• <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 ?

    h-adaptive Discontinuous Galerkin Method for Laminar Compressible Navier-Stokes Equations on Curved Mesh

    2016-12-01 03:18:45SunQiangLyuHongqiangWuYizhao

    Sun Qiang,Lyu Hongqiang,Wu Yizhao

    College of Aerospace Engineering,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,P.R.China

    h-adaptive Discontinuous Galerkin Method for Laminar Compressible Navier-Stokes Equations on Curved Mesh

    Sun Qiang,Lyu Hongqiang*,Wu Yizhao

    College of Aerospace Engineering,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,P.R.China

    An h-adaptive method is developed for high-order discontinuous Galerkin methods(DGM)to solve the laminar compressible Navier-Stokes(N-S)equations on unstructured mesh.The vorticity is regarded as the indicator of adaptivity.The elements where the vorticity is larger than a pre-defined upper limit are refined,and those where the vorticity is smaller than a pre-defined lower limit are coarsened if they have been refined.A high-order geometric approximation of curved boundaries is adopted to ensure the accuracy.Numerical results indicate that highly accurate numerical results can be obtained with the adaptive method at relatively low expense.

    h-adaptivity;high-order discontinuous Galerkin methods(DGM);N-S equations;high-order boundary approximation

    0 Introduction

    Discontinuous Galerkin(DG)methods[1-13]have received increasing attention in computational fluid dynamics in recent years due to various attractive features.Bassi and Rebay[3-5]developed a high-order discontinuous finite element method to solve the Euler and Navier-Stokes equations. Cockburn and Shu[6,7]devised a high-order accurate total variation bounded(TVB)Runge-Kutta discontinuous Galerkin(RKDG)method to simulate the nonlinear systems of conservation laws. More recently,high-order DG methods have been applied to solve various engineering problems[8-18]on unstructured grid.In fact,DG methods are similar to finite element methods which can achieve higher-order accuracy via using high-order polynomial approximation inside elements.Moreover,upwind scheme can be easily implemented through using appropriate numerical fluxes over element interfaces.In addition,DG methods lead to compact space discretization formulae for both the Euler and the Navier-Stokes(N-S)equations. The compactness of the methods has advantages for parallel implementation.

    Despite these advantages,DG methods still need to be improved in many respects,such as the shock-capturing and the huge computational expense caused by the high-order polynomial approximation[8-15].Usually,high discontinuity only exits locally,e.g.the boundary layer in the flow field.It will cost high expense to capture them by enhancing the order of the polynomials or generating more dense mesh globally.Adaptive DG methods are helpful to solve such problems. Thanks to the simple communication at element interfaces,elements with″hanging nodes″can be treated as elements without hanging nodes,which simplifies local mesh h-refinement.In addition, the communication at element interfaces allows different orders between neighboring elements. Several adaptive DG methods[19-23]have been developed to improve the accuracy and reduce the computational expense.

    It has been proved that high-order DG methods are inaccurate at curved solid walls if a piece-wise linear approximation of the geometry of the boundary is employed[3],and a higher-order boundary representation is necessary to ensure the accuracy of the solution.In the paper,an h-adaptive strategy is developed for DG methods to simulate compressible laminar N-S equations on highly accurate boundary.Because of the high intensity of the vorticity in boundary layer and shedding vortex regions,vorticity is used as the sensor of the h-adaptivity.Eor the steady case,a Newton method[24]is employed to solve the nonlinear discrete systems and the Block-Gauss Seidel[10,11]method is used to solve the resulting sparse linear system at each nonlinear iteration.The time integration of the unsteady case presented below can be accomplished by means of an explicit method. The four-stage Runge-Kutta scheme is used in the paper.Since DG methods are relatively sensitive to the initial guess,a hierarchical solution procedure is suggested[10,12].

    *Corresponding author,E-mail address:hongqiang.lu@nuaa.edu.cn.

    How to cite this article:Sun Qiang,Lyu Hongqiang,Wu Yizhao.h-adaptive discontinuous Galerkin method for laminar compressible Navier-Stokes equations on curved mesh[J].Trans.Nanjing Univ.Aero.Astro.,2016,33(5):566-575.

    http://dx.doi.org/10.16356/j.1005-1120.2016.05.566

    1 Governing Equations

    The two-dimensional laminar N-S equations can be written as follows

    where the conservative variables u and the cartesian components fe(u)and ge(u)of the inviscid (Euler)flux function Fe(u)are given by

    whereρ,P and e denote the density,pressure and the total internal energy per unit mass respectively.u and v are the velocity components.The total

    The cartesian components fv(u,?u)and gv(u,?u)of the viscous flux function Fv(u,?u) are given by

    2 DG Discretization

    The weak formulation of Eq.(1)can be obtained by multiplying a″test function″v,integrating over the domainΩand performing integration by parts

    where F(u,?u)=Fe(u)-Fv(u,?u),?Ωis the boundary ofΩ.

    The integrals over the domainΩcan be expanded into the sum of integrals over a collection of non-overlapping triangle elements{E}.The semi-discrete equations for element E can be written as

    where?E is the boundary of E.In each element, the functions uhand vh,which are the approximations to u and v,are given by

    where the expansion coefficients Uiand Videnotethe degrees of freedom of the numerical solution and the test function in element E,φithe n (shape)basis functions of degree p.Since Eq.(6) must be satisfied for any element E and function vhand vhare a linear combination of n shape functionsφi,Eq.(6)is equivalent to the following system

    Note that,no global continuity is enforced on u andφi,discontinuities are allowed over element interfaces.Elux terms are not unique at element interfaces due to the discontinuous function approximation.The physical normal flux F(uh,?uh)·n in Eq.(8)is replaced by a numerical flux H u-h,?u-h,u+h,?u+h,

    ( )n,which is calculated using the internal u-h,external interface state u+hand the normal vector n pointing outward from E.The numerical flux for the inviscid part of the equations can be analogous to those employed in upwind finite volume methods.In the paper,the LLE scheme is used[10,24].

    In the context of the DG method an auxiliary variableθ=?u is introduced for the treatment of the viscous flux.Since DG methods obey to the hyperbolic systems of conservation laws,the following system of two first-order equations is obtained

    Similar to the treatment of Eq.(1),the weak formulation of the first equation can be obtained by applying the DG discretization

    θcan be written as the following formulation

    The numerical flux function Hhincludes the inviscid numerical fluxand the viscous numerical flux function Hv.In the paper,Hvis given by the average value of the viscous fluxes on the interface.

    3 Relaxation

    By assembling together all the elemental contributions,the semidiscrete equations can be written as

    where M is the mass matrix,U the global vector of the degrees of freedom,and() R U the residual vector.Due to the block diagonal structure of M, the time integration of the unsteady problem presented below can be accomplished by means of an explicit method.In the paper,the TVB Runge-Kutta schemes is used[6].

    Eor steady problems,the Newton method[23]is used to solve the nonlinear system in Eq.(15)

    where w is the under-relaxation factor andΔUnis obtained by solving the following linear system

    In order to improve the conditioning of the linear system(17),a pseudo-time derivative is introduced to original discrete system[25]

    4 Adaptive Strategy

    The entire computation procedure starts from solving p=0(p is the order of the basic functions)solution on a very coarse initial grid.As the order p increases,the mesh needs to be refined in the region where the solution is not smooth enough.After a number of iteration steps,the solution in the region mentioned may become smooth enough.Then,the elements which have been refined should be coarsened to reduce the computational expense when the solution becomes smooth enough.

    The vorticity v exists everywhere in the viscous flow.Moreover,due to the great velocity gradient in the shear layer and the vortices,it can be huge in these regions.In the paper,the vorticity v is used as the adaptivity sensor.

    4.1 Mesh refinement

    During the computational process,elements should be refined when v is larger than the pre-defined upper limit.The″father″e(cuò)lement which needs to be refined is divided into four″child″e(cuò)lements(See Fig.1).

    It has been proved that the high-order DG method is inaccurate at curved solid walls if only a piecewise linear approximation of the boundary is employed and a higher-order boundary representa-tion can improve the accuracy of the solution[3]. In the paper,the edges on the solid wall of the boundary elements are represented by a high-order polynomial.The designed high-order(Sixthorder)curve can represent the real solid wall precisely(See the dash lines in Fig.1).

    Fig.1 Element refinement

    If the boundary elements need to be refined, the mid-point of the boundary edge is found according to the designed curve and the new″child″e(cuò)lements are generated by connecting it with the mid-points of the other two edges as shown in Fig.1.Two of the new″child″e(cuò)lements are on the solid wall and their boundary edge will also be represented by the high-order polynomial(See the dash lines in Fig.1).

    In order to avoid significant gradient in mesh size between neighboring elements,a smoothing strategy is employed.If element e in Fig.2 needs to be refined,the neighboring element f must also be refined to avoid extreme difference in local mesh size.In another word,the maximum difference between refinement times of neighboring elements is 1.At the same time,a minimum mesh size hminis pre-defined and the refinement will stop when the element′s genomic size reaches hminto avoid the unlimited refinement of the element.

    Fig.2 Smoothing strategy

    4.2 Mesh coarsening

    During the computation,solution in the elements which have been refined may become smooth enough.In order to reduce the expense, these elements can be coarsened.In this case,the four″child″e(cuò)lements will merge into one″father″e(cuò)lement where the vorticity v is smaller than the pre-defined lower limit.

    In Fig.3,the solid lines indicate the elements which are not on the solid wall.If the″father″e(cuò)lement is on the solid wall,its boundary edge will also be represented by a high-order polynomial to approach the real wall(See the dash lines in Fig. 3).Like in the refinement,in order to avoid extreme difference in local mesh size,″child″e(cuò)lements fi(i=0,1,2,3)cannot be merged(See Fig.2)if e is coarsened.In another word,mesh coarsening is the inverse operation of the mesh refinement and the max difference between refinement times of neighboring elements is 1.In addition,the initial element cannot be coarsened.

    Fig.3 Element coarsening

    4.3 Data storage structure of grid

    To ensure the high program transportability, the mesh adaptivity works as an independent module.It only changes the mesh and flow field solver module is not impacted.In the paper,all the information of the points,edges and elements is stored in a list structure.Fig.4 demonstrates the refinement of element E.

    Fig.4 Element increasing

    In Fig.4,E denotes the″father″e(cuò)lement which needs to be refined.The center″child″e(cuò)lement remains the same index as E,and the other three around the center″child″e(cuò)lement(See Fig.2)range at the end of the list.The same method is applied to the points and edges.Data transmission between grid module and flow field solver module will work well without any influence from mesh adaptivity.

    Similarly,Fig.5 shows that four″child″e(cuò)le-ments merge into a″father″e(cuò)lement.

    Fig.5 Element decreasing

    The three″child″e(cuò)lements fiwill be merged to the center″child″e(cuò)lement E,and accordingly the index of the elements after f3should be subtracted 3.

    Two flags are attached to each element to indicate the initial index and refinement times during the mesh refinement.The mesh coarsening will work according to these two flags and the relationship between neighboring elements.

    5 Numerical Results

    5.1 Transonic flow around NACA0012 airfoil

    Eirstly,the subsonic viscous flow around the NACA0012 airfoil(Ma=0.5,α=0°,Re=5 000) is simulated.The initial mesh contains 478 elements,260 grid points,and there are 32 grid points on the solid boundary(See Fig.6).

    Fig.7 demonstrates the Mach contours and the vorticity distribution obtained when p=4 on the initial grid.It is obvious that the solution is not smooth enough because of the coarse grid in the boundary layer,which suggests smaller mesh size in this region to improve the accuracy of the solution.

    In order to improve the accuracy of the solution and reduce the computational expense,the local adaptive method introduced above is applied. Fig.8(a)shows the final mesh and the vorticity v distribution,where only the local mesh near the boundary and in wake region is refined.Fig.8(b) shows the final local mesh after adaption compared with the initial mesh.

    Fig.9 depicts the Mach contours obtained with the adaptive method,where the solution is much smoother than that obtained on the initial mesh in Fig.7.In addition,Fig.9(b)shows the streamlines and the two symmetrical vortices[3]in the wake region are captured well.

    Fig.6 Initial grid

    Fig.8 Vorticity distribution and local grid after adaption

    Fig.7 Mach contours and vorticity v distribution when p=4

    Fig.9 Mach contours and streamlines after adaption

    Fig.10 Cpand Cfdistribution

    5.2 Von Karman vortex street

    The well-known Von Karman vortex street is simulated,where Ma=0.1,α=0,Re=150.The initial mesh is shown in Fig.11,which contains 1 114 elements and there are only 12 points on the solid boundary(See Fig.11).

    Fig.12 demonstrates the Von Karman vortex street obtained when p=4 on the initial grid.The solution is not smooth and the resolution of the vortices is low because the initial mesh is not fine enough.Unfortunately,shedding vortices are not captured precisely on the initial coarse mesh even if the high-order scheme is applied.On the other hand,the intensity of the vortices is low due to the big numerical dissipation which is mainly caused by the large mesh size.It is suggested that the mesh in these regions should be refined.

    Adaptive method introduced above is used in this case and the final local grid and Von Karman vortex street are shown in Fig.13.Due to the smaller mesh size in the boundary layer region andwake region after adaption,the solution is much smoother compared with that in Fig.12 and the intensity of the vortices is enhanced because of the low dissipation.

    Fig.11 Initial grid

    Fig.12 Von Karman vortex street on initial mesh

    Fig.13 Von Karman vortex street with adaptive method

    Fig.14 Von Karman vortex street with mesh adaptivity

    In the paper,refinement and coarsening always work simultaneously.The elements where the vorticity is greater than the pre-defined upper limit are refined,and those where the vorticity is smaller than the pre-defined lower limit are coarsened to reduce the computation and storage expense if they have been refined.Fig.14 shows the Von Karman vortex street with the adaptive method introduced above on several time of one period.

    The Von Karman vortex street is a quasisteady case because of its periodicity.The number of elements in the entire domain should vary in a small scale for which it is a good case to test the behavior of the introduced method.Fig.15 shows the history of the number of the elements over the entire domain,where the element number varies around 2 500.

    The evolution of the drag and lift coefficient in time is shown in Fig.16 while the period of vortex shedding(Strouhal number)is found to be St=0.185.In Table 1,the variations of lift coefficient Cland drag coefficient Cdare documented with amplitudes and mean values and the results of sixth-order finite difference scheme are also included as a reference[26]for comparison.It is clearly that the accuracy of lift and drag coefficient is drastically improved by using the adaptive method.

    Fig.15 Number of element during iteration

    Fig.16 Variation of lift and drag coefficient

    Tab.1 Comparison between lift and drag coefficient

    6 Conclusions

    An h-adaptive DG method is developed to solve the two-dimensional compressible laminar N-S equations.The vorticity v works well as the sensor of the mesh adaptivity in the subsonic viscous flow cases.In order to ensure the accuracy of the solution,a high-order approximation boundary is designed to approach the real solid wall during the h-adaptivity.Numerical results show that grid refinement and coarsening only work in the local region and the accuracy of the solution is improved at low expense.

    Acknowledgement

    This work was supported by the National Natural Science Eoundation of China(11272152).

    [1] REED W H,HILL T R.Triangular mesh methods for the neutron transport equation:Los Alamos Report LA-UR-73-479[R].1973.

    [2] LESAINT P,RAVIART P A.On a finite element method for solving the neutron transport equation[J]. Mathematical Aspects of Einite Elements in Partial Differential Equations,1974(33):89-123.

    [3] BASSI E,REBAY S.A high-order accurate discontinuous finite element method for the numerical solution of the compressible Navier-Stokes equations[J]. Journal of Computational Physics,1997,131(2): 267-279.

    [4] BASSI E,REBAY S.High-order accurate discontinuous finite element solution of the 2D Euler equations [J].Journal of Computational Physics,1997,138 (2):251-285.

    [5] BASSI E,REBAY S.A high order discontinuous Galerkin method for compressible turbulent flows [M].[S.l.]:Springer Berlin Heidelberg,2000:77-88.

    [6] COCKBURN B,SHU C W.The Runge-Kutta discontinuous Galerkin method for conservation laws V: multidimensional systems[J].Journal of Computational Physics,1998,141(2):199-224.

    [7] COCKBURN B,SHU C W.The local discontinuous Galerkin method for time-dependent convection-diffusion systems[J].SIAM Journal on Numerical Analysis,1998,35(6):2440-2463.

    [8] LU H,BERZINS M,GOODYER C E,et al.Adaptive high-order discontinuous Galerkin solution of elastohydrodynamic lubrication point contact problems[J].Advances in Engineering Software,2012, 45(1):313-324.

    [9] LU H,XU Y,GAO Y,et al.A CED-based high-order discontinuous Galerkin solver for three dimensional electromagnetic scattering problems[J].Advances in Engineering Software,2015,83:1-10.

    [10]LU H,SUN Q.A straight forward hp-adaptivity strategy for shock-capturing with high-order discontinuous Galerkin methods[J].Advances in Applied Mathematics and Mechanics,2014,6(1):135-144.

    [11]LU H,SUN Q,QIN W L.3D numerical solution of aero-noise with high-order discontinuous Galerkin method[J].Transactions of Nanjing University of Aeronautics&Astronautics,2013,30(3):227-231.

    [12]LV Hongqiang,ZHU Guoxiang,SONG Jiangyong, et al.High-order discontinuous Galerkin solution of linearized Euler equations[J].Chinese Journal of Theoretical and Applied Mechanics,2011,43(3): 621-624.(in Chinese)

    [13]LV H Q.High-order discontinuous Galerkin solution of low-Re viscous flows[J].Modern Physics Letters B,2009,23(3):309-312.

    [14]LV H Q,XU Y,GAO Y,et al.A high-order discontinuous Galerkin method for the two-dimensional time-domain Maxwell′s equations on curved mesh [J].Advances in Applied Mathematics&Mechanics,2016,8(1):104-116.

    [15]LV H Q,CAO K,WU L B Y,et al.High-order mesh generation for discontinuous Galerkin methodsbased on elastic deformation[J].Advances in Applied Mathematics&Mechanics,2016,8(4):693-702.

    [16]Zhang Laiping,Liu Wei,He Lixin,et al.A class of discontinuous Galerkin/finite volume hybrid schemes based on the″static re-construction″and″dynamic reconstruction″[J].Chinese Journal of Theoretical and Applied Mechanics,2010,42(6):1013-1022.(in Chinese)

    [17]YU J,YAN C.An artificial diffusivity discontinuous Galerkin scheme for discontinuous flows[J].Computers&Eluids,2013,75:56-71.

    [18]YU Jian,YAN Chao.Study on discontinuous Galerkin method for Navier-Stokes equations[J].Chinese Journal of Theoretical and Applied Mechanics,2010, 42(5):962-969.(in Chinese)

    [19]YANG X,JAMES A J,LOWENGRUB J,et al.An adaptive coupled level-set/volume-of-fluid interface capturing method for unstructured triangular grids [J].Journal of Computational Physics,2006,217 (2):364-394.

    [20]REMACLE J E,LI X,SHEPHARD M S,et al.Anisotropic adaptive simulation of transient flows using discontinuous Galerkin methods[J].International Journal for Numerical Methods in Engineering,2005, 62(7):899-923.

    [21]XU Yun,YU Xijun.Adaptive discontinuous Galerkin methods for hyperbolic conservation laws[J].Chinese Journal of Computational Physics,2009,26(2):159-168.(in Chinese)

    [22]WU Di,YU Xijun.Adaptive discontinuous Galerkin method for Euler equations[J].Chinese Journal of Computational Physics,2010,27(4):492-500.(in Chinese)

    [23]HARTMANN R,HOUSTON P.Adaptive discontinuous Galerkin finite element methods for the compressible Euler equations[J].Journal of Computational Physics,2002,183:508-532.

    [24]XIA Yidong,WU Yizhao,LV Hongqiang,et al. Parallel computation of a high-order discontinuous Galerkin method on unstructured grids[J].Acta Aerodynamica Sinica,2011,29(5):537-541.(in Chinese)

    [25]HILLEWAERT K,CHEVAUGEON N,GEUZAINE P,et al.Hierarchic multigrid iteration strategy for the discontinuous Galerkin solution of the steady Euler equations[J].International Journal for Numerical Methods in Eluids,2006,51(9/10):1157-1176.

    [26]INOUE O,HATAKEYAMA N.Sound generation by a two-dimensional circular cylinder in a uniform flow[J].Journal of Eluid Mechanics,2002,471: 285-314.

    Mr.Sun Qiang received B.S.degree from College of Aerospace Engineering,Nanjing University of Aeronautics and Astronautics in 2011.In September 2011,he became a post-graduate student at the Aerodynamics Department. His research is focused on the discontinuous Galerkin method and mesh adaptivity.

    Prof.Lv Hongqiang received B.S.degree from Aerodynamics Department of Nanjing University of Aeronautics and Astronautics in 1999 and M.S.degree in 2002 from the same university.He received Ph.D.and Doctor degrees from University of Leeds in 2006.In the same year,he joined in College of Aerospace Engineering of Nanjing University of Aeronautics and Astronautics.His current research interest includes the application of the discontinuous Galerkin methods and numerical simulation of the Maxwell equations.

    Prof.Wu Yizhao received B.S.degree from University of Science and Technology of China in 1968,and received M. S.degree in 1981 and Ph.D.degree in 1987 from Nanjing Aviation Institute.He is currently a professor and doctoral supervisor at College of Aerospace Engineering of Nanjing University of Aeronautics and Astronautics,and his research interests are computational fluid dynamics and multigrid.

    (Executive Editor:Xu Chengting)

    V211.3 Document code:A Article ID:1005-1120(2016)05-0566-10

    (Received 14 April 2015;revised 18 August 2015;acceped 5 September 2015)

    在线国产一区二区在线| 色吧在线观看| 桃红色精品国产亚洲av| 曰老女人黄片| 亚洲欧美日韩高清在线视频| 国产精品久久电影中文字幕| 成人av在线播放网站| 男女午夜视频在线观看| 99久久综合精品五月天人人| 操出白浆在线播放| 欧美午夜高清在线| 亚洲成人久久性| 日韩国内少妇激情av| 在线免费观看不下载黄p国产 | 久久久久久人人人人人| 国产熟女xx| 国产av一区在线观看免费| 国产精品精品国产色婷婷| 身体一侧抽搐| 看黄色毛片网站| 欧美在线一区亚洲| 日韩欧美免费精品| 国产高清视频在线观看网站| 国产亚洲av高清不卡| 久久久水蜜桃国产精品网| 757午夜福利合集在线观看| 国产 一区 欧美 日韩| 国产欧美日韩一区二区精品| 亚洲av日韩精品久久久久久密| 搡老岳熟女国产| 成人18禁在线播放| 女警被强在线播放| 欧美在线一区亚洲| 日韩三级视频一区二区三区| 两个人的视频大全免费| 亚洲国产日韩欧美精品在线观看 | 三级毛片av免费| 成人性生交大片免费视频hd| 操出白浆在线播放| 女警被强在线播放| 好男人在线观看高清免费视频| 亚洲av成人av| 巨乳人妻的诱惑在线观看| 99国产极品粉嫩在线观看| 一个人看的www免费观看视频| 人妻丰满熟妇av一区二区三区| 丰满人妻熟妇乱又伦精品不卡| 18禁黄网站禁片午夜丰满| 嫩草影院精品99| 1024香蕉在线观看| 午夜影院日韩av| 午夜视频精品福利| 999精品在线视频| 亚洲va日本ⅴa欧美va伊人久久| 亚洲av成人精品一区久久| 黑人欧美特级aaaaaa片| 男女那种视频在线观看| 国产久久久一区二区三区| 欧洲精品卡2卡3卡4卡5卡区| 亚洲第一欧美日韩一区二区三区| 精品久久蜜臀av无| 欧美国产日韩亚洲一区| 一卡2卡三卡四卡精品乱码亚洲| 欧美3d第一页| 欧美中文日本在线观看视频| 很黄的视频免费| 精品无人区乱码1区二区| 久99久视频精品免费| 真人一进一出gif抽搐免费| 日韩高清综合在线| 成人无遮挡网站| 俺也久久电影网| 又大又爽又粗| 亚洲九九香蕉| 亚洲熟妇中文字幕五十中出| 欧美黄色片欧美黄色片| 一进一出好大好爽视频| 国产精品一及| 中文字幕人妻丝袜一区二区| 曰老女人黄片| 欧美日韩亚洲国产一区二区在线观看| 色尼玛亚洲综合影院| 午夜久久久久精精品| 欧美一级毛片孕妇| 成人三级做爰电影| 国产精品久久电影中文字幕| 99久久综合精品五月天人人| 亚洲国产精品久久男人天堂| 精品久久久久久久久久久久久| 亚洲精品乱码久久久v下载方式 | 亚洲欧美激情综合另类| 日本撒尿小便嘘嘘汇集6| 少妇的丰满在线观看| 久久精品国产99精品国产亚洲性色| 精品日产1卡2卡| 99久久综合精品五月天人人| 精品午夜福利视频在线观看一区| 精品日产1卡2卡| 国产精品 欧美亚洲| 两个人看的免费小视频| 国产在线精品亚洲第一网站| 看免费av毛片| 在线国产一区二区在线| 一个人看视频在线观看www免费 | 成人永久免费在线观看视频| 久久精品亚洲精品国产色婷小说| 亚洲自偷自拍图片 自拍| 特级一级黄色大片| 国产黄片美女视频| 国产亚洲av高清不卡| 精品电影一区二区在线| 最好的美女福利视频网| www日本黄色视频网| 久久这里只有精品中国| 国产精品一区二区三区四区久久| 国产精品日韩av在线免费观看| 国内毛片毛片毛片毛片毛片| 国产精品久久视频播放| 精品欧美国产一区二区三| 在线看三级毛片| 狂野欧美激情性xxxx| 在线播放国产精品三级| 午夜精品一区二区三区免费看| 99久久99久久久精品蜜桃| 亚洲av成人一区二区三| 国语自产精品视频在线第100页| 亚洲中文字幕一区二区三区有码在线看 | 91字幕亚洲| 1000部很黄的大片| 欧美av亚洲av综合av国产av| 国内揄拍国产精品人妻在线| 一区福利在线观看| 1024香蕉在线观看| 国产精品九九99| 叶爱在线成人免费视频播放| 最近视频中文字幕2019在线8| 99国产精品一区二区蜜桃av| 在线免费观看不下载黄p国产 | 成人亚洲精品av一区二区| 中文字幕最新亚洲高清| 人妻丰满熟妇av一区二区三区| 91在线观看av| 国产精品国产高清国产av| 又紧又爽又黄一区二区| 国产爱豆传媒在线观看| 国产精品亚洲一级av第二区| 成人av一区二区三区在线看| 精品电影一区二区在线| 男女午夜视频在线观看| 九九久久精品国产亚洲av麻豆 | 两个人视频免费观看高清| 国产成人影院久久av| 午夜福利视频1000在线观看| 狂野欧美白嫩少妇大欣赏| 欧美3d第一页| 中文在线观看免费www的网站| 黑人欧美特级aaaaaa片| 国产熟女xx| 麻豆成人av在线观看| 亚洲电影在线观看av| 亚洲精品在线美女| 精品电影一区二区在线| 国产精品香港三级国产av潘金莲| 精品国产三级普通话版| АⅤ资源中文在线天堂| 黄频高清免费视频| 在线观看午夜福利视频| 男插女下体视频免费在线播放| 久久久国产成人免费| 日本撒尿小便嘘嘘汇集6| 久久久国产成人精品二区| 成人18禁在线播放| 成人精品一区二区免费| 搞女人的毛片| 国内精品一区二区在线观看| www日本黄色视频网| 日韩成人在线观看一区二区三区| 久久这里只有精品中国| 麻豆国产97在线/欧美| 舔av片在线| 一边摸一边抽搐一进一小说| 热99re8久久精品国产| 久久久国产成人精品二区| 亚洲国产精品久久男人天堂| 久久热在线av| 搡老熟女国产l中国老女人| 欧美激情久久久久久爽电影| 欧美日韩黄片免| 国产男靠女视频免费网站| 97人妻精品一区二区三区麻豆| 岛国视频午夜一区免费看| 久久久精品欧美日韩精品| cao死你这个sao货| 国产成人aa在线观看| 校园春色视频在线观看| 怎么达到女性高潮| 国产乱人伦免费视频| 欧美一区二区精品小视频在线| 精品久久久久久,| 国产欧美日韩一区二区三| av在线天堂中文字幕| 在线观看午夜福利视频| 日本黄色片子视频| xxx96com| 亚洲午夜精品一区,二区,三区| 成人av一区二区三区在线看| 一进一出好大好爽视频| 免费看美女性在线毛片视频| 久久九九热精品免费| 国产视频内射| 国产精品一区二区免费欧美| 好看av亚洲va欧美ⅴa在| 精品一区二区三区视频在线观看免费| 无遮挡黄片免费观看| 宅男免费午夜| 性色av乱码一区二区三区2| 在线观看午夜福利视频| www国产在线视频色| 脱女人内裤的视频| 日本熟妇午夜| 久久久久久九九精品二区国产| 黄色女人牲交| 一个人免费在线观看电影 | 色吧在线观看| 欧美一区二区国产精品久久精品| 久久久久国内视频| 国产日本99.免费观看| av黄色大香蕉| 99国产精品一区二区三区| 亚洲一区二区三区色噜噜| 在线观看一区二区三区| 亚洲中文av在线| 在线观看午夜福利视频| 国产日本99.免费观看| 久久久久久久久免费视频了| 一本综合久久免费| 成人特级黄色片久久久久久久| 亚洲成人精品中文字幕电影| 天堂√8在线中文| av在线天堂中文字幕| 两性夫妻黄色片| 色综合欧美亚洲国产小说| 看免费av毛片| 国产精品1区2区在线观看.| 亚洲成人精品中文字幕电影| 琪琪午夜伦伦电影理论片6080| 99久久无色码亚洲精品果冻| 99久国产av精品| 真人做人爱边吃奶动态| 精品国产超薄肉色丝袜足j| 国产精品av视频在线免费观看| 国产黄色小视频在线观看| 操出白浆在线播放| 怎么达到女性高潮| 亚洲成人免费电影在线观看| 五月伊人婷婷丁香| 欧美性猛交黑人性爽| 国产成人影院久久av| 特大巨黑吊av在线直播| 亚洲无线观看免费| 国产高清视频在线播放一区| 在线免费观看的www视频| 一个人观看的视频www高清免费观看 | 日本免费a在线| 可以在线观看的亚洲视频| 亚洲人成伊人成综合网2020| 精品午夜福利视频在线观看一区| 国产激情偷乱视频一区二区| 免费在线观看影片大全网站| 久久中文看片网| 免费搜索国产男女视频| 一卡2卡三卡四卡精品乱码亚洲| 日本熟妇午夜| 亚洲成人中文字幕在线播放| 国产精品自产拍在线观看55亚洲| 久久久色成人| 九色国产91popny在线| www日本在线高清视频| 日本五十路高清| 舔av片在线| 桃色一区二区三区在线观看| 一级毛片精品| 久久久久久九九精品二区国产| 老汉色av国产亚洲站长工具| 免费观看的影片在线观看| 国产人伦9x9x在线观看| 久久久久国产精品人妻aⅴ院| 日本五十路高清| 嫩草影院精品99| 亚洲va日本ⅴa欧美va伊人久久| 国产av在哪里看| 免费大片18禁| 久久精品国产99精品国产亚洲性色| 好看av亚洲va欧美ⅴa在| 亚洲av成人不卡在线观看播放网| 淫秽高清视频在线观看| 国产精品美女特级片免费视频播放器 | 99热精品在线国产| 国产极品精品免费视频能看的| 在线永久观看黄色视频| 麻豆av在线久日| 欧洲精品卡2卡3卡4卡5卡区| www日本在线高清视频| 日韩欧美精品v在线| 一夜夜www| 亚洲精品456在线播放app | 国产精品99久久久久久久久| 人人妻人人澡欧美一区二区| 香蕉丝袜av| 色视频www国产| 亚洲av成人一区二区三| 97碰自拍视频| 久久久久久大精品| 国产日本99.免费观看| 中文资源天堂在线| 国产精品久久久久久亚洲av鲁大| 国产黄a三级三级三级人| 国产淫片久久久久久久久 | 国产爱豆传媒在线观看| 99在线人妻在线中文字幕| 久久性视频一级片| 观看免费一级毛片| 动漫黄色视频在线观看| 一二三四社区在线视频社区8| 欧美色视频一区免费| 成人一区二区视频在线观看| 精品不卡国产一区二区三区| 欧美黄色片欧美黄色片| 日本一二三区视频观看| 国产成人av激情在线播放| 亚洲成人免费电影在线观看| 欧美黄色片欧美黄色片| 亚洲狠狠婷婷综合久久图片| 在线看三级毛片| 亚洲一区二区三区不卡视频| 在线视频色国产色| 91久久精品国产一区二区成人 | 亚洲av第一区精品v没综合| 女人被狂操c到高潮| 中文资源天堂在线| 少妇人妻一区二区三区视频| а√天堂www在线а√下载| 色av中文字幕| 成人永久免费在线观看视频| 精品久久久久久,| 亚洲aⅴ乱码一区二区在线播放| 精品午夜福利视频在线观看一区| 国产精品1区2区在线观看.| 床上黄色一级片| 美女扒开内裤让男人捅视频| 亚洲精品一区av在线观看| 久久午夜亚洲精品久久| 欧美乱色亚洲激情| 日韩三级视频一区二区三区| 亚洲av电影不卡..在线观看| 午夜福利在线观看免费完整高清在 | 欧美日本亚洲视频在线播放| 一个人免费在线观看电影 | 色哟哟哟哟哟哟| 亚洲熟妇熟女久久| 可以在线观看的亚洲视频| 一区二区三区国产精品乱码| av天堂在线播放| 日日干狠狠操夜夜爽| 精品久久久久久成人av| 一级黄色大片毛片| 久久亚洲精品不卡| 日韩高清综合在线| 欧美最黄视频在线播放免费| 亚洲专区中文字幕在线| 精品久久久久久久毛片微露脸| 99久国产av精品| 一区二区三区激情视频| 久久久水蜜桃国产精品网| 免费在线观看亚洲国产| 亚洲最大成人中文| 色噜噜av男人的天堂激情| 俺也久久电影网| 成人一区二区视频在线观看| 大型黄色视频在线免费观看| 成在线人永久免费视频| 亚洲av电影不卡..在线观看| 亚洲 欧美 日韩 在线 免费| 国产精品日韩av在线免费观看| 无人区码免费观看不卡| 搞女人的毛片| 九九久久精品国产亚洲av麻豆 | 成人三级做爰电影| 小说图片视频综合网站| 男女床上黄色一级片免费看| 三级毛片av免费| 少妇熟女aⅴ在线视频| 免费av毛片视频| 欧美日韩一级在线毛片| 黑人操中国人逼视频| 国产一区在线观看成人免费| 99riav亚洲国产免费| 99热精品在线国产| 无遮挡黄片免费观看| 99riav亚洲国产免费| 真人做人爱边吃奶动态| 欧美在线黄色| 香蕉国产在线看| 亚洲无线观看免费| 1024香蕉在线观看| 成年免费大片在线观看| 亚洲欧美精品综合一区二区三区| 哪里可以看免费的av片| 亚洲第一欧美日韩一区二区三区| 夜夜看夜夜爽夜夜摸| 一个人免费在线观看的高清视频| 午夜福利成人在线免费观看| 亚洲电影在线观看av| a级毛片a级免费在线| 狂野欧美激情性xxxx| 亚洲人成网站在线播放欧美日韩| 国产麻豆成人av免费视频| 免费在线观看成人毛片| 欧美精品啪啪一区二区三区| 国产精品久久久人人做人人爽| 一级作爱视频免费观看| 亚洲一区二区三区不卡视频| 久久婷婷人人爽人人干人人爱| 美女 人体艺术 gogo| 欧美日韩精品网址| 国产精品一及| 美女 人体艺术 gogo| 日韩精品中文字幕看吧| 色综合亚洲欧美另类图片| 午夜福利视频1000在线观看| 中文资源天堂在线| 国产成年人精品一区二区| 国产成人欧美在线观看| 国产精品久久久久久久电影 | 国产精品久久久av美女十八| 久久九九热精品免费| 久久精品亚洲精品国产色婷小说| 1024香蕉在线观看| e午夜精品久久久久久久| 日本撒尿小便嘘嘘汇集6| 色综合婷婷激情| 国产精品久久久久久精品电影| 美女 人体艺术 gogo| 精品不卡国产一区二区三区| 久久中文字幕一级| 蜜桃久久精品国产亚洲av| 此物有八面人人有两片| 免费看十八禁软件| 香蕉久久夜色| 日韩欧美三级三区| 又爽又黄无遮挡网站| 午夜视频精品福利| 欧美黑人巨大hd| 欧美日本视频| 97超视频在线观看视频| 婷婷丁香在线五月| 国产三级中文精品| 欧美成人一区二区免费高清观看 | 亚洲av免费在线观看| 性欧美人与动物交配| 91字幕亚洲| 桃红色精品国产亚洲av| 99国产精品一区二区三区| 国产午夜精品久久久久久| 日本三级黄在线观看| 欧美又色又爽又黄视频| 最近最新免费中文字幕在线| 真人做人爱边吃奶动态| 日本 av在线| 国内精品久久久久久久电影| 九九在线视频观看精品| 国产精品自产拍在线观看55亚洲| 欧美大码av| 国内揄拍国产精品人妻在线| x7x7x7水蜜桃| 老汉色∧v一级毛片| 亚洲精品久久国产高清桃花| 国产午夜精品论理片| 亚洲国产欧洲综合997久久,| 精品久久蜜臀av无| 国产99白浆流出| 日本免费a在线| 免费在线观看日本一区| 久久精品夜夜夜夜夜久久蜜豆| 很黄的视频免费| 欧美三级亚洲精品| 亚洲七黄色美女视频| 国产伦精品一区二区三区四那| 欧美午夜高清在线| 99久国产av精品| 国产精品久久久久久亚洲av鲁大| 丝袜人妻中文字幕| 久久精品亚洲精品国产色婷小说| 日韩欧美三级三区| 国产成人一区二区三区免费视频网站| 日本成人三级电影网站| 观看美女的网站| 欧美一级a爱片免费观看看| 99re在线观看精品视频| 精品一区二区三区视频在线 | 亚洲最大成人中文| 19禁男女啪啪无遮挡网站| 亚洲天堂国产精品一区在线| 男人舔女人下体高潮全视频| 99久久精品国产亚洲精品| 1000部很黄的大片| 高清毛片免费观看视频网站| www日本在线高清视频| 欧美性猛交黑人性爽| 黄色丝袜av网址大全| 久久人人精品亚洲av| 可以在线观看的亚洲视频| 午夜福利在线观看免费完整高清在 | 美女高潮喷水抽搐中文字幕| 在线播放国产精品三级| 欧美在线黄色| 在线看三级毛片| 精品电影一区二区在线| 免费观看的影片在线观看| 国产精品99久久99久久久不卡| 亚洲欧美一区二区三区黑人| 国产亚洲精品综合一区在线观看| 中文字幕人妻丝袜一区二区| 亚洲第一电影网av| 一区福利在线观看| 欧美一级毛片孕妇| 久久久国产欧美日韩av| 很黄的视频免费| 久久久久久九九精品二区国产| 好男人在线观看高清免费视频| 国产亚洲精品久久久久久毛片| 免费搜索国产男女视频| 国产精品乱码一区二三区的特点| 在线观看美女被高潮喷水网站 | 黑人操中国人逼视频| www.999成人在线观看| 国产人伦9x9x在线观看| 久久精品aⅴ一区二区三区四区| 成年免费大片在线观看| 激情在线观看视频在线高清| 亚洲精品国产精品久久久不卡| 亚洲国产中文字幕在线视频| 国产一级毛片七仙女欲春2| 51午夜福利影视在线观看| 91在线观看av| 久久久久久国产a免费观看| 91老司机精品| 久久婷婷人人爽人人干人人爱| 亚洲欧美精品综合久久99| 久久国产乱子伦精品免费另类| aaaaa片日本免费| 波多野结衣高清无吗| 午夜精品久久久久久毛片777| 精品一区二区三区视频在线观看免费| 毛片女人毛片| 麻豆成人av在线观看| www.www免费av| 午夜两性在线视频| 嫩草影院入口| 老司机在亚洲福利影院| 久久久久久久精品吃奶| 手机成人av网站| 99国产精品一区二区蜜桃av| 国产精品乱码一区二三区的特点| 偷拍熟女少妇极品色| 香蕉久久夜色| 在线观看美女被高潮喷水网站 | 久久人人精品亚洲av| 国产69精品久久久久777片 | 亚洲色图 男人天堂 中文字幕| 亚洲成人免费电影在线观看| 18禁裸乳无遮挡免费网站照片| 中文亚洲av片在线观看爽| 色播亚洲综合网| 国产精品1区2区在线观看.| 男女视频在线观看网站免费| 精品福利观看| 啪啪无遮挡十八禁网站| av天堂中文字幕网| 俺也久久电影网| 成人特级黄色片久久久久久久| 一本久久中文字幕| 亚洲一区二区三区色噜噜| 国产淫片久久久久久久久 | 变态另类丝袜制服| 丁香六月欧美| 久久久久久大精品| 欧美日本视频| 搡老妇女老女人老熟妇| 国产毛片a区久久久久| 亚洲av熟女| 亚洲色图av天堂| 天天躁日日操中文字幕| 一级黄色大片毛片| 欧美xxxx黑人xx丫x性爽| 国产亚洲av高清不卡| 毛片女人毛片| 国内少妇人妻偷人精品xxx网站 | 99视频精品全部免费 在线 | 三级男女做爰猛烈吃奶摸视频| 欧美xxxx黑人xx丫x性爽| 日本黄色视频三级网站网址| 男插女下体视频免费在线播放| 色哟哟哟哟哟哟| 欧美日韩一级在线毛片| 99国产极品粉嫩在线观看| 久久草成人影院| 男人舔女人下体高潮全视频| 久久久久精品国产欧美久久久| 又粗又爽又猛毛片免费看| 免费在线观看成人毛片| 成人三级黄色视频| 色av中文字幕| 欧美午夜高清在线| 亚洲在线自拍视频|