Advanced FSI Simulation for Extreme Events Using Isogeometric Techniques

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1 Advanced FSI Simulation for Extreme Events Using Isogeometric Techniques Y. Bazilevs Structural Engineering University of California, San Diego Collaborators: I. Akkerman, D.J. Benson, X. Deng, M.- C. Hsu, A. Korobenko, C.C. Long, A.L. Marsden, J. Yan

2 Isogeometric Analysis (IGA)! Hughes, Cottrell, and YB. First paper appeared in the Fall 2005! Based on technologies (e.g., NURBS, T-splines) from computational geometry used in:! Design (CAD)! Animation (CG)! Visualization (CG)! IGA = Exact geometry + the isoparametric concept in FEM! Includes standard FEA as a special case, but offers other possibilities:! Precise and efficient geometric modeling! Simplified mesh refinement! Superior approximation properties! Smooth basis functions! Integration of design and analysis

3 IGA Book (2009)! NURBS-based! Historical references! Fundamentals and tutorials! Includes details that are not in the papers! Pieces of code for! Basis function evaluation! NURBS data structures! Stiffness matrix assembly! Applications! Research directions

4 FSI! Moving-mesh method! ALE for fluid and Lagrangian for structure! Boundary-layer resolution! Fluid mesh moving/remeshing! Nonmatching discretization! IGA for structural mechanics! FEM or IGA for fluid mechanics " Volumetric meshing still remains an area of active research, so take advantage of automatic mesh generation! Additional challenges for quasi-direct coupling (necessary for some applications)! Exploring immersed FSI techniques for air-blast FSI applications! Techniques developed and implemented in an in-house parallel FSI solver! Explore customized solutions for industry and lab partners

5 Offshore Wind Turbine (62m Blade) 2000 Gearbox Rotor Hub Mass per unit length (kg/m) SNL ---- IGA Blade fraction Shaft Blade layout (composite laminate) Tower Mode (Hz) IGA: M1/M2/M3 Ref. 1 st Flapwise Bending 0.456/0.454/ st Edgewise Bending 0.681/0.679/

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7 Azimuth, FSI with yawing FSI without yawing NREL 5000 Aerodynamic torque Aerodynamic Torque, kn*m Omega, rad/s Azimuth, Rotor speed Time, s Time, s

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10 FSI of PVADs! Blood clots in up to 40% of pediatric patients! Too risky as destination therapy! Used as bridge to transplant! Need improvements in design Air Chamber Blood Chamber Prescribed flow rate: defines fill and eject stages Thin Flexible Membrane Outlets: either closed or open to resistance BCs. Valves not modeled Berlin Heart PVAD Membrane properties of the Penn State Device (Private communication with K. Manning, Bioengineering Department, Penn State)

11 Berlin Heart PVAD

12 PVAD Shape Op8miza8on in the Presence of FSI

13 Simulation of Heart Valves Valvular heart disease is a significant cause of mortality. Currently, valve repair and replacement are the only available treatments. Major drawback of mechanical heart valves is patients require anti-coagulation therapy. Clots formed by red blood cell and platelet damage can block flow in blood vessels.

14 Bioprosthetic Heart Valves Replacement heart valves are fabricated from biologically derived materials - bioprosthetic heart valves (BHVs). Functional properties close to native valves. Life of BHVs limited to years, with failure resulting from leaflet structural deterioration, mediated by fatigue and tissue mineralization. To improve BHV design important to understand the stress levels in the leaflets FSI is indispensible.

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16 FSI Book (2013) WILEY SERIES IN COMPUTATIONAL MECHANICS Computational Fluid-Structure Interaction Methods and Applications Yuri Bazilevs, Kenji Takizawa and Tayfun E. Tezduyar! Fundamentals of fluid and structural mechanics! Basics of FEM and IGA! Formulation of the coupled FSI problems at the continuous and discrete level! ALE and Space-Time FSI techniques! Treatment of nonmatching FSI discretizations! FSI coupling strategies! Basic examples and advanced applications from the authors research