共查询到20条相似文献，搜索用时 31 毫秒
1.
A parallel numerical finite difference model, employing the self-implicit method, for coupled heat and moisture transfer in unsaturated soil is presented. The model is programmed in Occam and executed on a parallel computing network of transputers. An assessment of the model was achieved via the simulation of a laboratory experiment. A very good correlation between experimental and numerical results was obtained. Comparison of results with those obtained from a parallel explicit method is also illustrated showing no significant difference. The computational time employing the new method was, however, found to be half of that obtained using the explicit method. The computational efficiency of the approach was also found to be very high. © 1997 John Wiley & Sons, Ltd. 相似文献
2.
This article presents a micromechanical approach to the problem of unsaturated water flow in heterogeneous porous media in
transient conditions. The numerical formulation is based on the two-scale model obtained previously by periodic homogenization.
It allows for a coupled solution of the non-linear flow equations at macroscopic and microscopic scales and takes into account
the macroscopic anisotropy of the medium and the local non-equilibrium of the capillary pressure. The model was applied to
simulate two-dimensional water infiltration at constant flux into an initially dry medium containing inclusions of square
and rectangular shapes. The numerical results showed the influence of the inclusion–matrix conductivity ratio and the local
geometry on the macroscopic behavior. The influence of the conductivity ratio manifested itself by the acceleration or retardation
of the onset of the macroscopic water flux at the outlet, while the local geometry (anisotropy) significantly affected the
macroscopic spatial distribution of the water flux. Such type of approach can be extended to simulate coupled phenomena (for
example hydro-mechanical problems) with evolving local geometry. 相似文献
3.
Constraint preconditioners have proved very efficient for the solution of ill-conditioned finite element (FE) coupled consolidation
problems in a sequential computing environment. Their implementation on parallel computers, however, is not straightforward
because of their inherent sequentiality. The present paper describes a novel parallel inexact constraint preconditioner (ParICP)
for the efficient solution of linear algebraic systems arising from the FE discretization of the coupled poro-elasticity equations.
The ParICP implementation is based on the use of the block factorized sparse approximate inverse incomplete Cholesky preconditioner,
which is a very recent and effective development for the parallel preconditioning of symmetric positive definite matrices.
The ParICP performance is experimented with in real 3D coupled consolidation problems, proving a scalable and efficient implementation
of the constraint preconditioning for high-performance computing. ParICP appears to be a very robust algorithm for solving
ill-conditioned large-size coupled models in a parallel computing environment. 相似文献
4.
This paper presents the results of the application of a numerical model of flow of water in unsaturated soil to simulate real field behaviour. Numerical predictions are compared with field-monitored results as part of an assessment of the approach adopted. The numerical approach is based on a finite element solution of Richards' theoretical formulation, adopting a finite difference recurrence relationship to model the transient nature of the problem. The field results have been collected by British Gas in Kimmeridge clay at a site in Swindon. The simulation addressed the autumn wetting of the soil during 1983. Comparisons of volumetric moisture content readings from the field and numerical predictions give good correlation. It is concluded that the numerical model has adequately represented field behaviour over the depth of interest. Taken in conjunction with previous results, it is claimed that the model should now be capable of use in a predictive mode. 相似文献
5.
H. R. Thomas 《国际地质力学数值与分析法杂志》1985,9(6):573-588
A theoretical model is presented to predict simultaneous transient coupled heat and moisture transfer in partly saturated soils. The formulation is in terms of volumetric moisture content, is two dimensional, includes gravitational flow and takes into account latent heat of vaporization effects. The numerical solution of the problem is accomplished by means of a finite element solution algorithm. Predictions from the numerical model are used to investigate the importance of gravitational flow, for the case of a soil stratum subjected to evaporation losses at the surface. The results achieved show good qualitative agreement with expected behaviour. 相似文献
6.
A comprehensive numerical model for the analysis of offshore foundations under a general transient loading is presented here. The theoretical basis of the model lies on the Swansea formulation of Biot’s equations of dynamic poroelasticity combined with a constitutive model that reproduces key aspects of cyclic soil behaviour in the frame of the theory of generalised plasticity. On the practical side, the adoption of appropriate finite element formulations may prevent the appearance of spurious numerical instabilities of the pore pressure field. In this respect, the use of a coupled enhanced-strain element is here proposed. On the other hand, the practicality of the presented model depends ultimately on its computational efficiency. Some practical recommendations concerning the solution strategies, the matrix storage/handling procedures and the parallel multi-processor computation are here provided. Finally, the performance of the model with a benchmark study case and its practical application to analyse the soil–structure interaction of an offshore monopile under a realistic transient storm loading are discussed. 相似文献
7.
建立了二维非恒定渗流的有限元并行计算模型,在windows操作系统下实现了基于消息传递的二维渗流的有限元并行计算。模型采用广义极小残余算法(GMRES)对方程组进行并行迭代求解,通过分析数据执行时的相关性和检验算法结构的固有串行性,将原有串行算法中的算法元直接并行化。对溪洛渡上游围堰的渗流分析进行了并行数值模拟,并针对水位骤降情况下非恒定渗流进行了并行计算,证明了模型的合理性。对模型进行了加速比测定,可以看出并行计算的效率随着问题规模的增加而逐渐提高。 相似文献
8.
非连续变形分析（DDA）方法严格满足平衡要求和能量守恒,具有完全的运动学及数值可靠性,但对大规模岩土工程问题的数值模拟耗时太长,尤其是线性方程组求解,并行计算可以很好地解决该问题。首先基于DDA方法的基本理论,阐述了适用于DDA方法中的基于块的行压缩法和基于“试验-误差”迭代格式的非零位置记录;其次,引入块雅可比迭代法并行求解DDA方法的线性方程组,并改进了相应的非零存储方法;最后,基于OpenMP实现了DDA线性方程组求解并行计算,并将其应用于地下洞室群的破坏过程分析,以加速比为并行效率的指标评价,结果表明,该并行计算策略可以极大提高DDA的计算效率,而且适合各种规模的问题。 相似文献
9.
感潮河网水流不仅受径流、潮汐动力的双重影响,还常受水闸调度等人类活动的影响,水动力条件极为复杂。针对水闸调度影响下感潮河网复杂水动力及其伴随物质输移扩散模拟,提出了考虑水闸调度并集成输运对流项的水流-输运通量耦合求解器,建立了基于非结构网格Godunov格式的二维水流-输运耦合数学模型。采用具有时空二阶精度的MUSCL-Hancock预测-校正格式,结合变量重构限制器技术,在保证计算精度的同时避免了数值振荡。运用斜底三角单元网格表达水闸线状地形,并通过地形调整模拟了水闸启闭过程。算例研究表明,该模型计算精度高,可有效模拟水闸调度影响下感潮河网水流运动及污染物输运过程,具有较好的推广应用价值。 相似文献
10.
A finite element model is developed to simulate the behaviour of an aquifer used as storage space for a compressed air energy storage (CAES) system. The governing equations describing a two-phase flow of air and water are coupled non-linear partial differential equations and are solved by the Galerkin approach. The resulting computer model is applied to a gas percolation problem. Upon verification of the numerical results, the model is employed to simulate the air-water displacement in a storage reservoir during daily air cycling. The corresponding saturation variations and the effects of reservoir permeability on the system are presented. The results obtained are essential in establishing storage design and stability criteria for long-term operation of compressed air energy storage systems. 相似文献
11.
Nadia Laredj Hanifi Missoum Karim Bendani Mustapha Maliki 《Arabian Journal of Geosciences》2011,5(5):935-942
Knowledge of transport processes of heat and moisture in soils of arid zones is vital to understanding the environmental and economic impacts of many activities: agriculture, waste disposal, geoenvironmental practices and earth sciences. Through extensive review and study on the different aspects of coupled transfer processes in swelling porous media, a general mathematical model for coupled heat, moisture, air flow and deformation problems in clayey soils is proposed in a consistent and unified manner. The model is characterized by the presence of a deformable solid matrix filled with two fluid phases (liquid water and air). In the proposed model, both pore water and air transfers are assumed to be governed by the generalized Darcy’s law. Fully coupled, non-linear partial differential equations are established and then solved by using a Galerkin weighted residual approach in space domain and an implicit integrating scheme in time domain. The obtained model has been finally validated by means of some case tests for the prediction of the thermo-hydro-mechanical behaviour of unsaturated swelling soils. The calculated relative errors between experimental and numerical results are 3% for temperature and 7% for stresses. Consequently, the developed numerical model predicts satisfactory results, compared to experimental test measures. The model is applicable to two-dimensional problems with various initial and boundary conditions; non-linear soil parameters can be easily included in this model. 相似文献
12.
In a previous paper1 the authors have developed and implemented a new boundary element (BE) model to simulate and predict land subsidence occurring over three-dimensional gas/oil fields in a homogeneous and isotropic half-space. The approach relies on Betti's reciprocal theorem and makes use of the classical fundamental solution of Boussinesq in the framework of the theory of linear poroelasticity. The BE method is here extended to inhomogeneous, transversally anisotropic soils by the aid of a two-dimensional finite element (FE) model which provides a fundamental numerical solution for the actual multi-layer setting of the subsurface system. The new FE–BE approach is then used to simulate the subsidence caused by gas production over the deep reservoir of Campo Ravenna Terra, Ravenna (Italy) from 1950 to 1980. The results compare very favourably with the outcome from a full more expensive three-dimensional FE model of the same occurrence. 相似文献
13.
为高效高精度地模拟流域雨洪过程,应用动力波法求解二维圣维南方程,并耦合水文过程,建立了包含流域降雨产流、汇流、下渗以及洪水演进等过程的高性能流域雨洪数值模型。该模型的优势在于使用非结构网格,可较好地处理不规则边界,准确贴合复杂地形表面,使得模型能精确计算模拟流域雨洪过程,同时引入GPU技术加速计算,使得大尺度流域雨洪计算成为可能。最后,将模型应用于V型经典算例及2个实际流域雨洪算例,所得结果与实测吻合较好,计算所用时间较短,表明该模型可以快速且精确模拟流域雨洪过程。研究结果有助于实现对实际流域雨洪灾害进行合理高效的预测,为应急抢险工作提供有力支撑。 相似文献
14.
《Tectonophysics》2001,330(1-2):141-151
In modelling sediment compaction and mineral reactions, the rheological behaviour of sediments is typically considered as poroelastic or purely viscous. In fact, compaction due to pressure solution and mechanical processes in porous media is far more complicated. A generalised model of viscoelastic compaction and the smectite to illite mineral reaction in hydrocarbon basins is presented. A one-step dehydration model of the mineral reaction is assumed. The obtained non-linear governing equations are solved numerically and different combinations of physical parameters are used to simulate realistic situations in typical sedimentary basins. Comparison of numerical simulations with real data has shown very good agreement with respect to both the porosity profile and the mineral reaction. 相似文献
15.
采用非饱和的渗流应力耦合模型分析了糯扎渡水电站2#导流洞的开挖过程,导流洞部分洞身穿过节理带,洞顶水头较高。详细地讨论了高水头和节理带对施工过程的影响。节理带采用描述高密度平行节理组的各向异性节理本构来逼近;考虑开挖引起的介质变形对渗透系数的影响;考虑排水引起的饱和度变化对渗透系数的影响。所用的非饱和瞬态耦合模型可以模拟出开挖引起的EDZ区域孔隙水压力急剧升高、有效应力减小、渗透系数动态的变化以及排水对洞室稳定性的提高。数值模拟的计算结果与国外类似试验的一般性观测结论相吻合,因此,可以用来评价水位以下隧洞施工方法和施工速度的合理性和经济性。 相似文献
16.
采用一维-二维耦合数学模型对溃堤洪水进行模拟,可以发挥两者优势,提高计算效率。将基于黎曼近似解Godunov格式的一维、二维水流数学模型通过堰流公式进行耦合,实现交界面的水力要素交互;一维、二维模型均采用中心形式的有限体积法求解,分别采用HLL格式和Roe格式计算界面通量,具有一致的空间同步性。通过经典算例验证了模型的可靠性和稳定性,应用耦合模型对1998年松花江干流胖头泡溃堤洪水进行了模拟计算,较好地模拟了溃堤洪水的演进过程与淹没范围,对200年一遇洪水的分洪效果进行了分析,为此区域的分洪利用及松花江中上游防洪调度提供参考依据。 相似文献
17.
18.
2017年神狐海域第一次试开采成功后,许多学者应用数值模拟对试采数据进行研究,但模拟结果与实际试采数据存在偏差.为了探求原因,本研究建立了二维柱坐标系下水合物降压开采数学模型,开发了相应的程序,能够模拟渗透率等储层参数非均匀分布条件下开采过程,同时能够模拟开采井压力等动态参数对开采过程的影响.通过数值实验,得出偏差原因:（1）泥质粉砂型储层存在水敏性,水合物分解产生的淡水引起粘土膨胀,使渗透率下降;（2）须将开采井压力作为动态输入参量.据此,修正了渗透率模型,考虑了开采井压力随时间的变化,得到的模拟产气量与试采数据十分接近,使降压开采数值模拟更逼近实际情况. 相似文献
19.
针对溃坝水流数值模拟面临的复杂地形和不规则边界等问题,基于结构网格建立了适应复杂地形和不规则边界的溃坝水流数值模拟有限体积模型（HydroM2D）。模型基于具有守恒特性的二维浅水方程,利用HLLC格式的近似Riemann解计算网格界面通量,利用MUSCL-Hancock法不断向前积分,使模型在时空上具有二阶精度;对源项进行离散处理确保模型的稳定性;模型引入有效干湿边界和不规则地形边界处理方法,准确模拟了干湿单元的动态交替和复杂边界上的水流特性。最后分别利用水槽试验、物理模型和实际算例对模型进行验证。结果表明,该模型对不同情景下的溃坝洪水模拟结果和实测资料以及现有模型模拟结果具有较高的一致性,模拟精度较高,稳定性较好,具有推广应用价值。 相似文献
20.
In this paper, a numerical solution for the electro-osmosis consolidation of clay in multi-dimensional domains at large strains is presented, with the coupling of the soil mechanical behaviour, pore water transport and electrical fields being considered. In particular, the Modified Cam Clay model is employed to describe the elasto-plastic behaviour of clay, and some empirical expressions are used to consider the nonlinear variation of the hydraulic and electrical conductivities of the soil mass during the consolidation processes. The implementation of the theoretical model in a finite element code allows for analysis of the evolution of the transient response of the clay subjected to electro-osmosis treatment. The proposed model is verified via comparison with data from a large strain electro-osmosis laboratory test, to demonstrate its accuracy and effectiveness. Various numerical examples are also investigated to study the deformation characteristics and time-dependent evolution of the excess pore pressure. Finally, a well-documented field application of electro-osmosis is simulated to provide further verification. The results show that the numerical solution is effective in predicting the nonlinear behaviour of clay during electro-osmosis consolidation. 相似文献