scattering of an incoming wave train by a discontinuity at the upper surface of the ocean over a uniform porous bottom of finite depth is considered here in the framework of linearized water wave theory. by employing residue calculus method, the reflection and transmission coefficient are obtained. these coefficients are computed numerically for different values of the porosity parameter g and ...

it is well known that, contaminant transportation is a major problem in coastal zones and has to be faced when coastal structures are being planned. sea pollution not only causes environmental damage, but also impacts quality and population of sea resources. oil is the most important pollutant, pollutants emanating from industries, ships, drilling and exploration in the seabed, ship sewage, tox...

Synodontis nigriventris is a surface-feeding facultative air-breather that swims inverted with its zoological ventral side towards the water surface. Their near-surface drag is about double the deeply submerged drag (due to wave drag) and roughly twice the sum of frictional and pressure drags. For streamlined technical bodies, values of wave drag augmentation near the surface may be five times ...

Direct numerical simulation of turbulent channel flow over a compliant surface has been performed to evaluate the friction drag reduction effect. It is found that a slight drag reduction is observed over a compliant surface. This observation indicates that drag reduction is possible using a compliant surface that is deformed passively by wall pressure fluctuation. A small wall displacement and ...

The Zenneck THz surface wave (Z-TSW) on metals is discussed with respect to its difficulty in generation and measurement. The spatial collapse of the extent of the Z-TSW evanescent field, upon the addition of a sub-wavelength dielectric layer on the metal surface, is explained by a simple model, in good agreement with exact analytical theory. Experimental measurements of the THz surface wave on...

Abstract. Vegetation in wetlands is a large-scale nature-based resource providing myriad of services for human beings and the environment, such as dissipating incoming wave energy protecting coastal areas. For understanding height attenuation by vegetation, there are two main traditional calibration approaches to drag effect acting on vegetation. One them based rule that decays through vegetate...

The octopus arm requires special motor control schemes because it consists almost entirely of muscles and lacks a rigid skeletal support. Here we present a 2D dynamic model of the octopus arm to explore possible strategies of movement control in this muscular hydrostat. The arm is modeled as a multisegment structure, each segment containing longitudinal and transverse muscles and maintaining a ...

A procedure for tailoring a blended wing-body con guration to reduce its computed wave drag is described. The method utilizes an iterative algorithm within the framework of rst-order linear theory. Four computed examples are included. In each case, the zero-lift wave drag was reduced without an increase in drag due to lift. Introduction In the initial rough-cut state of supersonic conguration d...