Friction relaxation model for fast transient flows

摘要: The thesis deals with the problem of friction during rapid transient 1-D flows in a pipe caused by water hammers. evolution wall shear stress is interpreted terms two steps. first step dramatic change passage pressure wave; corresponding new value much greater than predicted steady-state. second step, which begins after wave, relaxation process; here decreases, tending to steady-state average velocity. Extended Irreversible Thermodynamics theory proposed as tool model process. Friction Relaxation Model presented this describes both steps hammers, and therefore it enables take into account information about velocity gradient at wall, otherwise not available 1D modelling.