The falling needle viscometer. A new technique for viscosity measurements

The Falling Ball Viscometer (FBV) is a device in which a sphere falls under the influence of gravity in a infinite fluid medium. This device makes it possible to determine the viscosity of the fluid on the basis of a utilization of Stokes' solution. However, in attempts to obtain precise measurements, certain problems have arisen which are related to difficulties in obtaining spheres of proper quality and dimensions, and to the necessity of applying a 'wall correction'. The present investigation is concerned with an approach to eliminate some of these difficulties by making use of a new device, the 'Falling Needle Viscometer' (FNV). The advantages of the FNV are discussed. A Stokes' type of solution can be obtained because of the simpler geometry of the cylinder, and a correction of the data for the wall is unnecessary. Other advantages are related to the replacement of the sphere by a 'needle'.