针对自由表面流动与弹性结构的流固耦合计算效率低、计算耗时长的问题,将流体体积法与基于结构-虚拟弹性体的快速动网格方法相结合,发展了一种适用于自由表面流动的高效流固耦合方法。使用流体体积(volume of fluid,VOF)法对流体自由表...针对自由表面流动与弹性结构的流固耦合计算效率低、计算耗时长的问题,将流体体积法与基于结构-虚拟弹性体的快速动网格方法相结合,发展了一种适用于自由表面流动的高效流固耦合方法。使用流体体积(volume of fluid,VOF)法对流体自由表面进行追踪;将流体域视为虚拟弹性体并构建结构-虚拟弹性体系统,以流固耦合界面的多相流体力为激励求解系统的动力学方程得到结构振动位移和流场网格变形;在每一个时间步内依次求解流体流动、结构变形和流场动网格,实现流固耦合计算。基于发展的方法计算了溃坝水流冲击下弹性挡板的流固耦合响应,得到了溃坝水流的自由液面和弹性挡板的运动行为,结果表明:自由液面演变和弹性挡板振动位移的计算结果与已有算法的结果吻合良好;在同等网格规模下,与已有算法相比本文方法可减少33.3%的计算时间;在水流冲击作用下,弹性挡板向冲击侧小幅弯曲。随后水流沿挡板左侧上升并形成射流,挡板向另一侧大幅弯曲。最后由于两侧流体的阻尼,挡板振幅逐渐衰减。展开更多
The effects of a harmonically exciting monopole source on an infinitely long cylindrical cavity embedded entirely within a fluid-saturated poroelastic formation of infinite extent are examined theoretically.It is assu...The effects of a harmonically exciting monopole source on an infinitely long cylindrical cavity embedded entirely within a fluid-saturated poroelastic formation of infinite extent are examined theoretically.It is assumed that the source is located outside the cavity at a specified distance from the borehole axis.The magnitudes of the hoop and radial stresses beside the pore pressures exerted on the interface and inside the porous medium surrounding the borehole are calculated and discussed.Biot's poroelastic modeling along with three types of boundary conditions for the cylindrical interface including the ideal fluid,empty borehole,and rigid inclusion with a hard boundary is employed for the analysis.Utilizing a proper translational addition theorem for expressing the incident spherical wave in terms of cylindrical wave expansions,the proposed boundary conditions at the interface are satisfied.Stresses are formulated by means of wave potential functions in a three-dimensional(3D)manner.The effects of the frequency and the radial distance between the source and borehole on the induced stresses are examined for the first cylindrical modes over frequency spectra.Two permeability conditions for the interface and three types of soils for the porous formation are considered throughout the analysis.To give an overall outline of the study,a numerical example is presented.The results clearly indicate that the distance is a key parameter and has considerable effects on the induced stress values.In addition,the interface permeability condition and soil characteristics play an important role in determining the dynamic response of the borehole.Finally,the obtained results are compared with the relevant analyses existing in the literature for some limit cases,and good agreement is achieved.展开更多
文摘针对自由表面流动与弹性结构的流固耦合计算效率低、计算耗时长的问题,将流体体积法与基于结构-虚拟弹性体的快速动网格方法相结合,发展了一种适用于自由表面流动的高效流固耦合方法。使用流体体积(volume of fluid,VOF)法对流体自由表面进行追踪;将流体域视为虚拟弹性体并构建结构-虚拟弹性体系统,以流固耦合界面的多相流体力为激励求解系统的动力学方程得到结构振动位移和流场网格变形;在每一个时间步内依次求解流体流动、结构变形和流场动网格,实现流固耦合计算。基于发展的方法计算了溃坝水流冲击下弹性挡板的流固耦合响应,得到了溃坝水流的自由液面和弹性挡板的运动行为,结果表明:自由液面演变和弹性挡板振动位移的计算结果与已有算法的结果吻合良好;在同等网格规模下,与已有算法相比本文方法可减少33.3%的计算时间;在水流冲击作用下,弹性挡板向冲击侧小幅弯曲。随后水流沿挡板左侧上升并形成射流,挡板向另一侧大幅弯曲。最后由于两侧流体的阻尼,挡板振幅逐渐衰减。
文摘The effects of a harmonically exciting monopole source on an infinitely long cylindrical cavity embedded entirely within a fluid-saturated poroelastic formation of infinite extent are examined theoretically.It is assumed that the source is located outside the cavity at a specified distance from the borehole axis.The magnitudes of the hoop and radial stresses beside the pore pressures exerted on the interface and inside the porous medium surrounding the borehole are calculated and discussed.Biot's poroelastic modeling along with three types of boundary conditions for the cylindrical interface including the ideal fluid,empty borehole,and rigid inclusion with a hard boundary is employed for the analysis.Utilizing a proper translational addition theorem for expressing the incident spherical wave in terms of cylindrical wave expansions,the proposed boundary conditions at the interface are satisfied.Stresses are formulated by means of wave potential functions in a three-dimensional(3D)manner.The effects of the frequency and the radial distance between the source and borehole on the induced stresses are examined for the first cylindrical modes over frequency spectra.Two permeability conditions for the interface and three types of soils for the porous formation are considered throughout the analysis.To give an overall outline of the study,a numerical example is presented.The results clearly indicate that the distance is a key parameter and has considerable effects on the induced stress values.In addition,the interface permeability condition and soil characteristics play an important role in determining the dynamic response of the borehole.Finally,the obtained results are compared with the relevant analyses existing in the literature for some limit cases,and good agreement is achieved.
