ISSN:0022-1686    

DOI:10.1080/00221689209498943

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The artificial circulation and the mixing of temperature stratified water induced by an air bubble plume were studied in laboratory experiments. The time evolution of the spatial distribution of water temperatures was measured. The data were analyzed and gave information on the development of flow patterns and entrainment rates. Of particular interest were the development of the upwelling region, location of the plunge line, temperature structure in the farfield, and water entrainment by the bubble plume and by the plunging flow.

ISSN:0022-1686    

DOI:10.1080/00221689209498944

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A simple model of two-dimensional (depth averaged) flow in topographic gyres by wind action on a shallow model lake is shown to produce chaotic particle motions in the case where the wind alternately blows from two prescribed directions. The nature of the motions of the advected particles is of the generic type known from Hamiltonian systems: islands of regular motion surround elliptic periodic points and chaotic regions are related to hyperbolic periodic points. The effect of vertical-shear dispersion is simulated by adding random displacements to the advective particle displacements. The contributions of chaotic advection and shear dispersion to the growth of the mean distance between particles are examined in some detail.

ISSN:0022-1686    

DOI:10.1080/00221689209498945

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The movement on dry and wet beds of two-dimensional flood waves resulting from the instantaneous break of a dam are experimentally investigated using wave meters and pressure transducers in order to record the water depth variations and analyze the behaviour of the resulting flow. All measured data refer to a converging- diverging open-channel flume configuration of rectangular cross section equipped with a hypothetical dam located right at the throat of the flume. Measured signals were recorded and processed via a data aquisition system. The applied measurement technique was very satisfactory, simple and economic. The two-dimensional flow behaviour was well detected. Computational results, using a previously developed unsteady two-dimensional flow computer program were also compared with measurements and the comparisons were satisfactory. The measured data can also be used by other research workers in order to validate their numerical codes.

ISSN:0022-1686    

DOI:10.1080/00221689209498946

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The stability of water-surface oscillations is investigated for the case of a tailrace surge chamber shared by two or more generating units in a hydroelectric power plant. Two kinds of turbine governing are applied for the condition of small-amplitude surge perturbations. Critical stability conditions for the surge chamber are derived by linearizing the ordinary differential equations describing the lumped system. As compared with the result achieved by previous researchers, the common surge chamber requires smaller horizontal crosssection for surge stability. A combination of the proposed manners of governing can be utilized in certain power plants in order to achieve an economical design of the surge chambers.

ISSN:0022-1686    

DOI:10.1080/00221689209498947

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

To analyze flows in channel expansions and contractions, two-dimensional, depth-averaged, unsteady flow equations in a transformed coordinate system are solved numerically by using the MacCormack scheme. The non-rectangular physical domain is converted into a rectangular computational domain. This transformation allows the use of an orthogonal grid and an easier inclusion of side wall boundaries. The unsteady flow model is used to obtain steady flow solutions by treating the time variable as an iteration parameter and letting the solution converge to the steady state. The results of the mathematical model are compared with experimental data. The comparison of the computed and measured results show satisfactory agreement in cases where the assumption of hydrostatic pressure distribution is valid. The capability of the model for handling mixed super- and sub-critical flows in a channel transition is demonstrated.

ISSN:0022-1686    

DOI:10.1080/00221689209498948

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This paper describes the use of the McCormack explicit finite difference scheme and the treatment of the boundary problem in the development of a one-dimensional simulation model that solves the St. Venant equations of the unsteady open channel flow. External and internal boundaries are considered. Various illustrative cases are presented to show the efficiency of this technique.

ISSN:0022-1686    

DOI:10.1080/00221689209498949

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The paper describes the salient features of a three-dimensional finite difference code at present under development for Large Eddy Simulation of free-surface turbulence. It is essential in this application that the numerical approximations conserve mass, momentum, and kinetic + potential energy while allowing for large movements of the free surface and these are presented in detail for cells cut by the surface. The surface advancement is by a combined Volume-of-Fluid and height function method which conserves mass exactly over finite time steps, but does not permit breaking waves. Momentum is advanced by control volume techniques, and the potential singularity caused by very small surface cells is avoided by a new split-merge technique which is numerically stable. Results are presented for a two-dimensional inviscid large amplitude wave in a periodic box.

ISSN:0022-1686    

DOI:10.1080/00221689209498950

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Dilute polymer solutions of sufficiently high molecular weight generally exhibit the phenomenon of drag reduction in turbulent flows. This has been usually studied by conducting either pressure drop/flow rate measurements or axial velocity profile measurements.

ISSN:0022-1686    

DOI:10.1080/00221689209498951

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

REGULAR AND RANDOM WAVE PRESSURES AROUND LARGE DIAMETER SUBMARINE PIPELINE NEAR OCEAN BEDK. Subbiah, N. Jol hi Shan kar and Hin-Fatt Cheong, Vol. 29, No. 1, 1991, pp. 49-66

ISSN:0022-1686    

DOI:10.1080/00221689209498952

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor