" Compitational Fluid Flow Dynamic Analysis on I.C Engine using ANSYS"

Abstract Background and Objectives Provisional and culotte are the most commonly used techniques in left main (LM) stenting. The impact of different post-dilation techniques on fluid dynamic of LM bifurcation has not been yet investigated. The aim of this study is to evaluate, by means of computational fluid dynamic analysis (CFD), the impact of different post-dilation techniques including proximal optimization technique (POT), kissing balloon (KB), POT-Side-POT and POT–KB-POT, 2-steps Kissing (2SK) and Snuggle Kissing balloon (SKB) on flow dynamic profile after LM provisional or culotte stenting. Methods We considered an LM-LCA-LCX bifurcation reconstructed after reviewing 100 consecutive patients (mean age 71.4 ± 9.3 years, 49 males) with LM distal disease. The diameters of LAD and LCX were modelled according to the Finnet’s law as following: LM 4.5 mm, LAD 3.5 mm, LCX 2.75 mm, with bifurcation angle set up at 55°. Xience third-generation stent (Abbot Inc., USA) was reconstructed and virtually implanted in provisional/cross-over and culotte fashion. POT, KB, POT-side-POT, POT-KB-POT, 2SK and SKB were virtually applied and analyzed in terms of the wall shear stress (WSS). Results Analyzing the provisional stenting, the 2SK and KB techniques had a statistically significant lower impact on the WSS at the carina, while POT seemed to obtain a neutral effect. In the wall opposite to the carina, the more physiological profile has been obtained by KB and POT with higher WSS value and smaller surface area of the lower WSS. In culotte stenting, at the carina, POT-KB-POT and 2SK had a very physiological profile; while at the wall opposite to the carina, 2SK and POT–KB-POT decreased significantly the surface area of the lower WSS compared to the other techniques. Conclusion From the fluid dynamic point of view in LM provisional stenting, POT, 2SK and KB showed a similar beneficial impact on the bifurcation rheology, while in LM culotte stenting, POT-KB-POT and 2SK performed slightly better than the other techniques, probably reflecting a better strut apposition.

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A flash photography method for the measurements of the fluid flow dynamic of a fluid dispensing system

Measurement ◽

10.1016/j.measurement.2017.01.050 ◽

2017 ◽

Vol 102 ◽

pp. 57-63 ◽

Cited By ~ 1

Author(s):

S. Boonsang ◽

W. Lertkittiwattanakul

Keyword(s):

Fluid Flow ◽

Flow Dynamic ◽

Fluid Dispensing ◽

Photography Method

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Flow Dynamic Analysis by Contrast-Enhanced Imaging Techniques of Medium Cutoff Membrane Hemodialyzer

Blood Purification ◽

10.1159/000516411 ◽

2021 ◽

pp. 1-9

Author(s):

Anna Lorenzin ◽

Gianlorenzo Golino ◽

Massimo de Cal ◽

Giordano Pajarin ◽

Sergio Savastano ◽

...

Keyword(s):

Blood Flow ◽

Dynamic Analysis ◽

Imaging Techniques ◽

Nuclear Imaging ◽

Theoretical Explanation ◽

Flow Dynamic ◽

Effective Removal ◽

Middle Molecules ◽

New Perspective ◽

End Stage

Introduction: Medium cutoff (MCO) membranes represent an interesting innovation in the field of hemodialysis. Given the correlation between large (PM >25 kDa) middle molecules (LMM) and clinical outcomes, the possibility to broaden the spectrum of solutes removed in hemodialysis with MCO membranes introduces a new perspective for end-stage kidney disease patients. Due to low diffusion coefficients of LMM, the use of convection is required to maximize extracorporeal clearance. High convective rates are achieved with high-flux membranes in hemodiafiltration, a technique not available in the US. In case of the MCO membrane, remarkable clearances of LMM are achieved combining the permeability of the membrane with a significant amount of internal convection. The mechanism of filtration-backfiltration inside the dialyzer enables effective removal of LMM in a technique called expanded hemodialysis (HDx). Given such theoretical explanation, it is important to demonstrate the blood and ultrafiltration rheology inside the MCO dialyzer. Method: This study for the first time describes flow dynamic parameters and internal cross-filtration, thanks to specific radiology and nuclear imaging techniques. Results: Flow dynamic analysis of the blood and dialysate compartment confirms excellent distribution of velocities and an excellent matching of blood and dialysate. Average blood flow velocity allows for wall shear rates adequate to avoid protein stagnation at the blood membrane interface and increase in blood viscosity. Cross-filtration analysis demonstrates a remarkable filtration/backfiltration flux reaching values >30 mL/min at a blood flow of 300 mL/min and zero net filtration. Conclusion: The MCO dialyzer Theranova 400 appears to have a design optimized to perform expanded hemodialysis (HDx).

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Computational Flow Dynamic Analysis of Right and Left Atria in Patent Foramen Ovale: Potential Links with Atrial Fibrillation

Journal of Atrial Fibrillation ◽

10.4022/jafib.1852 ◽

2018 ◽

Vol 10 (5) ◽

Cited By ~ 1

Author(s):

Gianluca Rigatelli,

Keyword(s):

Atrial Fibrillation ◽

Dynamic Analysis ◽

Patent Foramen Ovale ◽

Foramen Ovale ◽

Flow Dynamic

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Effectiveness of the segment method in absolute and joint coordinates when modelling risers

Acta Mechanica ◽

10.1007/s00707-019-02532-6 ◽

2019 ◽

Vol 231 (2) ◽

pp. 435-469

Author(s):

Iwona Adamiec-Wójcik ◽

Lucyna Brzozowska ◽

Stanisław Wojciech

Keyword(s):

Fluid Flow ◽

Dynamic Analysis ◽

Equations Of Motion ◽

Lagrange Equations ◽

Internal Fluid ◽

Joint Coordinates ◽

Sea Current ◽

Internal Fluid Flow ◽

Absolute Coordinates ◽

Nonlinear Equations Of Motion

Abstract This paper presents two formulations of the segment method: one with absolute coordinates and the second with joint coordinates. The nonlinear equations of motion of slender links are derived from the Lagrange equations by means of the methods used in multibody systems. Values of forces and moments acting in the connections between the segments are defined using a new and unique procedure which enables the mutual interaction of bending and torsion to be considered. The models take into account the influence of the velocity of the internal fluid flow on the riser’s dynamics. The dynamic analysis of a riser with fluid flow requires calculation of the curvature by approximation of the Euler angles with polynomials of the second order. The influence of the sea environment, such as added mass of water, drag and buoyancy forces as well as sea current, is considered. In addition, the influence of torsion is discussed. Validation is carried out for both models by comparing the authors’ own results with those obtained from experimental measurements presented in the literature and from COMSOL, Riflex and Abaqus software. The validation is concerned with vibrations of cables and the riser with internal fluid flow as well as with frequencies of free and forced vibrations of a riser fully or partially submerged in water. The numerical effectiveness of both formulations is examined for dynamic analysis of the riser, whose top end is moving in a horizontal plane. Conclusions concerned with the effectiveness of both formulations of the segment method and the influence of torsional vibrations on numerical results are formulated.

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