摘要:

AbstractPredictions are reported for two‐dimensional, steady, incompressible flows over rearward‐facing steps for both laminar and turbulent conditions. The standard k‐ϵ turbulence model was used for the turbulent flow. Attention was focused on obtaining accurate solutions to the differential equations. It is concluded that some of the serious discrepancies that have occurred between prediction and observation, and attributed in earlier studies to the inadequacy of the turbulence model, may have been due to the inaccuracy of the so

ISSN:0271-2091    

DOI:10.1002/fld.1650040802

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractRay methods are used in coastal and harbour wave disturbance investigations where the area to be modelled is large compared to the wavelength. The interpretation of forward‐plotted ray diagrams, once obtained, has always been a difficult problem. The technique described in this paper calculates wave amplitudes during the ray plotting process and requires only minor modifications to existing ray plotting programs. The idea is to superimpose a grid of square elements over the entire sea area under study, and to perform a spatial averaging of the rays crossing each square element. This ‘square‐averaging’ technique has a number of advantages. It smooths the rapid amplitude variations near caustics, calculates the interference of several wave trains, and generates amplitudes automatically in a square array covering the whole studied sea area. Two types of sensitivity tests are carried out. These tests are designed to determine the accuracy of the predicted wave amplitudes with respect to: (1) the square size per wavelength, and (2) the ray density. These two factors largely determine the computing storage, time and cost of a ray model. An upper limit on the square size per wavelength and a lower limit on the ray density are o

ISSN:0271-2091    

DOI:10.1002/fld.1650040803

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractSeveral explicit schemes are presented fortriangular P0andP1finite elements. A first‐order accurate upwindP0scheme is compared to a FLIC type method. A second‐order accurate Richtmyer scheme is constructed. Applications are given for the Euler system of conservation laws in the 2‐dimensional

ISSN:0271-2091    

DOI:10.1002/fld.1650040804

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe fluid forces resulting from wave interaction with large submerged structures may be calculated using numerical procedures based on the solution of the associated boundary‐value problem. In this paper, the analysis of wave interaction with a fixed submerged object of arbitrary cross‐section and infinite length using a two‐dimensional boundary value formation based on linear diffraction theory is summarized. Subsequently, the application of the boundary element method to obtain a solution is presented. The numerical considerations are emphasized with particular reference to computational efficiency.Numerical results are presented in the form of dimensionless wave force plots for various structural shapes. In the case of a bottom‐seated half cylinder, for which there exists a closed‐form solution, comparisons are made between results generated using both boundary element and equivalent finite element approaches. In the case of a submerged cylinder, comparisons are made between boundary element derived values and experimental results. The boundary element results compare well with both the closed‐form solution and the experime

ISSN:0271-2091    

DOI:10.1002/fld.1650040805

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractA relatively simple, yet efficient and accurate finite difference method is developed for the solution of the unsteady boundary layer equations for both laminar and turbulent flows. The numerical procedure is subjected to rigorous validation tests in the laminar case, comparing its predictions with exact analytical solutions, asymptotic solutions, and/or experimental results. Calculations of periodic laminar boundary layers are performed from low to very high oscillation frequencies, for small and large amplitudes, for zero as well as adverse time‐mean pressure gradients, and even in the presence of significant flow reversal. The numerical method is then applied to predict a relatively simple experimental periodic turbulent boundary layer, using two well‐known quasi‐steady closure models. The predictions are shown to be in good agreement with the measurements, thereby demonstrating the suitability of the present numerical scheme for handling periodic turbulent boundary layers. The method is thus a useful tool for the further development of turbulence models for more complex unsteady

ISSN:0271-2091    

DOI:10.1002/fld.1650040806

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650040807

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650040808

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650040801

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY