摘要:

AbstractAn extension of the authors' previous methods is presented for the optimal control of flood propagation via a dam gate, based on a combination of the finite element and gradient methods. It is assumed in previous papers that the control duration is the same as the duration of the flood. However, the duration of the control does not necessarily coincide with that of the flood flow. To overcome this difficulty, the gradient method is applied to solve the free terminal time‐fixed terminal condition problem. It is shown that the water elevation can be controlled exactly the same as with the previously presented method. It is also shown that the computation can be terminated at a far shorter time than the terminal time of the floo

ISSN:0271-2091    

DOI:10.1002/fld.1650190602

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractNumerical models based on the vortex lattice concept using free vortex lines have been developed for the calculation of separated flow about cranked wings. Various separated flow models are developed assuming the flow to be separated along the leading edges of (i) the inner wing, (ii) the entire wing and (iii) the inner wing and the outboard part of the outer wing. To illustrate the effects of separation, attached flow solutions are also obtained. Results are compared with available experimental results. Agreement with separated flow solutions is usually good except at very high incidence.

ISSN:0271-2091    

DOI:10.1002/fld.1650190603

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractA control‐volume‐based solution of the complete set of Navier‐Stokes equations for the laminar, three‐dimensional developing flow in straight, eccentric, cylindrical annular ducts is described. Numerical results for velocity and pressure development, pressure defect and entrance lengths are presented for a wide range of duct parameters, i.e. relative eccentricity ϵ and radius ratio γ. The present results match very well with earlier numerical solutions for the limiting cases of developing flow in concentric ducts and fully developed flow in eccentric ducts. Comparison with earlier approximate results for developing flow in eccentric ducts indicates that the approximate model predicts the velocity and pressure development with an error of about 10%. However, the development length predicted by the approximate model is grossly in error. The pressure defect and development length in eccentric ducts are very high compared with their counterparts in concentric ducts. The pressure defect, development length and maximum velocity increase with the radius ratio for eccentric ducts, while the reverse is true for concentric ducts. Also, the apparent friction factor decreases as the eccentricity

ISSN:0271-2091    

DOI:10.1002/fld.1650190604

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe streamfunction‐vorticity equations for incompressible two‐dimensional flows are uncoupled and solved in sequence by the finite element method. The vorticity at no‐slip boundaries is evaluated in the framework of the streamfunction equation. The resulting scheme achieves convergence, even for very high values of the Reynolds number, without the traditional need for upwinding. The stability and accuracy of the approach are demonstrated by the solution of two well‐known benchmark problems: flow in a lid‐driven cavity atRe⩽ 10,000 and flow over a backward‐facing s

ISSN:0271-2091    

DOI:10.1002/fld.1650190605

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractA new monotonic scheme for the approximation of steady scalar transport is formulated and implemented within a collocated finite‐volume/pressure‐correction algorithm for general turbulent flows in complex geometries. The scheme is essentially a monotonic implementation of the quadratic QUICK interpolation and uses a continuous and compact limiter to secure monotonicity. The principal purpose is to allow an accurate and fully bounded, hence stable, approximation of turbulence convection in the context of two‐equation eddy viscosity and Reynolds stress transport modelling of two‐ and three‐dimensional flows, both subsonic and transonic. Among other benefits, this capability permits an assessment to be made of the adequacy of approximating turbulence convection with first‐order upwind schemes in conjunction with higher‐order formulations for mean‐flow properties—a widespread practice. The performance characteristics of the bounded scheme are illustrated by reference to computations for scalar transport, for a transonic flow in a Laval nozzle, for one separated laminar flow and for two separated turbulent flows computed with a non‐linear RNG model and full Reyn

ISSN:0271-2091    

DOI:10.1002/fld.1650190606

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650190607

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650190608

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650190601

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY