Added Resistance of an AUV Moving Inside a Water Pipeline Due to Wall Proximity

This paper evaluates the added resistance of a torpedo shape AUV, moving inside a water pipeline, due to wall effects within the tube. Today, there are long length pipelines of water or petroleum that need to regular inspection. Early detection of failure will help to prevent breakdown and avoid the huge cost of an accident. As pipelines are enclosed environments and difficult to access, pipeline inspection robots are increasingly used for routine inspection and early failure detection. In the engineering cases, the pipes are full of liquid because there is no possibility for evacuating the pipe and interrupting the liquid transfer. It may be with or without flow of water. Therefore, the AUV must be able to afloat inside the pipe and perform non-contact inspection. In dry pipes, inspection device has contact with the walls and moves on them but in full pipes, the AUV moves such as a torpedo or submarine. The pipes have limited diameter and because of the wall effects on the fluid flow around the AUV, the resistance will be more than the free flow condition. This added resistance should be accounted accurately because it is necessary for determination of vehicle speed, power demand, range and duration of operation. This paper considers a torpedo shape AUV moving inside the pipes with the different diameter. The resistance of this modeling will be compared with the resistance of free steam modeling. This analysis is performed by the Flow Vision (V.2.3) software based on CFD method and solving the RANS equations.