FSI Approach Research Articles

Haemodynamics of giant cerebral aneurysm: A comparison between the rigid-wall, one-way and two-way FSI models

In this paper a computer simulation of a blood flow in cerebral vessels with a giant saccular aneurysm at the bifurcation of the basilar artery is performed. The modelling is based on patient-specific clinical data (both flow domain geometry and boundary conditions for the inlets and outlets). The hydrodynamic and mechanical parameters are calculated in the frameworks of three models: rigid-wall assumption, one-way FSI approach, and full (two-way) hydroelastic model. A comparison of the numerical solutions shows that mutual fluid- solid interaction can result in qualitative changes in the structure of the fluid flow. Other characteristics of the flow (pressure, stress, strain and displacement) qualitatively agree with each other in different approaches. However, the quantitative comparison shows that accounting for the flow-vessel interaction, in general, decreases the absolute values of these parameters. Solving of the hydroelasticity problem gives a more detailed solution at a cost of highly increased computational time.

INTRODUCTION TO NUMERICAL ANALYSIS OF DIRECTED FRAGMENTATION WARHEADS

The aim of the paper is to presents one of the possible approaches to the numerical analysis of the behaviour of directed fragmentation war heads. These kinds of warheads consists of: metallic or composite cover, explosive material and a driven and fragmentation liner. The explosives are initiated by a booster causes driving the liner in a few milliseconds up to about 900 m/s. The liner fragments into many parts during this intensive and dynamic load. The fragments move in a cone which dimensions depend on the warheads shape and mechanical parameters of others warheads parts. All of the warheads elements are selected to meet the assumed parameters. The fragments velocity, their mass or geometric dimensions and cone angle are the most important parameters of the warheads fragments. Such a warhead, in the initial phase of the liner driving can be numerically modelled in the field of the continuum damage mechanics. Such a description is presented in other papers. This approach in a further phase of driving cause the increases of inaccuracies. Therefore, this paper proposes the use of ALE and FSI approach to describe the behaviour of the fragmentation warheads. A three-dimensional numerical model of the directed fragmentation warheads was made in the MSC Patran, and the dynamic phenomena analysis used a nonlinear finite element method implemented in the LS-Dyna program.

Study the Effect of Fluid Medium toward Synthetic Cancellous Bone Structure

During daily activities, trabecular bone need to bear certain amount of load which also leads to movement of the bone marrow within the structure. The flow of the bone marrow within the trabecular bone structure cause the shear stress which affect the nutrient transport, the properties of the bone and also the bone fatigue life. The aim of this paper is to simulate the trabecular structure using FSI approach in order to study the effect of the fluid flow to the structure. In this study, idealized model with 50% of porosity was used in the simulation and 1mm displacement applied on top of the model. Three different types of analysis were used in order to differentiate between CFD, CSM and FSI results. The results showed significant value between these analyses was concluded that FSI approaches is the best to mimic the real body condition.

2012 Summer Bioengineering Conference Student Paper Competition

The Bioengineering Division sponsors a Student Paper Competition at the annual Summer Bioengineering Conference (SBC). There are three competition levels: Ph.D., M.S., and B.S. There are also cash awards for the top three student papers in each level. The competition is divided into multiple technical areas to provide for a fair evaluation of student work. We are pleased to recognize the following awardees from the 2012 SBC.First Place: Jeffrey D. Hyypio, University of Minnesota, “A Microscale Collagen-Fibrin Interacting Network Model With Comparison To Experimental Results.”Second Place: Kelly M. Seymour, Elizabethtown College, “Computational Analysis of Microstructure of Ultra High Molecular Weight Polyethylene for Total Joint Replacement.”Third Place: Bethany S. Powell, Valparaiso University, “The Effects of Shoe Architecture on Impact Forces During Gait: A Continuation Study.”First Place: David Schreier, University of Wisconsin “The Role of Collagen Synthesis in Ventricular and Vascular Adaptation to Hypoxic Pulmonary Hypertension.”Second Place: Joseph R. Dolensky, Georgia Tech, “The Effect of Pulmonary Hypertension on Tricuspid Valve Coaptation in Normal and Pathologic Valve Geometries: An in vitro Study.”Third Place: Daniel P. Brown, University of Pittsburgh, “The Effect of Anterior Dislocation on the Mechanical Properties of the Inferior Glenohumeral Ligament.”First Place: Stephanie Beeman, Virginia Tech, “Upper Body Kinematics of Relaxed Volunteers, Braced Volunteers, Hybrid III ATD, and PMHS in Low-Speed Frontal Sled Tests.”Second Place: Jason Miller, University of Washington, “Walking Mode Classification From Myoelectric and Inertial Fusion.”Third Place: Steven Boronyak, Vanderbilt University, “Biomechanical Effects of Radio Frequency Ablation With Simultaneous Cryogenic Anchoring.”First Place: Brianne K. Connizzo, University of Pennsylvania, “Altered Mechanical Properties and Fiber Realignment in Diabetic Mouse Supraspinatus and Achilles Tendons.”Second Place: Lauren Ferris, University of Kansas “A Performance Test to Assess Strategies to Transfer Weight During Knee Flexion and Extension With Rotation for Individuals With a Total Knee.”Third Place: Sarah Wohlman, Northwestern University, “A Biomechanical Model of the Thumb That Effectively Replicates Endpoint Forces Produced by Human Subjects and Measured in Anatomical Specimens.”First Place: Yasutaka Tobe, Waseda University “Investigation on a Relationship Between Hemodynamics and Wall-Thinning in an Unruptured Human Cerebral Aneurysm.”Second Place: Amy Silverstein, University of Pennsylvania, “Mesenchymal Stem Cell Morphology in a Fibrous Microenvironment With Length Scales Matching the Native Meniscus.”Third Place: Haijiao Liu, University of Toronto, “Characterization of the Elasticity of Valve Interstitial Cells on Soft Substrates Using Atomic Force Microscopy.”First Place: Christopher B. Arena, Virginia Tech/Wake Forest, “Phase Change Electrodes for Reducing Joule Heating During Irreversible Electroporation.”Second Place: Zhenpeng Qin, University of Minnesota, “Thermal Analysis Measurement of Gold Nanoparticle Interactions With Cell and Biomaterial.”Third Place: Thomas Claiborne, Stony Brook University, “Development and Optimization of a Novel Polymeric Prosthetic Heart Valve Using the Device Thrombogenicity Emulation Methodology.”First Place: Ian Campbell, Georgia Tech/Emory University, “Histology-Based, Lesion-Specific Modeling of Relative Stress Distributions Indicates Plaque Rupture Unlikely in Mice.”Second Place: Bahar Fata, University of Pittsburgh, “Regional Biomechanical and Microstructural Alterations of the Ovine Main Pulmonary Artery During Postnatal Growth.”Third Place: Lucas H. Ting, University of Washington, “Hemodynamic Shear Regulates Intercellular Forces and Permeability of Endothelial Cell Monolayers.”First Place: Christopher S. Szot, Virginia Tech/Wake Forest, “Characterizing the Phenotypic Response of Endothelial Cells Cultured on Proangiogenic in vitro Tumor Mimics.”Second Place: Bryce Whited, Virginia Tech, “A Nondestructive Fiber-Based Imaging System to Assess Tissue-Engineered Vascular Grafts.”Third Place: Véronique Peiffer, Imperial College London, “Age-Related Differences in Hemodynamics of the Rabbit Aorta and Comparison With Average Maps of Atherosclerotic Lesion Prevalence.”First Place: Sevan R. Oungoulian, Columbia University, “Articular Cartilage Wear Characterization With a Particle Sizing and Counting Analyzer.”Second Place: Andrew Meyer, University of Florida, “Evaluation of a Novel Statistical Method for EMG-to-Moment Estimation During Gait.”Third Place: Ryan Koppes, Rensselaer Polytechnic Institute, “Transient and Steady-State Force Enhancement in the Drosophila Jump Muscle.”First Place: Baptiste Coudrillier, Johns Hopkins University, “Effects of the Scleral Collagen Structure on the Biomechanical Response of the Optic Nerve Head.”Second Place: Michael Fernandez, Columbia University, “Direct Measurement of Human Cervical Tissue Permeability.”Third Place: Stefaan W. Verbruggen, National University of Ireland, Galway, “Loading-Induced Interstitial Fluid Flow in Bone Mechanobiology: An FSI Approach to the Osteocyte Environment.”First Place: Erik H. Clayton, Washington University-St. Louis, “Viscoelastic Properties of Living Human Brain by Local Frequency Estimation Applied to Distortional Wave Fields.”Second Place: Mohammad F. Hadi, University of Minnesota, “Microscale Fiber Network Structure Affects the Simulated Macroscale Failure of Collagen Gel Tissue Analogs.”Third Place: Sudhir Khetan, University of Pennsylvania, “Stem Cell Fate Within 3D Hydogels is Mediated by Network Structure-Dependent Traction Generation.”

Flow Induced Deflection and Stress on Flexible Printed Circuit Board in Fan-Cooled Electronic Systems: FSI Approach

Flexible printed circuit boards (FPCBs) are going to replace rigid boards (PCBs) in numerous electronic devices due to their reduced thickness and ability to bend and adapt to various shapes. Deflection and stress are key factors affecting the reliability of FPCBs. In this paper, the fluid flow solver FLUENT and structural solver ABAQUS, are used to study the deflection and stress induced by axial flow fan on FPCBs, in the fan sucking mode. The flow is assumed to be 3-D, laminar, compressible, and steady. The effect of air flow rate on the force acting on the components mounted on the FPCB is analyzed. In the structural simulation using ABAQUS, the deflection and stress are observed for nine cases of different mounting options of the FPCB, at a fixed air flow rate. The proper selections of air flow rate and mounting option are found to be crucial in minimizing the flow induced deflection and stress in FPCBs.

Rescattering effects in charmless [formula omitted] decays

Final-state interaction effects in charmless B ¯ u , d , s → P P decays are studied. Our main results are as follows: (i) Theoretical results are in agreement with data in the presence of FSI. (ii) The B ¯ → π + π − and π 0 π 0 decay rates are suppressed and enhanced respectively by FSI. (iii) The FSI has large impact on direct CP asymmetries ( A ) of many modes. (iv) The deviation( Δ A ) between A ( B ¯ 0 → K − π + ) and A ( B − → K − π 0 ) can be understood in the FSI approach. (v) Sizable and complex color-suppressed tree amplitudes, which are crucial for the large π 0 π 0 rate and Δ A , are generated through exchange rescattering. (vi) The B − → π − π 0 direct CP violation is very small and is not affected by FSI. (vii) Several B ¯ s decay rates are enhanced. (viii) Time-dependent CP asymmetries S in B ¯ d , s decays are studied. The Δ S ( B ¯ 0 → K S η ′ ) is very small ( ⩽ 1 % ). We found that the asymmetries | S | for B ¯ s 0 → η η , η η ′ and η ′ η ′ decays are all below 0.06.

3D fluid–structure-contact interaction based on a combined XFEM FSI and dual mortar contact approach

Finite deformation contact of flexible solids embedded in fluid flows occurs in a wide range of engineering scenarios. We propose a novel three-dimensional finite element approach in order to tackle this problem class. The proposed method consists of a dual mortar contact formulation, which is algorithmically integrated into an eXtended finite element method (XFEM) fluid–structure interaction approach. The combined XFEM fluid–structure-contact interaction method (FSCI) allows to compute contact of arbitrarily moving and deforming structures embedded in an arbitrary flow field. In this paper, the fluid is described by instationary incompressible Navier–Stokes equations. An exact fluid–structure interface representation permits to capture flow patterns around contacting structures very accurately as well as to simulate dry contact between structures. No restrictions arise for the structural and the contact formulation. We derive a linearized monolithic system of equations, which contains the fluid formulation, the structural formulation, the contact formulation as well as the coupling conditions at the fluid–structure interface. The linearized system may be solved either by partitioned or by monolithic fluid–structure coupling algorithms. Two numerical examples are presented to illustrate the capability of the proposed fluid–structure-contact interaction approach.

Multiscale sequentially-coupled arterial FSI technique

Multiscale versions of the Sequentially-Coupled Arterial Fluid–Structure Interaction (SCAFSI) technique are presented. The SCAFSI technique was introduced as an approximate FSI approach in arterial fluid mechanics. It is based on the assumption that the arterial deformation during a cardiac cycle is driven mostly by the blood pressure. First we compute a “reference” arterial deformation as a function of time, driven only by the blood pressure profile of the cardiac cycle. Then we compute a sequence of updates involving mesh motion, fluid dynamics calculations, and recomputing the arterial deformation. The SCAFSI technique was developed and tested in conjunction with the stabilized space–time FSI (SSTFSI) technique. Beyond providing a computationally more economical alternative to the fully coupled arterial FSI approach, the SCAFSI technique brings additional flexibility, such as being able to carry out the computations in a spatially or temporally multiscale fashion. In the test computations reported here for the spatially multiscale versions of the SCAFSI technique, we focus on a patient-specific middle cerebral artery segment with aneurysm, where the arterial geometry is based on computed tomography images. The arterial structure is modeled with the continuum element made of hyperelastic (Fung) material.

Sequentially-Coupled Arterial Fluid–Structure Interaction (SCAFSI) technique

The Sequentially-Coupled Arterial Fluid–Structure Interaction (SCAFSI) technique is one of the special techniques developed recently by the Team for Advanced Flow Simulation and Modeling (T☆AFSM) for FSI modeling of blood flow and arterial dynamics. The SCAFSI technique, which was introduced as an approximate FSI approach in arterial fluid mechanics, is based on the assumption that the arterial deformation during a cardiac cycle is driven mostly by the blood pressure. In the SCAFSI, first we compute a “reference” arterial deformation as a function of time, driven only by the blood pressure profile of the cardiac cycle. Then we compute a sequence of updates involving mesh motion, fluid dynamics calculations, and recomputing the arterial deformation. Although the SCAFSI technique was developed and tested in conjunction with the stabilized space–time FSI (SSTFSI) technique, it can also be used in conjunction with other FSI modeling techniques categorized as moving-mesh methods. The SSTFSI technique is based on the Deforming-Spatial-Domain/Stabilized Space–Time (DSD/SST) formulation and includes the enhancements introduced recently by the T☆AFSM. The arterial structures can be modeled with the membrane or continuum elements, both of which are geometrically nonlinear, and the continuum element can be made of linearly-elastic or hyperelastic material (Mooney–Rivlin or Fung). Here we provide an overview of the SCAFSI technique and present a number of test computations for abdominal aortic and cerebral aneurysms, where the arterial geometries used in the computations are close approximations to the patient-specific image-based data.

Arterial fluid mechanics modeling with the stabilized space–time fluid–structure interaction technique

AbstractWe present an overview of how the arterial fluid mechanics problems can be modeled with the stabilized space–time fluid–structure interaction (SSTFSI) technique developed by the Team for Advanced Flow Simulation and Modeling (T★AFSM). The SSTFSI technique includes the enhancements introduced recently by the T★AFSM to increase the scope, accuracy, robustness and efficiency of this class of techniques. The SSTFSI technique is supplemented with a number of special techniques developed for arterial fluid mechanics modeling. These include a recipe for pre‐FSI computations that improve the convergence of the FSI computations, using an estimated zero‐pressure arterial geometry, and the sequentially coupled arterial FSI (SCAFSI) technique. The recipe for pre‐FSI computations is based on the assumption that the arterial deformation during a cardiac cycle is driven mostly by the blood pressure. The SCAFSI technique, which was introduced as an approximate FSI approach in arterial fluid mechanics, is also based on that assumption. The need for an estimated zero‐pressure arterial geometry is based on recognizing that the patient‐specific image‐based geometries correspond to time‐averaged blood pressure values. In our arterial fluid mechanics modeling the arterial walls can be represented with the membrane or continuum elements, both of which are geometrically nonlinear, and the continuum element is made of hyperelastic (Fung) material. Test computations are presented for cerebral and abdominal aortic aneurysms, where the arterial geometries used in the computations are close approximations to the patient‐specific image‐based data. Copyright © 2007 John Wiley & Sons, Ltd.