共查询到15条相似文献,搜索用时 46 毫秒
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针对界面附近粒子光滑函数截断和非物理穿透问题,提出一种气-液界面边界条件的处理方法.当界面附近支持域出现不同材料粒子,每步计算可在支持域设置虚粒子,按照密度分配方法给虚粒子物理量赋值,并对界面附近粒子引入气-液两相阻力.采用SPH方法和Level-Set方法,计算运动激波对气-液界面作用问题,两者计算结果一致,初步验证了气-液界面边界条件处理的适用性.用SPH方法分别计算超声速气流中的圆截面液柱绕流和下落问题,界面两侧粒子压力和法向速度连续,给出弓形激波、回流区和下游回流区等定性合理结果.表明本文方法可适度避免界面附近流体粒子光滑截断和粒子非物理穿透现象、界面附近流场数值振荡. 相似文献
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氘作为重要的核聚变原料,其热物性数据是基础,而气液相界面特性和相变规律又是热物性的关键.国内外对氘的相界面特性研究甚少.本文基于分子动力学方法,采用截断移位Lennard-Jones 12-6势能函数模型描述原子间的相互作用,并考虑分子内部原子间键的谐振作用,对氘的气液界面特性及气液固相变过程进行了仿真研究,得到了氘在不同温度下气液界面过渡区域的厚度、表面张力值等;获得了氘的密度随相变过程的变化规律,并由此得出氘的熔沸点温度,上述计算结果与实验及文献值吻合良好.不仅从微观层面上揭示了氘的宏观热物性表征机理,而且所建立的仿真模型可直接用于预测缺乏实验工况下的氘热物性. 相似文献
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本文以水平微圆管内气液两相环状流气液界面为研究对象,通过分析重力、表面张力和界面剪切力对环状流液膜厚度的影响,重点考虑Rayleigh不稳定性对气液界面的依存关系,得到了不同管径和气核直径变化时不稳定性的变化规律,并分析拟合了最危险波长和气核直径的关联式,为后续建立高热流密度条件下微通道内强化传热理论模型奠定基础. 相似文献
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对背面有热流输入的矩形毛细微槽群横截面上的气液分界面形状进行了理论分析,在一定条件下对Wayner蒸发模型进行简化,根据等壁温条件推出蒸发薄液膜区域热流密度近似为定值,通过流体动力学理论推导出了微槽横截面薄液膜区域液膜厚度变化的关系式,并与Wayner蒸发模型的计算结果进行了比较。进一步提出了全新的交界线区域长度的判定方法,根据蒸发薄液膜区域总换热量计算得到蒸发薄液膜区域的长度,交界处接触角,以及固有弯月面区域的曲率半径,从而最终得出了微槽横截面整个气液分界面的形状曲线,理论分析表明:槽宽、热流密度、过热度等因素对蒸发薄液膜区域长度、接触角以及固有弯月面曲率半径等参数有较大的影响。 相似文献
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Doklady Physics - For the first time, the effect of pressure fluctuations on the averaged shear stress in a shear viscous flow over a two-dimensional rectangular microcavity containing a pulsating... 相似文献
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In this paper Williamson fluid is taken into account to study its peristaltic flow with heat effects. The study is carried out in a wave frame of reference for symmetric channel. Analysis of heat transfer is accomplished by accounting the effects of non-constant thermal conductivity and viscosity and viscous dissipation. Modeling of fundamental equations is followed by the construction of closed form solutions for pressure gradient, stream function and temperature while assuming Reynold's number to be very low and wavelength to be very long. Double perturbation technique is employed, considering Weissenberg number and variable fluid property parameter to be very small. The effects of emerging parameters on pumping, trapping, axial pressure gradient, heat transfer coefficient, pressure rise, velocity profile and temperature are analyzed through the graphical representation. A direct relation is observed between temperature and thermal conductivity whereas the indirect proportionality with viscosity. The heat transfer coefficient is lower for a fluid with variable thermal conductivity and variable viscosity as compared to the fluid with constant thermal conductivity and constant viscosity. 相似文献
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A. A. Gavrilov K. A. Finnikov Ya. S. Ignatenko O. B. Bocharov R. May 《Journal of Engineering Thermophysics》2018,27(4):474-488
Laminar flow of a power-law fluid over a sphere is considered for unbounded shear flow. The Navier–Stokes equations with power-law viscosity are solved numerically using an in-house developed CFD package. Vorticities structures downstream of particle are suppressed for powerlaw fluid. The shear rate influence on drag force is negligible for power index close to unit, and the drag force appreciably decreases with falling power index. For small Reynolds numbers, the lift force coefficient monotonically decreases against the power index and exhibits an opposite behavior for moderate values of Reynolds numbers. The results of the parametric studies are used to derive correlations for the drag force and to detect the hydrodynamic differences from uniform flow. The investigation parameters varied within the following ranges: power-law index 0.3 ≤ n ≤ 1, Reynolds number 0 < Re ≤ 150, and dimensionless shear rate 0.05 ≤ s ≤ 0.4. 相似文献
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The compression and inflammation of reactive gas bubbles in bubble detonation waves have been studied, and the considerable influence of the fluid (liquid or vapor) on the detonation parameters has been found. It has been shown numerically that the final values of the pressure and temperature significantly decrease if the temperature dependence of the adiabatic index is taken into account at the compression stage. The parameters of reactive gas combustion products in the bubble have been calculated in terms of an equilibrium model, and the influence of the fluid that remains in the bubble in the form of microdroplets and vapor on these parameters has been investigated.
相似文献12.
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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Hiroshi Matsuoka 《Journal of statistical physics》2012,148(5):933-950
For a quantum system in a steady state with a constant current of heat or particles driven by a temperature or chemical potential difference between two reservoirs attached to the system, the fluctuation theorem for the current was previously shown to lead to the Green-Kubo formula for the linear response coefficient for the current expressed in terms of the symmetrized correlation function of the current density operator. In this article, we show that for a quantum system in a steady state with a constant rate of work done on the system, the fluctuation theorem for a quantity induced in the system also leads to the Green-Kubo formula expressed in terms of the symmetrized correlation function of the induced quantity. As an example, we consider a fluid in a steady shear flow driven by a constant velocity of a solid plate moving above the fluid. 相似文献
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Flow of Newtonian Fluid in Non-Uniform Tubes with Application to Renal Flow: A Numerical Study 下载免费PDF全文
In this paper, a numerical method employing a finite difference
technique is used for an investigation of
viscous, incompressible fluid flow in a tube with absorbing wall
and slowly varying cross-section. The effect
of fluid absorption through permeable wall is accounted by
prescribing flux as a function of axial distance.
The method is not restricted by the parameters in the problem
such as wave number, permeability parameter,
amplitude ratio and Reynolds number. The effects of these parameters
on the radial velocity and mean pressure
drop are studied and the results are presented graphically. Comparison
is also made between the results obtained by
perturbation method of solution and present approach. 相似文献