摘要:

AbstractCertain free surface flows exhibit in nature negligible vertical accelerations and as a result the pressure within the fluid remains hydrostatic. The method of characteristics is developed as a solution technique for the integration of the partial differential equations describing this kind of flow. The equations are integrated over the depth to provide a two‐dimensional model which is then tested and validated by comparing its results with tide‐induced flows occurring in a number of cases where either analytical or observational data are available for comparison. On the basis of the results of the 2D model, a finite difference 3D model is developed which provides the values of the unknown velocitiesu,vandwalong the three axesx,yandz. This combined 2D–3D model is verified by applying it in cases of wind‐induced flow inside closed or open basins for which the classical Ekman solution may be used as a testin

ISSN:0271-2091    

DOI:10.1002/fld.1650140402

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractWaves generated by submarine landslides are treated as three‐dimensional flows of a perfect incompressible fluid. For the solution of the Cauchy‐Poisson problem a time‐discretization is applied which leads at each time step to a non‐homogeneous free surface condition; the solution is then divided into two parts. The first part, subject to the true free surface condition, is computed in a simplified domain with constant depth. The second part involves a homogeneous free surface condition, a corrected bottom condition and the true bathymetry. In the case of constant depth, unconditional stability of the time discretization is derived. In the case of variable depth, mass and energy conservation is derived. Numerical results are presented. Comparison is made with other methods for the generation of axisymmetric waves. The transient propagation along a rectilinear coast is studied, including a comparison between two different bathymetries; trapping of energy is o

ISSN:0271-2091    

DOI:10.1002/fld.1650140403

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractA general numerical method for the solution of the complete Reynolds‐averaged Navier‐Stokes equations for 2D or 3D flows is described. The method uses non‐orthogonal co‐ordinates, Cartesian velocity components and a pressure‐velocity‐coupling algorithm adequate for non‐staggered grid systems. The capability of the method and the overall performance of the κ–ϵ eddy viscosity model are demonstrated by calculations of 2D and 3D flow over a hill. Solution error estimations based on fine grids, e.g. 320 × 192 control volumes, together with comparisons with standard turbulence model modifications, low‐Reynoldsnumber or streamline curvature effects, have allowed the investigation of model drawbacks in predicting turbulent flows over s

ISSN:0271-2091    

DOI:10.1002/fld.1650140404

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe time‐dependent turbulent Navier–Stokes equations are solved numerically by a finite element method with an algebraic eddy viscosity model (Baldwin–Lomax formulation) for oscillating turbulent channel flows. The method of averaging is used to analyse the resulting periodic motion of the fluid. Numerical results are obtained for various Strouhal numbers and relative amplitudes. A comparison is made between the numerical and published experimental results. It appears that for low relative amplitudes in a certain range of frequencies the agreement is satisfa

ISSN:0271-2091    

DOI:10.1002/fld.1650140405

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractTheoretical research to simulate twin‐jet impingement with cross‐flow has been undertaken. An impinging twin jet coupled with cross‐flow in closed ground effect has been studied by using the compressible Navier‐Stokes equation with a Jones–Launder κ–ϵ two‐equation turbulence model. The velocity results without cross‐flow were compared with the data of Saripalliet al. and found to show good agreement. The calculated results show that several recirculating zones are distributed around the flow field. Their size and location are closely related to the jet exit height above the ground, the nozzle space and the strength of cross‐flow. In addition, a fountain upwash flow occurs between the nozzles, and two low‐pressure recirculating zones are induced by the interaction between the nozzle mainstream and the fountain upwash flow. This induce a loss of lift force of the aircraft. The effects of the cross‐flow induce the sudden decrease in the lift force of the aircraft; the stronger the cross‐flow, the lower is the lif

ISSN:0271-2091    

DOI:10.1002/fld.1650140406

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe mathematical formulation of a three‐dimensional shallow sea model using a modal expansion in the veitical is briefly described.The importance of the time discretization of the vertical diffusion term and bottom friction term is discussed in some detail. Both stability theory and numerical calculations show the importance of time centring or evaluating the modal form of the viscosity term at the higher time step in order to develop a numerically efficient algorithm. Similar analysis and calculations show that in shallow water it is essential to time centre or evaluate bottom friction at the higher time step. In the case of linear bottom friction it is shown that this condition can be readily accomplished. However, using a quadratic friction formulation (a more physically realistic form), this cannot be readily achieved. A new algorithm is presented whereby a stable solution can be obtained even in shallow water using quadratic bottom frictio

ISSN:0271-2091    

DOI:10.1002/fld.1650140407

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe finite difference scheme developed by Liu et al. for the Newtonian jet swell problem has been improved: an algebraic approach has been adopted for the numerical mapping; a new formulation for free surface iteration has been proposed; the discrete flow equations have been solved by a combination of the successive line underrelaxation method and the Picard method. With these modifications we are capable of achieving more accurate numerical solutions and a substantial saving in computing time.

ISSN:0271-2091    

DOI:10.1002/fld.1650140408

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650140409

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650140401

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY