Simulation Of Fluid-structure Interaction Problems Research Articles

Coupling of an SPH-based solver with a multiphysics library

A two-way coupling between the Smoothed Particle Hydrodynamics-based (SPH) code with a multiphysics library to solve complex fluid-solid interaction problems is proposed. This work provides full access to the package for the use of this coupling by releasing the source code, completed with guidelines for its compilation and utilization, and self-contained template setups for practical uses of the novel implemented features, is provided here. The presented coupling expands the applicability of two different solvers allowing to simulate fluids, multibody systems, collisions with frictional contacts using either non-smooth contact (NSC) or smooth contact (SMC) methods, all integrated under the same framework. The fluid solver is the open-source code DualSPHysics, highly optimised for simulating free-surface phenomena and structure interactions, uniquely positioned as a general-purpose Computational Fluid Dynamics (CFD) software with a GPU-accelerated solver. Mechanical systems that comprise collision detection and/or multibody dynamics are solved by the multiphysics library Project Chrono, which uses a Discrete Element Method (DEM). Therefore, this SPH-DEM coupling approach can manage interactions between fluid and complex multibody systems with relative constraints, springs, or mechanical joints. Program summaryProgram title: DualSPHysics-ChronoCPC Library link to program files:https://doi.org/10.17632/g2cc37dw4f.1Licensing provisions: DualSPHysics and DSPHChronoLib under GNU Lesser General Public License (LGPL); Project Chrono under BSD-3-Clause License.Programming language: C++ and CUDANature of problem: The simulation of turbulent free-surface flows in interaction with complex fixed or floating structures is essential to address typical marine and coastal engineering problems. The Smoothed Particle Hydrodynamics (SPH) method is particularly suitable for solving this type of nonlinear problems. However, this type of application usually requires mechanical restrictions between the different structural elements (spherical joints, hinges, or springs), as well as the correct simulation of collisions between solid objects. In these cases, it is necessary to combine the SPH method with other numerical methods that allow performing these multiphysics simulations.Solution method: DualSPHysics-Chrono is a two-way coupling between an SPH solver and a multiphysics library that combines fluid simulation using a Lagrangian approximation and interactions between solids using Discrete Element Method (DEM). DualSPHysics solver is a GPU-optimized implementation of the SPH method that allows efficient simulation of fluid-structure interaction problems. Whereas Project Chrono is a DEM implementation for simulating multibody dynamics that includes collision detection and numerous mechanical constraints to solve complex mechanisms. The coupling of DualSPHysics and Project Chrono combines the capabilities of both models under a free software framework.Additional comments including restrictions and unusual features: The SPH solver includes a version implemented with CUDA (Compute Unified Device Architecture) to exploit the parallelism of NVIDIA graphics processing units (GPUs).

An Eulerian finite-volume approach of fluid-structure interaction problems on quadtree meshes

A quadtree-based fully Eulerian finite volume approach for the simulation of fluid-structure interaction problems is presented. Both fluid and structure phases, which are assumed to be incompressible and viscous, are solved monolithically on the whole computational domain. The discretization stencils are limited to the first layer of neighbors thus enhancing the efficiency of the parallel computations while limiting the numerical order of the finite volume discretizations that can be reached. The behavior of hyperelastic structures is described with the non-linear Mooney-Rivlin model. The simulation of several two dimensional test cases is performed on uniform and quadtree grids and results are compared with the literature. To illustrate the versatility of the numerical model presented, a biomedical application, the axisymmetric simulation of a blood flow in a cardiac pump, is presented.

Adaptive mesh refinement immersed boundary method for simulations of laminar flows past a moving thin elastic structure

One of the critical issues in numerical simulation of fluid-structure interaction problems is inaccuracy of the solutions, especially for flows past a stationary thin elastic structure where large deformations occur. High resolution is required to capture the flow characteristics near the fluid-structure interface to enhance accuracy of the solutions within proximity of the thin deformable body. Hence, in this work, an algorithm is developed to simulate fluid-structure interactions of moving deformable structures with very thin thicknesses. In this algorithm, adaptive mesh refinement (AMR) is integrated with immersed boundary finite element method (IBFEM) with two-stage pressure-velocity corrections. Despite successive interpolation of the flow field by IBM, the governing equations were solved using a fixed structured mesh, which significantly reduces the computational time associated with mesh reconstruction. The cut-cell IBM is used to predict the body forces while FEM is used to predict deformation of the thin elastic structure in order to integrate the motions of the fluid and solid at the interface. AMR is used to discretize the governing equations and obtain solutions that efficiently capture the thin boundary layer at the fluid-solid interface. The AMR-IBFEM algorithm is first verified by comparing the drag coefficient, lift coefficient, and Strouhal number for a benchmark case (laminar flow past a circular cylinder at Re = 100) and the results showed good agreement with those of other researchers. The algorithm is then used to simulate 2-D laminar flows past stationary and moving thin structures positioned perpendicular to the freestream direction. The results also showed good agreement with those obtained from the arbitrary Lagrangian-Eulerian (ALE) algorithm for elastic thin boundaries. It is concluded that the AMR-IBFEM algorithm is capable of predicting the characteristics of laminar flow past an elastic structure with acceptable accuracy (error of ∼0.02%) with only ∼1% of the computational time for simulations with full mesh refinement.

Numerical simulation of capillary dynamics of thin liquid layers at high-frequency oscillations of deformable substrate

The numerical simulation of fluid-structure interaction problems is topical both from an applied point of view (in connection with the need to create various technical devices) and theoretical ones (it’s caused by the development of methods, algorithms, and HPC systems). Fluid-structure interaction is complex and requires a solution of both the elastodynamic and the hydrodynamics equations. The partitioned approach to solving fluid-interaction problems is one of the most common. Its allows solving each of the physical problems independently, using specific numerical schemes and a proprietary parallelism model. However, in this approach, a procedure for coupling solutions on the interface boundary is necessary to carry out. This article is considered the numerical simulation of forced oscillation of the liquid layer located on the surface of a bending plate. Forced vibrations of the cantilevered plate are excited by the piezoelectric element. At the excitation of vibrations, the thin layer of viscous liquids has flowed to antinodes of vibrations of the oscillated plate.

Numerical simulation of the interactions between fluid and structure in application of the MPS method assisted with the large eddy simulation method

The Moving-Particle Semi-implicit (MPS) method is a type of meshless Lagrangian calculation technique that uses particles to perform calculations instead of meshes. This method is straightforward and has a high computational efficiency. In this paper, a Lagrangian model for the numerical simulation of fluid-structure interaction problems is proposed. In the proposed method, both the fluid and the structure are described by the MPS. The fluid is fully coupled with the solid that can undergo large structural deformations. In practical engineering, many existing fluid problems involve turbulent flows. The large eddy simulation (LES) method is a major means of studying turbulence. The modified MPS method with the LES method is applied in two-dimensional dam-break problems, which validates the use of the MPS method for solving fluid-structure coupled problems with turbulent flows. By taking the meshless advantage of the MPS method, a preliminary simulation of the plate break problem is carried out, and the simulation results are theoretically verified.

A partitioned fully explicit Lagrangian finite element method for highly nonlinear fluid‐structure interaction problems

SummaryIn this work, a fully explicit partitioned method for the simulation of Fluid Structure Interaction (FSI) problems is presented. The fluid domain is modelled with an explicit Particle Finite Element Method (PFEM) based on the hypothesis of weak compressibility. The Lagrangian description of the fluid is particularly effective in the simulation of FSI problems with free surface flows and large structural displacements, since the fluid boundaries are automatically defined by the position of the mesh nodes. A distinctive feature of the proposed FSI strategy is that the solid domain is modelled using the explicit integration FEM in an off‐the‐shelf commercial software (Abaqus/Explicit). This allows to perform simulations with a complete and advanced description on the structural domain, including advanced structural material models and contact. The structure‐to‐fluid coupling algorithm is based on a technique derived from the Domain Decomposition Methods, namely, the Gravouil and Combescure algorithm. The method allows for arbitrarily large interface displacements using different time incrementation and nonconforming meshes in the different domains, which is an essential feature for the efficiency of an explicit solver involving different materials. The resulting fully explicit and fully lagrangian finite element approach is particularly appealing for the possibility of its efficient application in a large variety of highly non‐linear engineering problems.

Numerical simulation of fluid‐structure interaction problems by a coupled SPH‐FEM approach

AbstractIn scientific computing there is a great interest in numerical simulation of fluid‐structure interaction (FSI) problems. Within this work a numerical approach to simulate fluid‐structure interactions between elastic structures and weakly incompressible fluids is developed. For the fluid part and the solid part the Smoothed Particle Hydrodynamics method (SPH) and the Finite Element Method (FEM) are used, respectively. To transfer the resulting reaction forces from the fluid particles onto the structure's surface two methods are implemented, investigated and compared. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

A novel 2D algorithm for fluid solid interaction based on the smoothed particle hydrodynamics (SPH) method

In this study, a pure Lagrangian algorithm for numerical simulation of fluid-structure interaction problems is proposed based on the Smoothed Particle Hydrodynamics (SPH) method. A new treatment of boundary conditions at the interfaces is introduced that provides the possibility of simultaneous integration of governing equations for all particles, regardless of its material type. The proposed algorithm is capable of dealing with large deformations of hypo elastic solids. The method is validated by comparison of numerical results with other numerical simulations and also examining the consistent behaviors of the algorithm for different parameters.

A SEMI-IMPLICIT APPROACH FOR FLUID-STRUCTURE INTERACTION BASED ON AN ALGEBRAIC FRACTIONAL STEP METHOD

We address the numerical simulation of fluid-structure interaction problems characterized by a strong added-mass effect. We propose a semi-implicit coupling scheme based on an algebraic fractional-step method. The basic idea of a semi-implicit scheme consists in coupling implicitly the added-mass effect, while the other terms (dissipation, convection and geometrical nonlinearities) are treated explicitly. Thanks to this kind of explicit–implicit splitting, computational costs can be reduced (in comparison to fully implicit coupling algorithms) and the scheme remains stable for a wide range of discretization parameters. In this paper we derive this kind of splitting from the algebraic formulation of the coupled fluid-structure problem (after finite-element space discretization). From our knowledge, it is the first time that algebraic fractional step methods, used thus far only for fluid problems in computational domains with rigid boundaries, are applied to fluid-structure problems. In particular, for the specific semi-implicit method presented in this work, we adapt the Yosida scheme to the case of a coupled fluid-structure problem. This scheme relies on an approximate LU block factorization of the matrix obtained after the discretization in time and space of the fluid-structure system. We analyze the numerical performances of this scheme on 2D fluid-structure simulations performed with a simple 1D structure model.

A methodology and computational system for the simulation of fluid-structure interaction problem

In this paper a flexible finite element computational tool developed to investigate fluid-structure interaction applications in two dimensions is described. We consider problems which can be modelled as a viscous incompressible fluid flow and a rigid body-spring system interacting nonlinearly with each other. The coupling is dealt with the use of an interface approach, in which each physics involved is solved with different schemes and the required information is transferred through the interface of both systems. This approach is, at least in principle, very flexible and computationally efficient as the best available scheme can be adopted to solve each physics. Here, a stabilized FEM considering the ALE (Arbitrary Lagrangian-Eulerian) formulation with Crank-Nicholson time-integration is employed for the fluid-dynamics analysis, and the Newmark Method is used for the structural dynamics. Several important tools were incorporated into our system including different possibilities for the mesh movement algorithm, the computational domain decomposition into regions with and without mesh deformation, and the remeshing strategy (either global or local) to keep the necessary mesh quality. As application we present a study of the forced lock-in phenomena and a preliminary investigation on the suppression (or at least the reduction) of the vortex induced vibrations (VIV) on a solid circular cylinder using an idealization of a periodic acoustic excitation.

A comparative study of dynamic mesh updating methods used in the simulation of fluid-structure interaction problems with a non-linear free surface

This paper compares the performance of three mesh movement algorithms: Laplacian smoothing, linear spring analogy and torsion spring analogy for a fluid mesh update in staggered fluid-structure interaction (FSI) simulations with a non-linear free surface. The mesh updating schemes are applied to simulate three representative cases of the above-stated dual moving boundary problem. The performances of the algorithms are gauged on the basis of their ability to delay the initiation of a complete remesh of the fluid domain while maintaining solution accuracy. To satisfy this dual objective, the mesh-updating algorithm should not only prevent mesh failure but should also maintain well-shaped triangles. The reasons for the failure of different schemes are explained and suitable modifications are suggested/implemented to enhance thier performance. It is shown that these modifications prove to be very successful in improving the effectiveness of the algorithms.

A Numerical Method on Cartesian Grid for Image-based Blood Flow Simulation

We have developed a numerical method on Cartesian grid for image-based blood flow simulation. Cartesian grid has advantages for grid generation for the complex and moving boundary problems. Interpolated Differential Operator (IDO) scheme with Local Mesh Refinement method are effectively introduced for blood flow simulations. In order to simulate flow interacting with elastic vessel on Cartesian grid, a new technique INTERGRID has been developed and it is shown that the simulation of fluid-structure interaction problems that structure does not displace over the resolution of grid is carried out.

Dynamic simulation of fluid-structure interaction problems involving large-amplitude sloshing

Dynamic simulation of fluid-structure interaction problems involving large-amplitude sloshing

Analysis and Compensation of Numerical Damping in a One-Dimensional Aeroelastic Problem

In this paper we present analysis methods for a family of staggered schemes that are used in the numerical simulation of fluid-structure interaction problems. The analysis has two goals: to identify the numerical damping errors, in particular those due to the discrete coupling between the fluid and the structure, and to improve the accuracy of the numerical results by compensating these errors. The first analysis method presented is based on the modified equation of the numerical scheme, and the second method is an eigenvector analysis. Both methods provide corrections of the coupled integration schemes in order to eliminate numerical effects, when the system's frequency is known. Other methods are proposed in order to achieve the same goal when this frequency is not known a priori.