Parallel Analysis of Incompressible Flow and Structure Interaction Using Partitioned Iterative Method

Body-fitted and Cartesian grid methods are two typical types of numerical approaches used for modelling fluid–structure interaction problems. Despite their extensive applications, there is a lack of comparing the performance of these two types of approaches. In order to do this, the present paper presents benchmark numerical solutions for two two-dimensional fluid–structure interaction problems: flow-induced vibration of a highly flexible plate in an axial flow and a pitching flexible plate. The solutions are obtained by using two partitioned fluid–structure interaction methods including the deforming-spatial-domain/stabilized space–time fluid–structure interaction solver and the immersed boundary–lattice Boltzmann method. The deforming-spatial-domain/stabilized space–time fluid–structure interaction solver employs the body-fitted-grid deforming-spatial-domain/stabilized space–time method for the fluid motions and the finite-difference method for the structure vibrations. A new mesh update strategy is developed to prevent severe mesh distortion in cases where the boundary does not oscillate periodically or needs a long time to establish a periodic motion. The immersed boundary–lattice Boltzmann method uses lattice Boltzmann method as fluid solver and the same finite-difference method as structure solver. In addition, immersed boundary method is used in the immersed boundary–lattice Boltzmann solver to handle the fluid–structure interaction coupling. Results for the characteristic force coefficients, tail position, plate deformation pattern and the vorticity fields are presented and discussed. The present results will be useful for evaluating the performance and accuracy of existing and new numerical methodologies for fluid–structure interaction.

The objective of this brief review is to showcase recent applications of sharp-interface immersed boundary (IB) method to computationally challenging problems in fluid–structure interaction (FSI). The sharp-interface IB method is briefly reviewed and a scheme to strongly couple the flow and structural solver is discussed. The following applications have been discussed. First, the vortex-induced vibration of a cylinder has been presented. Second, FSI benchmarks of an elastic and a viscoelastic splitter attached on a cylinder involving large-scale flow-induced deformation have been presented. Third, numerical simulations of a FSI benchmark in a heated channel, demonstrating augmentation in convective heat transfer, have been reviewed. Finally, the flow-induced deformation of a thin elastic plate due to blast loading has been presented. In all of these FSI problems, the IB method has been successfully employed to simulate the coupled fluid and structural dynamics.

Key Words: Fluid-Structure Coupled Analysis(유체-구조연계해석), Low-Pressure Turbine(저압터빈), SweptbackWing(후퇴익), NASA Rotor 37초록: 본논문에서는, 운전조건에서의저압최종단블레이드에대하여약결합유체-구조연계해석기법을이용한해석이수행되었다. 저압터빈최종단에대한해석이전에경계조건에대한검증을위하여15도후퇴익과NASARotor 37을대상으로예비해석이수행되었다. 각각의해석결과들을기존문헌들과비교하였다. 15도후퇴익에대한안정상태와불안정상태에서동적FSI해석이수행되었다. 해석결과변위가일정한안정상태에비하여고속에서는0.05 초만에발산하는결과를산출하였다. NASA Rotor 37의정상상태해석결과를바탕으로정적·동적FSI해석을수행하여뒷전의변형크기에대하여정적FSI 결과와동적FSI간의차이가있음을확인하였다. 저압최종단블레이드의형상측정및동특성시험을바탕으로해석모델을생성하였다. 이를바탕으로, 운전조건에서저압최종단블레이드에대한정적유체-구조연계해석을성공적으로수행하였다.Abstract: In this study, a loosely coupled fluid-structure interaction (FSI) analysis was conducted for a low-pressure(LP) final-stage rotor blade. Preliminary FSI analyses of a 15° sweptback wing and a NASA Rotor 37 compressorblade were performed for verifying the boundary conditions. The results were compared with the established literaturesfor each model. The FSI analysis of the 15° sweptback wing was carried out under both stable and unstableconditions. The excessive deformation of the wing was observed within 0.05 s under the unstable condition which ishigher than the divergence speed of a wing compared with the stable condition. On the basis of the results of asteady-state study, an unsteady state FSI analysis was conducted for a NASA Rotor 37. Different deformations wereobserved at trailing edge of the blade in the static FSI and dynamic FSI analysis. A 3D FE model of a LP rotor wasgenerated from the span-wise section data. In order to develop a reasonable model, an impact test was performed andcompared to the FE model. Using this FE model, the steady-state FSI analysis was performed successfully.

<abstract> <bold>Abstract.</bold> Pressure-compensating (PC) emitters can maintain a constant discharge within a wide range of working pressures, thus they have extensive application prospect in mountain regions where the hydraulic pressure in irrigation systems often changes greatly. Although the rapid design method for non-PC emitters based on CFD is quite mature at present, common CFD method is not suitable for the design of PC emitters because there exists a two-way coupling interaction between the fluid flow and elastic diaphragm. In order to improve the design accuracy and efficiency of PC emitters, the fluid-structure interaction (FSI) analysis was studied in this paper. In the FSI analysis procedure, adaptive mesh repair was adopted to refine the distorted fluid mesh. Incremental method and displacement-pressure finite element formula were used for the nonlinear analysis of the incompressible material. In this paper, SST K-ω turbulence model was used for the fluid analysis, while contact analysis method and Neo-Hookean Mooney-Rivlin rubber material model were adopted for the structure analysis. The results showed that the discharge was adjusted by a very small deformation of the diaphragm to reach a steady state. At last, compared with the test results carried out using the test samples made by rapid prototyping, the analyzed values were a little larger while the maximum relative deviation was within 2.5%. This verified that PC emitter's discharge could be predicted by FSI analysis accurately. In conclusion, FSI analysis is an efficient way to improve the design accuracy and reduce the test times for PC emitters.

A high-order fluid–structure interaction framework with application to shock-wave/turbulent boundary-layer interaction over an elastic panel

Numerical simulation of the fluid–structure interaction for two simple fuel assemblies

The present study introduces a Gauss-Seidel fluid-structure interaction (FSI) method including the flow solver, structural statics solver and a fast data transfer technique, for the research of structural deformation and flow field variation of rotor blades under the combined influence of steady aerodynamic and centrifugal forces. The FSI method is illustrated and validated by the static aeroelasticity analysis of a transonic compressor rotor blade, NASA Rotor 37. An improved local interpolation with data reduction (LIWDR) algorithm is introduced for fast data transfer on the fluid-solid interface of blade. The results of FSI calculation of NASA Rotor 37 show that when compared with the radial basis function (RBF) based interpolation algorithm, LIWDR meets the interpolation accuracy requirements, while the calculation cost can be greatly improved. The data transmission time is only about 1% of that of RBF. Moreover, the iteration step of steady flow computation within one single FSI has little impact on the converged aerodynamic and structural results. The aerodynamic load-caused deformation accounts for nearly 50% of the total. The effects of blade deformation on the variations of aerodynamic performance are given, demonstrating that when static aeroelasticity is taken into account, the choke mass flow rate increases and the peak adiabatic efficiency slightly decreases. The impact mechanisms on performance variations are presented in detail.

Modeling concept and numerical simulation of ultrasonic wave propagation in a moving fluid-structure domain based on a monolithic approach

Numerical Simulation of Oil Tank Behavior Under Seismic Excitation. Fluid – Structure Interaction Problem Solution

Transcatheter aortic valve replacement (TAVR) is a minimally invasive procedure that provides an effective alternative to open-heart surgical valve replacement for treating advanced calcific aortic valve disease patients. However, complications, such as valve durability, device migration, paravalvular leakage (PVL), and thrombogenicity may lead to increased overall post-TAVR morbidity and mortality. A series of numerical studies involving a self-expandable TAVR valve were performed to evaluate these complications. Structural studies were performed with finite element (FE) analysis, followed by computational fluid dynamics (CFD) simulations, and fluid-structure interaction (FSI) analysis. The FE analysis was utilized to study the effect of TAVR valve implantation depth on valve anchorage in the Living Heart Human Model, which is capable of simulating beating heart during repeated cardiac cycles. The TAVR deployment cases where no valve migration was observed were then used to calculate the post-deployment thrombogenic potential via CFD simulations. FSI analysis followed to further assess the post-deployment TAVR hemodynamic performance for different implantation depths. The deployed valves PVL, geometric and effective orifice areas, and the leaflets structural and flow stress magnitudes were compared to determine the device optimal landing zone. The combined structural and hemodynamic analysis indicated that with the TAVR valve deployed at an aft ventricle position an optimal performance was achieved in the specific anatomy studied. Given the TAVR's rapid expansion to younger lower-risk patients, the comprehensive numerical methodology proposed here can potentially be used as a predictive tool for both procedural planning and valve design optimization to minimize the reported complications.

A strong-coupled method combined finite element method and lattice Boltzmann method via an implicit immersed boundary scheme for fluid structure interaction

Inflatable aerodynamic decelerators are being developed as a new technology for atmospheric reentry. Flexible aeroshells have been observed to deform under aerodynamic loads, and to investigate their behavior, fluid-structure interaction (FSI) analysis that considers the coupling between high enthalpy flow and structural flexibility is appropriate. This study investigated the FSI behavior of a flexible aeroshell in the supersonic regime, where compression effects are prominent, with the objective of elucidating the influence of structural deformation on the resulting aerodynamic forces. Numerical simulations were conducted with and without structural deformation under two angle-of-attack (AOA) conditions. The results showed that at non-zero AOA, asymmetric deformation of the structure, caused noticeable changes in the flow and aerodynamic forces. In contrast, at zero AOA, the influence of structural flexibility was relatively small. These findings indicate that FSI analysis is especially important for accurately evaluating flexible aeroshells in supersonic flows under inclined flight conditions.

A phase-field/ALE method for simulating fluid–structure interactions in two-phase flow

In this contribution, we discuss the pros and cons of using the Smoothed Particle Hydrodynamics (SPH) method in providing support to multiphysics simulations. The Lagrangian SPH method is proposed to address a fluid-structure interaction (FSI) problem in which the response of a flexible baffle with elastic behavior is solved by using three modeling strategies: I) a dynamic structural solver of 3D bonded rigid bodies with rotations, based on a Lumped-Parameter Method (LPM); II) a non-linear Finite Element Method structural solver (FEM), based on the Euler-Bernoulli beam model; and III) a unified SPH-based for continuum mechanics based on a Total Lagrangian formulation. The present work uses the open-source code DualSPHysics as the fluid solver and different options now available in this code to represent flexible structures. The FSI simulated process starts with a gravity-driven fluid mass that hits a flexible plate experiences wide motion excursions (comparable to its length) in a relatively short time. The fluid phase is consistently solved with a weakly compressible SPH-based solver, whereas the three solution strategies are used to model the flexibility of the solid element. By discussing the the computational performance, and the solvers particle resolution sensitivity, the outcome of this research enables understanding the requirements of each software implementation to optimize the performance scalability.

From the Editor