A simulation model for the formation and evolution of frazil in open c
hannels is developed. In this model, the primary nucleation is assumed
to be due to mass exchange of seeding crystals at the free surface. T
he model of frazil crystals growth is based on the rate of heat transf
er between crystals and the ambient turbulent flow. Secondary nucleati
on and flocculation are simulated based on binary collisions of frazil
particles. The model is validated with existing experimental data. It
is capable of simulating the variation of water temperature during th
e frazil formation period and the evolution of size and concentration
distributions of frazil in the flow. Effects of the surface heat excha
nge, the rate of seeding, and the flow condition are examined.