Shear- thinning or dilatant: When shear stress is applied, viscosity increases. There are four types of non-newtonian fluids. It is completely opposite to Newtonian fluids.Įxamples are toothpaste, paint, ketchup shampoo, butter yogurt. In this type, the viscosity changes, when the shear stress is applied. The relationship between the shear stress and viscosity is linear for this type of fluid.Įxamples are water, mineral oil, alcohol, gasoline. It is independent of the shear stress applied to them in respect to time. In this type, the viscosity of the fluid remains constant. The two types of fluids based on newton’s law of viscosity are: The shear stress between the two adjacent layers of the fluid is directly proportional to the negative gradient velocity between the two adjacent layers of the fluid. The law states that the shear stress is directly proportional to the velocity gradient. The SI units ae meter square per second ( m 2 / s ) and centimeter square per second ( c m 2 / s ) or stokes (St).ġ c m 2 / s = 1 S t 1 m 2 / s = 10000 S t K i n e m a t i c v i s cos i t y = D y n a m i c v i s cos i t y D e n s i t y ν = μ ρ When two different fluids of equal amount are taken in an identical viscometer and allowed to flow under the influence of gravity, the liquid which is more viscous takes a longer time than the low viscous fluid. It is a measure of the resistance flow of a fluid under the influence of gravity. The kinematic viscosity ( ν) is defined as the ratio of the viscosity of a fluid to its density. The SI units of dynamic viscosity are Pascal second (Pas) and dynes second per square centimeter (dyne s/cm 2) or poise (P), which is defined by Jean Poiseuille who discovered viscosity.ġ mPa s= 1 centiPoise Kinematic viscosity V i s cos i t y = S h e a r s t r e s s V e l o c i t y g r a d i e n t μ = F A d v d x Dynamic viscosityĭynamic viscosity or absolute viscosity or viscosity is defined as the ratio of shearing stress (F/A) to the velocity gradient of the fluid. They are dynamic viscosity and kinematic viscosity. Therefore, the density of fluid is 0.445 kg per cubic m.There are two kinds of viscosity. Formula for Kinematic ViscosityĪs we know that it is the ratio of dynamic viscosity to fluid mass density. Kinematic viscosity can be computed by dividing the absolute viscosity of a fluid with the fluid mass density. This is the ratio of the dynamic viscosity to its density, i.e. Therefore, Kinematic viscosity is the measurement of the inherent resistance of a fluid to flow when no external force is imparted except gravity. The units of kinematic viscosity are established on time and area of fluid. It is from time to time also known as momentum diffusivity. Whereas Kinematic viscosity is the sort of viscosity that is computed by calculating the ratio of the fluid mass density to the dynamic fluid, viscosity or absolute fluid viscosity. The shearing stress between the layers of a no turbulent fluid which is moving in straight parallel lines may be defined for a Newtonian fluid. It is at a unit velocity while maintaining a unit distance apart in the fluid. 
dynamic viscosity coefficient is a measure of internal resistance. There are two related measures of fluid viscosity: Dynamic and Kinematic.Ībsolute viscosity i.e. Viscosity is a concept where fluid shows struggle against a flowing, which is being distorted due to extensional stress forces or shear stress. Let us learn it! Definition of Kinematic Viscosity In this article, the student will learn about the kinematic viscosity formula in particular. Thus, we may say that viscosity is the measure of a fluid’s resistance to flow. It happens when layers of fluids attempt to slide by one another. As we know that the shear resistance in a fluid is due to its inter-molecular friction exerted. Clearly, the viscosity of a fluid is the measurement of the resistance for gradual deformation due to shear stress or tensile stress. Viscosity is the important property of fluid while analyzing the liquid behavior and fluid motion near solid boundaries.
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