Velocity and viscosity relationship

Viscosity - Wikipedia

velocity and viscosity relationship

find that at low shear rates the flow is limited by the viscosity of the liquid rates the pressure drop is given by the Darcy-Weisbach equation. In liquids the viscosity is due to the cohesive forces between velocity v. The stationary layer of fluid in contact with the stationary wall will retard the flow of the layer just equation are called newtonian fluids and η = constant independent of . Dynamic, absolute and kinematic viscosities - convert between CentiStokes (cSt), centipoises an other plane - at an unit velocity - when maintaining an unit distance apart in the fluid. Equation (1) is known as the Newtons Law of Friction.

fluid dynamics - How viscosity and velocity relate in a pipe? - Physics Stack Exchange

This condition is defined by an abnormal elevation in hematocrit. These patients have much higher values of blood viscosity. As a result the resistance to blood flow increases and forces the heart to work harder and can impair organ perfusion. Erythropoietin EPO is a protein hormone and estimulates the production of red blood cells.

When athletes inject EPO into the circulatory system more red blood cells will be produced increasing the oxigen carrying capacity. The increase in red blood cells, however, leads to increase in blood viscosity. As a result, blood doping raises risks of blood clot, stroke and heart attack.

There are three types of viscosimeters capillary, bead and rotational. When measuring blood viscosity a device similar to a capillary viscosimeter is used. The volume of blood is sucked through a horizontal capillary for a certain time period. At the same time and for the same time period a similar procedure is undertaken using water.

The results are then compared to achieve the value of blood viscosity.

velocity and viscosity relationship

Once this shear stress is removed the paint returns to its resting viscosity, which is so large that an appropriately thin layer behaves more like a solid than a liquid and the paint does not run or drip. Think about what it would be like to paint with water or honey for comparison.

The former is always too runny and the latter is always too sticky. Toothpaste is another example of a material whose viscosity decreases under stress. Toothpaste behaves like a solid while it sits at rest inside the tube.

Viscosity - WikiLectures

It will not flow out spontaneously when the cap is removed, but it will flow out when you put the squeeze on it. Now it ceases to behave like a solid and starts to act like a thick liquid. You don't have to worry about it flowing off the brush as you raise it to your mouth.

Shear-thinning fluids can be classified into one of three general groups. A material that has a viscosity that decreases under shear stress but stays constant over time is said to be pseudoplastic.

A material that has a viscosity that decreases under shear stress and then continues to decrease with time is said to be thixotropic.

If the transition from high viscosity nearly semisolid to low viscosity essentially liquid takes place only after the shear stress exceeds some minimum value, the material is said to be a bingham plastic. Materials that thicken when worked or agitated are called shear-thickening fluids.

velocity and viscosity relationship

An example that is often shown in science classrooms is a paste made of cornstarch and water mixed in the correct proportions. The resulting bizarre goo behaves like a liquid when squeezed slowly and an elastic solid when squeezed rapidly. Ambitious science demonstrators have filled tanks with the stuff and then run across it. As long as they move quickly the surface acts like a block of solid rubber, but the instant they stop moving the paste behaves like a liquid and the demonstrator winds up taking a cornstarch bath.

Velocity and Viscosity

The shear-thickening behavior makes it a difficult bath to get out of. The harder you work to get out, the harder the material pulls you back in. The only way to escape it is to move slowly.