A numerical study on the modeling and local characteristics of a predetermined freak wave has been conducted with Computational Fluid Dynamics method. Following the available experimental investigations, a numerical wave tank was accordingly set up based on openfoam source packets. The experimental flap-type wave-maker motion was employed directly to reproduce a specific freak wave. The effects of mesh scheme on freak wave modeling were investigated in depth. Reasonable agreements were achieved between the numerical and experimental results. The wavelet transform method was applied to demonstrate the energy structures of freak wave trains. Special attentions were paid to the particle velocities as well as the dynamic pressure. The results showed that insufficient mesh resolutions could probably result in energy dissipations and phase errors of high-frequency wave components during wave propagations which in turn lead to the shifts of focal positions of freak waves. The particle velocities near the wave crest are extremely large, indicating possible severe wave breaking and impact loads. The theoretical values of similar-shape regular waves could considerably underestimate the particle velocities of freak waves.