• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    A sharp interface approach for cavitation modeling using volume-of-fluid and ghost-fluid methods *

    2017-03-14 07:06:14ThadMichaelJianmingYangFrederickStern

    Thad Michael , Jianming Yang , Frederick Stern

    1. NSWC Carderock Division, 9500 MacArthur Blvd., West Bethesda, MD 20817, USA,E-mail:thad.michael@navy.mil

    2. Fidesi Solutions LLC, PO Box 734, Iowa City, IA 52244, USA

    3. IIHR-Hydroscience and Engineering, University of Iowa, Iowa City, IA 52242, USA

    Introduction

    Cavitation is the term for the change of state from liquid to vapor when it is caused by a lowpressure region within the flow field at an ambient temperature. Although the physical mechanism is the same, in contrast the term boiling is used to describe the change of state from liquid to vapor when it is caused by a local increase in temperature at the ambient pressure. For cavitation, the phase change rate is governed by the local pressure, while for boiling it is governed by the local temperature.

    Cavitation degrades the performance of lifting surfaces found on ships, such as propeller blades and rudders. In addition to reducing lift, the violent collapse of cavitation bubbles can also remove material leading to further degradation and possible failure.

    Potential flow cavitation models have been developed for propellers in Refs.[1,2]. The cavity is treated as additional thickness and the location is solved iteratively. A number of cavitation models for viscous flows have been developed, primarily for homogenous mixture models. Some examples are Refs.[3,4]. A more recent model in Ref.[5] adds the effect of noncondensable gas within the bubbles. Recent computations in Refs.[6-9] using models of this type have compared well with hydrofoil experiments. For visualization, the cavity interface is assumed to be at a constant volume fraction, typically 0.5. For summaries of recent research on cavitation models, especially,homogeneous mixture models, and their applications,the reader is referred to [10-13].

    Sharp interface phase change models have been used to compute film boiling in Refs.[14,15]. Here we seek to apply similar techniques to the problem of cavitation, with the development of a suitable model for phase change due to cavitation.

    The focus of this paper is the development of a model for predicting the phase change rate suitable for use with a sharp interface and the necessary models and methods to support this combination. The model is implemented in a two-phase incompressible viscous flow solver with a sharp interface approach. Results are presented for a cavitating hydrofoil. The results are analyzed to reveal details of the physics of the reentrant jet and cavity shedding. The averaged results are compared with experimental data.

    1. Mathematical model

    1.1 Incompressible viscous flow

    The Navier-Stokes equations for the incompressible viscous flow of the liquid and vapor phases are written as follows:

    where I is the identity matrix and where μ is the viscosity of the fluid and

    1.2 Phase change

    With phase change, a volume source must be added due to the different densities of liquid and vapor.The volume source satisfies the requirement for mass conservation and results in a jump in the fluid velocity at the interface so that Eq.(1) becomes

    where m˙ is the mass flux between phases and the subscripts l and v stand for liquid and vapor, respectively.

    1.3 Interface tracking

    A volume of fluid (VOF) method described in Ref.[16] with the addition of a velocity component due to phase change is used to track the interface position. Without phase change, the boundary between liquid and vapor moves with a velocity which is continuous across the interface. Phase change introduces a velocity discontinuity at the interface which is proportional to the phase change rate and the difference in density across the interface. The VOF equation is

    where U is the interface velocity, defined relative to the local liquid or vapor velocity by

    wherefu is the fluid velocity, and ρfis the fluid density and f is liquid or vapor. This satisfies the conservation of mass between the phases at the interface.

    1.4 Modeling mass flux between phases

    The rates of vaporization and condensation are determined by a simplification of the Rayleigh-Plesset equation which assumes a spherical bubble subject to uniform pressure variations wherevapp is the vapor pressure,0gp is the initial partial pressure of non-condensable gasses,0R is the initial radius of the bubble, S is the surface tension,and γ is the ratio of the gas heat capacities. The third term on the right-hand side represents the effect of the non-condensable gasses. The last two terms on the right represent the effects of surface tension and viscosity, respectively.

    The surface tension can be neglected for all but the smallest bubbles and the viscous effects can be neglected for the Reynolds numbers of interest in ship flows. By also neglecting the non-condensable gasses,the equation can be integrated with respect to time and simplified to yield

    This simplification is the foundation of several cavitation models used with two-phase mixture models where further assumptions about bubble number or size are utilized to arrive at a surface area and mass flux.

    With a sharp interface method, the bubble must be larger than the cell to be accurately modeled. If the radius is sufficiently large, it is reasonable to represent it by a plane within the cell, as in the volume of fluid method. Then, the velocity is

    where n is the interface normal. Because a local pressure will be used in place of the far field pressure,a constant is needed for correlation. With this addition,and a simplification, the mass flux can be expressed:

    whereeC andcC are the coefficients of evaporation and condensation, respectively. See Ref.[17] for a more detailed derivation.

    2. Numerical methods

    2.1 Flow solver

    The CFD code CFDShip-Iowa v6.2[18]is the foundation for this development. It is an incompressible Navier-Stokes solver utilizing an orthogonal curvilinear grid. The velocity components are defined at the centers of cell faces while other quantities are defined at the cell centers. A finite difference approach is used, except for the pressure Poisson equation which is solved with a finite volume approach. For cavitation modeling, a first-order Euler method is used for time advancement for simplicity.

    Hypre library[19]is used for the parallel solution of the Poisson equation. With the volume source due to phase change, the Poisson equation is

    where G radi(p) is collocated with the velocity components and incorporates the jump conditions due to surface tension and gravity as described in Ref.[20].For stability, the phase change rate from Eq.(11) is modeled semi-implicitly, as described in Ref.[17],resulting in this pressure Poisson equation

    where E is a constant related to the fluid densities

    For the momentum equation, a ghost fluid method is employed. This method was also used in Refs.[14,15] to model boiling with a sharp interface phase change model. CFDShip-Iowa v6.2 includes surface tension, density, and viscosity changes at the interface[20]. The ghost fluid method is used only to account for the velocity jump normal to the interface due to the volume source.

    Fig.1 Hydrofoil geometry with six-degree angle-of-attack

    Fig.2 Leading edge of the foil and grid resolution

    Fig.3 Pressure distribution on the foil without cavitation, 2-D calculation. Experimental data is from Ref.[23]

    A parallel fast marching method developed in Ref.[21] was also modified to extend the velocity components from one side of the interface to the other such that the velocity normal to the interface is constant. The extended velocity field is not conservative. However, only the extended values that are close to the interface are used to solve the momentum equation in the phase of interest and the approximation is reasonable near the interface. The momentum equation is solved separately for each phase and the intermediate velocity fields are then combined using the level set function to discriminate between phases.

    Fig.4 (Color online) Cavity evolution at 1.25 cavitation number (p = - 0 .625), time series from a-h

    2.2 Volume of fluid and level set

    The VOF method is used for interface reconstruction and advection as described in Ref.[16]. An operator splitting strategy is used to advect the interface separately in each coordinate direction. The velocity used for VOF advection is the interface velocity field computed by applying Eq.(11) to the two-phase velocity field.

    The level set scalar is reinitialized from the VOF using a parallel fast marching method described in Ref.[21].

    2.3 Interface area and location

    In the earlier implementation of this cavitation model described in Ref.[17], some discrepancies arose between the definition of the interface location used for the ghost fluid method and the volume source.The ghost fluid velocity extension utilizes the level set function interpolated to the face centers where the ve-locity is defined. Previously, the volume source was determined by the interface area from the VOF interface reconstruction. However, the two methods could lead to contradictions when the interface was close to a cell face.

    Fig.5 (Color online) Cavity trailing edge showing stagnation point and reentrant jet

    Fig.6 (Color online) Middle of cavity showing bulge where reentrant jet begins to push outward into cavity. (For clarity, vectors are only shown at every other point.)

    To eliminate this problem, a marching cubes method has been implemented following the method in Ref.[22]. By interpolating the level set function from cell centers to face centers, edge centers, and corners, a triangulated surface is obtained which is consistent with the interface used for the velocity extension in the ghost fluid method. The interface area can then be determined directly from the area of the triangles in each cell and used in the finite volume implementation of the pressure Poisson equation with a volume source. The triangulated surface is also useful for visualization.

    3. Results and discussion

    3.1 Two dimensions

    Previous computations with simple 2-D bubble cases showed that the velocity jump is well represented and the pressure and velocity distributions around the bubble follow the analytical solutions[17].

    Computations have been made for a hydrofoil tested in Ref.[23]. The thickness of the hydrofoil is 9%of the chord length with a NACA 66 distribution. The camber is 2% of the chord length with a NACA a = 0.8 distribution. In the experiment, the span of the foil was equal to the chord. The angle-of-attack is 6o.

    Here, a 2-D slice of the foil is modeled with an O-grid with 2 048 cells wrapping around the foil and 256 cells in the surface normal direction. The radius of the O-grid is about 10 chord lengths. Upstream, the inlet velocity is specified. Downstream, the pressure is specified. The geometry is shown in Fig.1 and Fig.2 shows a detail of the mesh near the leading edge.

    The cells near the surface of the foil are approximately square and approximately constant size. The fixed resolution is important to accurately capture the bubbles.

    A calculation without cavitation verifies the pressure distribution is accurately predicted on the foil,as shown in Fig.3. The computed lift coefficient of 0.824 is 3.3% greater than the experiment6ally measured value at the Reynolds number of 2×10.

    With the cavitation number set to 1.25 to match the experiment, a time series of the initial cavity development is shown in Fig.4. Note that the contour legend shown in Fig.4 applies to all figures with pressure contours and that p in the figures is normalized with ρ U2. so that the vapor pressure is p=-0 .625. The sequence shows that as the cavity grows downstream, a thin layer of liquid remains on the foil surface. This is because the downstream growth of the cavity is driven mainly by advection and there is a no-slip condition on the surface of the foil.

    The stagnation point at the downstream end of the cavity causes a high pressure at that location which tends to force liquid back upstream, underneath the cavity, as shown in Fig.5. This flow characteristic is often called the reentrant jet.

    As shown in Fig.5, the vapor flow at the outer surface of the cavity follows the liquid flow on the other side of the interface downstream. Drops of liquid from under the cavity are carried downstream and collect in the downstream portion of the cavity.

    A short distance from the stagnation point, the pressure in and under the cavity is equal and the liquid under the cavity can easily find its way into the cavity,as shown in Fig.6.

    Figure 7 shows a time series near the middle of the cavity. The liquid under the cavity is pushed up into the cavity by the flow of the reentrant jet from downstream (a, b). As the finger of liquid approaches and touches the outer surface of the cavity, it is drawn downstream (c, d), stretches (e, f) and breaks up into separate regions (g, h).

    Fig.7 (Color online) Reentrant jet flow under and into cavity, time series from a-h

    If sufficient liquid collects in the downstream end of the cavity, or if a finger of liquid from the reentrant jet destabilizes the cavity enough to allow a high pressure to develop between the upstream and downstream portions of the cavity, the downstream portion of the cavity will be shed downstream and will gradually disappear as the vapor becomes liquid again.

    The current model does not capture the effect of the non-condensable gasses that diffuse into the cavity and will remain in the bubble after the vapor becomes liquid again.

    Figure 8 is a time sequence showing the flow field where, qualitatively, the downstream portion of the cavity begins to separate from the upstream portion before moving downstream while the upstream cavity sheds some additional vapor regions and shrinks. There is no sudden shift in the flow patterns.It appears that liquid accumulates under and among the cavities until the liquid displaces the cavities sufficiently high into the flow field for them to be swept downstream.

    Following shedding, the development of the new cavity is more complex than the initial development shown in Fig.4. There is not a single vapor-filled cavity, but instead a group of them occupying a similar extent to that shown in Fig,4(h) and Fig.8. The physical processes appear to be similar, including the recirculation or the reentrant jet and increasing liquid fraction.

    Fig.8 (Color online) Shedding. The first image is an overview of the cavity shape at shedding, the arrow indicates the location shown in the other images. The other images show the flow at the point where shedding appears to initiate at times just before, during, and after shedding

    Fig.9 Grid near foil leading edge. The similar discretization in all three directions is important for capturing bubbles with a sharp interface method

    Fig.10 Pressure distribution on the foil without cavitation, 3-D calculation averaged across span. Experimental data is from Ref.[23]

    3.2 Three dimensions

    The same hydrofoil is modeled in three dimensions with an O-grid of 1 024 cells wrapping around the foil, 1 024 cells in the spanwise direction, and 128 cells in the surface normal direction. In the area of interest near the foil surface on the suction side, the cells are approximately cubes. The surface grid near the foil leading edge and a cut through the grid in a plane normal to the span is shown in Fig.9.

    Fig.11 (Color online) Inception bubbles near the leading edge of the foil

    Three calculations have been made: (1) the non-cavitating foil, (2) the cavitating foil initialized with a 2-D cavitating solution, and (3) the cavitating foil from inception.

    Fig.12 (Color online) Close up of inception bubbles near the leading edge of the foil

    Fig.13 (Color online) Close up near the leading edge of the foil showing bubble growth, merging, and advection

    As expected, the non-cavitating 3-D pressure distribution is similar to the 2-D wetted pressure distribution. However, there are some variations due to the fineness of the grid. The fine grid results in a DNS-like unsteady behavior, with vortices shed from the leading edge on the suction side. Averaging over the span of the foil shows the expected results, shown in Fig.10.

    A 3-D cavitating calculation has been initiated.Figures 11 through 13 show cavitation inception near the leading edge of the foil. The inception model generates a bubble of fixed radius, large enough to include several cells. The bubbles are then free to evolve and merge. It is clear from the calculations that the evolution of the bubbles is dominated by advection.

    The pattern in the initial spanwise spacing,clearly visible in Fig.12, is due to one of the criteria in the inception model. The inception model requires that the center of a new bubble be a bit more than one radius from the nearest interface. Consequently, the model tends to create a line of bubbles along the low-pressure region at the leading edge.

    Only the initial startup of the 3-D calculation has been completed. As the bubbles stretch, break up, and interact with others, it is found that the stability of the computation is affected. A major reason might be the under-resolved bubbles generated in the process. A bubble model may be required to improve the numerical stability. On the other hand, Refs.[24,25] proposed a multi-scale approach to smoothly bridge large size cavities captured by level sets and small bubbles described by a discrete singularity model. Future work will require a closer look into similar models.

    4. conclusions

    A sharp interface cavitation model has been developed and implemented. The method utilizes a simplification of the Rayleigh-Plesset equation to compute the interface velocity used to advect the interface between the liquid and vapor phases.

    The method has been demonstrated in two dimensions with a hydrofoil and found to offer insight into the mechanism of cavity evolution. The results show the formation of the reentrant jet and how instabilities in the reentrant jet perturb the cavity.Increasing liquid content, particularly near the leading edge of the cavity seems to gradually lead to cavity shedding.

    The method in three dimensions has proved to be more challenging. Of course, complex geometries and moving boundaries in 3-D will pose additional difficulties to the current approach with the orthogonal curvilinear grid requirement. It is believed that together with unstructured mesh approaches or immersed boundary approaches[26]this method will lead to viable high-fidelity cavitation calculations in the near future.

    This research was supported by the NSWC Carderock ILIR program and by the US Office of Naval Research (Grant No. N000141-01-00-1-7), with Dr. Ki-Han Kim as the program manager. The computations were performed on computers at AFRL and Navy DoD Supercomputing Resource Centers.

    [1] Lee C. S. Prediction of steady and unsteady performance of marine propellers with or without cavitation by numerical lifting surface theory [D]. Doctoral Thesis, Cambridge,Massachusetts, USA: Massachusetts Institute of Technology, 1979.

    [2] Kerwin J. E., Kinnas S. A., Lee J. T. et al. A surface panel method for the hydrodynamic analysis of ducted propellers [J]. SNAME Transactions, 1987, 95: 93-122.

    [3] Merkle C. L., Feng J. Z., Buelow P. E. O. Computational modeling of the dynamics of sheet cavitation [C]. Third International Symposium on Cavitation. Grenoble, France,1998.

    [4] Kunz R. F., Boger D. A., Chyczewski T. S. et al. Multiphase CFD analysis of natural and ventilated cavitation about submerged bodies [C]. Proceedings of FEDSM ’99,3rd ASME/JSME Joint Fluids Engineering Conference.San Francisco, California, USA, 1999.

    [5] Singhal A. K., Athavale M. M., Li H. et al. Mathematical basis and validation of the full cavitation model [J].Journal of Fluids Engineering, 2002, 124(3): 617-624.

    [6] Kim S. E., Brewton S. A multiphase approach to turbulent cavitating flows [C]. Proceedings of the 27th Symposium on Naval Hydrodynamics. Seoul, Korea, 2008.

    [7] Kim S. E., Schroeder S., Jasak H. A multi-phase CFD framework for predicting performance of marine propulsors [C]. The 13th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery.Honolulu, Hawaii, USA, 2010.

    [8] Kim S. E., Schroeder S. Numerical study of thrust-breakdown due to cavitation on a hydrofoil, a propeller, and a waterjet [C]. Proceedings of the 28th Symposium on Naval Hydrodynamics. Pasedena, California, USA, 2010.

    [9] Bensow R. E., Huuva T., Bark G. Large eddy simulation of cavitating propeller flows [C]. 27th Symposium on Naval Hydrodynamics. Seoul, Korea, 2008.

    [10] Zhang, L. X., Zhang N., Peng X. X. et al. A review of studies of mechanism and prediction of tip vortex cavitation inception [J]. Journal of Hydrodynamics, 2015, 27(4):488-495.

    [11] Luo X. W., Jin B., Tsujimoto Y. A review of cavitation in hydraulic machinery [J]. Journal of Hydrodynamics, 2016,28(3): 335-358.

    [12] Chen Y., Lu C. J., Chen X. et al. Numerical investigation of the time-resolved bubble cluster dynamics by using the interface capturing method of multiphase flow approach[J]. Journal of Hydrodynamics, 2017, 29(3): 485-494.

    [13] Zhang D. S., Shi W. D., Zhang G. J. et al. Numerical analysis of cavitation shedding flow around a three-dimensional hydrofoil using an improved filter-based model[J]. Journal of Hydrodynamics, 2017, 29(2): 361-375.

    [14] Son G., Dhir V. K. A level set method for analysis of film boiling on an immersed solid surface [J]. Numerical Heat Transfer, Part B: Fundamentals, 2007, 52(2): 153-177.

    [15] Gibou F., Chen L., Nguyen D. et al. A level set based sharp interface method for the multiphase incompressible Navier-Stokes equations with phase change [J]. Journal of Computational Physics, 2007, 222: 536-555.

    [16] Wang Z., Yang J., Stern F. A new volume-of-fluid method with a constructed distance function on general structured grids [J]. Journal of Computational Physics, 2012, 231(9):3703-3722.

    [17] Michael T., Yang J., Stern F. Sharp interface cavitation modeling using volume-of-fluid and level set methods [J].Proceedings of the ASME 2013 Fluids Engineering Summer Meeting. Incline Village, Nevada, USA, 2013.

    [18] Suh J., Yang J., Stern F. The effect of air-water interface on the vortex shedding from a vertical circular cylinder [J].Journal of Fluids and Structures, 2011, 27(1): 1-22.

    [19] Falgout R. D., Jones J. E., Yang U. M. The design and implementation of hypre, a library of parallel high performance preconditioners (Bruaset A. M., Tveito A.Numerical solution of partial differential equations on parallel computers) [M]. Berlin, Germany: Springer-Verlag,2006, 51: 267-294.

    [20] Yang J., Stern F. Sharp interface immersed-boundary/level-set method for wave-body interactions [J]. Journal of Computational Physics, 2009, 228(17): 6590-6616.

    [21] Yang J., Stern F. A highly scalable massively parallel fast marching method for the Eikonal equation [J]. Journal of Computational Physics, 2017, 332: 333-362.

    [22] Lewiner T., Lopes H., Vieira A. W. et al. Efficient implementation of Marching Cubes’ cases with topological guarantees [J]. Journal of Graphics Tools, 2003, 8(2):1-15.

    [23] Shen Y. T., Dimotakis P. E. The influence of surface cavitation on hydrodynamic forces [C]. 22nd American Towing Tank Conference. St Johns, Newfoundland,Canada, 1989.

    [24] Hsiao C. T., Ma J., Chahine G. L. Multiscale two-phase flow modeling of sheet and cloud cavitation [J]. International Journal of Multiphase Flow, 2017, 90: 102-117.

    [25] Ma J., Hsiao C. T., Chahine G. L. A physics based multiscale modeling of cavitating flows [J]. Computers and Fluids, 2017, 145: 68-84.

    [26] Yang J. Sharp interface direct forcing immersed boundary methods: A summary of some algorithms and applications[J]. Journal of Hydrodynamics, 2016, 28(5): 713-730.

    久久天堂一区二区三区四区| 两个人免费观看高清视频| 久久狼人影院| 久久中文字幕一级| 操出白浆在线播放| 精品高清国产在线一区| 亚洲专区中文字幕在线| 国产免费现黄频在线看| 久9热在线精品视频| 国产激情久久老熟女| 中文字幕精品免费在线观看视频| 91成人精品电影| 女性生殖器流出的白浆| 国产精品偷伦视频观看了| 国产成人啪精品午夜网站| 我要看黄色一级片免费的| 99久久人妻综合| 成年人免费黄色播放视频| 欧美日韩成人在线一区二区| 亚洲国产欧美在线一区| 下体分泌物呈黄色| 久久久精品免费免费高清| 成年美女黄网站色视频大全免费| 成年女人毛片免费观看观看9 | 天天操日日干夜夜撸| 女人精品久久久久毛片| 两性午夜刺激爽爽歪歪视频在线观看 | 日韩电影二区| 久久久水蜜桃国产精品网| 亚洲五月婷婷丁香| 精品少妇久久久久久888优播| 亚洲欧美激情在线| 99精品欧美一区二区三区四区| 色精品久久人妻99蜜桃| 搡老乐熟女国产| 久久久久国产精品人妻一区二区| avwww免费| 99国产综合亚洲精品| 别揉我奶头~嗯~啊~动态视频 | 五月开心婷婷网| 一区在线观看完整版| 亚洲情色 制服丝袜| 一边摸一边抽搐一进一出视频| 国产精品麻豆人妻色哟哟久久| 黑丝袜美女国产一区| 国产成人av教育| 真人做人爱边吃奶动态| 精品亚洲乱码少妇综合久久| 国产亚洲精品久久久久5区| 日本wwww免费看| 国产1区2区3区精品| 亚洲国产欧美日韩在线播放| 国产一区二区三区在线臀色熟女 | 国产淫语在线视频| 亚洲激情五月婷婷啪啪| 国产日韩一区二区三区精品不卡| 天堂俺去俺来也www色官网| 午夜福利一区二区在线看| 精品福利永久在线观看| 欧美精品av麻豆av| 啦啦啦啦在线视频资源| 五月开心婷婷网| 18禁黄网站禁片午夜丰满| 高潮久久久久久久久久久不卡| 少妇 在线观看| 少妇被粗大的猛进出69影院| 如日韩欧美国产精品一区二区三区| 精品第一国产精品| 成人av一区二区三区在线看 | 两性午夜刺激爽爽歪歪视频在线观看 | 亚洲欧美一区二区三区黑人| 最新的欧美精品一区二区| 国产av又大| 女人精品久久久久毛片| 国产高清国产精品国产三级| 一本综合久久免费| 侵犯人妻中文字幕一二三四区| 国产欧美日韩一区二区三区在线| 亚洲国产毛片av蜜桃av| 啦啦啦 在线观看视频| 国产精品av久久久久免费| 免费人妻精品一区二区三区视频| 一区二区av电影网| 国产精品欧美亚洲77777| 欧美乱码精品一区二区三区| 十八禁人妻一区二区| 麻豆av在线久日| 麻豆国产av国片精品| 法律面前人人平等表现在哪些方面 | 免费av中文字幕在线| 热re99久久国产66热| 亚洲三区欧美一区| 日本91视频免费播放| 国产免费现黄频在线看| 老鸭窝网址在线观看| 这个男人来自地球电影免费观看| 日韩精品免费视频一区二区三区| 18禁国产床啪视频网站| 高清视频免费观看一区二区| 亚洲人成77777在线视频| 天堂中文最新版在线下载| 大香蕉久久成人网| 另类亚洲欧美激情| 999精品在线视频| av天堂在线播放| 国产真人三级小视频在线观看| a级片在线免费高清观看视频| 久久精品人人爽人人爽视色| 国产精品 国内视频| 久久这里只有精品19| 精品第一国产精品| 久久久久精品国产欧美久久久 | 欧美日韩av久久| 婷婷成人精品国产| 好男人电影高清在线观看| 免费黄频网站在线观看国产| 午夜福利视频在线观看免费| 自拍欧美九色日韩亚洲蝌蚪91| 久久ye,这里只有精品| 国产精品久久久久久精品电影小说| 国产一区有黄有色的免费视频| 少妇裸体淫交视频免费看高清 | 亚洲国产看品久久| 纵有疾风起免费观看全集完整版| 日韩中文字幕视频在线看片| 欧美人与性动交α欧美软件| 日本91视频免费播放| 久久中文字幕一级| 亚洲成国产人片在线观看| 国产亚洲精品一区二区www | 成人18禁高潮啪啪吃奶动态图| 免费在线观看视频国产中文字幕亚洲 | 老司机影院毛片| 桃红色精品国产亚洲av| 国产人伦9x9x在线观看| 女性被躁到高潮视频| av天堂在线播放| 叶爱在线成人免费视频播放| 一区二区av电影网| 日日夜夜操网爽| 黄网站色视频无遮挡免费观看| 欧美变态另类bdsm刘玥| 天堂中文最新版在线下载| 汤姆久久久久久久影院中文字幕| 午夜老司机福利片| av天堂久久9| 欧美 亚洲 国产 日韩一| 不卡一级毛片| 久久精品熟女亚洲av麻豆精品| 国产精品.久久久| 十八禁人妻一区二区| 欧美一级毛片孕妇| 亚洲 欧美一区二区三区| 亚洲中文字幕日韩| 日韩电影二区| 狠狠狠狠99中文字幕| 国产区一区二久久| 久久国产精品人妻蜜桃| 狠狠精品人妻久久久久久综合| 肉色欧美久久久久久久蜜桃| 人人澡人人妻人| 久久精品国产a三级三级三级| cao死你这个sao货| 99久久综合免费| 啦啦啦免费观看视频1| a在线观看视频网站| 国产成人免费无遮挡视频| 在线观看人妻少妇| 国产色视频综合| 咕卡用的链子| 亚洲av美国av| 亚洲免费av在线视频| 九色亚洲精品在线播放| 午夜福利在线免费观看网站| 国产人伦9x9x在线观看| 波多野结衣av一区二区av| 色精品久久人妻99蜜桃| 一本久久精品| 久久中文看片网| 女警被强在线播放| 亚洲精品成人av观看孕妇| 亚洲国产看品久久| 日韩欧美一区二区三区在线观看 | 老熟女久久久| 80岁老熟妇乱子伦牲交| 亚洲欧美精品自产自拍| 久久精品久久久久久噜噜老黄| 黄色a级毛片大全视频| 国产成+人综合+亚洲专区| 亚洲精品在线美女| 国产一卡二卡三卡精品| 久久久久久久久久久久大奶| 成年女人毛片免费观看观看9 | 女性生殖器流出的白浆| 久久这里只有精品19| 日日摸夜夜添夜夜添小说| 国产成人系列免费观看| 久久精品久久久久久噜噜老黄| 欧美激情久久久久久爽电影 | 18禁黄网站禁片午夜丰满| 欧美激情久久久久久爽电影 | 精品一区二区三区四区五区乱码| 国产精品国产三级国产专区5o| 老司机影院毛片| 国产高清videossex| www.自偷自拍.com| 母亲3免费完整高清在线观看| 脱女人内裤的视频| 国产一卡二卡三卡精品| 大片电影免费在线观看免费| 日韩欧美国产一区二区入口| 青草久久国产| 美女国产高潮福利片在线看| 国产欧美亚洲国产| 久久国产精品人妻蜜桃| 国产淫语在线视频| 十分钟在线观看高清视频www| 亚洲熟女毛片儿| 亚洲性夜色夜夜综合| av一本久久久久| 乱人伦中国视频| 一级,二级,三级黄色视频| 亚洲色图综合在线观看| 蜜桃在线观看..| 99热网站在线观看| 国产无遮挡羞羞视频在线观看| 国产亚洲精品久久久久5区| 久久久久久久久免费视频了| 搡老岳熟女国产| 波多野结衣一区麻豆| 老司机亚洲免费影院| 啦啦啦 在线观看视频| 亚洲国产中文字幕在线视频| videos熟女内射| 国产色视频综合| 岛国在线观看网站| 日韩视频一区二区在线观看| 成人国产av品久久久| 精品国产乱子伦一区二区三区 | 午夜激情久久久久久久| 97精品久久久久久久久久精品| 国产伦理片在线播放av一区| 日韩制服骚丝袜av| 无限看片的www在线观看| 男人舔女人的私密视频| 亚洲av日韩在线播放| svipshipincom国产片| 999久久久精品免费观看国产| 美女高潮到喷水免费观看| 亚洲成国产人片在线观看| 一级a爱视频在线免费观看| www.999成人在线观看| 99久久精品国产亚洲精品| 美女国产高潮福利片在线看| 国产不卡av网站在线观看| 纵有疾风起免费观看全集完整版| 50天的宝宝边吃奶边哭怎么回事| 秋霞在线观看毛片| 高清视频免费观看一区二区| 日本一区二区免费在线视频| 国产免费一区二区三区四区乱码| 老熟女久久久| 桃花免费在线播放| 国产精品久久久久成人av| 美女午夜性视频免费| 精品福利永久在线观看| av一本久久久久| 97精品久久久久久久久久精品| 热99久久久久精品小说推荐| 超色免费av| 日本av手机在线免费观看| 伊人久久大香线蕉亚洲五| 欧美日韩亚洲综合一区二区三区_| 十分钟在线观看高清视频www| 欧美 亚洲 国产 日韩一| 少妇被粗大的猛进出69影院| 美女扒开内裤让男人捅视频| 欧美97在线视频| 性少妇av在线| 日韩制服丝袜自拍偷拍| 在线观看免费午夜福利视频| 蜜桃国产av成人99| 大香蕉久久成人网| 日韩一区二区三区影片| 久久天躁狠狠躁夜夜2o2o| 人妻人人澡人人爽人人| videosex国产| 91精品伊人久久大香线蕉| 深夜精品福利| 久久国产精品人妻蜜桃| 午夜影院在线不卡| 久久性视频一级片| 亚洲成人手机| 久久精品aⅴ一区二区三区四区| 欧美成狂野欧美在线观看| 丰满少妇做爰视频| 久久精品aⅴ一区二区三区四区| 99久久国产精品久久久| 97精品久久久久久久久久精品| 在线天堂中文资源库| 两人在一起打扑克的视频| 国产精品久久久久久精品电影小说| 国产精品久久久人人做人人爽| 亚洲精华国产精华精| 久久人人爽av亚洲精品天堂| 亚洲中文字幕日韩| 国产成人精品在线电影| 一本色道久久久久久精品综合| 一本大道久久a久久精品| 久久毛片免费看一区二区三区| 国产av又大| 日日夜夜操网爽| 欧美av亚洲av综合av国产av| 男女边摸边吃奶| 制服人妻中文乱码| 国产亚洲一区二区精品| 美女高潮到喷水免费观看| 可以免费在线观看a视频的电影网站| 麻豆乱淫一区二区| 亚洲第一青青草原| 久久香蕉激情| 两性午夜刺激爽爽歪歪视频在线观看 | 一级毛片女人18水好多| 悠悠久久av| 狠狠婷婷综合久久久久久88av| 熟女少妇亚洲综合色aaa.| 亚洲三区欧美一区| 日韩熟女老妇一区二区性免费视频| 一本—道久久a久久精品蜜桃钙片| 午夜激情av网站| 精品乱码久久久久久99久播| 亚洲国产av影院在线观看| 久久久久网色| 美女高潮到喷水免费观看| 美女扒开内裤让男人捅视频| 成年动漫av网址| 色综合欧美亚洲国产小说| 十八禁高潮呻吟视频| 18禁黄网站禁片午夜丰满| 少妇粗大呻吟视频| bbb黄色大片| 国产高清视频在线播放一区 | 亚洲少妇的诱惑av| 国产97色在线日韩免费| 亚洲欧美色中文字幕在线| 两人在一起打扑克的视频| 亚洲伊人色综图| 99久久国产精品久久久| 人人妻,人人澡人人爽秒播| 18禁黄网站禁片午夜丰满| 国产欧美日韩一区二区三区在线| 最黄视频免费看| 飞空精品影院首页| 欧美人与性动交α欧美精品济南到| 亚洲三区欧美一区| 亚洲人成电影观看| 久久久精品区二区三区| 成人黄色视频免费在线看| 欧美日韩黄片免| 久久九九热精品免费| 在线观看www视频免费| 十八禁人妻一区二区| 国产视频一区二区在线看| 亚洲国产欧美一区二区综合| 久热爱精品视频在线9| 日韩人妻精品一区2区三区| 777久久人妻少妇嫩草av网站| 美女大奶头黄色视频| 男人爽女人下面视频在线观看| 国产成人精品久久二区二区91| 老司机亚洲免费影院| 亚洲七黄色美女视频| 欧美性长视频在线观看| 高清黄色对白视频在线免费看| 欧美国产精品va在线观看不卡| 国产亚洲精品久久久久5区| 亚洲欧美清纯卡通| 亚洲七黄色美女视频| 男人爽女人下面视频在线观看| 精品福利永久在线观看| 秋霞在线观看毛片| 国产av又大| 女人被躁到高潮嗷嗷叫费观| 亚洲国产av影院在线观看| av天堂在线播放| 最新在线观看一区二区三区| 天天影视国产精品| 亚洲avbb在线观看| 亚洲精品一二三| 久久人人爽av亚洲精品天堂| 岛国毛片在线播放| 大片免费播放器 马上看| 成在线人永久免费视频| 中文字幕精品免费在线观看视频| 久久精品国产亚洲av高清一级| 国产老妇伦熟女老妇高清| 国产成人精品无人区| 9热在线视频观看99| 亚洲精品自拍成人| 999精品在线视频| 欧美日韩福利视频一区二区| 女人高潮潮喷娇喘18禁视频| 午夜激情久久久久久久| 91麻豆精品激情在线观看国产 | 久久国产精品大桥未久av| 女人爽到高潮嗷嗷叫在线视频| 免费观看av网站的网址| 丝袜脚勾引网站| 中亚洲国语对白在线视频| 国产亚洲av高清不卡| 超色免费av| 免费在线观看影片大全网站| 国产麻豆69| 97在线人人人人妻| 欧美另类亚洲清纯唯美| 黄片小视频在线播放| 久久99热这里只频精品6学生| 大香蕉久久网| 搡老熟女国产l中国老女人| 国产伦人伦偷精品视频| 午夜激情av网站| a在线观看视频网站| 婷婷成人精品国产| 日韩一卡2卡3卡4卡2021年| 欧美精品高潮呻吟av久久| 国产精品免费大片| 欧美黑人欧美精品刺激| 热re99久久国产66热| 中文字幕另类日韩欧美亚洲嫩草| 国产精品一区二区精品视频观看| 精品久久蜜臀av无| 久热这里只有精品99| 91大片在线观看| 亚洲av美国av| 亚洲国产欧美网| 久久中文字幕一级| 国产精品1区2区在线观看. | 性高湖久久久久久久久免费观看| 亚洲专区字幕在线| 亚洲精华国产精华精| 亚洲精品在线美女| 高清欧美精品videossex| 亚洲久久久国产精品| 真人做人爱边吃奶动态| 51午夜福利影视在线观看| 水蜜桃什么品种好| 制服诱惑二区| 国产在线一区二区三区精| 一本色道久久久久久精品综合| h视频一区二区三区| 91大片在线观看| 久久av网站| 国产免费视频播放在线视频| 亚洲精品中文字幕一二三四区 | 国产精品国产av在线观看| 黑人欧美特级aaaaaa片| 亚洲av电影在线进入| 不卡av一区二区三区| 伊人亚洲综合成人网| 激情视频va一区二区三区| bbb黄色大片| 国产精品麻豆人妻色哟哟久久| 黑人猛操日本美女一级片| 精品少妇黑人巨大在线播放| 国产亚洲精品一区二区www | 99国产精品一区二区蜜桃av | 黄色视频在线播放观看不卡| 亚洲天堂av无毛| 涩涩av久久男人的天堂| 久久久久精品国产欧美久久久 | 久久影院123| 国产亚洲欧美在线一区二区| 热99国产精品久久久久久7| 一级,二级,三级黄色视频| 飞空精品影院首页| 中文字幕色久视频| 91麻豆精品激情在线观看国产 | 纵有疾风起免费观看全集完整版| 另类精品久久| 成人国语在线视频| 丁香六月天网| 亚洲av男天堂| 新久久久久国产一级毛片| 亚洲一卡2卡3卡4卡5卡精品中文| 亚洲欧美激情在线| 亚洲国产欧美一区二区综合| 欧美国产精品va在线观看不卡| 中文字幕另类日韩欧美亚洲嫩草| 99九九在线精品视频| 国产亚洲欧美在线一区二区| 啦啦啦中文免费视频观看日本| 久久天堂一区二区三区四区| 国产精品免费大片| 国产一区有黄有色的免费视频| 夜夜夜夜夜久久久久| 乱人伦中国视频| 午夜老司机福利片| 午夜视频精品福利| 别揉我奶头~嗯~啊~动态视频 | 最近最新免费中文字幕在线| 欧美精品啪啪一区二区三区 | 成人影院久久| 国产主播在线观看一区二区| √禁漫天堂资源中文www| 99精品欧美一区二区三区四区| 午夜91福利影院| 亚洲国产欧美一区二区综合| 天天躁夜夜躁狠狠躁躁| 亚洲国产中文字幕在线视频| 岛国毛片在线播放| 曰老女人黄片| 汤姆久久久久久久影院中文字幕| 建设人人有责人人尽责人人享有的| 91av网站免费观看| 大香蕉久久成人网| 我要看黄色一级片免费的| 91av网站免费观看| 欧美精品啪啪一区二区三区 | 男女下面插进去视频免费观看| 亚洲欧美清纯卡通| 欧美xxⅹ黑人| 国产精品一区二区精品视频观看| 一级,二级,三级黄色视频| 亚洲欧美精品综合一区二区三区| 久久精品人人爽人人爽视色| 国产精品一区二区在线观看99| 91老司机精品| 丝袜喷水一区| 狠狠狠狠99中文字幕| 我要看黄色一级片免费的| 国产伦理片在线播放av一区| 亚洲av男天堂| 亚洲精品一区蜜桃| 色婷婷av一区二区三区视频| 国产亚洲精品第一综合不卡| 大码成人一级视频| 成年动漫av网址| 久久人人爽av亚洲精品天堂| 性高湖久久久久久久久免费观看| 午夜福利影视在线免费观看| 俄罗斯特黄特色一大片| 一区二区三区乱码不卡18| 男女之事视频高清在线观看| 一本久久精品| 69av精品久久久久久 | 亚洲精品国产av成人精品| 精品免费久久久久久久清纯 | 可以免费在线观看a视频的电影网站| 免费在线观看完整版高清| 亚洲专区字幕在线| 后天国语完整版免费观看| 国产精品麻豆人妻色哟哟久久| 我的亚洲天堂| 国产成人精品久久二区二区91| 久久久久久久大尺度免费视频| 精品欧美一区二区三区在线| 19禁男女啪啪无遮挡网站| 欧美日韩精品网址| 精品一区二区三区四区五区乱码| 欧美老熟妇乱子伦牲交| 老司机深夜福利视频在线观看 | 国产在线观看jvid| av国产精品久久久久影院| 啪啪无遮挡十八禁网站| 久久精品国产a三级三级三级| 中国国产av一级| 国产伦人伦偷精品视频| 成人av一区二区三区在线看 | 国产一区二区激情短视频 | 女警被强在线播放| 国产又色又爽无遮挡免| av电影中文网址| 国产av又大| 精品一品国产午夜福利视频| 精品少妇内射三级| 免费高清在线观看视频在线观看| 国产精品麻豆人妻色哟哟久久| 一区二区三区四区激情视频| 老鸭窝网址在线观看| 午夜免费成人在线视频| 91老司机精品| 啪啪无遮挡十八禁网站| 亚洲少妇的诱惑av| 精品国产乱子伦一区二区三区 | 纯流量卡能插随身wifi吗| 男女高潮啪啪啪动态图| 国产有黄有色有爽视频| 少妇粗大呻吟视频| www.熟女人妻精品国产| 肉色欧美久久久久久久蜜桃| 国产欧美日韩一区二区三区在线| 欧美精品av麻豆av| 51午夜福利影视在线观看| 天天躁夜夜躁狠狠躁躁| 成人18禁高潮啪啪吃奶动态图| 男女免费视频国产| 国产深夜福利视频在线观看| 亚洲情色 制服丝袜| 纵有疾风起免费观看全集完整版| 99国产极品粉嫩在线观看| 50天的宝宝边吃奶边哭怎么回事| 亚洲av欧美aⅴ国产| av线在线观看网站| 国产成人av激情在线播放| 国产成人精品无人区| av线在线观看网站| 我的亚洲天堂| 中亚洲国语对白在线视频| 波多野结衣av一区二区av| 啦啦啦视频在线资源免费观看| 欧美亚洲 丝袜 人妻 在线| 亚洲国产看品久久| 丰满少妇做爰视频| 国产成人系列免费观看| 一级毛片精品|