Fluids & Types of Fluid Flow's
The Fluid Flow is classified as,steady and unsteady, compressible and in compressible, viscous and nonviscous, and rotational and irrotational. Some of these characteristics reflect properties of the liquid itself, and others focus on how the fluid is moving.
Fluid evenness: Steady and unsteady flow:
Fluid flow can be steady or unsteady, depending on the fluid’s velocity:
• Steady: In steady fluid flow, the velocity of the fluid is constant at any point.
• Unsteady: When the flow is unsteady, the fluid’s velocity can differ between any two points.
For example, suppose you’re sitting by the side of a stream and note that the water flow is not steady: You see eddies and backwash and all kinds of swirling. Imagine velocity vectors for a hundred points in the water, and you get a good picture of unsteady flow — the velocity vectors can be pointing all over the map, although the velocity vectors generally follow the stream’s overall average flow.
Fluid squeezability: Compressible and in compressible flow:
Fluid flow can be compressible or in compressible, depending on whether you can easily compress the fluid. Liquids are usually nearly impossible to compress, whereas gases (also considered a fluid) are very compressible.
A hydraulic system works only because liquids are in compressible — that is, when you increase the pressure in one location in the hydraulic system, the pressure increases to match everywhere in the whole system. Gases, on the other hand, are very compressible — even when your bike tire is stretched to its limit, you can still pump more air into it by pushing down on the plunger and squeezing it in.
Fluid spinning: Rotational and irrotational flow:
Fluid flow can be rotational or irrotational. If, as you travel in a closed loop, you add up all the components of the fluid velocity vectors along your path and the end result is not zero, then the flow is rotational.
To test whether a flow has a rotational component, you can put a small object in the flow and let the flow carry it. If the small object spins, the flow is rotational; if the object doesn't spin, the flow is irrotational.
Fluid thickness: Viscous and non viscous flow:
Liquid flow can be viscous or non viscous. Viscosity is a measure of the thickness of a fluid, and very gloppy fluids such as motor oil or engine oil are called viscous fluids.
Viscosity is actually a measure of friction in the fluid. When a fluid flows, the layers of fluid rub against one another, and in very viscous fluids, the friction is so great that the layers of flow pull against one other and hamper that flow.
Viscosity usually varies with temperature, because when the molecules of a fluid are moving faster (when the fluid is warmer), the molecules can more easily slide over each other. So when you pour pancake syrup, for example, you may notice that it’s very thick in the bottle, but the syrup becomes quite runny when it spreads over the warm pancakes and heats up.
Fluid moving: Laminar and turbulent flow:
Fluid flow can be laminar then the fluid particles move along well-defined paths or stream line and all the stream lines are straight and parallel. Thus the particles move in laminas or layers glinding smoothly over the adjacent layer. This type of flow is also called stream line flow or viscous flow.
Turbulent flow is that type of flow in which the fluid particles move in a Zig-Zag way. Due to movement of fluid particles in a Zig-Zag way, the eddies formation takes place which are responsible for high energy loss.
LAQSHYA Institute of Technology & Sciences