In this particular scenario, the honey poured will take its own time running down the hair and face of that person. Now, let us consider another situation in which you pour 1000 ml of honey on a person's head. The effect of viscosity is important in a variety of disciplines, for example, in the study of fluids and gasses, as it governs their behavior.ĭo you know what will happen if you pour 1000 ml of water on a person's head? The water flows through the person's hair and then over the face. If the flow is a stream of uniform velocity, there is zero viscosity if, on the other hand, the velocity is turbulent and chaotic, there will be some viscosity. If the fluid is caused to flow smoothly and regularly, there will be no viscosity. More simply, it is the resistance to a simple flow. In physics, Viscosity is defined as the measure of the resistance of a fluid to flow.
This value must be converted back to 1.004 x 10^-6 m²/s for use in calculations.The measure of a fluid's resistance to flow is known as viscosity. Water at a temperature of 20☌ has a viscosity of 1.004 x 10^-6 m²/s When the equations are rationalized the fluid head term is eliminated leaving the units of Kinematic viscosity as area / time.ġ.0 m²/s = 10000 Stokes = 1000000 Centistokes The motive force driving the fluid out of the cup is the head of fluid, which is also contained within the equation that makes up the volume of the fluid. Kinematic viscosity value of the fluid in Centistokes (cSt). The timings can be used in a formula to estimate the Viscosity can be measured by timing the flow of a known volume of fluid from a This value must be converted back to 1.002 x 10^-3 Pa
Temperature of 20☌ has a viscosity of 1.002 Centipoise. Pascals can be combined with time (seconds) to define dynamic viscosity.Ĭentipoise (cP) is commonly used to describe dynamic viscosity because water at a The Pascal unit (Pa) is specifies pressure, or stress = force per area Laminar flow will occur where the Reynold's number is less than 2300.įrom the above equation it can be determined that the dimensions of viscosity are force multiplied by time divided by length squared or FT/L² The units of viscosity in the English system and the SI system are: To determine whether the flow is laminar or turbulent requires that you calculate the Reynold's number of the flowing fluid. However, the above equation is not applicable for turbulent flow where a large amount of the shear stress is due to the exchange of momentum between adjacent layers of the fluid. This results in the important equation for fluid shear for viscous or laminar flow: The derivative dv/dy is called the velocity gradient. Viscosity is usually denoted by the Greek symbol μ (mu) and is defined as the ratio of shearing stress τ (Greek letter tau) to the rate of change of velocity, v, which in mathematical terms can be expressed as dv/dy (where this is the derivative of the of the velocity with respect to the distance y). Fluid Viscosity Properties Fluid Viscosityįluid Viscosity, sometimes referred to as dynamic viscosity or absolute viscosity, is the fluid's resistance to flow, which is caused by a shearing stress within a flowing fluid and between a flowing fluid and its container.
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