Using theoretical principles, the components of drag (friction D , pressure D and wave D ) of a single-seat kayak were analysed. The purpose was to examine the effect of changes in wetted surface area due to changes in kayaker's weight and the relative contribution of D , D and D to the total passive drag as function of velocity. The total passive drag values were based on experimental data collected in a single-seat kayak. Three different kayaker simulated weights were tested - 65, 75 and 85 kg. D was the drag component that contributed the greatest percentage (between 60 and 68% at 5.56 m/s the top velocity tested) to the total passive drag for all the velocities tested and simulated weights. D was the most affected by the increase in kayaker's simulated weight, mainly when comparing 65/75 to 85 kg. Results support the importance of a kayak design selection that minimises the kayak's drag for the individual weight of the kayaker. Also, the results suggest that the path for better hydrodynamic kayak performance should seek changes that can reduce D , D and D with D offering the most potential to reduce passive drag.
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http://dx.doi.org/10.1080/14763141.2017.1357748 | DOI Listing |
Sci Robot
November 2024
Faculty of Science and Engineering, University of Groningen, Groningen, Netherlands.
Gliding birds lack a vertical tail, yet they fly stably rudderless in turbulence without needing discrete flaps to steer. In contrast, nearly all airplanes need vertical tails to damp Dutch roll oscillations and to control yaw. The few exceptions that lack a vertical tail either leverage differential drag-based yaw actuators or their fixed planforms are carefully tuned for passively stable Dutch roll and proverse yaw.
View Article and Find Full Text PDFSci Rep
October 2024
Abrikosov Center for Theoretical Physics, MIPT, Dolgoprudnyi, Moscow Region, Russia, 141701.
We study the effect of Coulomb drag between graphene layers in presence of viscosity term. To do this, we use the simple model of Stokes equations for drift velocities in active and passive layers, known as Pogrebinskii's approach. The solution to these equations allows us to find the potential distribution, and thus the non-local drag resistance of passive layer.
View Article and Find Full Text PDFSensors (Basel)
September 2024
Department of Mechanical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9, Canada.
This paper presents a novel centrifugal microfluidic approach (so-called lab-on-a-CD) for magnetic circulating tumor cell (CTC) separation from the other healthy cells according to their physical and acquired chemical properties. This study enhances the efficiency of CTC isolation, crucial for cancer diagnosis, prognosis, and therapy. CTCs are cells that break away from primary tumors and travel through the bloodstream; however, isolating CTCs from blood cells is difficult due to their low numbers and diverse characteristics.
View Article and Find Full Text PDFAAPS PharmSciTech
September 2024
R&D Director Oleochemistry, Gattefossé Group, Saint‑Priest, France.
Percutaneous delivery is explored as alternative pathway for addressing the drawbacks associated with the oral administration of otherwise efficacious drugs. Short of breaching the skin by physical means, the preference goes to formulation strategies that augment passive diffusion across the skin. One such strategy lies in the use of skin penetration and permeation enhancers notably of hydroxylated solvents like propylene glycol (PG), ethanol (EtOH), and diethylene glycol monoethyl ether (Transcutol, TRC).
View Article and Find Full Text PDFHeliyon
July 2024
School of Mechanical and Materials Engineering, University College Dublin, Belflied, Dublin 4, D04 PR94, Ireland.
This paper addresses the critical role of drag reduction technology in the evolution of road vehicle design amidst the ongoing climate crisis. With transportation accounting for a substantial portion of the EU's greenhouse gas emissions, the shift towards alternatively powered vehicles highlights the need for innovative solutions to extend range, reduce fuel consumption, and lower emissions. This review thoroughly outlines the literature on appendable drag reduction devices, encompassing both passive and active techniques, and their applicability across a variety of road vehicles, including light and heavy-duty transport.
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