Euler-Lagrange Coupling Research Articles

Two-phase flow LES of the sedimentation process of a particle cloud

To predict the sedimentation process practically with high resolution, a large eddy simulation (LES) is performed. A solid/liquid two-phase flow model based on the Euler–Lagrange coupling is developed. Then the discrete element method is applied to calculate inter-particle forces during individual particle motion. The computational grid scale of the Eulerian fluid method is less than the particle diameter to simulate a wake induced by settling particles. Comparison of the simulated and experimental results for the particle sedimentation process verified the performance of the developed numerical model. Finally, the mechanism of the inner structure of the settling particles is investigated from a computational point of view. Consequently, the positive relationship between the turbulence-energy production rate and the inter-particle collisions would be shown.

Lagrangian–Lagrangian simulations of solid–liquid flows in a bead mill

Solid–fluid multiphase flows are often encountered in chemical engineering operations, such as bead milling, slurry transport, and mixing. Numerical simulation is a promising approach for the design and investigation of operational conditions. In previous studies, an Eulerian–Lagrangian coupling method was developed for solid–liquid flows. However, it is difficult to apply this method to moving boundary problems because of the excessive calculation costs due to adaptive mesh or sliding mesh. To solve the difficulty, a Lagrangian–Lagrangian coupling method has been developed, which couples the Discrete Element Method (DEM) for the solid phase and the Moving Particle Semi-Implicit (MPS) method for the fluid phase. It can successfully calculate solid–fluid flows and has been validated, although it has been applied only to two-dimensional systems. In the present study, we develop a three-dimensional DEM–MPS method and apply it to bead mill systems, and show the effectiveness of the method. The simulation results, namely, the solid particle distribution and velocity are compared with experimental results and we thus demonstrate the validity of the method.

A global coupled Eulerian-Lagrangian model and 1 × 1 km CO<sub>2</sub> surface flux dataset for high-resolution atmospheric CO<sub>2</sub> transport simulations

Abstract. We designed a method to simulate atmospheric CO2 concentrations at several continuous observation sites around the globe using surface fluxes at a very high spatial resolution. The simulations presented in this study were performed using the Global Eulerian-Lagrangian Coupled Atmospheric model (GELCA), comprising a Lagrangian particle dispersion model coupled to a global atmospheric tracer transport model with prescribed global surface CO2 flux maps at a 1 × 1 km resolution. The surface fluxes used in the simulations were prepared by assembling the individual components of terrestrial, oceanic and fossil fuel CO2 fluxes. This experimental setup (i.e. a transport model running at a medium resolution, coupled to a high-resolution Lagrangian particle dispersion model together with global surface fluxes at a very high resolution), which was designed to represent high-frequency variations in atmospheric CO2 concentration, has not been reported at a global scale previously. Two sensitivity experiments were performed: (a) using the global transport model without coupling to the Lagrangian dispersion model, and (b) using the coupled model with a reduced resolution of surface fluxes, in order to evaluate the performance of Eulerian-Lagrangian coupling and the role of high-resolution fluxes in simulating high-frequency variations in atmospheric CO2 concentrations. A correlation analysis between observed and simulated atmospheric CO2 concentrations at selected locations revealed that the inclusion of both Eulerian-Lagrangian coupling and high-resolution fluxes improves the high-frequency simulations of the model. The results highlight the potential of a coupled Eulerian-Lagrangian model in simulating high-frequency atmospheric CO2 concentrations at many locations worldwide. The model performs well in representing observations of atmospheric CO2 concentrations at high spatial and temporal resolutions, especially for coastal sites and sites located close to sources of large anthropogenic emissions. While this study focused on simulations of CO2 concentrations, the model could be used for other atmospheric compounds with known estimated emissions.

METODOLOGI PENGEMBANGAN MODEL SIMULASI UNTUK EVALUASI KESELAMATAN PENUMPANG FREEFALL LIFEBOAT

Aulia Windyandari, in paper simulation model of development method for passenger savety evaluation of freefaal lifeboat explain that since the launching procedure of Freefall Lifeboat (FFL) may have an impact with the water surface, the occupant injury is possible be occured in the evacuation process of the offshore structures. The FFL shock acceleration has been conducted by the impact force when the lifeboat entry the water surface. If the shock acceleration over the human conciousness allowance, the serious injury will be happened during the FFL launching.According to the conditions, the IMO regulations have standard for the acceptance criteria of FFL shock acceleration induced by water entry impact load. The results measurement of Combined Acceleration Ratio Index (CAR) or Combined Dynamic Response Ratio Index (CDRR) should be comply with the IMO index criteria.In this paper, the methodology of FFL acceleration response prediction by the simulation model analysis will be proposed. The simulation model will be developed by using LS-Dyna code. The Simplified Arbitratry Lagrangian Eulerian Coupling will be used to define the coupling analysis between the Lifeboats (Lagrangian elements) with Water Fluids (the Eulerian Elements)Keywords: Free Fall Lifeboat, Response Acceleration, Impact Load

An improved immersed boundary method with direct forcing for the simulation of particle laden flows

An efficient approach for the simulation of finite-size particles with interface resolution was presented by Uhlmann [M. Uhlmann, An immersed boundary method with direct forcing for the simulation of particulate flows, J. Comput. Phys. 209 (2005) 448–476.]. The present paper proposes several enhancements of this method which considerably improve the results and extend the range of applicability. An important step is a simple low-cost iterative procedure for the Euler–Lagrange coupling yielding a substantially better imposition of boundary conditions at the interface, even for large time steps. Furthermore, it is known that the basic method is restricted to ratios of particle density and fluid density larger than some critical value above 1, hence excluding, for example, non-buoyant particles. This can be remedied by an efficient integration step for the artificial flow field inside the particles to extend the accessible density range down to 0.3. This paper also shows that the basic scheme is inconsistent when moving surfaces are allowed to approach closer than twice the step size. A remedy is developed based on excluding from the force computation all surface markers whose stencil overlaps with the stencil of a marker located on the surface of a collision partner. The resulting algorithm is throughly validated and is demonstrated to substantially improve upon the original method.

Numerical Study of Liquid-Solid Impact Using Lagrangian-Eulerian Coupling Method

The fluid-structure interaction of a water droplet impact on a compressible solid has been studied. By using Lagrangian-Eulerian coupling method, the dynamics in water droplet and deformation in solid has been analyzed and discussed. It is shown that computational impact pressure on the central axis at the initial stage is in good agreement with theoretical prediction. The onset of jetting time is later than theoretical considerations and the incompressible stream line flow is not immediately established after the shock envelope overtakes contact periphery. The pressure at the contact periphery decreases gradually after shock wave departure. The deformation of solid is examined and found that the depression in the central impact area is considerably larger than the outer region. Comparisons with experimental observation show that the deformation simulated can account for the deformation patterns of metal in some way.

CM-JP-8 FSI analysis of simple folded airbag deployment model using Lagrangian-Eulerian coupling method based on level set

In this study,we investigate into application of a contact model to the Lagrangian-Eulerian coupling method based on level sets in order to simulate fluid-structure interaction(FSI) such as folded airbag deployment.The present coupling method combines Lagrangian structure and Eulerian fluid solvers and uses Block Gauss-Seidel iterations with Aitken relaxation.As the difference from other Lagrangian-Eulerian coupling methods,our algorithm has two characteristics: generation of the accurate level set function by using virtual nodes arranged in the normal direction to the structure and application of the Dirichlet boundaiy conditions for the fluid solver by using the level set function and the gradient so as to satisfy the kinematic condition.As a first step of complex folded airbag deployment analysis,a simple folded airbag deployment model is handled.As a result,we confirm that the airbag inflates with self-contact and show the algorithmic performance.

Development of Numerical Analysis of Multiphase Flow in Powder Technology

The state-of-the-art of numerical simulation models and methods in gas-solid two-phase flows in powder technology field is briefly reviewed. Eulerian-Lagrangian coupling simulations have been largely developed in the last three decades,especially the DEM-CFD coupling simulation has become popular, and widely used in many operations of powder technology. It is expected that the mesoscopic flow models and two-fluid models will be improved by using the multiscale-modeling strategy.

402 レベルセットに基づいたLagrangian-Eulerian coupling methodの並列計算についての検討(OS4.大規模並列・連成解析と関連話題(1),OS・一般セッション講演)

402 レベルセットに基づいたLagrangian-Eulerian coupling methodの並列計算についての検討(OS4.大規模並列・連成解析と関連話題(1),OS・一般セッション講演)

LS-DYNA 코드의 유체-구조 연성해석 기법을 이용한 자유낙하식 구명정의 가속도 응답 추정

During certification of freefall lifeboats, it is necessary to estimate the injury potential of the impact loads exerted on the occupants during water entry. This paper focused on the numerical simulation to predict the acceleration response during the impact of freefall lifeboats on the water using FSI(Fluid-Structure Interaction) analysis technique of LS-DYNA code. FSI problems could be conveniently simulated by the overlapping capability using Arbitrary Lagrangian Eulerian(ALE) formulation and Euler-Lagrange coupling algorithm of LS-DYNA code. Through this study, it could be found that simulation results were in relatively good agreement with experimental ones in the acceleration peak values, and that the loading conditions were very sensitive to the acceleration responses by the experimental and simulation results.

Numerical Approach in Predicting the Formation Process of Tandem Explosively Formed Projectile

In order to find a proper resolution scheme for the formation process of tandem Explosively Formed Projectile (EFP) from shaped charge with double liners (SCDLL). 2D hydrocode was used to study the formation and penetration of SCDLL impelled by detonation products. The simulation is conducted to compare the effect of the following three resolution techniques on the prediction of velocity and shaped of EFP: Lagrangian, Eulerian-Lagrangian Coupling and Eulerian. In the simulation, shaped charge with one high explosive and two liners, ignited at the center point is studied. The results obtained from simulations are compared to experimental X-ray pictures. The simulation results including the Lagrangian resolution applied on liners agree well with experimental results when the friction coefficient between two liners is set to 0.28. The study results can provide important reference for engineers to analyze and design the tandem EFP.

FEM Analysis of Joint Interface Formation in Magnetic Pressure Seam Welding

The magnetic pressure seam welding is one of the candidate methods to join thin sheet smart and multifunctional materials. In this research, to examine the mechanism of magnetic pressure welding from a dynamic viewpoint, numerical simulation of the impact was carried out by using a commercial Euler-Lagrange coupling software MSC.Dytran (MSC.Software) as a first step of the computational studies, where the joint between Fe and Al was employed according to the previous experimental researches. From the serial numerical results, it was found that the increase of temperature at the joint interface was not enough to melt Al or Fe in the range of collision velocity and angle studied in this report. Also, it was revealed that the very large mean stress occurred at the interface which could be considered as the pressure at joint interface and Al moved with high velocity along the interface. Moreover, it was found that there were two patterns of plastic strain distribution near the joint interface depending on the collision velocity and collision angle. Finally, it can be concluded that the plastic strain pattern might be related to the success of magnetic pressure seam welding.

Hydroelastic analysis of insulation containment of LNG carrier by global–local approach

AbstractThe insulation containment of liquefied natural gas (LNG) carriers is a large‐sized elastic structure made of various metallic and composite materials of complex structural composition to protect the heat invasion and to sustain the hydrodynamic pressure. The goal of the present paper is to present a global–local numerical approach to effectively and accurately compute the local hydroelastic response of a local containment region of interest. The global sloshing flow and hydrodynamic pressure fields of interior LNG are computed by assuming the flexible containment as a rigid container. On the other hand, the local hydroelastic response of the insulation containment is obtained by solving only the local hydroelastic model in which the complex and flexible insulation structure is fully considered and the global analysis results are used as the initial and boundary conditions. The interior incompressible inviscid LNG flow is solved by the first‐order Euler finite volume method, whereas the structural dynamic deformation is solved by the explicit finite element method. The LNG flow and the containment deformation are coupled by the Euler–Lagrange coupling scheme. Copyright © 2008 John Wiley & Sons, Ltd.

Application of the ALE technique for underwater explosion analysis of a submarine liquefied oxygen tank

The design of submarines has continually evolved to improve survivability. Explosions may induce local damage as well as global collapse to a submarine. Therefore, it is important to realistically estimate the possible damage conditions due to underwater explosions in the design stage. The present study applied the Arbitrary Lagrangian–Eulerian (ALE) technique, a fluid–structure interaction approach, to simulate an underwater explosion and investigate the survival capability of a damaged submarine liquefied oxygen tank. The Lagrangian–Eulerian coupling algorithm, the equations of state for explosives and seawater, and the simple calculation method for explosive loading were also reviewed. It is shown that underwater explosion analysis using the ALE technique can accurately evaluate structural damage after attack. This procedure could be applied quantitatively to real structural design.

A new fluid structure coupling

The modelling of parachutes at Irvin Aerospace Inc. was based on the penalty Euler-Lagrange coupling method to compute the interaction between an Arbitrary Lagrange Euler formulation for the air flow and an updated Lagrangian finite element formulation for the canopy dynamics. This approach did not permit the effect of fabric porosity to be accounted for. In this paper, a new porosity Euler-Lagrange coupling models the fabric permeability by assessing the interaction forces based on the Ergun porous flow model. This paper provides validations for the technique when considering parachute applications and discusses the interest of this development to the parachute designer.

Porous parachute modelling with an Euler-Lagrange coupling

A newly developed approach for tridimensional fluid-structure interaction with a deformable thin porous media is presented. The method presented couples a Arbitrary Lagrange Euler formulation for the fluid dynamics and a updated Lagrangian finite element formulation for the thin porous medium dynamics. The interaction between the fluid and porous medium are handled by a Euler-Lagrange coupling, for which the fluid and structure meshes are superimposed without matching. The coupling force is computed with an Ergun porous flow model. As test case, the method is applied to an anchored air parachute placed in an air stream.

Techniques for Numerical Simulations of Concrete Slabs for Demolishing by Blasting

The subject of this article is the numerical simulation of concrete under explosive loading using a meshbased and a meshfree discretization technique. The presented techniques are verified by experimental data. Experimental evidence suggests that the complete stress-strain history relation must be considered as a basis for constitutive modeling if concrete is subjected to high loading rates. These dynamic phenomena cause a retardation of damage activation which must be taken into account when constitutive modeling is pursued on mesolevel instead of microlevel. By including a dynamic relaxation formulation within the framework of a general three-dimensional coupled continuum damage-plasticity law, it is shown that the solution of the wave propagation problem in materials with strain-softening becomes independent of mesh size. As the simulation of concrete under contact detonation causes severe numerical problems because of the large deformations, special numerical spatial discretization techniques have to be used. In this article we compare the results of a concrete slab under contact detonation using the finite element method code LS-DYNA with an arbitrary Lagrangian Eulerian coupling and the results obtained by a MLSPH code developed at our institute with experimental data. The same constitutive model for concrete and the same equation of state for the explosive is implemented in the two codes. The results of the different numerical simulations and the experimental data agree with each other well.

Euler-Lagrange coupling for porous parachute canopy analysis

We apply a new Euler-Lagrange coupling method to 3-D parachute problems, which generally involve fluid-structure interactions between a flexible, elastic, porous parachute canopy and a high-speed airflow. The method presented couples an Arbitrary Lagrange Euler formulation for the fluid dynamics and an updated Lagrangian finite element formulation for the parachute canopy. The Euler-Lagrange coupling handles fluid-structure interaction without matching the fluid and structure meshes. In order to take account of the effect of the parachute permeability, this coupling computes interaction forces based on the Ergun porous flow model. This paper provides validations for the technique when considering parachute applications and discusses the interest of this development to the parachute designer.&nbsp

A new fluid structure coupling Application to parachute modelling

The modelling of parachutes at Irvin Aerospace Inc. was based on the penalty Euler-Lagrange coupling method to compute the interaction between an Arbitrary Lagrange Euler formulation for the air flow and an updated Lagrangian finite element formulation for the canopy dynamics. This approach did not permit the effect of fabric porosity to be accounted for. In this paper, a new porosity Euler-Lagrange coupling models the fabric permeability by assessing the interaction forces based on the Ergun porous flow model. This paper provides validations for the technique when considering parachute applications and discusses the interest of this development to the parachute designer.

Porous parachute modelling with an Euler-Lagrange coupling

A newly developed approach for tridimensional fluid-structure interaction with a deformable thin porous media is presented. The method presented couples a Arbitrary Lagrange Euler formulation for the fluid dynamics and a updated Lagrangian finite element formulation for the thin porous medium dynamics. The interaction between the fluid and porous medium are handled by a Euler-Lagrange coupling, for which the fluid and structure meshes are superimposed without matching. The coupling force is computed with an Ergun porous flow model. As test case, the method is applied to an anchored air parachute placed in an air stream.