The Experts below are selected from a list of 4581 Experts worldwide ranked by ideXlab platform
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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A parametric study of Valve orientation on the flow patterns of the Penn State pulsatile pediatric ventricular assist device.
ASAIO journal (American Society for Artificial Internal Organs : 1992), 2010Co-Authors: Breigh N. Roszelle, Steven Deutsch, Keefe B. ManningAbstract:Abstract Because of the shortage of organs for transplant in pediatric patients with end-stage heart failure, Penn State is developing a pneumatically driven 12 cc pulsatile pediatric ventricular assist device (PVAD). A major concern is the flow field changes related to the volume decrease and its effect on device thrombogenicity. Previous studies of similar devices have shown that changes in the orientation of the inlet Valve can lead to improvement in the flow field. Herein, the fluid dynamic effects of orientation changes at both the inlet and Outlet Valves are studied. Using two-dimensional particle image velocimetry, we examine the flow field in vitro using an acrylic model of the PVAD in a mock circulatory loop. Regardless of Valve orientation, the overall flow pattern inside the PVAD remains similar, but important differences were seen locally in the wall shear rates, which is notable because shear rates >500 s may prevent thrombus formation. As the inlet Valve was rotated toward the fluid side of the PVAD, we observed an increase in inlet jet velocity and wall shear rates along the inlet port wall. A corresponding rotation of the Outlet Valve increases the wall shear rate along the outer wall near the device Outlet. Wall shear rates were all higher when both Valves were rotated toward the fluid side of the device, with the best rates found at orientations of +15 degrees for both the inlet and Outlet Valves. Overall, orientations of +15 degrees or +30 degrees of both the inlet and Outlet Valve resulted in an increase in wall shear rates and could aid in the reduction of thrombus formation inside the PVAD.
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Flow behavior within the 12-cc Penn State pulsatile pediatric ventricular assist device: an experimental study of the initial design.
Artificial organs, 2008Co-Authors: Keefe B. Manning, Brandon D Wivholm, Ning Yang, Arnold A. Fontaine, Steven DeutschAbstract:Planar particle image velocimetry was used to explore the flow behavior of the newly designed 12-cc Penn State pneumatic pediatric assist pump. Wall shear maps complemented the velocity data. Bjork-Shiley Monostrut 17-mm mechanical heart Valves were used in the inlet and Outlet ports. In comparison with larger Penn State pumps, the 12-cc device is not only smaller but has reduced Valve effective orifice areas and more highly angled Valve ports. In contrast to results from the larger pumps, the flow field was highly three dimensional during early diastole with poorer penetration by the Valve inlet jet. This led to a later start to a "wall washing" rotational pattern. A significant separation region, never before observed, was created upstream of the Outlet Valve leaflet during late diastole--effectively reducing the area and increasing the pressure drop through the Valve. Wall shear maps suggest that regions of low shear might persist throughout the cycle at the bottom of the pump on the Outlet side. An attempt to improve the flow field characteristics by exploring different Valves, Valve orientations and inlet Valve angles, systolic/diastolic flow timing, and perhaps a larger Outlet Valve was planned.
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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A parametric study of Valve orientation on the flow patterns of the Penn State pulsatile pediatric ventricular assist device.
ASAIO journal (American Society for Artificial Internal Organs : 1992), 2010Co-Authors: Breigh N. Roszelle, Steven Deutsch, Keefe B. ManningAbstract:Abstract Because of the shortage of organs for transplant in pediatric patients with end-stage heart failure, Penn State is developing a pneumatically driven 12 cc pulsatile pediatric ventricular assist device (PVAD). A major concern is the flow field changes related to the volume decrease and its effect on device thrombogenicity. Previous studies of similar devices have shown that changes in the orientation of the inlet Valve can lead to improvement in the flow field. Herein, the fluid dynamic effects of orientation changes at both the inlet and Outlet Valves are studied. Using two-dimensional particle image velocimetry, we examine the flow field in vitro using an acrylic model of the PVAD in a mock circulatory loop. Regardless of Valve orientation, the overall flow pattern inside the PVAD remains similar, but important differences were seen locally in the wall shear rates, which is notable because shear rates >500 s may prevent thrombus formation. As the inlet Valve was rotated toward the fluid side of the PVAD, we observed an increase in inlet jet velocity and wall shear rates along the inlet port wall. A corresponding rotation of the Outlet Valve increases the wall shear rate along the outer wall near the device Outlet. Wall shear rates were all higher when both Valves were rotated toward the fluid side of the device, with the best rates found at orientations of +15 degrees for both the inlet and Outlet Valves. Overall, orientations of +15 degrees or +30 degrees of both the inlet and Outlet Valve resulted in an increase in wall shear rates and could aid in the reduction of thrombus formation inside the PVAD.
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Flow behavior within the 12-cc Penn State pulsatile pediatric ventricular assist device: an experimental study of the initial design.
Artificial organs, 2008Co-Authors: Keefe B. Manning, Brandon D Wivholm, Ning Yang, Arnold A. Fontaine, Steven DeutschAbstract:Planar particle image velocimetry was used to explore the flow behavior of the newly designed 12-cc Penn State pneumatic pediatric assist pump. Wall shear maps complemented the velocity data. Bjork-Shiley Monostrut 17-mm mechanical heart Valves were used in the inlet and Outlet ports. In comparison with larger Penn State pumps, the 12-cc device is not only smaller but has reduced Valve effective orifice areas and more highly angled Valve ports. In contrast to results from the larger pumps, the flow field was highly three dimensional during early diastole with poorer penetration by the Valve inlet jet. This led to a later start to a "wall washing" rotational pattern. A significant separation region, never before observed, was created upstream of the Outlet Valve leaflet during late diastole--effectively reducing the area and increasing the pressure drop through the Valve. Wall shear maps suggest that regions of low shear might persist throughout the cycle at the bottom of the pump on the Outlet side. An attempt to improve the flow field characteristics by exploring different Valves, Valve orientations and inlet Valve angles, systolic/diastolic flow timing, and perhaps a larger Outlet Valve was planned.
Alexander Nila - One of the best experts on this subject based on the ideXlab platform.
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Face Coverings, Aerosol Dispersion and Mitigation of Virus Transmission Risk
arXiv: Medical Physics, 2020Co-Authors: Ignazio Maria Viola, Brian Peterson, Gabriele Pisetta, Geethanjali Pavar, Hibbah Akhtar, Filippo Menolascina, Enzo Mangano, Katherine E. Dunn, Roman Gabl, Alexander NilaAbstract:The SARS-CoV-2 virus is primarily transmitted through virus-laden fluid particles ejected from the mouth of infected people. In some countries, the public has been asked to use face covers to mitigate the risk of virus transmission - yet, their outward effectiveness is not ascertained. We used a Background Oriented Schlieren technique to investigate the air flow ejected by a person while quietly and heavily breathing, while coughing, and with different face covers. We found that all face covers without an Outlet Valve reduce the front flow through jet by more than 90 per cent. For the FFP1 and FFP2 masks without exhalation Valve, the front throughflow does not extend beyond one half and one quarter of a metre, respectively. Surgical and hand-made masks, and face shields, generate several leakage jets, including intense backward and downwards jets that may present major hazards. We also simulated an aerosol generating procedure (extubation) and we showed that this is a major hazard for clinicians. These results can aid policy makers to make informed decisions and PPE developers to improve their product effectiveness by design.
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.
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A parametric study of Valve orientation on the flow patterns of the Penn State pulsatile pediatric ventricular assist device.
ASAIO journal (American Society for Artificial Internal Organs : 1992), 2010Co-Authors: Breigh N. Roszelle, Steven Deutsch, Keefe B. ManningAbstract:Abstract Because of the shortage of organs for transplant in pediatric patients with end-stage heart failure, Penn State is developing a pneumatically driven 12 cc pulsatile pediatric ventricular assist device (PVAD). A major concern is the flow field changes related to the volume decrease and its effect on device thrombogenicity. Previous studies of similar devices have shown that changes in the orientation of the inlet Valve can lead to improvement in the flow field. Herein, the fluid dynamic effects of orientation changes at both the inlet and Outlet Valves are studied. Using two-dimensional particle image velocimetry, we examine the flow field in vitro using an acrylic model of the PVAD in a mock circulatory loop. Regardless of Valve orientation, the overall flow pattern inside the PVAD remains similar, but important differences were seen locally in the wall shear rates, which is notable because shear rates >500 s may prevent thrombus formation. As the inlet Valve was rotated toward the fluid side of the PVAD, we observed an increase in inlet jet velocity and wall shear rates along the inlet port wall. A corresponding rotation of the Outlet Valve increases the wall shear rate along the outer wall near the device Outlet. Wall shear rates were all higher when both Valves were rotated toward the fluid side of the device, with the best rates found at orientations of +15 degrees for both the inlet and Outlet Valves. Overall, orientations of +15 degrees or +30 degrees of both the inlet and Outlet Valve resulted in an increase in wall shear rates and could aid in the reduction of thrombus formation inside the PVAD.
Gaurav Jain - One of the best experts on this subject based on the ideXlab platform.
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A class of discontinuous dynamical systems IV. A laboratory air–water system
Chemical Engineering Science, 2003Co-Authors: Kannan M. Moudgalya, Shivesh Kumar Singh, K.p. Madhavan, Gaurav JainAbstract:Abstract An air–water experimental system consisting of two inlets and one Outlet is constructed and characterised. It reaches the state of sliding mode, or equivalently, two phase slug flow. The linear hydraulic model proposed in the literature is adequate to describe it. Experimental data are used to tune this model. The resistance to the flow of air through the Outlet Valve during the two phase flow is much larger than that when air alone flows out. At the operating range, the resistance to water flow is not affected by the presence of air.
