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Research Papers

Validation of a CFD Methodology for Positive Displacement LVAD Analysis Using PIV Data

[+] Author and Article Information
Richard B. Medvitz1

Applied Research Laboratory, Pennsylvania State University, University Park, PA 16802rbm120@psu.edu

Varun Reddy, Keefe B. Manning

Department of Bioengineering, Pennsylvania State University, University Park, PA 16802

Steve Deutsch

Applied Research Laboratory and Department of Bioengineering, Pennsylvania State University, University Park, PA 16802

Eric G. Paterson

Applied Research Laboratory and Department of Mechanical and Nuclear Engineering, Pennsylvania State University, University Park, PA 16802

1

Corresponding author.

J Biomech Eng 131(11), 111009 (Oct 21, 2009) (9 pages) doi:10.1115/1.4000116 History: Received December 11, 2008; Revised June 16, 2009; Posted September 01, 2009; Published October 21, 2009

Computational fluid dynamics (CFD) is used to asses the hydrodynamic performance of a positive displacement left ventricular assist device. The computational model uses implicit large eddy simulation direct resolution of the chamber compression and modeled valve closure to reproduce the in vitro results. The computations are validated through comparisons with experimental particle image velocimetry (PIV) data. Qualitative comparisons of flow patterns, velocity fields, and wall-shear rates demonstrate a high level of agreement between the computations and experiments. Quantitatively, the PIV and CFD show similar probed velocity histories, closely matching jet velocities and comparable wall-strain rates. Overall, it has been shown that CFD can provide detailed flow field and wall-strain rate data, which is important in evaluating blood pump performance.

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Copyright © 2009 by American Society of Mechanical Engineers
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Figures

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Figure 1

Computational mesh used for the analysis of the 50 cc LVAD. Grid includes Bjork–Shiley monostrut valves with support struts. The figure shows the definition of the valve orientation angle along with the regions where the valve viscosity closure model was applied.

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Figure 2

Instantaneous chamber volume and resultant mitral and aortic port flow rates for the computations of the LVAD operating at 4.2 LPM and 86 BPM

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Figure 3

CFD extraction planes located 3 mm, 5 mm, and 7 mm from the front face of the LVAD, at the mitral and aortic port centerlines parallel to the pusher plate, and through the mitral port perpendicular to the pusher plate 5 mm inside of the port centerline. The strain rate extraction arcs for the mitral and aortic ports along with the chamber are labeled.

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Figure 4

Computational and in vitro velocity magnitude contours at the 3 mm plane comparing the CFD against the PIV results at 4.2 LPM and 86 BPM. The 0.375 time step displays the probe locations where PIV and CFD velocity time histories were extracted.

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Figure 5

In vitro and CFD in-plane velocity magnitude comparisons at four points on the 3 mm measurement plane. The symbols show the PIV data and the solid lines the CFD data. The figures correspond to extraction points 75% out from the chamber center at the (a) 3 o’clock, (b) 6 o’clock, (c) 9 o’clock, and (d) 12 o’clock positions, as shown in Fig. 3.

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Figure 6

Computational and in vitro in-plane velocity magnitude contours at a plane 5 mm to the inside of the mitral port centerline

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Figure 7

In-plane velocity magnitude contours at a plane through the center of the mitral and aortic ports parallel to the pusher plate. (a) shows the mitral port during early diastole, (b) shows the mitral port during late diastole, and (c) shows the aortic port during systole. The left image for each port and time step shows the in vitro results while the right image shows the CFD results.

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Figure 8

Wall-strain rate histories showing in vitro and computational results in (a) the mitral port M1 and M2 locations, (b) the aortic port A1 and A3 locations, and (c) the chamber C3–C6 locations

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