ABSTRACT
Experiments in a rectangular open channel were carried out to evaluate the interfacial friction factor for salt wedges, under steady and unsteady conditions. From the experimental results obtained under steady conditions, reverse operations by a one dimensional two-layer model were performed to obtain values of interfacial friction factor,fi, and the results were then compared with published data. Considering the entrainment mixing and a side-wall friction in an open channel, fi compared favorably with Kaneko’s empirical formula. However, the results were smaller than those obtained from the curves of Dermissis et al. [1][2]. In particular, entrainment coefficients were generally smaller, compared with interfacial mixing rates, Eg, obtained by Grubert, when the interfacial transition layer is in a supercritical state. Therefore, if we apply fi, obtained by Dermissis et al. or Ea. obtained by Grubert[6] for computations of salt wedges, wedge lengths become remarkably short, due to excessive evaluation of fi. On the other hand, computed results of unsteady salt wedges showed much better reappearance toward variations of flow fields as well as wedge lengths when a tidal period is 600 seconds and using Kaneko’s empirical formula as fi, compared with using fi proposed by Suga[11].
