New methods of reducing streaming current (a comparison of calculated and experimental results)

Two well known methods of reducing streaming current are the introduction of interface activation substances and the roughening of the inner surface of the pipe wall. Numerous reports have been published on experiments concerning interface activation agents. But there have been very few experiments indeed concerning the wall surface roughening method. In addition to conducting experiments on the roughening of pipe walls, the authors have tried to discuss the factors involved in the reduction of streaming current, with the aid of solutions to Navier-Stokes equations with the use of a CRAY X-MP/14se super computer. To summarise their results, it has been found that an intimate relation exists between the streaming current and the area of pipe wall exposed to direct contact with the main path of flow in the liquid. If grooves are cut in the inner wall of the pipe, vortices occur, and since the main liquid flow then no longer comes into direct contact with the pipe wall a reduction can be observed in the streaming current.