Abstract
This paper presents the analysis of the modes of a viscometer optical fiber vibration based on a simplified mathematical model. The initial quasilinear equation with discontinuous coefficients, which describes the vibration of an optical fiber partially immersed in liquid, is reduced to the telegraph equation with constant effective coefficients. The form of these coefficients is chosen such a way to capture the most important physics of the immersed fiber's vibration. The subsequent analytical solution of the model in an attempt to give results that accurately follow the trends of experimental results.