VISCOSITY

I.                   BASIC THEORY

Rheological derived from the Greek rheo and logos mean flow. So rheological berari means the study of liquid flow and solid deformation. Rheological closely related to the viscosity

The viscosity (thickness) can be considered as part of the friction on the inside of a fluid viscosity because existence, then to move one of the fluid layer above another layer or so that one surface to glide over the surface among the other when the surfaces have a layer of fluid. It must be done in style. Both liquid and liquid is thick (viscous) of the gas. (Drs. Zemusky. 1962)

The viscosity of the fluid viscosity is a measure that states the size of the friction in the fluid. The greater the viscosity of the fluid, the more difficult an object is moving in the fluid. In the liquid, the viscosity generated by the force of cohesion between liquid molecules. While the gas viscosity arising as a result of collisions between molecules of liquid (Supriyanto. 2005)

Viscosity can be thought of as the friction between the substance flow, due to the thickness of the core must be done so that a layer of substance flowing style to glide over the other layers, or to a surface to slide against the other or both of them if there is substance flow. Both liquid and gaseous substances have a viscosity, although higher viscosity liquids than in gases (Sutejo. 2005)

Fluid Flow: Viscosity

                        Viscosity is the degree of internal friction in the fluid

 The internal friction is associated with the resistance between two adjacent layers of the fluid moving relative to each other

Characteristics of an Ideal Fluid

                        1.The fluid is nonviscous

                        There is no internal friction between adjacent layers

                        2. The fluid is incompressible

                            Its density is constant

                        3.The fluid is steadyIts

                            velocity, density and pressure do not change in time

                        4. The fluid moves without turbulence

     No eddy currents are present

(http://www.physics.wayne.edu/~apetrov/PHY2130/)

Viscosity associated with the objec viskeus or phase between the solid and liquid phases that occur when solids become soggy before the liquid when heated. Not all solid material had viskeus before it becomes liquid. In phase viscosity of such material does not flow freely like a liquid because of the barriers between its parts or between layers of other movements.

The viscosity of none other than talk about the friction between the parts - parts or layers of liquid or fluid in general is moving from one to another. Of course, friction or resistance is caused by the attractive force between molecules dance

Stokes formula
            Friction force between solid surfaces with the fluid medium it moves will be proportional to the relative velocity of motion object to the medium.

            Basically obstacles in the fluid motion is caused by friction between the fluid attached to the surface of the object with the fluid next to it where the friction force is proportional to fluid viscosity coefficient

According to Stokes, the friction force is given by the so-called formula Stoks

            The amount is called the coefficient of viscosity η of liquid substances or flida with units()

            When a block slides across a rough floor, it experiences a frictional force oposing the motion. Similarry, a fluid following past astationary surface experiences a force oposing the flow. This tendency to risist flow is rererred to as the viscosity of a fluid like water more viscous, and fluids like honey and motor oil are characterized by high viscosity

Table Viscosities (η) of farious fluids (N.s/m²)

Honey	10
Glycerine (200)	1,50
10-wt motor oil (300)	0,250
Whole blood (370)	2,72 x 10-3
Water (00)	1,79 x 10-3
Water (200)	2,82 x 10-3
Water (1000)	1,0055 x 10-4
Air (200)	1,82 x 10-3

            The viscosity of the liquid is much greater than the viscosity of the gas and the price was reduced rapidly when the temperature increases. The viscosity of liquids decreases with increasing temperature decreases         (Reid, Robert. 1990)