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This paper presents a potential based boundary element method for solving a nonlinear free surface flow problem for a ship moving with a uniform speed in finite depth of water. The free surface boundary condition is linearized by the systematic method of perturbation in terms of a small parameter up to third order. The surfaces are discretized into flat quadrilateral elements and the influence coefficients are calculated by Morino's analytical formula. Dawson's upstream finite difference operator is used in order to satisfy the radiation condition. The second order solution gives better result than the first or third order solution. So the present method with the second order solution can be adopted as a powerful tool for the hydrodynamic analysis of the thin ship in finite depth of water. 相似文献
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The tbough one year cormsion potential and polarisation resistanoc for 3 kinds of stals in seabottomedment of Liaodong Bay were measured with the “MD” method.The measurements wiIl have some thoretical and pndital talues. The thooretical valoc lies in thatthe reoorded changing process of the practital corrosion case can be basis for indoor discussion andeectrochemical on the corrosion practical value lies in that the obtained datu canbe basis for designing and controlling elatrochemical protation syttems. In fact, it is very difficult tomeasure in situ the cornosion parnders of steeIs in sea sediment. 相似文献
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Results from numerical investigations regarding the exchange of HNO3, NH3, and NH4NO3 between the atmosphere and the biosphere are presented. The investigations were performed with a modified inferential method which is based on the generally accepted micrometeorological ideas of the transfer of momentum, sensible heat and matter near the Earth's surface and the chemical reactions among these nitrogen compounds. This modified inferential method calculates the micrometeorological quantities (such as the friction velocity and the fluxes of sensible and latent heat), the height-invariant fluxes of the composed chemically conservative trace species with group concentrationsc
1=[HNO3]+[NH4NO3] (total nitrate),c
2=[NH3]+[NH4NO3] (total ammonia), andc
3=[HNO3]-[NH3] as well as the fluxes of the individual nitrogen compounds. The parameterization of the fluxes is based on the flux-gradient relationships in the turbulent region of the atmospheric surface layer. The modified inferential method requires only the data of wind velocity, temperature, humidity and concentrations (HNO3, NH3, and NH4NO3) measured at a reference height by stations of a monitoring network. 相似文献
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A. Bongartz S. Schweighoefer C. Roose U. Schurath 《Journal of Atmospheric Chemistry》1995,20(1):35-58
The mass accommodation coefficient of ammonia gas on water has been determined by measuring the absorption rate of 50–200 ppm NH3 in one atm of air or helium into a liquid jet of 97 µm diameter as function of the exposed jet length, and comparing the results with numerical simulations which treat as the only free parameter. The model considers in detail transport of NH3 by molecular diffusion, penetration of the gas/water interface, hydrolysis in the acidified water, and transport of the solutes from the surface into the jet. A correction is applied for the time evolution of the jet surface speed, using literature data on the fluid mechanics of liquid jets. The result of nine sets of independent measurements is
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Measures of local relief, regional relief, and slope were calculated from digital elevation models (DEMs) for 50 bedrock units in the Ridge and Valley and Blue Ridge provinces of Tennessee. Each of these measures was normalized and the three were then averaged to produce the erosional resistance index (ERI). Bedrock units with higher ERI values include coarse clastics, intermediate clastics, and metaplutonics. Units with lower values include shales, limestones, limestones plus dolostones, and carbonates plus fine clastics. Dolostones tend to have intermediate values. The calculated ERI values were compared with subjective ratings by a geologist with decades of field experience in east Tennessee. Generally, the agreement between the two ratings was good, the most glaring exception being several shales with improbably high ERI values. These turned out to be thin units cropping out beneath very hard sandstones, allowing them to stand higher and steeper than would otherwise be possible. A systematic method for detecting such erroneously high ERI values is suggested. Inspection of a drainage map superimposed on the geology map shows that in a given area, streams tend to flow on rock units with the lowest ERI values. In addition, statistical analysis shows that bedrock units with the lowest ERI values are, on average, almost three times closer to the nearest stream and six times as likely to have streams flowing on them than are units with highest values. Further, the effect of ERI on stream location is strongest for streams with drainage areas between 1 and 30 km2. Thus, small streams appear to be subject to greater lithologic control than are larger streams. 相似文献
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