The proper design of a left ventricular assist device (LVAD) requires an understanding of the pump's fluid dynamic and biocompatible properties. A hydraulically efficient system minimizes the power required for pumping. Biocompatibility refers to the ability to pump blood with minimal hemolysis and thrombus formation. Typically, shear stresses below a threshold level will not damage blood significantly. A fluid dynamic analysis of a prototype centrifugal pump designed for use as an LVAD was performed to establish flow characteristics. A flow visualization technique using Amberlite particles suspended in a glycerin/water blood analogue was used. The system was illuminated with a 1 mm planar beam strobed helium-neon laser, and the results were recorded photographically. An analysis of photographs revealed laminar and turbulent flows with vortices within an illuminated plane in both the inlet and outlet port areas. From these data, velocity and shear stress profiles were generated that showed possible areas of improvement. It was concluded that the outlet port design could be improved by changing its angle and the continuity of its expansion. The inlet port could also be improved by smoothing the transition area between the inlet tube and the pump body to allow for gradual acceleration of the entering fluid.
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Acta Bioeng Biomech
June 2024
1School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai, China.
: Brain tissue immersed in cerebrospinal fluid often exhibits complex mechanical behaviour, especially the nonlinear stress- strain and rate-dependent responses. Despite extensive research into its material properties, the impact of solution environments on the mechanical behaviour of brain tissue remains limited. This knowledge gap affects the biofidelity of head modelling.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
February 2025
École polytechnique fédérale de Lausanne, School of Engineering, Institute of Mechanical Engineering, Unsteady Flow Diagnostics Laboratory, Lausanne 1015, Switzerland.
Airborne insects generate a leading edge vortex when they flap their wings. This coherent vortex is a low-pressure region that enhances the lift of flapping wings compared to fixed wings. Insect wings are thin membranes strengthened by a system of veins that does not allow large wing deformations.
View Article and Find Full Text PDFLangmuir
January 2025
Research Center of Fluid Machinery Engineering and Technology, Jiangsu University, Zhenjiang 212013, China.
Cavitation has been a hot research topic for scholars in various fields because of the intense mechanical, chemical, and thermal effects of bubble collapse. It forms a cluster of bubbles, and the bubbles will affect, interfere with, and couple with each other. To grasp the main factors affecting bubble collapse and the interbubble mechanism, the paper adopts the molecular dynamics simulation combined with the coarse-grained force field to study the collapse process of the double bubble model and takes the dynamic shape change of the bubbles, the local velocity distribution, and the local pressure distribution as the object to summarize the position angle, the shock velocity, and the bubble distance on the collapse law and the primary and secondary influence relationship and then reveals the interbubble mechanism.
View Article and Find Full Text PDFLab Chip
January 2025
Department of Biotechnology and Bioengineering, Izmir Institute of Technology, Izmir 35430, Turkiye.
Centrifugation is crucial for size and density-based sample separation, but low-volume or delicate samples suffer from loss and impurity issues during repeated spins. We introduce the "Spinochip", a novel microfluidic system utilizing centrifugal forces for efficient filling of dead-end microfluidic channels. The Spinochip enables versatile fluid manipulation with a single reservoir for both inlet and outlet functions.
View Article and Find Full Text PDFCommun Eng
January 2025
School of Civil and Environmental Engineering, Nanyang Technological University, Singapore, Singapore.
Designing safe and reliable routes is the core of intelligent shipping. However, existing methods for industrial use are inadequate, primarily due to the lack of considering company preferences and ship maneuvering characteristics. To address these challenges, here we introduce a methodological framework that integrates maritime knowledge and autonomous maneuvering model.
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