共查询到19条相似文献,搜索用时 140 毫秒
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VOF法模拟剪切流动下液滴的变形和断裂运动 总被引:1,自引:0,他引:1
本文对剪切作用下悬浮液滴在另一种不相融的液体中的变形和断裂过程进行了数值模拟.采用VOF(Volume ofFluid)法中的三维PLIC(Piecewise Linear Interface Calculation)算法实现界面的重构和输运,交错网格下投影法离散表面张力为源项的不可压缩Navier-Stokes方程.... 相似文献
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本文采用自适应移动网格与Level Set函数相耦合的方法来实现气-液两相流的数值模拟与计算.作为自适应网格方法的一种,移动网格方法主要是为了解决发展方程的计算问题而设计的方法.文中给出了移动网格的生成方程,并针对方程的非线性,给出了一种半隐式的离散方法用于进行求解.本文将移动网格方法与Level Set方法相耦合,将控制流体运动的Navier-Stokes方程以及追踪相界面的Level Set方程转换到曲线坐标下,应用一套曲线坐标方程组来同时描述气、液两相流的运动规律,成功实现了对气-液两相流问题的数值模拟.通过对顶盖驱动流的计算以及对液滴沉降现象的模拟计算,验证了本文方法的可靠性.本文对常重力与微重力下两气泡融合的发展规律进行了数值模拟,通过分析对比,得到了重力对两气泡融合变形的影响规律. 相似文献
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在动态网格上通过耦合求解流动控制方程和结构动力学方程, 发展了一种舵面控制下飞行器运动响应过程中气动弹性数值模拟研究方法.流动控制方程采用N-S方程, 结构动力学采用线性模态叠加方法, 其中流动控制方程空间离散采用基于非结构网格的有限体积方法, 对流通量采用计算HLLC格式, 非定常时间离散采用基于LU-SGS的双时间步长方法.模拟中, 气动运动和结构变形在双时间步长方法推进过程中采用改进松耦合方法, 气动网格与结构网格之间信息交换采用无限平板样条法实现, 飞行器的运动和变形采用基于重叠网格和Delaunay图映射变形网格相结合的方法进行处理.采用多个考核算例对发展的数值方法进行考核验证, 结果表明该方法可以高效精确模拟舵面开环控制下飞行器运动响应过程中的气动弹性特性. 相似文献
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叙述了一种模拟电介质电润湿(electrowetting on dielectric,EWOD)下的微液滴的运动的数值方法. 采用二阶投影法求解N-S方程和level set 函数,并利用零level set函数俘获液滴运动界面,在液体与固体接触的边界上,通过引入动态接触角表征电介质表面润湿性随电势的改变. 数值计算基于MAC网格,模拟了2维微管道内与固体壁面接触的变润湿性的两种液体的分界面形状、平板上的微液滴在不同电势作用下处于不同湿润性的形态,以及微管道内改变接触角液滴的运动变形过程等算例.
关键词:
电浸润
接触角
level set函数
投影法 相似文献
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对传统的光滑粒子动力学方法进行了改进, 改进的光滑粒子动力学方法对传统粒子方法中的核近似式和粒子近似式进行了修正, 采用Riemann 算法求解光滑粒子动力学流体控制方程, 添加了表面张力的计算程序, 考虑了表面张力对液滴溅落的影响. 应用改进的光滑粒子动力学方法对液滴静止状态下冲击液面的飞溅过程进行了数值模拟. 计算结果表明, 改进的光滑粒子动力学方法能够有效地描述液滴溅落液面的动力学特性和自由表面变化特征, 能够得到稳定精度的结果. 相似文献
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We investigate the deformation and breakup in shear flow of an encapsulated drop in which both the core and shell are Newtonian fluids. The equations of motion are solved numerically using a level set method to track interface motion. We consider the case of a drop stretched to a given length in constant shear and then allowed to relax. A range of morphologies is produced, and novel kinematics occur, due to the interaction of the core and outer interfaces. A phase diagram is presented to describe the morphologies produced over a range of capillary numbers and core interfacial tensions. 相似文献
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Chunfeng Zhou Pengtao Yue James J. Feng Carl F. Ollivier-Gooch Howard H. Hu 《Journal of computational physics》2010,229(2):498-511
This work presents a three-dimensional finite-element algorithm, based on the phase-field model, for computing interfacial flows of Newtonian and complex fluids. A 3D adaptive meshing scheme produces fine grid covering the interface and coarse mesh in the bulk. It is key to accurate resolution of the interface at manageable computational costs. The coupled Navier–Stokes and Cahn–Hilliard equations, plus the constitutive equation for non-Newtonian fluids, are solved using second-order implicit time stepping. Within each time step, Newton iteration is used to handle the nonlinearity, and the linear algebraic system is solved by preconditioned Krylov methods. The phase-field model, with a physically diffuse interface, affords the method several advantages in computing interfacial dynamics. One is the ease in simulating topological changes such as interfacial rupture and coalescence. Another is the capability of computing contact line motion without invoking ad hoc slip conditions. As validation of the 3D numerical scheme, we have computed drop deformation in an elongational flow, relaxation of a deformed drop to the spherical shape, and drop spreading on a partially wetting substrate. The results are compared with numerical and experimental results in the literature as well as our own axisymmetric computations where appropriate. Excellent agreement is achieved provided that the 3D interface is adequately resolved by using a sufficiently thin diffuse interface and refined grid. Since our model involves several coupled partial differential equations and we use a fully implicit scheme, the matrix inversion requires a large memory. This puts a limit on the scale of problems that can be simulated in 3D, especially for viscoelastic fluids. 相似文献
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A new finite-difference method for the numerical solution of gas dynamics equations is proposed. This method is a uniform
monotonous finite-difference scheme of second-order approximation on time and space outside of domains of shock and compression
waves. This method is based on inputting adaptive artificial viscosity (AAV) into gas dynamics equations. In this paper, this
method is analyzed for 2D geometry. The testing computations of the movement of contact discontinuities and shock waves and
the breakup of discontinuities are demonstrated. 相似文献
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Energy transfer from higher modes of capillary vibrations of an incompressible liquid charged drop to the lowest fundamental
mode under four-mode resonance is studied. The resonance appears when the problem of nonlinear axisymmetric capillary vibration
of a drop is solved in the third-order approximation in amplitude of the multimode initial deformation of the equilibrium
shape of the drop. Although the resonant interaction mentioned above builds up the fundamental mode even in the first order
of smallness, its amplitude turns out to be comparable to a quadratic (in small parameter) correction arising from nonresonant
nonlinear interaction, since the associated numerical coefficients are small. 相似文献
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在方磁阱近似、各向同性位近似以及最低模近似下,用数值方法求解了简化的F-P方程。得到了若干数值结果,结果与物理分析相符合。同时,本文详细地叙述了数值方法。 相似文献
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在势流假设下, 考虑表面张力以及黏性修正, 建立自由液面在气泡破碎后全非线性运动的数值模型, 给出射流断裂和水滴撕裂的数值处理方法. 同时进行上浮气泡在自由液面破裂的实验研究, 数值解与实验值符合良好.为了研究自由液面在气泡破碎后的运动学机理和规律, 运用开发的程序研究了不同尺寸气泡破碎后的动态特性, 包括从气泡底部顶起的射流、射流断裂以及水滴分裂等复杂的物理现象, 总结了从射流上撕裂出的第一个水滴尺寸、撕裂时间以及最大射流速度的变化规律. 最后讨论了雷诺数与韦伯数对气泡破碎后自由液面运动的影响.
关键词:
气泡
自由液面
破碎
断裂 相似文献