![]() If you divide kinematic viscosity by the fluid density, you get absolute viscosity. The viscosity is obtained from a decay time measurement, and requires knowledge of the fluid density. Thus, dynamic viscosity is a measure of force, while kinematic viscosity is a measure of velocity. Vibrating wire viscometer is based on the damping of the transverse vibrations of a taut wire in the fluid, and minimizes or eliminates hydrodynamic correction terms. This descending pellet acts as a piston, forcing the gas through a fine capillary.This mercury “piston” establishes a constant pressure difference across the fine capillary.The weight of the pellet and the internal diameters of both tubes being known, the time of descent of the mercury between given points permits calculation of the volume rate of flow of the gas through the capillary under constant pressure difference, providing data which allows the computation of the viscosity of the gas. Dynamic viscosity refers to the force that a fluid requires to move through its internal molecular friction in order to keep flowing and Kinematic viscosity. Forming a perfect internal seal between the spaces on its either side, the mercury pellet will, at any inclination of the tube, quickly come to a steady descending velocity. $$\mu=\kappa \cdot t \cdot (\rho_b-\rho)$$įalling body viscometer is very similar to the rolling body viscometer with the exception that the ball is replaced with a piston.Ĭapillary tube or Rankine viscometer - I don't know the governing equations required for this device.The basic principle of operation of the Rankine method is that a pellet of clean mercury, introduced into a properly sized glass tube filled with a gas, completely fills the cross section of the tube. Dynamic viscosity is the scientific concept defining the viscosity as a ratio between two measured quantities: the shear stress imposed on the product and the. Dynamic viscosity is also termed ' absolute viscosity ' and is the tangential force per unit area required to move one horizontal plane with respect to the other at unit velocity when maintained a unit distance apart by the fluid. The rolling ball viscometer measures the absolute viscosity of an fluid using the following general equation.My source PhD thesis by Kegang Ling from Texas A&M university, 2010 My understanding is that only the kinematic viscosity can be measured directly (with the devices that I am aware of) and then to get the dynamic viscosity you must adjust the kinematic viscosity by the fluid's volumetric mass density. Can dynamic viscosity be measured directly and without knowing fluid density? If so, how?
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