Abstract
This paper presents experimental data and theoretical grounds of the forced vibration of a partially immersed fiber in liquid. An optical method utilizing a forward light scattering pattern has been used to detect small (< 1.0 μm) vibrational amplitude of the fiber. The physical and mathematical model of the partially immersed fiber vibration has been put forward. Based on an analytical solution of the model without damping, natural frequencies of this system have been found; they are roots of the transcendental equation. An "effective" velocity of the wave propagation over the fiber has been introduced; it allows one to find out the physical meaning of normal modes. Numerical method for solution of the problem has been proposed. Numerical computations carried out in the wide ranges of the different liquids and depths agree well with experiment data. Based on numerical results it was shown that variations of the maximum vibrational amplitude and the bandwidth can be presented by the linear functions of the coordinate (ρ <sub>s</sub> μ <sub>s</sub> ) <sup>1/2</sup> . It allows one to suggest a simple way for viscosity extraction from both the vibrational amplitude and bandwidth variation, and derive an explicit formula for the achievable accuracy of the viscosity sensing.