[1] The aerodynamic friction between air and sea is an important part of the momentum balance in the development of tropical cyclones. Measurements of the drag coefficient, relating the tangential stress (frictional drag) between wind and water to the wind speed and air density, have yielded reliable information in wind speeds less than 20 m/s (about 39 knots). In these moderate conditions it i...

The influence of applied normal load and roughness on the tribological behavior between the indenter and sample surface during nanoindentation-based scratching has been experimentally investigated by using different surfaces (fused silica and diamond-like carbon) featuring various degrees of roughness. At a sufficiently low applied normal load, wherein the contact is elastic, the friction coeff...

uncertainty is undoubtedly an inevitable part of programming process. a lot of effective factors in the water resources’ performance are not deterministic while their values are surely needed for the design and implantation of water systems. since an optimal design of water distribution systems is in demand of a just evaluation of the costs, efficient operation of such systems calls for a prope...

We demonstrate the utility of using the equivalent bottom roughness for calculating the friction factor and the drag coefficient of a seagrass meadow for conditions in which the meadow height is small compared to the water depth. Wave attenuation induced by the seagrass Posidonia oceanica is evaluated using field data from bottom-mounted acoustic doppler veloci meters (ADVs). Using the data fro...

Different construction materials with different roughness used to make circular weirs highly affect surface roughness and, in turn, flow hydraulics passing over these structures.  In the present research, numerous experiments under different hydraulic conditions were performed on a physical model to study the effects of roughness on flow hydraulics over a circular weir. The flow hydraulics incl...

the objective of this research work is to evaluate the surface roughness of polyacrylonitrile (pan) nanowebs. for this purpose the nanowebs have been prepared in different concentrations of pan solution from 11 to 15% (by wt). surface roughness of nanowebs was evaluated by entropy algorithm (ent) as well as atomic force microscopy (afm) and then the results of two methods have been compared. to...