Fluid-structure interaction (FSI) is a class of mechanics-related problems with mutual dependence between the fluid and structure parts and it is observable nearly everywhere, in natural phenomena to ...many engineering systems. The primary challenges in developing numerical models with conventional grid-based methods are the inherent nonlinearity and time-dependent nature of FSI, together with possible large deformations and moving interfaces. Smoothed particle hydrodynamics (SPH) method is a truly Lagrangian and meshfree particle method that conveniently treats large deformations and naturally captures rapidly moving interfaces and free surfaces. Since its invention, the SPH method has been widely applied to study different problems in engineering and sciences, including FSI problems. This article presents a review of the recent developments in SPH based modeling techniques for solving FSI-related problems. The basic concepts of SPH along with conventional and higher order particle approximation schemes are first introduced. Then, the implementation of FSI in a pure SPH framework and the hybrid approaches of SPH with other grid-based or particle-based methods are discussed. The SPH models of FSI problems with rigid, elastic and flexible structures, with granular materials, and with extremely intensive loadings are demonstrated. Some discussions on several key techniques in SPH including the balance of accuracy, stability and efficiency, the treatment of material interface, the coupling of SPH with other methods, and the particle regularization and adaptive particle resolution are provided as concluding marks.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The Huai River Basin, China.
This study chooses the daily flow data of Huai River and its tributaries, Shi River and Hong River during 1959–2016. The co-occurrence of floods in different tributaries ...of the catchment is assessed by analyzing the flood peak and flood timing at three different gauging stations located in the river network. What’s more, the parameters(estimated from the 30-year scale time windows) of the marginal and joint distributions are assumed stationary and nonstationary respectively to explore how the trend of coincidence probability(CP) is effected by them.
The results show that, over the period analyzed, the most probable time of flood co-occurrence over the gauge stations in the study area tends to move backwards from 10 July to about 20 July. The probability of flood co-occurrence at the Bantai and Jiangjiaji gauging stations, which singularly experience an increase in flood peak, increases from 9.25×10−9(the 1st window) to 1.17×10−5(the 25th window) when the return period of flood is 20 year, while in the same condition, the CP of Bantai and Wangjiaba decreased from 6.16×10−6 to 2.48×10−7.
Display omitted
•Nonstationary coincidence probability analysis of the flood coincidence was performed.•The impacts of the marginal distribution parameters on the probability are analyzed.•The most likely coincidence time moves backward to July 20th during flood season.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•A new multi field coupled crystallization coupled model is proposed and validated.•The crystallisation process with ice crystal particle motion is simulated.•The effects of the particle radius, ...particle velocity and pipe width are discussed.
In this study, the ice formation behaviour in micro pipelines accompanied by free crystal movement was investigated using the using the coupled method of lattice Boltzmann method - phase field method - immersed boundary method (LBM-PFM-IBM) at the pore-scale. Firstly, we proposed a novel coupling method that significantly improved the accuracy of the PFM method 1 in simulating the growth rate of ice crystal tips at the pore scale. The calculation error, when compared to experimental results, was only 3.1%. Furthermore, we conducted numerical studies to examine the influence of particle velocity, particle size, and pipe width on ice blockage (IB) in pipelines where free crystal motion occurs using the proposed method. The results revealed that the mechanism of ice blockage at the micro scale differs significantly from that at the macro level. Increasing the velocity and size of free crystals was found to effectively suppress ice blockage, with the size of the crystals having a more substantial impact. On the other hand, the impact of pipeline width on ice blockage was not consistent. Changing the pipe width did not prove to be an effective means of preventing ice blockage from occurring.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The dynamic failure process of structures under extreme loadings is very common in many fields of engineering and science. The smoothed particle hydrodynamics (SPH) method offers inherent benefits in ...dealing with complex interfaces and large material deformations in extreme mechanics problems. However, SPH simulations for 3D engineering applications are time-consuming. To address this issue, we introduce MPI (Message Passing Interface) in our SPH scheme to reduce computational time. Some optimizations are adopted to ensure the massive computation of the SPH method. In particular, an optimized memory management strategy is developed to control the memory footprint. With the present MPI-based massive parallelization of the SPH method, several validation examples are tested and analyzed. By comparing the present numerical results with the reference data, the dynamic failure process of complex structures subjected to extreme loadings like explosive and impact loadings can be well captured. A large number of particles, up to 2.04 billion, are adopted in the present simulations. The scaling tests show that the scalability of the massively parallel SPH program achieves a maximum parallel efficiency of 97% on 10020 CPU cores.
•A massively parallel SPH computing framework is proposed for extreme mechanics problems.•An optimized memory management strategy is developed to reduce memory footprint and achieve better scalability.•A non-blocking MPI point-to-point communications scheme with parallel IO is implemented for large-scale SPH simulations.•A series of numerical examples demonstrate the scalability and accuracy of the present parallel SPH framework.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
As a typical fluid–structure interaction (FSI) problem, water entry involves violent fluid flows and changing free surfaces, which presents great challenges for numerical modeling. Smoothed Particle ...Hydrodynamics (SPH) is a Lagrangian particle method that has natural advantages in modeling free surfaces and moving interfaces. However, SPH is computationally expensive due to the search of particle–particle interactions, and it causes great difficulties for performing large-scale simulations of 3D FSI problems. In this work, we present an accelerated SPH framework based on the Graphics Processing Unit (GPU) techniques to study water entry problems. The multi-threading programmed by Compute Unified Device Architecture (CUDA) is applied to enhance the computational performance in terms of efficiency and scale. Compared to the Single-CPU-based strategy, the newly presented GPU-accelerated SPH method is computationally more efficient with a speedup over hundreds times and enables a larger memory available for large-scale simulations of around ten million particles for three-dimensional cases. With the GPU-accelerated SPH method, the 3D water entry of a circular cylinder is investigated with some kinematic and dynamic characteristics explained. The results demonstrate that the rotational characteristic of a 3D cylinder in water entry is related to the dimensionless number γ defined as the ratio of the initial inclination angle to the initial velocity angle. The rotation of a cylinder changes from anticlockwise to clockwise with the increase in γ. A transition value of γ exists between the anticlockwise to clockwise rotation, which focuses on the range from 1.0 to 6.0. Meanwhile, the water entry of a 3D circular cylinder leads to a violent impact on the bottom of the cylinder, which causes a peak value of pressure being a maximum value at the early stage of the water entry. It is also indicated that the selection of the initial inclination angle has a great effect on the maximum pressure.
•A GPU-accelerated SPH method for fluid–structure interaction problems is developed.•The GPU-accelerated SPH method can greatly improve the computational ability compared to CPU-based SPH.•The water entry characteristics of a 3D cylinder relate to the ratio of the initial inclination angle to velocity angle.•A cross-region that the trajectory of the centroid always passes through is determined by the initial velocity angle.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Four integrated SPH models are presented and compared for simulating natural convection.•The most suitable SPH model for natural convection is provided.•Natural convection for Ra=109 and Pr = 0.71 ...is successfully modeled for the first time by using the SPH method.•Mechanisms of the natural convection in a square cavity at different Rayleigh numbers are discussed.
This paper conducts the simulation of natural convection in a differentially heated square cavity at high Rayleigh numbers by using the smoothed particle hydrodynamics (SPH) method. Due to the decrease of the accuracy and stability, it is challenging for the SPH method to simulate natural convection at high Rayleigh numbers, and there are few reported SPH literatures of natural convection at Ra>106 for air (Pr = 0.71). In this study, four integrated SPH models are presented to simulate the natural convection and their accuracy and stability are assessed. These four SPH models are associated with Kernel Gradient Correction (KGC) to improve approximation accuracy and Particle Shifting Technology (PST) to regularize particle distribution while they are different in treating density diffusion and calculating the pressure term. The numerical results show that SPH model_4 (KGC, PST, δ-SPH and asymmetric pressure approximation) is the most suitable for simulating the closed natural convection problems, especially at high Rayleigh numbers. Good agreements with reference solutions are obtained by SPH model_4 for the natural convection at 104≤Ra≤108. Furthermore, the simulation of natural convection at Ra=109 is conducted by SPH model_4. The evolutions of thermal convection are described in detail. It is found that dynamics characteristic reveals that the dominant force is the pressure gradient, rather than the buoyancy force before the quasi-steady state. In addition, the chaotic motion at Ra=109 has significant influence to the heat transfer characteristic in the vertical boundary layers.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Free-surface flows, especially those associated with fluid-structure interactions (FSIs), pose challenging problems in numerical simulations. The authors of this work recently developed a smoothed ...particle element method (SPEM) to simulate FSIs. In this method, both the fluid and solid regions are initially modeled using a smoothed finite element method (S-FEM) in a Lagrangian frame, whereas the fluid regions undergoing large deformations are adaptively converted into particles and modeled with an improved smoothed particle hydrodynamics (SPH) method. This approach greatly improves computational accuracy and efficiency because of the advantages of the S-FEM in efficiently treating solid/fluid regions showing small deformations and the SPH method in effectively modeling moving interfaces. In this work, we further enhance the efficiency of the SPEM while effectively capturing local fluid information by introducing a multi-resolution technique to the SPEM and developing an effective approach to treat multi-resolution element-particle interfaces. Various numerical examples demonstrate that the multiresolution SPEM can significantly reduce the computational cost relative to the original version with a constant resolution. Moreover, the novel approach is effective in modeling various incompressible flow problems involving FSIs.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Hydroelastic fluid-structure interaction (FSI) problems usually involve nonlinear free surface flows, large structure deformations and changing interfaces, which present great challenges for ...numerical modeling. To deal with violent FSIs, the authors proposed a multi-resolution smoothed particle element method (M-SPEM), which adaptively simulates local fluid regions with an improved smoothed particle hydrodynamics (SPH) method and models other solid/fluid regions with a smoothed finite element method (S-FEM). Both computational accuracy in local fluid domain and entire efficiency can be improved by M-SPEM compared with the conventional partitioned FSI solvers based on SPH-FEM coupling schemes. In this work, an improved M-SPEM is developed and extended to simulate the complex hydroelastic FSI problems with structural deformations considered in the numerical model. To solve the accuracy reduction problem in the multi-resolution simulations, we developed a velocity and position correction technique for the generated fluid and virtual particles. The computational results demonstrated that the new correction technique can effectively improve the computational accuracy of M-SPEM while the corrected schemes produce results very close to the reference ones. The positions of the generated particles should also be appropriately optimized during the element-particle conversion process. With both accuracy and efficiency improved, the improved M-SPEM is proven to be suitable to deal with some challenging hydroelastic FSI problems.
•An improved M-SPEM approach is developed to model hydroelastic FSI problems.•The velocity and position correction technique is proposed to improve the computational accuracy.•The improved M-SPEM can greatly save computational cost compared to the general FEM-SPH coupling approaches.•The multi-resolution interfaces between elements and particles are handled by splitting ghost particles.•The M-SPEM is very effective for modeling challenging FSI problems involved with large structural deformations.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Display omitted
•A novel peridynamics (PD) model considering hydrogen absorption is proposed.•The hydriding reaction model can well reproduce the exothermic/endothermic reaction process.•The ...simulation results by the developed PD method agree well with the reference data.•The influence of cracks on hydrogen absorption performance is numerically studied.•Volumetric expansion effects on hydrogen absorption are analyzed by the PD model.
Numerical modelling and study of metal hydride bed with heat and mass transfer is a key to identify and predict the state of the storage device during absorption and desorption process. It is a great challenge to numerically study this problem considering cracks and volumetric expansion for conventional approaches due their limitations in treating discontinuities and large deformations. To effectively predict the hydrogen charging performance with the influences of cracks and volumetric expansion, a novel peridynamic (PD) model considering hydrogen absorption was proposed, which has not been used in most existing studies. The developed PD model was applied to simulate metal hydride reaction including depleted uranium (DU) and zirconium cobalt (ZrCo) in a thin-layer bed. The simulation results agreed well with both existing numerical solutions and experimental observations. The cracks were introduced to identify their influences on the performance of hydrogen absorption in a DU bed as a prototype. It is demonstrated that crack length and location had a significant influence on the absorption rate and average temperature evolution. With the increase in the crack length, the hydrogen absorption efficiency of the metal hydride bed (MHB) decreases dramatically due to the high bed temperature. The crack approaching the cooling boundary would greatly affect the temperature evolution, which causes the average H/M value to reach saturation later. Finally, the effects of the volumetric expansion were taken into consideration in the present PD model. Unlike ZrCo, the hydrogen kinetics performance would be overrated due to the neglection of the volumetric expansion in a DU bed.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Fluid-structure interaction (FSI) is a class of mechanics-related problems with mutual dependence between the fluid and structure parts and it is observable nearly everywhere, in natural phenomena to ...many engineering systems. The primary challenges in developing numerical models with conventional grid-based methods are the inherent nonlinearity and time- dependent nature of FSI, together with possible large deformations and moving interfaces. Smoothed particle hydrodynamics (SPH) method is a truly Lagrangian and meshfree particle method that conveniently treats large deformations and naturally captures rapidly moving interfaces and free surfaces. Since its invention, the SPH method has been widely applied to study different problems in engineering and sciences, including FSI problems. This article presents a review of the recent developments in SPH based modeling techniques for solving FSI-related problems. The basic concepts of SPH along with conventional and higher order particle approximation schemes are first introduced. Then, the implementation of FSI in a pure SPH framework and the hybrid approaches of SPH with other grid-based or particle-based methods are discussed. The SPH models of FSI problems with rigid, elastic and flexible structures, with granular materials, and with extremely intensive loadings are demonstrated. Some discussions on several key techniques in SPH including the balance of accuracy, stability and efficiency, the treatment of material interface, the coupling of SPH with other methods, and the particle regularization and adaptive particle resolution are provided as concluding marks. smoothed particle hydrodynamics (SPH), fluid-structure interaction (FSI), computational fluid dynamics (CFD), computational solid dynamics (CSD) PACS number(s): 02.70.-c, 46.15.-x, 47.11.-j, 83.50.-v
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
