Influence of channel shape on wave-generated parameters by a pressure source in shallow water

The present work is a numerical investigation into the waves generated by a pressure source moving in straight channels with a nonrectangular cross-channel depth profile. Wave fields generated by the moving pressure source are described, and the effects of channel bathymetry on the generated wave characteristics of wave height, wave-breaking location, wave-breaking type and intensity, and peel angle are presented. Four different channel cross-section shapes were investigated, and the results were analyzed. It was concluded that the maximum wave height depended primarily on pressure-source parameters and that the investigated channel shapes did not have a significant effect on the maximum wave height. All four investigated channels were able to generate plunging-shaped breaking waves. In addition, wave-breaking intensity and barrel shape could be controlled by beach-slope shape; however, beach slope did not have a considerable effect on the wave-breaking location. The width of the deep section of the channel had a significant effect on the breaking location. Widening the deep section of the channel moved the breaking point farther from the pressure source. According to the simulation results, it is possible to generate waves for an intermediate or expert surfer only by changing the pressure-source speed. According to the results, by changing the pressure-source speed, the peel angle changes, which is the best way to change the required skill level for surfing. In addition, changing the channel shape did not have a significant effect on the required skill level for surfing

An investigation into the effect of pressure source parameters and water depth on the wake wash wave generated by moving pressure source

In this study the effect of moving pressure source and channel parameters on the generated waves in a channel was numerically investigated. Draught, angle of attack and profile shape were investigated as parameters of pressure source and water depth and blockage factor as channel parameters on wave height. Firstly, the chosen Computational Fluid Dynamics (CFD) approach was validated with the experimental data over a range of speed. Then the CFD study was conducted for further investigations. It was shown that that by enlarging draught, angle of attack and beam of the pressure source, the wave height generated will be increased. Channel study showed that it is possible to increase the wave height generated by shallowing water for a given speed as long as the depth Froude number is subcritical and the wave height generated is independent of water depth for supercritical depth Froude numbers. The blockage factor has more influence at supercritical Froude depth values, while at subcritical Froude values is negligible compare with water dept

Biodiesel synthesis: influence of alkaline catalysts in methanol-oil dispersion

CAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPERJ - FUNDAÇÃO DE AMPARO A PESQUISA DO ESTADO DO RIO DE JANEIROCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOBiodiesel synthesis from soybean oil using methanol and alkaline catalysts occurs in the following two consecutive steps: dispersion of methanol in the oil and methanolysis. The effect of the alkaline catalysts NaOCH3, KOCH3, NaOH, and KOH in the dispersi302342349CAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPERJ - FUNDAÇÃO DE AMPARO A PESQUISA DO ESTADO DO RIO DE JANEIROCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPERJ - FUNDAÇÃO DE AMPARO A PESQUISA DO ESTADO DO RIO DE JANEIROCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOsem informaçãosem informaçãosem informaçãoThe authors would like to thank CAPES, FAPERJ, and CNPq (Brazilian agencies) for their financial suppor

Experimental Study on the Influence of Appendages on a Yacht Rolling at Zero Froude Number

Yachts tend to roll uncomfortably while at anchor, causing discomfort to the crew and passengers, generating additional stresses on equipment, and making such operations as embarking and disembarking hazardous activities. Currently, there is a dearth of data regarding roll motions at zero forward speed for hull shapes dominated by large appendages. Hence, an experimental study into the effect of large appendages on roll motion was undertaken. The model test results are presented, showing how changes in appendage geometry alter the roll response

Prediction and measurement of the roll motion of a sailing yacht at zero forward speed

The roll motion of a yacht at zero Froude number is investigated, motivated by limitations of existing theoretical models of roll motion when applied to bodies with large appendages. A time domain single degree of freedom roll model has been developed in order to identify the dominant excitation and damping sources. The canoe body forces were determined from a wave diffraction program whilst the appendages were treated as fully submerged flat plates. Calculation of the forces acting was based on a stripwise Morison formulation. A series of full scale validation experiments has also been conducted, in calm water and in ocean waves.The results show that the keel, rudder and sail dominate the damping, whilst the canoe body contributes very little. The hydrodynamic damping is non-linear with respect to wave amplitude, but the overall damping with a sail hoisted is only weakly non-linear with respect to wave amplitude because the sail dominates the damping, particularly in a wind field. The numerical model predicts a strong influence of wave heading which is not borne out by the full scale trials