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81.
The stability and accuracy of radiation type non‐reflective outflow boundary conditions, as well as the standard Neumann boundary condition with zero normal derivative, have been compared for the numerical simulation of a turbulent axisymmetric plume with Reynolds number of 7700 and Prandtl number of 0.71. Comparison of the performance of the boundary conditions with respect to each other, and to the results obtained for an extended domain, shows that a one‐dimensional scheme in which advection and diffusion terms are included in the radiation equation is the optimum approach for the plume simulation. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
82.
83.
A mechanical device specially designed for the application of low-level post-tensioning forces to glass fiber reinforced polymer
(GFRP) bars has been developed at the University of Missouri-Rolla. Some of the advantageous features of this device are that
it is simple to assemble and the low-level post-tensioning forces can be applied manually and safely without the need for
hydraulic jacks or heavy equipment. This device has been conceived with the main objective of retrofitting masonry buildings,
some of which remain in service despite large, open cracks leading to considerable instability and serviceability concerns.
According to the method derived in this paper, GFRP bars are installed in artificially imposed grooves and then post-tensioned
with low-level stresses with the main objective to partially close these cracks, such that the serviceability and in-plane
capacity of un-reinforced masonry (URM) buildings may be regained. In this paper we describe the mechanical components of
this device, along with its advantageous features and potential application for the retrofit of URM walls. 相似文献
84.
85.
Hironobu Sakagawa 《Journal of statistical physics》2007,129(3):537-553
We consider the d(≥3)-dimensional Gaussian lattice field confined between two hard walls. We show that the field becomes massive and identify
the precise asymptotic behavior of the mass and the variance of the field as the height of the wall goes to infinity. 相似文献
86.
采用黏性激波层基本方程组对有无泰氟龙烧蚀两种情况下的钝锥体化学非平衡绕流作了数值求解,以研究泰氟龙烧蚀对流场电子密度的影响规律.算例结果表明:泰氟龙烧蚀确有降低流场电子密度的效应.平衡催化壁工况下这种效应的强度,显著大于非催化壁工况下的强度;远下游截面处的这种效应的强度,显著大于驻点区的强度.此外,通过计算结果分析,对形成上述影响规律的原因作了初步讨论. 相似文献
87.
This article presents an experimental study of the vibro-acoustic response of a pipe excited by a fully-developed turbulent
air flow. First, the wall pressure field acting on the internal pipe wall is investigated. The power spectral density of the
wall pressure fluctuations is analyzed after cancellation of contaminating background noise. The convection velocity and correlation
lengths are calculated from measured cross-spectra, and the cross-spectra are expressed in Corcos model form. Second, the
vibro-acoustic response of the pipe is analyzed by referring to the structural modes of the pipe.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
88.
89.
采用复合式衬砌的隧道及地下工程,锚喷支护系统的耐久性直接影响结构的稳定性和运营年限。锚杆主体属于钢构件,极易遭受侵蚀。从采用复合式衬砌的隧道及地下工程的结构特点可知,对于一定形式的锚杆,所遭受的侵蚀作用主要取决于锚杆与来自围岩的侵蚀性地下水的相互作用。本文探讨了含硫化物围岩中影响锚杆侵蚀的主要因素,描述了侵蚀性地下水的形成,以及锚杆侵蚀作用的物理化学机理,并提出了基于此机理的含硫化物围岩中锚杆使用年限的估算方法。 相似文献
90.
G.A. Gerolymos E. Sauret I. Vallet 《Theoretical and Computational Fluid Dynamics》2004,17(5-6):407-431
This paper is concerned with recent advances in the development of near wall-normal-free Reynolds-stress models, whose single point closure formulation, based on the inhomogeneity direction concept, is completely independent of the distance from the wall, and of the normal to the wall direction. In the present approach the direction of the inhomogeneity unit vector is decoupled from the coefficient functions of the inhomogeneous terms. A study of the relative influence of the particular closures used for the rapid redistribution terms and for the turbulent diffusion is undertaken, through comparison with measurements, and with a baseline Reynolds-stress model (RSM) using geometric wall normals. It is shown that wall-normal-free rsms can be reformulated as a projection on a tensorial basis that includes the inhomogeneity direction unit vector, suggesting that the theory of the redistribution tensor closure should be revised by taking into account inhomogeneity effects in the tensorial integrity basis used for its representation. PACS 47.32.Fg; 47.85.Gj; 47.27.Eq 相似文献