Hi 1- How can justify two phenomenon 'Attenuation' and 'Packing' in fluid transients in pipelines? Is it possible to explain and account for those with newton's third law? 2- Regarding to what Chaudhry says in his book ('Applied Hydraulic Transients', P. 192 of 1979 edition, Chapter 7, Part 7.2. Definitions) Packing phenomenon will occurs in two steps: a) increasing as d-e and b) increasing as e-j. One of these increasing (d-e) because of 'slope in water surface, ...'. What does this increasing mean? If oil or water or another liquid flows from low level (Z0) to high level (Z1) in a pipeline (elevation of Z0<Z1), then this type of Packing will be occurred or not? I have not problem with second increasing in packing which occurs because of e-j packing. Thank you in advance.