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A theoretical analysis of velocity profiles in sediment-laden flows is presented by means of Prandtl-Karman mixing length theorem. The study shows that the upward velocity of liquid-phase caused by settling sediment leads to the invalidity of the log-law and Rouse equation. The theoretical analysis takes into account the upward velocity and shows: 1) the mean velocity in sediment-laden flows follows the log-law, but the Karman constant reduces in the main flow region, 2) sediment concentration reduces the mixing length of fluid particles, 3) flow resistance reduces with the presence of sediment concentration, and 4) the sediment concentration profile deviates from the well know Rouse equation. The experimental data agree well with the equations derived on the basis of non-zero wall velocity. It is found that the wall-normal velocity should not be neglected for density gradient flows because it induces more than for pure water flows. 相似文献
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Yang Qinliang Senior Engineer China Guangzhou Maritime Rescus & Salvag Company Guangzhou 《中国海洋工程》1993,(4)
- Based on the curve equation of towline in towing, this paper introduces the new concepts of the coefficient of shape extension and comprehensive extension of towline, infers related calculation formulas, and then gives some quantitative analyses on the magnitude of dynamic loads acting on the towline and the measures to increase the capacity of towline against the dynamic loads. 相似文献
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T.SONG Post-Doctoral Fellow School of Civil Structural Engineering Nanyang Technological University Nanyang Avenue Singapore . Presently Civil Engineer Engineering Depatment Technology Division Maritime Port Authority of Singapore. 《国际泥沙研究》1997,(3)
I.INTRODUCTIONBedloadtransportinsteadyuniformopenchannelflowhasbeenextensiVelystudied.Manyoftheformulasdevelopedforthepredictionofbedloadtransportinuniformopen-channelflowcanbebroughtinthefollowingform(ChienandWan,1983);ac=f(O)(l)xvhereacisthedimensionlessparameterofbedloadtranSPortandOisthedimensionlessparameterofflowintensity.TheseparametersaredefinedasfwheregsisthebedloadtranspoftratePerunitwidthindryweight;disthesedimentdiameter,Sisthebedslopeofthechannel;Rbisthehydraulicradiusdue… 相似文献
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J. E. W. WICHERS 《中国海洋工程》1999,(1)
—Most terminals for tankers are piers and sea islands,while other types include single pointmoorings and multiple-buoy moorings.The LNG and LPG carrier moored to the jetty is a very commonterminal for transfer of gas in open seas.It is important to estimate the motions and line tensions of theLNG carrier when it moors to a jetty in metocean environment.Normally,the motions of the LNG carrierwould be restricted by the loading arm,which is connected to LNG carrier＇s manifold.An example of125,000m~3 LNG carrier moored to a jetty exposed to a set of environment conditions is given.Amathematical model which is based on the equations of motion in the time domain is used to the analysisof LNG moored to an offshore jetty exposed to waves,swell,wind and current.By means of a time do-main computer program TERMSIM computations are carried out to determine and optimize the lay-outand/or orientation of the jetty and mooring gear in terms of forces in mooring lines and fenders and theenvelope of motions of the loadi 相似文献
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