【作者】 刘诚；

【导师】 沈永明；

【作者基本信息】 大连理工大学 ， 港口、海岸及近海工程， 2008， 博士

【摘要】 本文基于连续介质理论框架下的两相流理论,分别建立了直角坐标系和非正交曲线坐标系下的三维κ-ε-A_p和κ-ε-κ_p固液两相双流体湍流模型,研究水沙的运动特性以及泥沙运动引起的床面变形;同时在三维κ-ε-A_p固液两相双流体湍流模型的控制方程中考虑植被对水流的阻力作用以及植被存在诱发的水流湍动动能增加的效果,建立了考虑植被影响的三维κ-ε-A_p固液两相双流体湍流模型,研究水生植被对水流泥沙运动以及床面变形的影响。通过全面分析国内外三维水沙数学模型的进展,指出了目前三维水沙数学模型存在的几点不足,提出采用连续介质理论框架下的双流体模型研究固液两相湍流运动的优势,并在周力行和刘大有两位学者所建立的两相流理论的基础上,推导出张量形式的κ-ε-κ_p固液两相双流体湍流模型和考虑植被影响的κ-ε-A_p固液两相双流体湍流模型。建立了直角坐标系下的三维κ-ε-A_p和κ-ε-κ_p固液两相双流体湍流模型,采用有限差分法求解模型的控制方程,通过数值计算试验室小型顺直水平和垂直方管内挟沙水流中的泥沙颗粒数密度、液相时均流速、固相时均流速、液相脉动流速和固相脉动流速的三维分布,并与试验测量结果进行比较,验证了所建立的三维κ-ε-A_p和κ-ε-κ_p固液两相双流体湍流模型在研究固液两相湍流方面的可靠性,展示了κ-ε-κ_p固液两相双流体湍流模型相对于κ-ε-A_p固液两相双流体湍流模型的优势。建立了非正交曲线坐标系下的三维κ-ε-κ_p固液两相双流体湍流模型,曲线坐标系中的ξ-η平面严格正交,ξ-ζ面和η-ζ平面非正交,采用有限体积法求解模型的控制方程,通过计算S型弯道内的水流运动验证了所建立的模型中液相模块的准确性:通过模拟120°弯道内水流和泥沙的运动验证了所建立的模型中悬沙模块的准确性:通过模拟120°弯道和180°弯道内的水流运动、悬沙运动、床沙运动和床面变形,验证了所建立的模型中床面变形模块的准确性。经过详细比较三维固液两相单流体湍流模型和三维κ-ε-κ_p固液两相双流体湍流模型在水沙两相流动和床面变形数值结果中的异同之后,认为三维κ-ε-κ_p固液两相双流体湍流模型能够更加准确地模拟弯道内水流的横向流速对泥沙横向运动的影响。在非正交曲线坐标系下的三维κ-ε-A_p固液两相双流体湍流模型的相关控制方程中添加植被阻力项或者植被诱发的湍动动能生成项,建立了考虑植被影响的三维κ-ε-A_p固液两相双流体湍流模型,通过计算顺直水槽中全部宽度内布置淹没或者非淹没的水生植被后水流的垂直结构、顺直水槽内局部区域布置非淹没的水生植被后水流的平面结构、60°弯曲水槽内局部区域布置非淹没的水生植被后水流的三维运动结构验证了模型中液相模块的准确性;通过计算顺直水槽内布置淹没的水生植被后的水流和悬沙的运动研究了植被对悬沙运动的影响;通过计算顺直水槽内局部区域布置水生植被后的水流泥沙运动和床面变形情况以及60°弯曲水槽内局部区域布置非淹没的水生植被后的水流泥沙运动和床面变形情况验证了模型中床面变形模块的准确性。床面变形的数值结果之间的比较表明考虑植被影响的三维κ-ε-A_p固液两相双流体湍流模型的精度比三维固液两相单流体湍流模型的精度高。更多还原

【Abstract】 This thesis developed a three-dimensionalκ-ε-A_p and aκ-ε-κ_p solid-liquid two-phase two-fluid turbulence models in both Cartesian coordinate system and non-orthogonal curvilinear coordinate system based on continuum theory to study the water-sediment movement.Furthermore,by taking account the drag force and additional turbulent kinetic energy due to vegetation into the relevant governing equations of above mentioned models,a three-dimensionalκ-ε-A_p solid-liquid two-phase two-fluid turbulence model with the effect of vegetation was constructed to investigate the influence of vegetation on water-sediment movement.After reviewing the progress of the three-dimensional water-sediment mathematical models,the disadvantages of one-fluid turbulence model(diffusion model)and the advantages of the solid-liquid two-phase two-fluid turbulence models were analyzed. Following Zhou lixing’s and Liu dayou’s works,theκ-ε-A_p andκ-ε-k_p solid-liquid two-phase two-fluid turbulence model with interphase actions in tensor form were developed.Theκ-ε-A_p andκ-ε-κ_p solid-liquid two-phase two-fluid turbulence model in Cartesian coordinate system were constructed and were solved by finite difference method. Three-dimensional characteristics of particle number density,time-averaged and fluctuation velocities of solid-liquid two phases in both horizontal and vertical rectangular pipes were computed,and the numerical results are in good agreement with measured results.Numerical results also proved the advantages ofκ-ε-κ_p solid-liquid two-phase two-fluid turbulence model overκ-ε-A_p solid-liquid two-phase turbulence model.A three-dimensionalκ-ε-κ_p solid-liquid two-phase two-fluid turbulence model in non-orthogonal curvilinear coordinate system was proposed to study water-sediment movement with complicated computational boundaries,which was solved by finite-volume method in adaptive grids.The flow structure in an S-shaped flume was used to validate the liquid-phase module,the movement of water flow and sediment in a 120°bend was used to validate the solid-phase module by computing the sediment concentration,longitudinal velocity,transverse velocity and vertical velocity,the movement of bed-load and channel bed aggradation and degradation processes in 120°and 180°bends were used to validate the bed topography deformation module.Comparisons between numerical results and experimental results show that two-fluid turbulence model describes the effect of secondary flow on the transverse sediment transport better than one-fluid turbulence model.A three-dimensionalκ-ε-A_p solid-liquid two-phase two-fluid turbulence model with the effect of vegetation on flow and sediment movement was constructed by adding the drag force or turbulent kinetic energy due to vegetation into relevant control equations. Experimental results in a flume covered with emergent and submerged vegetation validate the vertical flow structure changes due to vegetation.Experimental results in a partly vegetated straight open channel and a partly vegetated 60°channel bend validate the plan flow structure changes and three dimensional flow structure changes due to vegetation.The model also was used to investigate the vertical profiles of sediment concentration and the horizontal velocities of both liquid phase and solid phase in vegetated channels.The bed-load module and bed topography deformation module with the effect of vegetation were validated by sediment movement and channel bed aggradation and degradation processes in a straight partly center-vegetated flume and a 60°partly vegetated channel bend.更多还原