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Keefe B. Manning - One of the best experts on this subject based on the ideXlab platform.
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Flow Visualization of the Penn State Pulsatile Pediatric Ventricular Assist Device Cannulae and Change in Outlet Valve Placement
Cardiovascular Engineering and Technology, 2011Co-Authors: Breigh N. Roszelle, Steven Deutsch, Michael G. Fickes, Keefe B. ManningAbstract:Due to the lack of long-term mechanical circulatory supPort options for children, Penn State is developing a pneumatically driven 12 cc pulsatile pediatric ventricular assist device (PVAD). The reduction in volume, however, necessary to accommodate pediatric patients leads to changes in the functional fluid mechanics. One area that has not been previously observed is the flow upstream and downstream of the inlet and Outlet valves. In particular an area of blockage, that includes a large area of stagnant flow, has been observed upstream of the Outlet valve that could cause an increase in blood damage. In order to measure the flow upstream and downstream of the Ports, we deploy a 50 mm acrylic valve extension. The Outlet valve is moved downstream of the Outlet Port in an attempt to eliminate a flow blockage region upstream of the valve. We mount the PVAD to a mock circulatory loop that models the systemic circulation under normal physiological conditions, with a 40% hematocrit blood analog as the fluid. Two dimensional particle image velocimetry is used to measure the flow. As expected, the flow patterns in the body of the device remain similar to those without the extension, except near the Outlet Port. Non-uniform flow is observed upstream of both the inlet and Outlet valves and regurgitation is observed upstream of the inlet valve. The relocation of the Outlet valve leads to a more uniform outflow and the blockage region is eliminated. The observations of non-uniform flow upstream of the inlet valve are a new and imPortant observation when considering computational models. Also, the new Outlet flow pattern associated with the relocation of the Outlet valve reduces the potential for blood damage. Studies with a relocated valve in a clinical model are being considered.
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Flow field study comparing design iterations of a 50 cc left ventricular assist device.
Asaio Journal, 2011Co-Authors: Jason C. Nanna, Jennifer A. Wivholm, Steven Deutsch, Keefe B. ManningAbstract:The Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure (REMATCH) study shows that implanted ventricular assist devices improve survival time and quality of life when used as a permanent therapy in patients who do not qualify for heart transplant. The success of the pulsatile 70 cc stroke volume left ventricular assist device (LVAD) developed by Penn State has led to the development of a 50 cc stroke volume pump for use in patients with smaller chest cavities to benefit a larger patient population. The initial 50 cc pump shows regions of in vivo thrombus formation, which correlate to low wall shear rates within the device. In an in vitro evaluation of three new designs (V-2, V-3, and V-4) of the 50 cc LVAD, identical except for the location and orientation of their Outlet Ports, particle image velocimetry (PIV) is used to capture planar flow field data within the pumps. V-2 has an Outlet Port that is located parallel to the inlet. In V-3, the Outlet Port is rotated away from the inlet Port, with the intention of minimizing the amount of fluid turning needed to exit the device. With V-4 the Outlet Port is moved to the center of the pump to prolong the desirable rotational flow. PIV data were taken at six planar locations within the pump. Although the modifications to the Outlet Port locations serve their intended purpose, they also introduce unwanted changes in the flow. Poorer wall washing and weaker rotational flow are observed with V-3 and V-4. Although the differences between the devices are subtle, the device that has the most desirable flow characteristics is V-2.
Steven Deutsch - One of the best experts on this subject based on the ideXlab platform.
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Flow Visualization of the Penn State Pulsatile Pediatric Ventricular Assist Device Cannulae and Change in Outlet Valve Placement
Cardiovascular Engineering and Technology, 2011Co-Authors: Breigh N. Roszelle, Steven Deutsch, Michael G. Fickes, Keefe B. ManningAbstract:Due to the lack of long-term mechanical circulatory supPort options for children, Penn State is developing a pneumatically driven 12 cc pulsatile pediatric ventricular assist device (PVAD). The reduction in volume, however, necessary to accommodate pediatric patients leads to changes in the functional fluid mechanics. One area that has not been previously observed is the flow upstream and downstream of the inlet and Outlet valves. In particular an area of blockage, that includes a large area of stagnant flow, has been observed upstream of the Outlet valve that could cause an increase in blood damage. In order to measure the flow upstream and downstream of the Ports, we deploy a 50 mm acrylic valve extension. The Outlet valve is moved downstream of the Outlet Port in an attempt to eliminate a flow blockage region upstream of the valve. We mount the PVAD to a mock circulatory loop that models the systemic circulation under normal physiological conditions, with a 40% hematocrit blood analog as the fluid. Two dimensional particle image velocimetry is used to measure the flow. As expected, the flow patterns in the body of the device remain similar to those without the extension, except near the Outlet Port. Non-uniform flow is observed upstream of both the inlet and Outlet valves and regurgitation is observed upstream of the inlet valve. The relocation of the Outlet valve leads to a more uniform outflow and the blockage region is eliminated. The observations of non-uniform flow upstream of the inlet valve are a new and imPortant observation when considering computational models. Also, the new Outlet flow pattern associated with the relocation of the Outlet valve reduces the potential for blood damage. Studies with a relocated valve in a clinical model are being considered.
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Flow field study comparing design iterations of a 50 cc left ventricular assist device.
Asaio Journal, 2011Co-Authors: Jason C. Nanna, Jennifer A. Wivholm, Steven Deutsch, Keefe B. ManningAbstract:The Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure (REMATCH) study shows that implanted ventricular assist devices improve survival time and quality of life when used as a permanent therapy in patients who do not qualify for heart transplant. The success of the pulsatile 70 cc stroke volume left ventricular assist device (LVAD) developed by Penn State has led to the development of a 50 cc stroke volume pump for use in patients with smaller chest cavities to benefit a larger patient population. The initial 50 cc pump shows regions of in vivo thrombus formation, which correlate to low wall shear rates within the device. In an in vitro evaluation of three new designs (V-2, V-3, and V-4) of the 50 cc LVAD, identical except for the location and orientation of their Outlet Ports, particle image velocimetry (PIV) is used to capture planar flow field data within the pumps. V-2 has an Outlet Port that is located parallel to the inlet. In V-3, the Outlet Port is rotated away from the inlet Port, with the intention of minimizing the amount of fluid turning needed to exit the device. With V-4 the Outlet Port is moved to the center of the pump to prolong the desirable rotational flow. PIV data were taken at six planar locations within the pump. Although the modifications to the Outlet Port locations serve their intended purpose, they also introduce unwanted changes in the flow. Poorer wall washing and weaker rotational flow are observed with V-3 and V-4. Although the differences between the devices are subtle, the device that has the most desirable flow characteristics is V-2.
Breigh N. Roszelle - One of the best experts on this subject based on the ideXlab platform.
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Flow Visualization of the Penn State Pulsatile Pediatric Ventricular Assist Device Cannulae and Change in Outlet Valve Placement
Cardiovascular Engineering and Technology, 2011Co-Authors: Breigh N. Roszelle, Steven Deutsch, Michael G. Fickes, Keefe B. ManningAbstract:Due to the lack of long-term mechanical circulatory supPort options for children, Penn State is developing a pneumatically driven 12 cc pulsatile pediatric ventricular assist device (PVAD). The reduction in volume, however, necessary to accommodate pediatric patients leads to changes in the functional fluid mechanics. One area that has not been previously observed is the flow upstream and downstream of the inlet and Outlet valves. In particular an area of blockage, that includes a large area of stagnant flow, has been observed upstream of the Outlet valve that could cause an increase in blood damage. In order to measure the flow upstream and downstream of the Ports, we deploy a 50 mm acrylic valve extension. The Outlet valve is moved downstream of the Outlet Port in an attempt to eliminate a flow blockage region upstream of the valve. We mount the PVAD to a mock circulatory loop that models the systemic circulation under normal physiological conditions, with a 40% hematocrit blood analog as the fluid. Two dimensional particle image velocimetry is used to measure the flow. As expected, the flow patterns in the body of the device remain similar to those without the extension, except near the Outlet Port. Non-uniform flow is observed upstream of both the inlet and Outlet valves and regurgitation is observed upstream of the inlet valve. The relocation of the Outlet valve leads to a more uniform outflow and the blockage region is eliminated. The observations of non-uniform flow upstream of the inlet valve are a new and imPortant observation when considering computational models. Also, the new Outlet flow pattern associated with the relocation of the Outlet valve reduces the potential for blood damage. Studies with a relocated valve in a clinical model are being considered.
R. Maiti - One of the best experts on this subject based on the ideXlab platform.
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Distributor valve Port sequences in epitrochoid generated rotory piston machine type hydrostatic units
Archive of Applied Mechanics, 1992Co-Authors: R. MaitiAbstract:Theoretical guidelines of selecting the inlet-Outlet Port sizes, their position and sequences of the flow distributor valves used in epitrochoid generated rotary piston machine type hydrostatic units have been established in the present analysis. The formulae can also be used for programmable control of the inlet-Outlet Port sequences where a separate valve is used instead of the conventional distributor valve.
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Distributor valve Port sequences in epitrochoid generated rotory piston machine type hydrostatic units
Archive of Applied Mechanics, 1992Co-Authors: R. MaitiAbstract:Theoretical guidelines of selecting the inlet-Outlet Port sizes, their position and sequences of the flow distributor valves used in epitrochoid generated rotary piston machine type hydrostatic units have been established in the present analysis. The formulae can also be used for programmable control of the inlet-Outlet Port sequences where a separate valve is used instead of the conventional distributor valve. Theoretische Richtlinien zur Auswahl der Eintritt-Austrittsschlitzgröße, ihrer Lage und Folgen bei in epitrochoiden Drehkolbenhydrostatikeinheiten verwandten Flußverteilerventilen werden in der vorliegenden Analyse aufgestellt. Die Formeln können auch für die programmierbare Kontrolle der Eintritt-Austrittsschlitzfolgen benutzt werden, wenn man statt des gebräuchlichen Verteilerventils ein einzelnes Ventil einsetzt.
Jay M. Khodadadi - One of the best experts on this subject based on the ideXlab platform.
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Computational Study of Turbulent Forced Convection Flow in a Square Cavity with Ventilation Ports
Numerical Heat Transfer Part A-applications, 2011Co-Authors: E. Sourtiji, Mofid Gorji-bandpy, S.f. Hosseinizadeh, Jay M. KhodadadiAbstract:A numerical study of turbulent forced convection flow inside a square cavity with inlet and Outlet Ports is performed. The position of the inlet Port is fixed but the location of the Outlet Port is varied along the four walls of the cavity to investigate the best position corresponding to the maximum heat transfer rate and minimum pressure drop in the cavity. The diagram of the local and total Nusselt numbers and the coefficient of the pressure drop are plotted with respect to the position of the Outlet Port in order to realize the best configuration of the system. It is found that the pressure drop and total heat transfer rate in the cavity vary drastically depending on the Reynolds number and the position of the Outlet Port, and it is deduced that the case with the Outlet Port positioned on the right side of the bottom wall, for the cases with wide Ports and the one with the Outlet Port located on the left wall for the cases with thin Ports, are the best positions to obtain the best performance of the s...
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Forced convection in a square cavity with inlet and Outlet Ports
International Journal of Heat and Mass Transfer, 2006Co-Authors: S. M. Saeidi, Jay M. KhodadadiAbstract:Abstract A finite-volume-based computational study of steady laminar forced convection inside a square cavity with inlet and Outlet Ports is presented. Given a fixed position of the inlet Port, the location of the Outlet Port is varied along the four walls of the cavity. The widths of the Ports are equal to 5%, 15% and 25% of the side. By positioning the Outlet Ports at nine locations on the walls for Re = 10, 40, 100 and 500 and Pr = 5, a total of 108 cases were studied. For the shortest distance between the inlet and Outlet Ports along the top wall, a primary clockwise (CW) rotating vortex that covers about 75–88% of the cavity is observed. As the Outlet Port is lowered along the right wall, the CW primary vortex diminishes in strength, however a counter-clockwise (CCW) vortex that is present next to the top right corner grows in size. With the Outlet Port moving left along the bottom wall, the CW primary vortex is weakened further and the CCW vortex occupies nearly the right half of the cavity. The pressure drop varies drastically depending on Re and the position of the Outlet Port. If the Outlet Port is on the opposite or the same wall as the inlet, the pressure drop is smaller in comparison to a case where it is located on the adjacent walls. The maximum pressure drop occurs when the Outlet Port is on the left side of the bottom wall and the minimum is achieved where the Outlet is on the middle of the right wall. Regions of high temperature gradient are consistently observed at the interface of the throughflow and next to the solid walls on both sides of the Outlet Port. Local Nusselt numbers are low at three corners when no Outlet Port is present in their vicinity, whereas intense heat transfer rate is observed on the two sides of the Outlet Port. Between these minima and maxima, the local Nusselt number can vary drastically depending on the flow and temperature fields. By placing the Outlet Port with one end at three corners, maximum overall Nusselt number of the cavity can be achieved. Minimum overall heat transfer of the cavity is achieved with the Outlet Port located at the middle of the walls. The case exhibiting maximum heat transfer and minimum pressure drop is observed when the Outlet Port is located at dimensionless wall coordinate (2 + 0.5W).
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Forced Convection in a Square Cavity With Inlet and Outlet Ports
Volume 2 Parts A and B, 2004Co-Authors: S. M. Saeidi, Jay M. KhodadadiAbstract:A finite-volume-based computational study of steady laminar forced convection inside a square cavity with inlet and Outlet Ports is presented. Given a fixed position of the inlet Port, the location of Outlet Port is varied along the four walls of the cavity. The widths of the Ports are equal to 5, 15 and 25 percent of the side. By positioning the Outlet Ports at 9 locations on the walls for Re = 10, 40, 100 and 500 and Pr = 5, a total of 101 cases were studied. For high Re and with the shortest distance between the inlet and Outlet Ports along the top wall, a primary CW rotating vortex that covers about 70 to 80 percent of the cavity is observed. Similar cases with smaller Re exhibit identical flow patterns but with weaker vortices as Re is lowered. As the Outlet Ports is lowered along the right wall, the CW primary vortex diminishes its strength; however a CCW vortex that is present next to the top right corner covers a greater Portion of the cavity. With the Outlet Port moving left along the bottom wall, the CW primary vortex is weakened further and the CCW vortex occupies nearly the right half of the cavity. The temperature fields are directly related to the presence of the multiple vortices in the cavity. Regions of high temperature gradient are consistently observed at the interface of the throughflow and next to the solid walls on both sides of the Outlet Port. Local Nusselt numbers are low at 3 corners when no Outlet Port is present in their vicinity, whereas intense heat transfer rate is observed on the two sides of the Outlet Port. Between these minima and maxima, the local Nusselt number can vary drastically depending on the flow and temperature fields. By placing the Outlet Port with one end at the 3 corners, maximum total Nusselt number of the cavity can be achieved. Minimum total heat transfer of the cavity is achieved with the Outlet Port located at the middle of the walls.Copyright © 2004 by ASME
