scholarly journals An error estimator for transmitting boundary conditions in fluid-structure interaction problems

2011 ◽  
Author(s):  
N. Bouaanani ◽  
B. Miquel
Keyword(s):  
Boundary Conditions ◽  
Fluid Structure Interaction ◽  
Error Estimator ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Transmitting Boundary

Goal-Oriented Mesh Adaptivity for Fluid-Structure Interaction with Application to Heart-Valve Settings

2012 ◽  
Vol 59 (1) ◽  
pp. 73-99 ◽  
Author(s):  
Thomas Wick
Keyword(s):  
Heart Valve ◽  
Fluid Structure Interaction ◽  
Computational Cost ◽  
Coupling Scheme ◽  
Error Estimator ◽  
Computational Domain ◽  
Mesh Adaptivity ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Mesh Adaption

Goal-Oriented Mesh Adaptivity for Fluid-Structure Interaction with Application to Heart-Valve SettingsWe apply a fluid-structure interaction method to simulate prototypical dynamics of the aortic heart-valve. Our method of choice is based on a monolithic coupling scheme for fluid-structure interactions in which the fluid equations are rewritten in the ‘arbitrary Lagrangian Eulerian’ (ALE) framework. To prevent the backflow of structure waves because of their hyperbolic nature, a damped structure equation is solved on an artificial layer that is used to prolongate the computational domain. The increased computational cost in the presence of the artificial layer is resolved by using local mesh adaption. In particular, heuristic mesh refinement techniques are compared to rigorous goal-oriented mesh adaption with the dual weighted residual (DWR) method. A version of this method is developed for stationary settings. For the nonstationary test cases the indicators are obtained by a heuristic error estimator, which has a good performance for the measurement of wall stresses. The results for prototypical problems demonstrate that heart-valve dynamics can be treated with our proposed concepts and that the DWR method performs best with respect to a certain target functional.

scholarly journals Fluid-Structure Interaction Modeling of Abdominal Aortic Aneurysms: The Impact of Patient-Specific Inflow Conditions and Fluid/Solid Coupling

2013 ◽  
Vol 135 (8) ◽  
Author(s):  
Santanu Chandra ◽  
Samarth S. Raut ◽  
Anirban Jana ◽  
Robert W. Biederman ◽  
Mark Doyle ◽  
...  
Keyword(s):  
Velocity Profile ◽  
Boundary Conditions ◽  
Fluid Structure Interaction ◽  
Aortic Aneurysms ◽  
Patient Specific ◽  
Fluid Structure ◽  
Inlet Velocity ◽  
Structure Interaction ◽  
Biomechanical Assessment ◽  
Fully Coupled

Rupture risk assessment of abdominal aortic aneurysms (AAA) by means of biomechanical analysis is a viable alternative to the traditional clinical practice of using a critical diameter for recommending elective repair. However, an accurate prediction of biomechanical parameters, such as mechanical stress, strain, and shear stress, is possible if the AAA models and boundary conditions are truly patient specific. In this work, we present a complete fluid-structure interaction (FSI) framework for patient-specific AAA passive mechanics assessment that utilizes individualized inflow and outflow boundary conditions. The purpose of the study is two-fold: (1) to develop a novel semiautomated methodology that derives velocity components from phase-contrast magnetic resonance images (PC-MRI) in the infrarenal aorta and successfully apply it as an inflow boundary condition for a patient-specific fully coupled FSI analysis and (2) to apply a one-way–coupled FSI analysis and test its efficiency compared to transient computational solid stress and fully coupled FSI analyses for the estimation of AAA biomechanical parameters. For a fully coupled FSI simulation, our results indicate that an inlet velocity profile modeled with three patient-specific velocity components and a velocity profile modeled with only the axial velocity component yield nearly identical maximum principal stress (σ1), maximum principal strain (ε1), and wall shear stress (WSS) distributions. An inlet Womersley velocity profile leads to a 5% difference in peak σ1, 3% in peak ε1, and 14% in peak WSS compared to the three-component inlet velocity profile in the fully coupled FSI analysis. The peak wall stress and strain were found to be in phase with the systolic inlet flow rate, therefore indicating the necessity to capture the patient-specific hemodynamics by means of FSI modeling. The proposed one-way–coupled FSI approach showed potential for reasonably accurate biomechanical assessment with less computational effort, leading to differences in peak σ1, ε1, and WSS of 14%, 4%, and 18%, respectively, compared to the axial component inlet velocity profile in the fully coupled FSI analysis. The transient computational solid stress approach yielded significantly higher differences in these parameters and is not recommended for accurate assessment of AAA wall passive mechanics. This work demonstrates the influence of the flow dynamics resulting from patient-specific inflow boundary conditions on AAA biomechanical assessment and describes methods to evaluate it through fully coupled and one-way–coupled fluid-structure interaction analysis.

FLUID STRUCTURE INTERACTION AND ADMITTANCE BOUNDARY CONDITIONS: SETUP OF AN ANALYTICAL EXAMPLE

2011 ◽  
Vol 19 (01) ◽  
pp. 63-74 ◽  
Author(s):  
STEFFEN MARBURG ◽  
ROBERT ANDERSSOHN
Keyword(s):  
Boundary Conditions ◽  
Fluid Model ◽  
Fluid Structure Interaction ◽  
Interaction Model ◽  
Structural Elements ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Admittance Matrix ◽  
Simulation Techniques ◽  
Starting Point

Often, acoustic simulation techniques suffer from errors of the computational model and its parameters. Quantification of the boundary condition is a crucial point for simulations. In particular, the boundary admittance is often unknown and hard to quantify. This article demonstrates how to reduce a fluid-structure interaction model to a pure fluid model with local or nonlocal admittance boundary conditions. Starting point is a BEM formulation for the fluid and a FEM formulation for the structure. An admittance matrix is derived from this formulation. Then, the multidimensional BEM–FEM formulation is adjusted to a one-dimensional example, a duct with structural elements at both ends. Two configurations are investigated, one with local admittance boundary conditions and one with nonlocal admittance boundary conditions which result in a diagonal and in a fully populated admittance matrix, respectively.

Boundary Conditions for Fluid-Structure Interaction

2016 ◽  
pp. 433-491
Author(s):  
Timm Krüger ◽  
Halim Kusumaatmaja ◽  
Alexandr Kuzmin ◽  
Orest Shardt ◽  
Goncalo Silva ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Fluid Structure Interaction ◽  
Fluid Structure ◽  
Structure Interaction

scholarly journals Analysis and Optimisation of Thermo-Mechanical Coupling Load of Cylinder Head Considering Fluid-Structure Interaction for a Marine High-Power Diesel Engine

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3597
Author(s):  
Lei Hu ◽  
Jianguo Yang ◽  
Yonghua Yu ◽  
Fei Dong
Keyword(s):  
Diesel Engine ◽  
Boundary Conditions ◽  
Cylinder Head ◽  
Fluid Structure Interaction ◽  
Cooling Water ◽  
Fluid Structure ◽  
Mechanical Coupling ◽  
Structure Interaction ◽  
Fuel Supply ◽  
Valve Opening

A one-dimensional model of the diesel engine working process was established, and thermal boundary conditions of gases contacting with a cylinder head were determined by comparing them with the results of a routine test. A fluid-structure interaction model between the cooling water and cylinder head passages was established in which boundary conditions of cooling water were obtained by computational fluid dynamics analysis. Simultaneously, considering the pressure mechanical load in the cylinder, temperature and the stress distribution of the cylinder head were analysed by the model with a thermo-mechanical coupling load. The model was validated using the temperature hardness plug method. Four parameters of intake valve opening, exhaust valve opening, fuel supply beginning, and compression ratio were selected as influencing factors, and the thermo-mechanical coupling load of the cylinder head was optimised by the Taguchi and analysis of variance method subsequently. The study indicates that the error of the calculation model for the cylinder head’s thermal-mechanical coupling load is within ±1.5%, and the proportion of the thermal stress in the cylinder head thermal-mechanical coupling stress is above 90%. The fuel supply beginning has the greatest influence on the thermal load of the cylinder head. Based on the optimisation methods within the required power range, the maximum temperature and maximum thermo-structural coupling stress of the cylinder head are decreased by about 10.05 K and 7.13 MPa in the nose bridge area, respectively.

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