摘要:

AbstractThe paper presents a new method for the numerical solution of transient linear heat conduction problems. In the proposed method, the transient linear heat conduction equation is first integrated with respect to time over subsequent intervals. Then the resulting set of elliptic equations is discretized in space according to a finite‐element procedure. The method is unconditionally stable. At the end of the paper, the effectiveness of the proposed method is assessed through some numerical example

ISSN:1069-8299    

DOI:10.1002/cnm.1640100602

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractIn the paper a computation code based on the finite‐element method for temperature evolutions in composite elements with internal cavities is presented. It is suitable for the analysis of various thermal problems encountered in mechanical and civil engineering such as fire risk assessment. It is based on a plane isoparametric triangular element with six nodes allowing the modelling of curved boundaries. In order to analyse composite steel‐concrete elements and to take into account the non‐linearities coming from the temperature‐dependent material properties and from the boundary conditions, an implicit integration scheme is used. Another advantage of the program is the possibility of describing internal cavities with convection and radiation exchanges. In order to show the capacity of the program two examples are presented. Comparisons have been made with experimental and other numerical results, exhibiting very good ag

ISSN:1069-8299    

DOI:10.1002/cnm.1640100603

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractIn finite‐element analysis of transient heat conduction, oscillatory results are quite common. Several criteria for eliminating oscillation which permit choice of time step length and/or element mesh and type are sensibly derived and proved with a different methodology from those of previous work. Numerical examples are presented to show their validity and usefulnes

ISSN:1069-8299    

DOI:10.1002/cnm.1640100604

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractA speculation is presented to explain in physical terms the biblical story in which the withdrawal and return of the sea saved the Hebrews but drowned the army of Pharaoh. The explosion of the volcano on the island of Thira (Santorini) is speculated to be connected with this biblical story.To support our proposition concerning depression and flooding waves, we have made a numerical calculation with a highly accurate computer code and provided an outline of the PLIM method (piecewise linear interpolation method) used. This calculation is numerically very challenging because the volcano is located far from the shore and hence detailed discretization is not practical. In addition, we show that if a less accurate numerical method is used, the whole phenomenon is lost because of numerical errors.Our simple approach provides a withdrawal and return of the water to the shore that is sufficiently large, but the duration of this occurence is only a few minutes. The opportunity for a much longer duration as a consequence of other phenomena has not been excluded, however.

ISSN:1069-8299    

DOI:10.1002/cnm.1640100605

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractNumerical modelling of geometrically evolving domains, such as multistep construction, accretion and excavation, has always been of great interest to geotechnical engineers. Stress, strain and pore‐pressure changes depend on hydromechanical properties and the loading process. Several techniques are proposed in the literature for numerical simulation of excavation or backfilling processes. These are mostly based on a natural methodology that consists in dividing the problem into several time steps, each coinciding with the addition or removal of one layer which is then modelled by means of several elements. Unfortunately, as in these methods the evolving parameters and their relative influence are not explicit, it is not possible to determine their accuracy. A more rigorous approach lies in the geometrical transformation of the studied domain, depending on the time variable for a reference domain in which the conservation equations are verified. The application of this methodology implies a great number of calculations. By using limited development techniques of the Jacobian of transformations it is possible to reduce the volume of computations. Such a technique results in approximations which can be evaluate

ISSN:1069-8299    

DOI:10.1002/cnm.1640100606

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractChan and Elman (1989) have recently shown that heuristic Fourier analysis can be used to determine approximate convergence rates of iterative methods. Here we present a simple procedure and useful relations that facilitate the practical application of this method. The procedure is based on the fact that the mesh spacinghis typically small, so that attention may be restricted to the asymptotic behaviour of the convergence rateRfor smallh.We accordingly derive simple expressions for the first few coefficients in a Taylor series expansion ofRin powers ofh.These coefficients are expressed in terms of derivatives with respect tohof the complex Fourier growth factor ξ rather than its modulus |ξ|. The required derivatives can then be obtained by implicit differentiation without explicitly solving for ξ, which further simplifies the analysis. The overall procedure is illustrated by applying it to the Jacobi, Gauss‐Seidel and successive overrelaxation methods, for which we obtain results asymptotically equivalent to those of Chan and Elman. We also analyse the effect of second‐order Richardson acceleration on the Jacobi method, for which we obtain an asymptotic convergence rate in precise agreement with classical an

ISSN:1069-8299    

DOI:10.1002/cnm.1640100607

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe possibility of improving heat transfer rates by the imposition of a wavy boundary led to this extension of direct simulation of heat transfer in turbulent flow in a channel. This part of the paper shows how a pattern of micro‐riblets on the surface and parallel to the flow is incorporated into the solution of the Navier‐Stokes and temperature equations. The channel is two‐dimensional with walls at different but uniform temperatures, and the fluid properties are constant. The presence of the patterns presents a considerable computational problem that can be largely overcome by the use of a discrete Green function technique. The method is illustrated by making short‐time calculations of the velocity and temperature fields for a Prandtl number of 0.72, a Reynolds number based on channel half‐width and bulk velocity of 2800, and a sinusoidal pattern with a height of 5 w

ISSN:1069-8299    

DOI:10.1002/cnm.1640100608

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

ISSN:1069-8299    

DOI:10.1002/cnm.1640100609

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

ISSN:1069-8299    

DOI:10.1002/cnm.1640100601

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY