Kinematic viscosity is a standard property of a Newtonian fluid whereas absolute (dynamic) viscosity refers to how a fluid (particularly a non-Newtonian fluid) resists flow under an external force (such as a pump). The symbol for kinematic viscosity is nu: ν and its SI units are m/s 2.Īlso in common use is the Stoke (St) although this is often quoted as cSt (centiStoke). Kinematic viscosity is the ratio of absolute (dynamic) viscosity (μ) – see the previous sections - to density (ρ) and is a measure of a fluid’s inherent resistance to flow when no external force, except gravity, is acting on it. The symbol for absolute (dynamic) viscosity is mu: µ (although eta η is also sometimes used).ġ Ns/m 2 = 1 Kg/ms = 10 P = 1000 cP What is Kinematic Viscosity? Also in common use is Poise (P) although this is often quoted as cP (centiPoise). The SI unit for absolute (dynamic) viscosity is Ns/m 2 (or 1Kg/ms). The constant of proportionality, µ, is defined as the absolute (dynamic) viscosity.Ībsolute (dynamic) viscosity is a measure of how a fluid resists the deformation of shear stress due to its inter-molecular friction. Under laminar flow conditions, for many fluids, the shear stress ( tau: τ ) between two layers parallel to the direction of flow, separated by a perpendicular distance, Δy, is proportional to the difference in velocity between the layers (Δv). Treating a fluid in the laminar flow regime as a series of parallel layers, shear stress is the tangential force required to move one horizontal plane, with respect to its neighbour, at constant velocity. The velocity at which the transition between laminar and turbulent flow occurs is related to viscosity. At high fluid velocities, eddy currents are formed which lead to random mixing throughout the flow cross-section. What is laminar flow?Īt low velocities, fluids flow through pipes in a regular manner with no vertical mixing across the wave front. The definition of viscosity is based on laminar, non-turbulent, flow. This can be complex as viscosity can be affected by temperature, pumping speed, pipe dimensions, and, with some fluids, it may also change over time. Viscosity is a measure of a fluid’s resistance to flow, a property that affects how it will behave in a pump and in pipework. View all measurement unit conversion calculators on the same page (may not work with all browsers requires Iframe).Terms Associated with Viscosity and Shear What is Viscosity? The calculators require that your browser has java script enabled. Values lower than 0.001 will be displayed in the e-format e.g. Values of 10 000 or greater will be displayed in the e-format e.g. Values are given to seven significant figures ( the odd result may show 9's or 0's over running). All results shown will be equivalent values. To use the measurement conversion calculators simply enter a number value into the desired field and click calculate. Dynamic viscosity is the tangential force per unit area (shear or tangential stress) required to move one horizontal plane with respect to the other at unit velocity when maintained a unit distance apart by the fluid (velocity gradient or rate of shear).ĬONVERSION CALCULATORS Convert between Different Units of Measurement Index of Unit Converters Sorry, your browser does not support JavaScript, which is needed to run this calculatorĭynamic Viscosity (absolute viscosity, coefficient of viscosity) Definition:Ī measure of the resistance to flow of a fluid under an applied force. Pascal second (newton second per square metre) UNIT CONVERSION CALCULATOR (absolute viscosity, coefficient of viscosity) centipoise DYNAMIC VISCOSITY UNIT CONVERSION CACULATOR DYNAMIC VISCOSITY
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