In order to predict fluid motion induced by sediment dumped into a vertical pipe, a numerical model is developed. The numerical model is based on fundamental equation of incompressible fluid with the Boussinesq approximation and the Volume Of Fluid method is applied to trace water surface in a vertical pipe. According to comparison with laboratory experimental results, calculated results reasonably agree with experimental ones in qualitatively. The estimation results by the developed model on thickness and progressive velocity of turbidity mass on the bottom are presented with maximum ambient fluid velocity.
