in what conditions and on what type surfaces boundry layer separates from flow surfaces?

Answer 1

Well, as I understand it. The boundry layer idea is that at the surface a fluid (gas or liquid) touches the wall of a pipe or the wing of an airplane the fluid in contact with the surface of the wall is considered to be stuck to it and not moving.

Then you have a boundry layer on which the viscous friction works and you have a velocity gradient between 0 and the velocity of the bulk fluid. Depending on the reynolds number, whether the flow is laminar or turbulent you will have another velocity gradient or plug flow.

To have boundry layer separation the surface must be discontinuous like the trailing edge of a wing, discharge end of a pipe or a change in the diameter. The boundary layer separation is said to cause (Drag)

Answer 2

interior the Earth what's taking place interior this 12,seven hundred km diameter ball we call the Earth? countless the Earth’s inner shape is an 'knowledgeable guess' (specifically from seismology), because of the fact the longest drill we've has purely penetrated 12.6 km – and there’s 6,3 hundred km between us and the centre of the Earth. in spite of those barriers, all of us understand that the centre of the Earth is amazingly warm. We purely would desire to drill a small thank you to computer screen temperature rises of a few 25°C according to km , so in some unspecified time sooner or later, each and every little thing would be so warm that we would strike molten rock like the lava that flows from volcanoes. although, user-friendly experience tells us that this speedy upward push in temperature we see from floor drilling would desire to not proceed indefinitely or the centre of the Earth would be warmer than the sunlight. The presently usual concept of the Earth’s shape is that it has a center (a superb inner center and a liquid outer center), a viscous mantle (divided into an greater mantle and mantle), and a silicate crust. We have faith that gravitational allure and melting has properly regarded after the composition of the Earth so as that dense components have been pulled to the middle, leaving lighter components on the exterior to form the crust. The center Recording the era of time it takes refracted and meditated seismic waves generated by utilising earthquakes to commute via diverse layers of the Earth has instructed us lots appropriate to the form and site of issues under the crust. as an occasion, S-waves can't bypass via the Earth’s center in any respect, collectively as the alterations in seismic speed between layers reason some waves to refract in accordance to Snell's regulation and different waves to replicate like mild from a replicate. in keeping with study of dense meteorites (areas of alternative planets), we are in a position to quite assume that the Earth’s good center consists specifically of iron (around eighty p.c.), with small quantities of nickel. The liquid outer center consists of iron blended with nickel and hint quantities of lighter components. at modern, we've faith that convection in the liquid outer center blended with the rotation of the Earth motives the Earth’s magnetic container.