摘要:

AbstractFive numerical schemes are compared using convergence studies in the framework of the hydrostatic Sandia Ocean Modeling System (SOMS). Three resolutions are used, 40, 20 and 10 km, with respectively three, seven and 15 layers and time steps of 60, 30 and 15 min, so 15 convergence calculations are performed. The same geophysical prototype problem (exhibiting baroclinic instability in a statically stable environment) is used for all calculations.All five schemes are second‐order‐accurate in space, but those using four‐point interpolations for the Coriolis and pressure gradient terms are shown to produce much more accurate results, with relatively little extra computation, than schemes using two‐point interpolations.Convergence is also indicated with decreasing horizontal diffusivities of 107, 106, and 105cm2s−1. Using 107cm2s−1diffusivities causes substantial damping of the dominant instabilities during the 30‐day integrations performed, but using 106cm2s−1results in little damping and yields results very close to those using 105cm2s−1.A barotropic (vertically averaged flow) cyclonic northern basin gyre is explained as a weakly forced circulation. Its equilibrium amplitude is determined by a balance between dissipation effects due to horizontal mixing and diffusion, and weak second‐order driving associated with thermodynamic forcing and vorticity dissipation at the basin bottom. It is thus quite sensitive to model dissipation but can be well described by SOMS owing to SOMS' low nu

ISSN:0271-2091    

DOI:10.1002/fld.1650110202

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractA technique is proposed to model flows with free surfaces using the control volume method. The free surface is tracked by determining the locations of the ambient pressure in the domain. Special conditions are imposed on the nodes in the vicinity of the free surface. Flow visualization experiments are carried out to determine the free surface shapes and velocity distributions during the filling of a cylindrical container with water. Computations are carried out to model the flow in the experimental test case using a mesh transformation and the free surface treatment. The proposed free surface treatment yields results of better accuracy as compared with the results using the free slip condition. The predicted locations and heights of the spout are reasonable.

ISSN:0271-2091    

DOI:10.1002/fld.1650110203

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractAn efficient algorithm is presented for the solution of the equations of isentropic gas dynamics with a general convex gas law. The scheme is based on solving linearized Riemann problems approximately, and in more than one dimension incorporates operator splitting. In particular, only two function evaluations in each computational cell are required. The scheme is applied to a standard test problem in gas dynamics for a polytropic gas.

ISSN:0271-2091    

DOI:10.1002/fld.1650110204

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe purpose of this paper is to examine the effects of using non‐orthogonal boundary‐fitted grids for the numerical solution of the shallow water equations. Two geometries with well known analytical solutions are introduced in order to investigate the accuracy of the numerical solutions. The results verify that a reasonable departure from orthogonality can be allowed when the rate of change of cell areas is kept sufficiently small (i.e. it is not necessary to create a strictly orthogonal grid when the grid is sufficiently smoo

ISSN:0271-2091    

DOI:10.1002/fld.1650110205

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractA finite volume multigrid procedure for the prediction of laminar natural convection flows is presented, enabling efficient and accurate calculations on very fine grids. The method is fully conservative and uses second‐order central differencing for convection and diffusion fluxes. The calculations start on a coarse (typically 10 × 10 control volumes) grid and proceed to finer grids until the desired accuracy or maximum affordable storage is reached. The computing times increase thereby linearly with the number of control volumes.Solutions are presented for the flow in a closed cavity with side walls at different temperatures and insulated top and bottom walls. Rayleigh numbers of 104, 105and 106are considered. Grids as fine as 640 × 640 control volumes are used and the results are believed to be accurate to within 0–01%. Second‐order monotonic convergence to grid‐independent values is observed for all predicted q

ISSN:0271-2091    

DOI:10.1002/fld.1650110206

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractDifferent finite element schemes are investigated with respect to their application in numerical weather prediction. Different methods of staggering of variables are considered. The tests concern the accuracy of a Rossby wave prediction and the generation of noise in a geostrophic adjustment process. Theoretical results concerning the noise level of different schemes are confirmed by computations with a one‐dimensional model. Favourable results were obtained by hybrid schemes, using different Galerkin treatments for different terms of the dynamic equation

ISSN:0271-2091    

DOI:10.1002/fld.1650110207

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractA rigorous model of the fully elliptic flow over the blade‐to‐blade stream surface in an annular aerofoil cascade is developed. The model accuracy stems from its precise simulation of the meridional hub‐to‐casing flow effects, including those of the shear stress components that are created by the spanwise velocity gradients. These stresses are unprecedentedly introduced in the flow‐governing equations in the form of source terms and are modelled as such. The final set of flow‐governing equations are solved using the Galerkin weighted residual method coupled with a biquadratic finite element of the Lagrangian type. The flow solution is verified against the numerical results of a fully three‐dimensional flow model and a set of experimental data, both concerning a low‐aspect‐ratio stator of an axial flow turbine under a low Reynolds number and subsonic flow operation mode. The numerical results in this case show well predicted aerofoil loading and pitch‐averaged exit flow conditions. Also evident is a substantial capability of the analysis in modelling such critical regions as the wake subdomain. It is further proven that the new terms in the governing equations enhance the quality of the numerical predictions in this cla

ISSN:0271-2091    

DOI:10.1002/fld.1650110208

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe numerical solution of the flow in a stepped channel constricted to half its width has been obtained for Reynolds numbers up to 2000 using Newton's iteration to solve the ensuing algebraic system. In order to avoid high‐frequency errors, a locally fine grid is effected near the corner by transformation of the independent variables. The results predict a downstream recirculation region, observed in experiments but not found in earlier numerical calculations. The inclusion of the Dennis–Hudson upwinding, added for stability in SOR methods, whilst giving the same characteristics of the flow, is less accurate by at least an order of magnit

ISSN:0271-2091    

DOI:10.1002/fld.1650110209

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650110210

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650110201

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY