Discussion of 'Evaluation of Unsteady Wall Shear Stress by Zielke's Method' by Alan E. Vardy and Jim M. B. Brown

摘要

The importance of Zielke's method for simulating unsteady pressurized flow goes well beyond the case of laminar transients for which it was originally proposed. In fact, the family of convolution-based one-dimensional models of unsteady friction for turbulent flow is derived from it. Moreover, Zielke's model was used recently to highlight the importance of the ratio of pipe length to wave speed for the relevance of unsteady friction (Storli and Nielsen 2011). As a consequence, any refined analysis of its performance is of interest [see, for example, the analysis of Bergant et al. (2001), in which the model's convergence and stability, as well as possible extensions to low Reynolds number turbulent transients, are examined].