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SUMMARY:Prosthetic aortic valve performance assessment: FSI simulations\, 
 spectral analysis and FTLE-based calcification prediction
DTSTART:20260310T161500
DTEND:20260310T170000
DTSTAMP:20260510T054708Z
UID:9592c7a48e17bb04221222814753a68fe0790a266770b0c67499ee37
CATEGORIES:Conferences - Seminars
DESCRIPTION:Pascal Corso\, Dr sc. ETH Zurich & MSc Mech. Eng.\n \nCalcifi
 c aortic valve leaflet degeneration remains a main cause of bioprosthetic 
 aortic valve failure and disturbed blood flow dynamics. This talk presents
  a computational framework combining high-order fluid-structure interactio
 n (FSI) simulations with dedicated spectral and Lagrangian analyses to cha
 racterise post-valvular flow disturbances and identify calcification-prone
  regions on valve leaflets.\nThe numerical FSI approach couples a sixth-or
 der finite-difference Navier–Stokes solver with a finite-element elastod
 ynamics formulation through variational L²-projection\, ensuring velocity
  and force continuity at the fluid-solid interface (Nestola et al.\, J. Co
 mput. Phys.\, 2019). Simulations capture transitional aortic flows at orif
 ice Reynolds number of 3\,800 as well as valve motion. The results have be
 en validated against tomographic particle image velocimetry and 4D Flow MR
 I measurements.\nThree-dimensional kinetic energy spectra are computed via
  FFT on concentric spherical shells positioned downstream of the valvular 
 orifice (Corso et al.\, Comput. Biol. Med.\, 2024). For a severe calcific 
 aortic stenosis\, the spectral decay follows Kolmogorov's -5/3 scaling acr
 oss a broad wavenumber range\, indicating canonical turbulent cascade. Bio
 prosthetic configurations characterised by large leaflet displacements thr
 oughout systole deviate from this behaviour\, suggesting that leaflet-moti
 on-induced helical flow structures partially suppress nonlinear energy tra
 nsfer. Novel field quantities\, namely modal kinetic energy anisotropy and
  normalised helicity intensity\, are introduced and shown to correlate inv
 ersely\, with correlation strength varying markedly across valve configura
 tions depending on leaflet kinematics.\nFor calcification prediction\, str
 ain-based finite-time Lyapunov exponents (FTLE) and wall shear stress (WSS
 ) fields are evaluated on leaflet surfaces from FSI results. Unsupervised 
 clustering (k-means) on these features enables objective risk stratificati
 on and calcific area prediction across tissue and polymeric valve configur
 ations\, with validation against micro-CT maps from explanted clinical spe
 cimens (Tsolaki\, Corso et al.\, Acta Biomater.\, 2023).\nThe talk conclud
 es with perspectives on integrating these diagnostic metrics into a Bayesi
 an optimisation loop for next-generation polymeric valve design.
LOCATION:CM 1 517 https://plan.epfl.ch/?room==CM%201%20517
STATUS:CONFIRMED
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