Dropwise condensation mechanisms when varying vapor velocity

•The effect of vapor velocity is investigated during dropwise condensation (DWC) of steam.•Heat transfer coefficient (HTC), droplet departing radius and droplet population are measured.•The condensation HTC increases with vapor velocity, while the droplet departing radius is reduced.•For the largest droplets radii, the drop-size distribution is lowered when increasing vapor velocity.•The effect of the vapor velocity on drop-size density and HTC is modeled.