Falling sphere method

Cupprammonium Solution. This solvent for NC used in determination of its viscosity by the falling sphere method, contains 30 2 g of pure Cu, 165 2g of NH40H (26 to 25%... 

Old observations on spheres falling through liquids are collected by Muncke.12 The falling sphere method seems to have been first used for viscous liquids (tar, glycerol) by Schottner, ho used 2-4 cm. diam. spheres in a vessel of 20 cm. diam. With. 13 cm. diam. tubes the rate of fall was slower. The values of 97 were larger than those found by Poiseuille s method. 

We had to choose one of the earliest and least precise of the numerous methods for viscosity measurements that have been developed over the years, because the falling-sphere method was the only one that could be adapted to low-temperature measurements. The determination of viscosity was made by measuring the resistance to motion of a falling sphere in the fluid. Since the viscosities measured in our experiments on aqueous-organic mixtures at cryogenic tern-... 

The falling-sphere method of viscosity determination also has many applications, and Stokes law may be applied in the form... 

Apparent viscosities were determined using a falling sphere method on samples that had been matured for more than a year. 

Numerous methods for measuring fluid viscosity exist, for example, capillary tube flow methods (Ostwald viscometer), Zahn cup method, falling sphere methods, vibrational methods, and rotational methods. Rotational viscometers measure the torque required to turn an object immersed or in contact with a fluid this torque is related to the fluid s viscosity. A well-known example of this type of system is the Couette viscometer. However, it should be noted that as some CMP slurries may be non-Newtonian fluids, the viscosity may be a function of the rotation rate (shear rate). An example of this is the dilatant behavior (increasing viscosity unda increasing shear) of precipitated slurries that have symmetrical particles [33]. Furthermore, the CMP polisher can be thought of as a large rotational plate viscometer where shear rates can exceed 10 s and possibly affect changes to the apparoit viscosity. The reader can refer to the comprehensive review of viscosity measurement techniques in the book by Viswanath et aL [34]. 

The falling sphere method was applied to study the progress of sol-gel transition by measuring the viscosity (Mizuno, 1985). 

The pulling-up-sphere method has been frequently employed to measure the viscosity of glass melts, instead of the falling sphere method. This is because many repeated runs are possible in the pulling-up-sphere method, when the viscosity of the melt is measured as a function of temperatme. 

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