Friction factor and von Kármán's κ in open channels with bed-load

Turbulent flow structures in alluvial channels with curved cross‐sections under conditions of downward seepage

“…Increase in the near‐bed streamwise velocities caused by the presence of downward seepage is in conformity with the findings of previous researchers (Oldenziel and Brink, ; Nezu, ; Maclean, ; Dey and Nath, ). Effect of sediment transport on von Karman's constant is visible in several studies (Bennett and Bridge, ; Nikora and Goring, ; Cooper, ; Koll, ; Gaudio et al ., ; Dey et al ., ). These researchers have reported that for flows with bed‐load transport, the value of von Karman's constant decreased from its universal value.…”

The von Kármán constant for flows over rough mobile beds. Lessons learned from dimensional analysis and similarity

“…This is compatible with a constant convergence limit of W m in Eq. (12), different than 1=0:4. One must also consider the possibility that there is no finite convergence limit for W m as P R becomes large, which carries other possibilities of asymptotic matching in the overlapping layer.…”

“…Hence, one may have j ðmÞ j ðf Þ ¼ 1, as implied by e.g. [40], among others, j ðmÞ j ðf Þ < 1, as argued by [12], among others, or j ðmÞ j ðf Þ > 1 depending on the relative magnitude of is, in the same range, 0:928. One obtains j ðmÞ j ðf Þ ¼ 1:058 which, considering the experimental uncertainty involved, may be considered 1.…”

“…Gaudio et al [12] conducted sand overfeeding experiments over a flat bed roughened with the same 1 mm sand. They reported a reduction of j that could be expressed by a non-linear function of the bedload volume concentration.…”

Analysing turbulence characteristics of flow over submerged flexible vegetated channel

“…The universal logarithmic law for the inner scaling region in the classical turbulent boundary layer is given by Von Kármán (1930) and subsequent universality of Von-Karman constant k. In case of alluvial river, the Von-Karman constant is not universal as confirmed by Gust and Southard (1983) and Bennett et al (1998) for smooth and transitional regimes and Bennett and Bridge (1995), Nikora and Goring (1999) and Dey and Raikar (2007) for full rough regime. Recently, Gaudio et al (2010) also discussed on non-universality of Von-Karman k in fluvial streams. The non-universality of Karman constant is also obtained in this study.…”