The calculation model of cold-state falling film flow outside horizontal tubes is established by volume of fluid(VOF)method. The distribution rules of liquid film thickness and velocity outside horizontal tubes under the flowing cold-state falling film condition are studied. Effects of sprinkle density

cross section position and distance from wall on velocity field are analyzed. The results of numerical calculation show that the flow velocity of liquid film outside horizontal tubes increases with the increasing sprinkle densities. The circumferential velocity of liquid film increases with the increasing circumferential angle at the cross section of falling film column. Moreover

the circumferential velocity of liquid film at middle cross section between adjacent falling film columns shows an ascending tendency with the increasing circumferential angle. The circumferential velocity of liquid film increases fast with the angle in the range of 30° to 110°

while the circumferential velocity of liquid film is smoothly changed in the range of 120° to 150°.