国外岩石高温高压实验研究

地壳和地幔介质的流变断裂实验研究是地球动力学研究中的重要一环。地壳中能量的积累和地球动力过程的驱动力等许多问题,用线性模型来分析已经不够了,需要发展介质的非线性理论,以建立较符合实际的物理模型。高温高压实验是有助于建立这种物理模型的重要手段。岩石高温高压实验方面的工作,国际上已有半个多世纪的历史。有许多国家,许多单位,以各种特点进...     

烟气运动的盐水模拟实验

本文介绍了用盐水在清水中运动模拟热烟气运动的盐水模拟实验原理和模拟实验的相似准则。我们研制了一个盐水模拟实验装置，进行了初步实验研究，得到一些与理论和在空气中烟气羽流实验相的实验结果。     

大型电厂直冷系统风效应风洞模拟

讨论了电厂空冷凝器风效应风洞模拟准则及其实验和测量手段,提出用回流率的概念作为衡量冷凝器效率的指标．运用该指标对某电厂空冷项目实例的实验结果表明：风速、空冷平台柱高和来流风向角对冷凝器的效率有着重要影响．由此得出在空气冷却电厂的初始设计阶段,结合当地风气象资料的风洞模拟实验是非常必要的．     

地幔对流研究的地球物理背景

六十年代出现的地球板块构造学说,使地球科学的基本概念和基本理论发生了革命性的飞跃和进展。板块构造学说的出现与发展一直与地幔对流的研究联系在一起。地幔对流研究已成为当代地球科学中的一个基础性的课题。本文企图通过评述近廿年来地幔对流研究的进展,说明它在地球科学中所占的这一重要地位。在Hess和Dietz提出的海底扩张假说中,海底岩石圈是被其下的地幔对流运动所带动的,犹如河水中漂流的木栰欢?地幔中究竟能不能发生对流运动,当时还是个有争议的问题。     

改善再入通讯的化学减轻实验研究

化学减轻改善再入通讯是现实可行的技术途径,它是通过固体烧蚀和液体喷射的方法实现的。本文探讨化学减轻的机理和利用电弧风洞进行模拟实验研究的方法。实验是在H11DF电弧风洞中完成的,采用微波和探针两种诊断手段。通过大量实验确定了防热材料的烧蚀产物对流场电子密度和对电波传输的影响,以及喷射备种亲电子液体对流场电子密度的影响,为筛选防热材料及鉴定其性能提供依据。     

小当量炸药深水爆炸气泡脉动模拟实验

为在实验室内开展深水爆炸气泡脉动规律研究, 通过增加水面大气压强来模拟水中静水压的方法, 建立可模拟深水环境的爆炸容器。开展不同模拟水深条件下的3种当量炸药的水下爆炸实验, 得到了气泡脉动过程图像, 验证小当量深水爆炸模拟实验与自由场实验的等效性, 分析气泡脉动周期与最大半径同模拟水深的关系。实验结果表明:容器壁面反射效应对气泡脉动过程的影响可以忽略不计, 模拟实验可等效为自由场实验; 深水爆炸气泡脉动周期及最大半径随流体静力深度增加的衰减系数分别为-0.83和-0.364。     

冲击载荷下饱和砂土渗流和破坏的实验研究1)

对饱和砂土在冲击载荷下发现的变形和流动效应进行了落锤模拟实验研究,发现砂土骨架出现纵向排水通道和横向断裂等现象,对可能影响这些现象的主要因素进行了对比的实验,对上述实验现象进行了初步的解释.     

冲击载荷下饱和砂土渗流和破坏的实验研究

对饱和破土在冲击载荷下发现的变形和流动效应进行了落锤模拟实验研究,发现砂土骨架出现纵向排水通道和横向断裂等现象,对可能影响这些现象的主要因素进行了对比的实验,对上述实验现象进行了初步的解释．     

多孔介质中天然气水合物注热+降压开采的实验研究

为研究注热与降压相结合的开采方式是否更加有利于天然气水合物的开采,在自制的天然气水合物开采模拟实验系统上进行了实验研究.在一维填砂模型中人工生成天然气水合物之后,进行先注热盐水然后再降低压力(注热+降压)的开采模拟实验,分析了开采过程中系统温度、电阻率变化规律以及产气量、能量效率等.结果表明:产气规律具有明显的阶段性,...     

金川露天矿边坡岩体移动和变形的光弹性软材料模拟实验研究

通过对边坡岩体破坏机理的光弹性力学模拟实验研究, 岩体在地应力作用和自重体积力作用下, 对露天矿边坡的力学状态具有明显地影响。实验采用了明胶软材料, 模型比例1：1100。实验模拟了在自重应力和构造应力作用下, 边坡岩体的位移和变形。     

Two bifurcation transition processes in floating half zone convection of larger Prandtl number fluid

Processes of the onset oscillation in the thermocapillary convection under the Earth's gravity are investigated by the numerical simulation and experiments in a floating half zone of large Prandtl number with different volume ratio. Both computational and experimental results show that the steady and axisymmetric convection turns to the oscillatory convection ofm=1 for the slender liquid bridge, and to the oscillatory convection before a steady and 3D asymmetric state for the case of a fat liquid bridge. It implies that, there are two critical Marangoni numbers related, respectively, to these two bifurcation transitions for the fat liquid bridge. The computational results agree with the results of ground-based experiments. The project supported by the National Natural Science Foundation of China (19789201) and the Ministry of Science and Technology of China (95-yu-34)     

Investigation of Convection in the Upper Mantle Connected Thermomechanically with the Subduction Zone and Its Geodynamic Application to the Arctic Region and North East Asia

Fluid Dynamics - The analytical solution to the problem of thermal convection in the upper mantle adjoined to the subduction zone is constructed. The results of seismotomographic mantle shooting...     

Mantle convection: A review

The solid-state convection in the Earth mantle is characterized by plate tectonics, which shapes the tectonic activities of the Earth, and superplumes as broad hot regions chemically distinct from the surrounding regions in deep lower mantle. Recent numerical studies of mantle convection suggest that the rigidly moving plates occur on the Earth because the rupture strength of plate margins is sufficiently low, while that of plate interiors is high enough to inhibit spontaneous formation of new plate boundaries by the weight of the plates themselves. This implies that the activity of plate tectonics has fluctuated much in the Earth history. Recent numerical studies also suggest that the superplumes develop owing to the chemical differentiation of the mantle by ridge magmatism. Superplumes have probably induced frequent and vigorous hot spot volcanism in the early Earth. It is now within reach to construct an integrated model for tectonic and structural evolution of the mantle in the Earth and other terrestrial planets.     

地球物理流体动力学的发展和室内实验研究的影响

系统介绍了大气、海洋与新兴的地质系统中的流体力学,尤其是通过室内实验的研究进展．详细描述了诸如羽流、湍流、卷挟、异重流、海洋环流、混合层、双扩散、盐指、锋面、岩浆库、地幔对流、板块运动、热斑等有趣的地球物理现象,它们对于了解因浮力引起的对流的机理是十分重要的．同时在气候、环境、灾害、成矿等领域有广泛的应用．论文反映了在 Ｇ．Ｉ． Ｔａｙｌｏｒ, Ｇ．Ｋ． Ｂａｔｃｈｅｌｏｒ领导下剑桥研究组的风格──通过小型室内实验了解机理,再用应用数学方法求解问题,他们对流体力学的发展作出了重大贡献．     

Non-linear convection due to compositional and thermal buoyancy in Earth's outer core

The linear stability of convection due to compositional and thermal buoyancy in Earth's outer core has been investigated. We have obtained the values of Takens-Bogdanov bifurcation points by plotting graphs of neutral curves corresponding to stationary and oscillatory convection for different values of physical parameters. We have derived a non-linear two-dimensional Landau-Ginzburg equation with real coefficients near the onset of stationary convection at a supercritical pitchfork bifurcation and two non-linear one-dimensional coupled Landau-Ginzburg type equations with complex coefficients near the onset of oscillatory convection at a supercritical Hopf bifurcation. We have studied Nusselt number contribution from a Landau-Ginzburg equation at the onset of stationary convection. We have discussed the stability regions of standing and travelling waves. We have also discussed the occurrence of secondary instabilities such as Eckhaus, zigzag and Benjamin-Feir instabilities. We have also derived the non-linear amplitude equation near the Takens-Bogdanov bifurcation point.     

Effect of Thermal Modulation on the Onset of Convection in a Viscoelastic Fluid Saturated Porous Layer

The effect of thermal modulation on the onset of convection in a horizontal, anisotropic porous layer saturated by a viscoelastic fluid is investigated by a linear stability analysis. Darcy’s law with viscoelastic correction is used to describe the fluid motion. The perturbation method is used to find the critical Rayleigh number and the corresponding wavenumber for small amplitude thermal modulation. The stability of the system characterized by a correction Rayleigh number is calculated as a function of the thermal and mechanical anisotropy parameters, the viscoelastic parameters and the frequency of modulation. It is found that the onset of convection can be delayed or advanced by the factors represented by these parameters. The results of the problem have possible implications in mantle convection.     

An experimental study of influence of hot water consumption rate on the thermal stratification inside a horizontal mantle storage tank

In this study the thermal characteristics of horizontal mantle heat exchangers are investigated for application in active solar water heaters. Some important parameters such as flow rate, thermal short circuit, average temperature, and convection heat transfer coefficient and inlet velocity have been investigated too. The results show that the thermal efficiency of the storage tank is critically impaired by the effect of short circuit phenomenon and mixing caused by turbulence.     

Sharp entry and transition effects for laminar combined convection of water in vertical tubes

In previous work the authors showed a sharp entry to have a definite effect on laminar forced convection to water in a vertical circular tube. The study has been extended to situations of strong aiding natural convection, and new experimental data and numerical predictions are reported. The expected entry effect is confirmed, but it is found to be less marked in a strong combined convection field than in the previous forced convection study. The experimental data also include evidence of transition from laminar flow, and a possible criterion of transition is investigated, based on the axial location of minimum local Nusselt number. This is experimental and predictive data for this criterion are compared with the experimental correlation of Lawrence and Chato based on a criterion of temperature fluctuations     

A linear stability analysis on the onset of thermal convection of a fluid with strongly temperature-dependent viscosity in a spherical shell

A linear stability analysis was performed in order to study the onset of thermal convection in the presence of a strong viscosity variation, with a special emphasis on the condition for the stagnant-lid (ST) convection where a convection takes place only in a sublayer beneath a highly viscous lid of cold fluid. We consider the temporal evolution (growth or decay) of an infinitesimal perturbation superimposed to a Boussinesq fluid with an infinite Prandtl number which is in a static (motionless) and conductive state in a basally heated planar layer or spherical shell. The viscosity of the fluid is assumed to be exponentially dependent on temperature. The linearized equations for conservations of mass, momentum, and internal (thermal) energy are numerically solved for the critical Rayleigh number, Ra _c , as well as the radial profiles of eigenfunctions for infinitesimal perturbations. The above calculations are repeatedly carried out by systematically varying (i) the magnitude of the temperature dependence of viscosity, E, and (ii) the ratio of the inner and outer radii of the spherical shell, γ. A careful analysis of the vertical structure of incipient flows demonstrated that the dominance of the ST convection can be quantitatively identified by the vertical profile of Δ _h (a measure of conversion between horizontal and vertical flows), regardless of the model geometries. We also found that, in the spherical shell relevant to the Earth’s mantle (γ = 0.55), the transition into ST convection takes place at the viscosity contrast across the layer ${r_\eta\simeq10^4}$ . Taken together with the fact that the threshold value of r _η falls in the range of r _η for a so-called sluggish-lid convection, our finding suggests that the ST-mode of convection with horizontally elongated convection cells is likely to arise in the Earth’s mantle solely from the temperature-dependent viscosity.     

Turbulent thermal convection in wide horizontal fluid layers

Turbulence in thermal convection is investigated for flows in which the production of turbulence energy is due solely to buoyancy, and the statistics of the flow are homogeneous in horizontal planes. New experimental results for high Rayleigh number unsteady turbulent convection in a horizontal layer heated from below and insulated from above are presented and compared to turbulent Rayleigh convection, convection in the planetary boundary layer, and laboratory penetrative convection. Mean temperature fields are correlated in terms of wall layer scales and convection scales. Joint statistics of turbulent temperature and horizontal velocity and vertical velocity through fourth order are presented for the core region of the convection layer.This paper was presented at the Ninth Symposium on Turbulence, University of Missouri-Rolla, October 1–3, 1984