Effect of air cushion layer right before impact of a rigid body onto water surface has been investigated in this paper. The study is mainly focused on evaluation of cushioning pressure and the resulting free surface elevation. The air flow is assumed to be an irrotational flow which is governed by Laplace equation. The air problem and the resulting response of the water free surface are suppose...

background: there are many genera of free-living amoeba in the environment, but members of only four genera ( naegleria , acanthamoeba , balamuthia and sappinia ) have an association with human infection. water, soil and air are main sources of infective types of these pathogenic organisms for human. methods: totally, 30 samples were collected from the surface water sources of shiraz city, the ...

This article describes a 3D CFD (computational fluid dynamics) simulation implementation of the stepped planning hull in calm water. The turbulent free surface flow around the stepped planing hull is computed with a RANSE method, using the solver ANSYS-CFX. The turbulence model used is standard k–ε. In order to simulate the disturbed free surface, VOF model is implemented. The CFD model has bee...

Currently a new wave flume for hydraulic experiments near to prototype scale is under construction at Deltares. In the flume, modern measurement equipment will be installed. One of the potential sensor techniques is Terrestrial Laser Scanner (TLS) based range measurements of water waves. TLS range measurements are a very fast and accurate method for solid surfaces, providing temporal and spatia...

background: rivers and streams are important sources of surface waters. water quality of these resources depends on many factors including hydrologic, physicochemical and biological factors. these resources are important in terms of social, economic and political development.. zayanderood river is the only river in central basin of iran that has permanent fresh water. this river has an importan...

treated sea water is the most significant source of water and surfactant floods. the various chemicals employed in treatment plants should be compatible with surfactant systems. based on surface tension experiments, the activity of these chemicals is examined over a wide range of concentrations in different solutions, including distillated water, sea water by using three types of surfactant mix...

surface-piercing propellers (spps) have been widely used in high speed craft due to some desirable features such as high efficiency, omission of resistance of equipment attached to the propeller and proper functioning of cavitation. unlike the submerged propellers, theoretical methods have no significant application on simulation of sppsbecause of problems related to modeling of these propeller...