Calculation of Dynamic Coefficients for a Magnetically Levitated Artificial Heart Pump Using a CFD Approach

2008 ◽  
Author(s):  
Alexandrina Untaroiu ◽  
Houston G. Wood ◽  
Paul E. Allaire ◽  
Timothy W. Dimond
Keyword(s):  
Artificial Heart ◽  
Operating Conditions ◽  
Magnetic Suspension ◽  
Magnetic Bearings ◽  
Ventricular Assist Devices ◽  
Ventricular Assist ◽  
Fluid Medium ◽  
Fluid Forces ◽  
Operational Life ◽  
Rotating Impeller

The artificial heart community acknowledges the 3rd generation Ventricular Assist Devices (VADs) as the leading technology in mechanical blood pump development. This category consists of rotary pumps with no mechanical or fluid bearings in contact with the fluid medium, usually magnetic or noncontacting hydrodynamic bearings. A magnetic suspension prevents the rotating impeller from contacting the pump’s internal surfaces and reduces regions of stagnant and high shear flow that normally surround a fluid or mechanical bearing. Magnetic bearings have no moving parts in contact and thus do not wear over time; this generally lengthens the operational life of the pumps as compared to those supported by conventional bearings. Employing this 3rd generation technology, the University of Virginia has been developing a ventricular assist device (LifeFlow) with a rotor that is suspended entirely by magnetic bearings. In order to perform the stability analysis, the hydrodynamic effects of the rotating impeller should be included in the calculation. This study describes the method to calculate the stiffness, damping, and mass coefficients, based on the CFD prediction of radial fluid forces exerted on the impeller due to its eccentric position inside the pump housing over a range of operating conditions. In consideration of the suspension design, the fluid forces exerted on the levitated axial impeller were estimated using CFD such that any fluid perturbations would be accounted for and counterbalanced during the suspension and motor design phase.

Mayer Waves in Dogs with Total Artificial Heart

1992 ◽  
Vol 15 (10) ◽  
pp. 601-605 ◽  
Author(s):  
T. Yambe ◽  
S. Nitta ◽  
Y. Katahira ◽  
T. Sonobe ◽  
S. Naganuma ◽  
...  
Keyword(s):  
Artificial Heart ◽  
Maximum Entropy Method ◽  
Power Spectral Analysis ◽  
Entropy Method ◽  
Total Artificial Heart ◽  
Ventricular Assist Devices ◽  
Ventricular Assist ◽  
Mayer Waves ◽  
System A ◽  
Power Spectral

To assess the effect of a total artificial heart (TAH) on the autonomic nervous system a power spectral analysis of the hemodynamics in a TAH animal was done by the maximum entropy method. Two pneumatically driven sac-type ventricular assist devices were implanted as total biventricular bypass (BVB) in adult mongrel dogs to compare the differences between natural heart and TAH. Once the BVB was pumping, the natural heart was electrically fibrillated to constitute the BVB-type TAH model. In the arterial pressure waveform in animals with TAH, respiratory waves were not changed (97.7±24.6%) though Mayer waves were significantly decreased (47.5 ± 22.6%) compared with the animal with a natural heart. These results suggest that prosthetic hemodynamics in the TAH animal affect fluctuations in the cardiovascular system.

scholarly journals Analysis of Operating Modes for Left Ventricle Assist Devices via Integrated Models of Blood Circulation

Mathematics ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 1331 ◽  
Author(s):  
Sergey Simakov ◽  
Alexander Timofeev ◽  
Timur Gamilov ◽  
Philip Kopylov ◽  
Dmitry Telyshev ◽  
...  
Keyword(s):  
Left Ventricular ◽  
Operating Conditions ◽  
Ventricular Assist Devices ◽  
Circulatory Support ◽  
Left Ventricular Assist Devices ◽  
Ventricular Assist ◽  
Lumped Model ◽  
Assist Devices ◽  
Operating Modes ◽  
Mock Circulation

Left ventricular assist devices provide circulatory support to patients with end-stage heart failure. The standard operating conditions of the pump imply limitations on the rotation speed of the rotor. In this work we validate a model for three pumps (Sputnik 1, Sputnik 2, Sputnik D) using a mock circulation facility and known data for the pump HeartMate II. We combine this model with a 1D model of haemodynamics in the aorta and a lumped model of the left heart with valves dynamics. The model without pump is validated with known data in normal conditions. Simulations of left ventricular dilated cardiomyopathy show that none of the pumps are capable of reproducing the normal stroke volume in their operating ranges while complying with all criteria of physiologically feasible operation. We also observe that the paediatric pump Sputnik D can operate in the conditions of adult circulation with the same efficiency as the adult LVADs.

Investigation of Hydrodynamic Forces on Rotating and Whirling Centrifugal Pump Impellers

1996 ◽  
Author(s):  
R. Fongang ◽  
J. Colding-Jørgensen ◽  
R. Nordmann
Keyword(s):  
Centrifugal Pump ◽  
Fluid Model ◽  
Hydrodynamic Forces ◽  
Operating Conditions ◽  
Good Prediction ◽  
Single Vortex ◽  
Unsteady Forces ◽  
Fluid Forces ◽  
Rotordynamic Coefficients ◽  
Rotating Impeller

A 2-dimensional fluid model is developed to investigate the hydrodynamic forces exerted on a rotating impeller caused by the impeller-fluid-volute interaction in a centrifugal pump. In this model, the impeller periphery and the volute contour are replaced by a distribution of unsteady vortices. The impeller center is assumed to execute a whirling motion about the rotor center. This is an improvement of the earlier quasisteady flow model of Colding-Jørgensen (1980) where the impeller was taken as a single vortex-source point. The forces can be presented as a sum of a steady and an unsteady part. The rotordynamic coefficients are deduced from the unsteady forces decomposed into radial and tangential components relative to the orbit described by the impeller center. In comparison to most of the theoretical and experimental results found in the literature, the model seems to give good prediction. It appears clearly from this analysis that, under certain operating conditions, the fluid forces on the impeller have a destabilizing effect on the pump rotor.

Investigation of Hydrodynamic Forces on Rotating and Whirling Centrifugal Pump Impellers

1998 ◽  
Vol 120 (1) ◽  
pp. 179-185 ◽  
Author(s):  
R. Fongang ◽  
J. Colding-Jo̸rgensen ◽  
R. Nordmann
Keyword(s):  
Centrifugal Pump ◽  
Fluid Model ◽  
Hydrodynamic Forces ◽  
Operating Conditions ◽  
Good Prediction ◽  
Single Vortex ◽  
Unsteady Forces ◽  
Fluid Forces ◽  
Rotordynamic Coefficients ◽  
Rotating Impeller

A two-dimensional fluid model is developed to investigate the hydrodynamic forces exerted on a rotating impeller caused by the impeller-fluid-volute interaction in a centrifugal pump. In this model, the impeller periphery and the volute contour are replaced by a distribution of unsteady vortices. The impeller center is assumed to execute a whirling motion about the rotor center. This is an improvement of the earlier quasi-steady flow model of Colding-Jo̸rengsen (1980) where the impeller was taken as a single vortex source point. The forces can be presented as a sum of a steady and an unsteady part. The rotordynamic coefficients are deduced from the unsteady forces decomposed into radial and tangential components relative to the orbit described by the impeller center. In comparison to most of the theoretical and experimental results found in the literature, the model seems to give good prediction. It appears clearly from this analysis that, under certain operating conditions, the fluid forces on the impeller have a destabilizing effect on the pump rotor.

The cytochemical demonstration of bacteria in total artificial heart implant specimens

1987 ◽  
Vol 45 ◽  
pp. 778-779 ◽  
Author(s):  
J. Hanker ◽  
B. Giammara ◽  
J. Dobbins ◽  
W. DeVries
Keyword(s):  
Defense Mechanisms ◽  
Artificial Heart ◽  
Heart Valves ◽  
Opportunistic Pathogen ◽  
Total Artificial Heart ◽  
Ventricular Assist Devices ◽  
Prosthetic Heart Valves ◽  
Ventricular Assist ◽  
Cytochemical Demonstration ◽  
Biomaterial Surfaces

Implantation of the total artificial heart and its associated systems, such as the pneumatic driving system, or other cardiovascular prostheses such as ventricular assist devices, intravenous catheters, ventriculo-atrial shunts, pacemaker electrodes and prosthetic heart valves can be complicated by the problem of bacterial infection. Staphylococcus epidermidis. a ubiquitous commensal of human skin and mucous membranes normally does not cause disease in man. It is now recognized, however, as an opportunistic pathogen of biomaterial implants especially cardiovascular protheses. This is due to its ability to undergo transformation to produce mucoid or polysaccharide extracellular coating substances which promote its adherence to biomaterial surfaces and protect the bacteria against antibiotics and host defense mechanisms; this results in increased virulence of the slime-producing strains.

Sign in / Sign up

Export Citation Format

Share Document