{"title":"不规则火山粒子碰撞恢复系数的实验测量","authors":"Francesco Neglia, Emanuele Caruso, Fabio Dioguardi, Daniela Mele, Damiano Sarocchi, Roberto Sulpizio","doi":"10.1029/2024JB030445","DOIUrl":null,"url":null,"abstract":"<p>Dense volcanic granular flows are polydisperse in terms of grain size and density, and their flow characteristics are mainly governed by particle-particle collisions and frictional forces acting at the boundaries. The parameter measuring the energy dissipation during the collisions is the coefficient of restitution (<span></span><math>\n <semantics>\n <mrow>\n <mi>e</mi>\n </mrow>\n <annotation> $e$</annotation>\n </semantics></math>), which is proportional to the fraction of the original energy stored in the colliding particles that is restored to the same ones after the collision. <span></span><math>\n <semantics>\n <mrow>\n <mi>e</mi>\n </mrow>\n <annotation> $e$</annotation>\n </semantics></math> is fundamental in computational fluid dynamics (CFD) numerical models to simulate multiphase granular flows because it is required to solve the particles motion and the particle-particle momentum exchange. The calculation of <span></span><math>\n <semantics>\n <mrow>\n <mi>e</mi>\n </mrow>\n <annotation> $e$</annotation>\n </semantics></math> for irregular volcanic particles is an unsolved challenging problem, which is here addressed by colliding particles through a pendulum-type instrumental apparatus. <span></span><math>\n <semantics>\n <mrow>\n <mi>e</mi>\n </mrow>\n <annotation> $e$</annotation>\n </semantics></math> was calculated for volcanic particles with different density (<span></span><math>\n <semantics>\n <mrow>\n <mi>ρ</mi>\n </mrow>\n <annotation> $\\rho $</annotation>\n </semantics></math>), diameter (<span></span><math>\n <semantics>\n <mrow>\n <mi>d</mi>\n </mrow>\n <annotation> $d$</annotation>\n </semantics></math>) and particles size ratio (<span></span><math>\n <semantics>\n <mrow>\n <msub>\n <mi>d</mi>\n <mtext>ratio</mtext>\n </msub>\n </mrow>\n <annotation> ${d}_{\\text{ratio}}$</annotation>\n </semantics></math>), and the data were used to obtain linear relationships between <span></span><math>\n <semantics>\n <mrow>\n <mi>e</mi>\n </mrow>\n <annotation> $e$</annotation>\n </semantics></math> and the investigated parameters. Afterward, a multicollinearity analysis and a multiple regression were applied to all data to adequately predict the value of <span></span><math>\n <semantics>\n <mrow>\n <mi>e</mi>\n </mrow>\n <annotation> $e$</annotation>\n </semantics></math> knowing the values of <span></span><math>\n <semantics>\n <mrow>\n <mi>ρ</mi>\n </mrow>\n <annotation> $\\rho $</annotation>\n </semantics></math>, <span></span><math>\n <semantics>\n <mrow>\n <mi>d</mi>\n </mrow>\n <annotation> $d$</annotation>\n </semantics></math>, and <span></span><math>\n <semantics>\n <mrow>\n <msub>\n <mi>d</mi>\n <mtext>ratio</mtext>\n </msub>\n </mrow>\n <annotation> ${d}_{\\text{ratio}}$</annotation>\n </semantics></math>. The empirical law was finally validated against some large-scale experiments by using the multiphase CFD simulation tool Multiphase Flow with Interphase eXchanges. The CFD simulations inserting the predicted <span></span><math>\n <semantics>\n <mrow>\n <mi>e</mi>\n </mrow>\n <annotation> $e$</annotation>\n </semantics></math> showed a better agreement between simulated and experimental flow velocities, with an increase of the simulation accuracy up to 20%. Hence, the current paper proposes a simple instrumental apparatus to calculate <span></span><math>\n <semantics>\n <mrow>\n <mi>e</mi>\n </mrow>\n <annotation> $e$</annotation>\n </semantics></math>, demonstrating its importance in simulations of multiphase granular flows.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 7","pages":""},"PeriodicalIF":3.9000,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB030445","citationCount":"0","resultStr":"{\"title\":\"Experimental Measurements on the Coefficient of Restitution of Colliding Irregular Volcanic Particles\",\"authors\":\"Francesco Neglia, Emanuele Caruso, Fabio Dioguardi, Daniela Mele, Damiano Sarocchi, Roberto Sulpizio\",\"doi\":\"10.1029/2024JB030445\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>Dense volcanic granular flows are polydisperse in terms of grain size and density, and their flow characteristics are mainly governed by particle-particle collisions and frictional forces acting at the boundaries. The parameter measuring the energy dissipation during the collisions is the coefficient of restitution (<span></span><math>\\n <semantics>\\n <mrow>\\n <mi>e</mi>\\n </mrow>\\n <annotation> $e$</annotation>\\n </semantics></math>), which is proportional to the fraction of the original energy stored in the colliding particles that is restored to the same ones after the collision. <span></span><math>\\n <semantics>\\n <mrow>\\n <mi>e</mi>\\n </mrow>\\n <annotation> $e$</annotation>\\n </semantics></math> is fundamental in computational fluid dynamics (CFD) numerical models to simulate multiphase granular flows because it is required to solve the particles motion and the particle-particle momentum exchange. 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引用次数: 0
摘要
致密火山粒状流在粒度和密度上具有多分散性,其流动特征主要受颗粒碰撞和边界摩擦力的影响。测量碰撞过程中能量耗散的参数是恢复系数(e$ e$),它与碰撞后储存在碰撞粒子中的原始能量恢复到相同能量的比例成正比。e$ e$是模拟多相颗粒流的计算流体动力学(CFD)数值模型的基础,因为它需要求解颗粒运动和颗粒动量交换。不规则火山粒子的e$ e$计算是一个尚未解决的具有挑战性的问题,本文通过摆式仪器来解决粒子碰撞问题。E $ E $计算了不同密度的火山粒子(ρ $\rho $);直径(d$ d$)和粒径比(d ratio ${d}_{\text{ratio}}$),并利用数据得到了e$ e$与所研究参数之间的线性关系。之后,对所有数据进行多重共线性分析和多元回归,以充分预测e$ e$的值,并知道ρ $\rho $, d$ d$,和d比率${d}_{\text{ratio}}$。最后利用多相CFD模拟工具multiphase Flow with Interphase eXchanges,通过大型实验验证了经验规律。在CFD模拟中插入预测的e$ e$,结果表明模拟流速与实验流速吻合较好,仿真精度提高了20%。因此,本文提出了一种简单的仪器来计算e$ e$,这表明了它在多相颗粒流模拟中的重要性。
Experimental Measurements on the Coefficient of Restitution of Colliding Irregular Volcanic Particles
Dense volcanic granular flows are polydisperse in terms of grain size and density, and their flow characteristics are mainly governed by particle-particle collisions and frictional forces acting at the boundaries. The parameter measuring the energy dissipation during the collisions is the coefficient of restitution (), which is proportional to the fraction of the original energy stored in the colliding particles that is restored to the same ones after the collision. is fundamental in computational fluid dynamics (CFD) numerical models to simulate multiphase granular flows because it is required to solve the particles motion and the particle-particle momentum exchange. The calculation of for irregular volcanic particles is an unsolved challenging problem, which is here addressed by colliding particles through a pendulum-type instrumental apparatus. was calculated for volcanic particles with different density (), diameter () and particles size ratio (), and the data were used to obtain linear relationships between and the investigated parameters. Afterward, a multicollinearity analysis and a multiple regression were applied to all data to adequately predict the value of knowing the values of , , and . The empirical law was finally validated against some large-scale experiments by using the multiphase CFD simulation tool Multiphase Flow with Interphase eXchanges. The CFD simulations inserting the predicted showed a better agreement between simulated and experimental flow velocities, with an increase of the simulation accuracy up to 20%. Hence, the current paper proposes a simple instrumental apparatus to calculate , demonstrating its importance in simulations of multiphase granular flows.
期刊介绍:
The Journal of Geophysical Research: Solid Earth serves as the premier publication for the breadth of solid Earth geophysics including (in alphabetical order): electromagnetic methods; exploration geophysics; geodesy and gravity; geodynamics, rheology, and plate kinematics; geomagnetism and paleomagnetism; hydrogeophysics; Instruments, techniques, and models; solid Earth interactions with the cryosphere, atmosphere, oceans, and climate; marine geology and geophysics; natural and anthropogenic hazards; near surface geophysics; petrology, geochemistry, and mineralogy; planet Earth physics and chemistry; rock mechanics and deformation; seismology; tectonophysics; and volcanology.
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