摘要:

AbstractA two‐dimensional finite difference alternating direction implicit (ADI) scheme numerical model to solve the vertically integrated form of the non‐linear hydrodynamics equations and convection–diffusion equation has been developed for the description of tide flow and pollutant transport in Taipong Bay, China. Computer software for the modelling is well designed to reduce storage and costs of computation. The computed results agree quite well with the observations available. The tidal level, tidal current, residual current and organic pollution in the bay are discussed based on the computed results and observed data. Applications for the environmental problems along the coast of the bay are also mentioned br

ISSN:0029-5981    

DOI:10.1002/nme.1620270112

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractJacket structures have many sub‐sea appurtenances attached to them. For example, a typical jacket structure has hundreds of sacrificial anodes attached to its members. The fluid loading of these structures is calculated using Morison's formula. The force coefficients used in the equation are based on experiments carried out, for the most part, on single cylinders in laboratories in ideal flow. There are very few experimental data available for the fluid loading of cylinders with appurtenances. Moreover, it is not possible to calculate theoretically the loading on such configurations in flows of practical interest using approaches such as the finite element method. However, appurtenances can contribute significantly to the overall loading on a structure. This paper presents the preliminary theoretical work that has been carried out as part of a programme to establish a rational method for estimating the fluid loading on tubular members with appurtenance

ISSN:0029-5981    

DOI:10.1002/nme.1620270113

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe dynamic behaviour of marine vehicles in extreme sea states is a matter of great concern following some recent and dramatic mishaps. The complex problem of its prediction can be approached from the study, yet of broader scope, of non‐linear dynamic systems subjected to stochastic excitations. However, a general non‐linear stochastic dynamic theory is not yet available.A new technique, the so‐calledlinearize‐and‐matchmethod, for predicting the response statistics of non‐linear systems, is presented. Essentially, the technique involves the construction of an infinite series of linear systems aimed at the prediction of the response statistical moments of a given order.The linear systems are successively defined by linearizing the original, non‐linear system and matching the Volterra functional model response statistics to the desired order. The linear system for predicting second order statistics is shown to coincide with the one obtained using the method of equivalent linearization.Response probability distributions can be constructed from the knowledge of such statistics. Particular attention is devoted to the distribution of maximum entropy and its justification in such underdetermined moment problems.Finally, applications to the roll motion of ships serve to exemplify as well as to assess the accuracy and the versatility of the overall method. Response distributions of maxima so predicted compare very well with digital simulat

ISSN:0029-5981    

DOI:10.1002/nme.1620270114

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe paper deals with non‐Fickian dispersion of inert solutes in random permeability fields. Attention is focused critically on the statistical characterization of the porous medium which affects pollutant dispersion in groundwater. After a brief account of recent results of stochastic theories of transport in porous media and of the fundamental indications of large‐scale field experiments, it is inferred from numerical studies that the particular choice of an analytical form of covariance of log‐conductivity has a poor influence on the overall dispersion process. In fact, different covariance structures with the same macroscale (a measure of the distance between two points beyond which the permeability ceases to be correlated) yield very similar dispersion processes. The result has a noteworthy bearing on field studies of pollutant dispersion in groundwater because it underlines the reliability of exponential correlation structures yielding analytical expression for time‐varying macrodispersion coeff

ISSN:0029-5981    

DOI:10.1002/nme.1620270115

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractConsolidation problems associated with foundations for off‐shore structures are described and analysed using the finite element method. The structure itself and the soft underlying soil are modelled by finite elements with different constitutive relationships for each. Interfacial behaviour between the two is simulated by six‐noded elements, with a hyperbolic stress–strain relationship.Having modelled the soil–structure system behaviour during the consolidation stage, a soil–structure interaction analysis is then carried out for both shallow and deep foundations. Other important factors, such as the redistribution of stresses in the structure itself which have resulted from differential settlements, will also be inv

ISSN:0029-5981    

DOI:10.1002/nme.1620270116

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractIn this paper a mathematical model is presented, based on the application of an averaging technique, in which the equations governing the behaviour of saturated porous media are integrated (averaged) over the smallest dimension of the domain of the problem (thickness). This results in a two dimensional model, in which the three dimensional nature of the problem is accounted for. In fact, the solution is sought in terms of the mean values over the thickness of the field variables and of the transverse displacement components. For the solution of the resulting governing equations a partitioned procedure is employed, which improves the efficiency of the method. The proposed model is very useful in solving problems in which the spatial nature prevents the applications of two dimensional models.Examples are presented, which illustrate the validity of this approach.

ISSN:0029-5981    

DOI:10.1002/nme.1620270117

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

ISSN:0029-5981    

DOI:10.1002/nme.1620270101

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY