, in such an environment, the world-record sprinters would look probably more like the weightlifters. Q = $, which is only 6% of the density of the water. Slow moving air, maximum wind speed ~ 2.5 $m/s$Ī 2.5 m/s gust of wind would have dynamic pressure equal to.Pressure ~ 9 $MPa$ (comparable to 900m underwater on Earth!).Obviously we must neglect the high temperatures that would kill any human. I'm trying to conceptualize what it would be like to walk on the surface through supercritical carbon dioxide. ![]() The conditions on Venus's surface are extremely harsh. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |