A classical problem in fluid mechanics, laminar to turbulent transition in pipe flow, was investigated. Transition in pipe flow was first studied in detail by Reynolds (1883) and continued subsequently by numerous researchers. Nevertheless, there are still number of unknown issues that need clarification. As is well known, two distinct types of flow structure exist during a laminar to turbulent transition in pipes, namely puffs and slugs, termed by Wygnanski (1973). Investigations described in this dissertation were concentrated in the development of puffs and slugs in a pipe at different...