In layman’s terms, viscosity defines a fluid’s resistance to flow. The higher the viscosity of a liquid, the thicker it is and the greater the resistance to flow.

The greater a fluid’s viscosity, the greater the loads that it can with stand. The viscosity of a fluid must be adequate enough to separate moving parts at operating temperatures of the equipment.

The higher the number, the thicker the oil. The lower the number, the thinner the oil. For example, a rating of 5W-30 means that the oil will have a viscosity rating of 30 at 212℉, or 100℃, (an engine’s average operating temperature).

What is the relationship between fluid flow and viscosity? the higher the viscosity, the slower the flow rate. they are inversely proportional to one another.

The viscosity of a liquid usually depends on its temperature. Viscosity generally decreases as the temperature increases. Viscosity generally increases as the temperature decreases. The viscosity of a liquid is related to the ease with which the molecules can move with respect to one another.

The two main factors that affect viscosity are temperature and silica content.

Suspended particles cause an increase in the viscosity….Factors Affecting Viscosity:

• Temperature:
• Chemical Composition:
• Colloid Systems:
• Suspended Material:

A change in pH altered the viscosity of dispersion. As expected, a significant increase in apparent viscosity of commercial WPC-80 was evident at highly acidic (pH 3.0) and alkaline (pH 8.0) conditions.

Types of Viscosity

• Dynamic Viscosity (Absolute Viscosity)
• Kinematic Viscosity.

For example, water at 20°C has a viscosity of 1.002 cPs. Cold molasses is a highly viscous liquid, as every grandmother knows….What Is Viscosity?

Viscosity, resistance of a fluid (liquid or gas) to a change in shape, or movement of neighbouring portions relative to one another. Viscosity denotes opposition to flow. The reciprocal of the viscosity is called the fluidity, a measure of the ease of flow.

The resistance to such flow is called the viscosity. Liquids which flow very slowly, like glycerin or honey, have high viscosities. Those like ether or gasoline which flow very readily have low viscosities.

Ethyl alcohol

Solids have high viscosity because they cannot flow freely. Viscosity of liquids ranges from low to high whereas gases have a low viscosity. Hence, wood being a solid has a very high viscosity.

Viscosity describes a fluid’s internal resistance to flow and may be thought of as a measure of fluid friction. Thus, water is “thin”, having a low viscosity, while vegetable oil is “thick” having a high viscosity.

For example, honey has a much higher viscosity than water. Viscosity is highly dependent on temperature, decreasing with increased temperature….What is Viscosity.

Dynamic (absolute) Viscosity

Viscosity is the measure of resistance of a fluid to flow. A fluid that is highly viscous has a high resistance (like having more friction) and flows slower than a low-viscosity fluid. Honey would move slower than water, so honey would have a greater viscosity.

around 1.0 mPa⋅s

Dynamic viscosity is the resistance to movement of one layer of a fluid over another and is defined by Formula F7. 8. Kinematic viscosity is dynamic viscosity divided by density (Formula F7. 9) and is the ratio of viscous forces to inertia forces.

The dynamic viscosity has the dimension ML-1T-1 and the unit of kg/m.s (or, N.s/m2 or Pa. s). A common unit of dynamic viscosity is poise which is equivalent to 0.1 Pa.

The dynamic viscosity η (η = “eta”) is a measure of the viscosity of a fluid (fluid: liquid, flowing substance). The higher the viscosity, the thicker (less liquid) the fluid; the lower the viscosity, the thinner (more liquid) it is. SI unit of dynamic viscosity: [η] = Pascal-second (Pa*s) = N*s/m² = kg/m*s.

Simply put, dynamic viscosity gives you information on the force needed to make the fluid flow at a certain rate, while kinematic viscosity tells how fast the fluid is moving when a certain force is applied.

The resistance of a fluid to flow or deform when subjected to a force is called viscosity. Dynamic viscosity is expressed as the ratio of shear stress to shear strain….Difference Between Kinematic And Dynamic Viscosity.

Kinematic viscosity is a measure of a fluid’s internal resistance to flow under gravitational forces. It is determined by measuring the time in seconds, required for a fixed volume of fluid to flow a known distance by gravity through a capillary within a calibrated viscometer at a closely controlled temperature.

There are several formulas and equations to calculate viscosity, the most common of which is Viscosity = (2 x (ball density – liquid density) x g x a^2) ÷ (9 x v), where g = acceleration due to gravity = 9.8 m/s^2, a = radius of ball bearing, and v = velocity of ball bearing through liquid.

The kinematic viscosity is an atmospheric variable defined as the ratio between the dynamic viscosity μ and the density ρ of the fluid, i.e. and depends on both air temperature and pressure. For air at sea level pressure and 20 °C, ρ = 1

Its unit is Stoke or m2/s (1 stoke = 0.0001 m2 /s). ∴ C.G.S unit of kinematic viscosity is cm2/s.

Viscosity is a measure of a fluids propensity to flow. There are two kinds of viscosity commonly reported, kinematic and dynamic. Dynamic viscosity is the relationship between the shear stress and the shear rate in a fluid. The Kinematic viscosity is the relationship between viscous and inertial forces in a fluid.