![]() The estimated outside temperature between 288.15 and 394.25K may be possibly estimated by this model but accuracy may be lower. The average absolute deviation of dynamic viscosity and kinematic viscosity of FA at 288.15 and 394.25K are 4.14 and 4.37, respectively. The proposed equations are easy to use and the estimated dynamic viscosity and kinematic viscosity values of FA at different temperatures agree well with the literature values. Data collected from literatures were used to validate and support the proposed models. The proposed equations for estimating viscosity and density of FA are correlated to number of carbon atoms, number of double bond(s) and temperature. In this work, correlation of dynamic viscosity and kinematic viscosity of fatty acids (FA) are correlated to the Martin's rule of free energy additivity for estimated kinematic viscosity and dynamic viscosity from their own equations. This leads us to the fact that dynamic viscosity is a constant property, but kinematic viscosity is a derived property.Dynamic viscosity and kinematic viscosity are important physical properties of a liquid. Kinematic viscosity has units of diffusivity, (length) 2/s, which means that kinematic viscosity is sometimes known as diffusivity of momentum, dependent on thermal and mass diffusivity. In Newton’s Law of Viscosity equation, the proportionality constant is μ or dynamic viscosity. The ratio of shear stress to shear rate is defined as the viscosity. Newton’s Law of Viscosity states that shear stresses between parallel layers of fluid are proportional to the corresponding velocity gradients. Kinematic viscosity allows you to work out the speed at which the fluid moves when a certain force is applied.Its units come out as mass/(distance*time). Dynamic viscosity lets you work out the force needed to make a given fluid flow at a certain rate.The force necessary to move a plane of area A past another in a fluid is given by Equation 2.6.1 where V is the velocity of the liquid, Y is the separation between planes, and is the dynamic viscosity. Kinematic and dynamic viscosity measurements serve different purposes in calculations. The moving plane has area A and requires force F to overcome the fluid’s internal resistance. tomato ketchup.ĭifference between kinematic viscosity and dynamic viscosity Thixotropic fluids – decrease in viscosity when shaken, e.g.Rheopectic fluids – these increase in viscosity when shaken, e.g.corn starch combined with water – it gets thicker when stirred faster fluid. Shear-thickening fluids – the viscosity increases when the shear rate increases.wall paint – as you stir wall paint, it becomes increasingly fluid and liquidy. Kinematic viscosity () designates the quotient of the dynamic viscosity of the fluid handled and its density. Shear-thinning fluids – the viscosity decreases when the shear rate increases.They get this moniker because they follow the formula set out by Isaac Newton in his law of fluid mechanics.įluids that don’t exhibit constant viscosity across all shear rates are known as non-Newtonian fluids.Įxamples of some Newtonian fluids are gases, oil, water, alcohol, petroleum, etc.Įxamples of some non-Newtonian fluids include: Kinematic viscosity in Newtonian and non-Newtonian fluidsĪ Newtonian fluid is one that keeps a constant value of viscosity across all shear rates. The table below contains kinematic viscosity values for some common fluids. When used in this equation, the viscosity μ is often referred to as dynamic viscosity or absolute viscosity. Kinematic viscosity is measured in units of (length) 2/time – most commonly using centiStokes (cSt), where 1 Stoke = 1 cm 2/s.
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