in this paper twelve different empirical resistance coefficients expressed in terms of manning's roughness are used apiece in seventeen known compositing methods. the data obtained from ten different cross-sections of the sefidrood river, iran, are used for the evaluation of the empiricalformulas. the present case-study is selected from a reach with gravel bed topology. then no remarkable bed f...

abstract for investigating the effect of bed form in alluvial channels on the amount of bed load transport, a set of experiments was carried out in a tilting flume under unsteady flow conditions (hydrograph). the produced hydrographs were in triangular form with a maximum discharge of 30 to 45 lit/s/m. three size of sediment particles were used with equal to 1.5, 2.1 and 3.0mm, clear water with...

Three methods have been used to experimentally determine the roughness function (DU) for several rough surfaces. These include the rotating disk, the towed plate, and the velocity profile methods. The first two are indirect methods in as much as they rely on measurements of overall torque or resistance and boundary layer similarity laws to obtain DU, whereas the velocity profile method provides...

The radar backscattering coefficient of three types of soil surfaces at observation angles (10°60°) have been calculated using integral equation model (IEM) for different values of root mean square (RMS) roughness heights and correlation lengths. The surfaces are represented by isotropic autocorrelation functions (exponential, 1.5 power and Gaussian). The dielectric constant (ε) of the soil, an...

Simultaneous measurements of the curves for wear versus distance, wear rate versus distance, and coefficient of friction versus distance were performed in situ to distinguish the transition from severe running-in wear to mild wear. The effects of the initial surface roughness on the severe running-in wear volume were investigated. Disk-on-plate friction and wear tests were carried out with SUS3...

The effect of structured roughness on the heat transfer of water flowing through minichannels was experimentally investigated in this study. The test channels were formed by two 12.7 mm wide 94.6 mm long stainless steel strips. Eight structured roughness elements were generated using a wire electrical discharge machining (EDM) process as lateral grooves of sinusoidal profile on the channel wall...

Soil roughness is a very important parameter affecting radar backscattering coefficient. This paper wants to introduce a new method to retrieve the combined roughness parameter 2 / Zs s l = on the condition of rough surface. To achieve this goal, two experiments are conducted: (1) Advanced Integral Equation Model (AIEM) is used to simulate backscattering coefficients; and (2) a new algorithm to...