caa a22 4500 469122390 CHVBK 20180323133142.0 cr unu---uuuuu 170328e19920101xx s 000 0 eng 10.1007/BF02368507 doi (NATIONALLICENCE)springer-10.1007/BF02368507 Computational fluid dynamics of left ventricular ejection [Elektronische Daten] [John Georgiadis, Mingyu Wang, Ares Pasipoularides] The present investigation addresses the effects of simple geometric variations on intraventricular ejection dynamics, by methods from computational fluid dynamics. It is an early step in incorporating more and more relevant characteristics of the ejection process, such as a continuously changing irregular geometry, in numerical simulations. We consider the effects of varying chamber eccentricities and outflow valve orifice-to-inner surface area ratios on instantaneous ejection gradients along the axis of symmetry of the left ventricle. The equation of motion for the streamfunction was discretized and solved iteratively with specified boundary conditions on a boundary-fitted adaptive grid, using an alternating-direction-implicit (ADI) algorithm. The unsteady aspects of the ejection process were subsequently introduced into the numerical simulation. It was shown that for given chamber volume and outflow orifice area, higher chamber eccentricities require higher ejection pressure gradients for the same velocity and local acceleration values at the aortic anulus than more spherical shapes. This finding is referable to the rise in local acceleration effects across the outflow axis. This is to be contrasted with the case of outflow orifice stenosis, in which it was shown that it is the convective acceleration effects that are intensified strongly. Pergamon Press plc, 1992 Cardiac fluid dynamics nationallicence Computational fluid dynamics nationallicence Intracardiac ejection flow nationallicence Alternating direction implicit algorithm nationallicence Intraventricular pressure gradients nationallicence Boundary fitted adaptive grid nationallicence Unsteady flow nationallicence h : grid size in computational domain nationallicence J : Jacobian of coordinate transformation nationallicence P,Q : control function for grid generation nationallicence r : radial coordinate (r=x) nationallicence u : velocity component in radial direction nationallicence U : average velocity nationallicence v : velocity component in axial direction nationallicence x,y : radial, axial coordinate, respectively nationallicence f x : ϖf/ϖx, partial derivative off with respect tox nationallicence α : x η 2 +y η 2 nationallicence β : x ξ x η+y ξ y η nationallicence γ : x ξ 2 +y ξ 2 nationallicence ξ, η : coordinates in the computational domain nationallicence Ψ : stream function nationallicence Georgiadis John The Departments of Mechanical Engineering and Biomedical Engineering School of Engineering, Duke University, Durham, NC aut Wang Mingyu The Departments of Mechanical Engineering and Biomedical Engineering School of Engineering, Duke University, Durham, NC aut Pasipoularides Ares The Departments of Mechanical Engineering and Biomedical Engineering School of Engineering, Duke University, Durham, NC aut Annals of Biomedical Engineering Kluwer Academic Publishers 20/1(1992-01-01), 81-97 0090-6964 20:1<81 1992 20 10439 https://doi.org/10.1007/BF02368507 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF02368507 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Georgiadis John The Departments of Mechanical Engineering and Biomedical Engineering School of Engineering, Duke University, Durham, NC aut NATIONALLICENCE 700 1- Wang Mingyu The Departments of Mechanical Engineering and Biomedical Engineering School of Engineering, Duke University, Durham, NC aut NATIONALLICENCE 700 1- Pasipoularides Ares The Departments of Mechanical Engineering and Biomedical Engineering School of Engineering, Duke University, Durham, NC aut NATIONALLICENCE 773 0- Annals of Biomedical Engineering Kluwer Academic Publishers 20/1(1992-01-01), 81-97 0090-6964 20:1<81 1992 20 10439 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer