Gravity currents generate a lot of interest for fluid mechanics scientists. The understanding of a fluid spreading on a surface allows a better apprehension of related geophysical, atmospheric phenomena and industrial applications. On the one hand this contribution talk will deal about mathematical models of thin liquid films spreading with constant and temperature-dependent viscosity and their simulation on COMSOL. On the other hand, the experiment of a free flow vizualisation of a thin viscous liquid layer and its processing on STREAMS will be discussed. Comparison of velocity field will be presented.