The influence of change in pressure usually is negligible. The viscosities of most fluids vary appreciably with changes in temperature. Some useful relationships are as follows:ġ square foot = 929.034 square centimetersġ dyne-second per sq cm = 1 poise = 100 centipoiseġ lb-sec/sq ft = 478.801 poises = 47,880.1 centipoise
The distinction between the dynamic and the kinematic viscosity should be carefully noted so that the correct parameter will be used as required in computations. Therefore, the dimensions of kinematic viscosity are The foregoing may be expressed by the equations The proportionality factor (μ) is the dynamic viscosity. The velocity distribution will be linear over the distance (d) and experiments show that the slope of the velocity line (v/d) will be directly proportional to the unit shearing force ( τ = F/A) for all "true" or "Newtonian" fluids. A force (F) is applied to and in the plane of the upper surface, causing it to move with a velocity (v) parallel to the lower fixed surface. 1 which shows two parallel plane surfaces of area (A) separated a distance (d) and the space between completely filled with fluid. (See the Kinematic and Dynamic Viscosity Conversion Tool to perform viscosity conversions.) The dynamic viscosity may be defined with the aid of Fig. There are two basic viscosity parameters: dynamic ( or absolute) viscosity and kinematic viscosity.
ANSI/HI 9.6.7 acts as a guideline that explains these effects. In rotodynamic pumps, fluid viscosity can have a significant impact on performance. For instance, molasses having the same specific gravity (1.48) and the same Brix rating (90) may vary in viscosity from 128,000 to 303,000 Seconds Saybolt Universal (SSU). There is no relation between the viscosity and the specific gravity of most liquids. Since motion or flow of a fluid is produced by shearing forces, viscosity is associated with fluid motion. The viscosity of a fluid (liquid or gas) is that property which tends to resist a shearing force. Viscosity Definitions and Methods of Measurement
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