scholarly journals Remoras pick where they stick on blue whales

2020 ◽  
Vol 223 (20) ◽  
pp. jeb226654
Author(s):  
Brooke E. Flammang ◽  
Simone Marras ◽  
Erik J. Anderson ◽  
Oriol Lehmkuhl ◽  
Abhishek Mukherjee ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Drag Reduction ◽  
Experimental Work ◽  
Ecological Monitoring ◽  
Video Recordings ◽  
Venturi Effect ◽  
Separating Flow ◽  
Dynamics Analyses ◽  
Blue Whales

ABSTRACTAnimal-borne video recordings from blue whales in the open ocean show that remoras preferentially adhere to specific regions on the surface of the whale. Using empirical and computational fluid dynamics analyses, we show that remora attachment was specific to regions of separating flow and wakes caused by surface features on the whale. Adhesion at these locations offers remoras drag reduction of up to 71–84% compared with the freestream. Remoras were observed to move freely along the surface of the whale using skimming and sliding behaviors. Skimming provided drag reduction as high as 50–72% at some locations for some remora sizes, but little to none was available in regions where few to no remoras were observed. Experimental work suggests that the Venturi effect may help remoras stay near the whale while skimming. Understanding the flow environment around a swimming blue whale will inform the placement of biosensor tags to increase attachment time for extended ecological monitoring.

Discrete element method–computational fluid dynamics analyses of flexible fibre fluidization

2021 ◽  
Vol 910 ◽  
Author(s):  
Yiyang Jiang ◽  
Yu Guo ◽  
Zhaosheng Yu ◽  
Xia Hua ◽  
Jianzhong Lin ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Discrete Element Method ◽  
Discrete Element ◽  
Dynamics Analyses ◽  
Element Method

Abstract

scholarly journals Variable cant angle winglets for improvement of aircraft flight performance

Meccanica ◽  
2020 ◽  
Vol 55 (10) ◽  
pp. 1917-1947
Author(s):  
J. E. Guerrero ◽  
M. Sanguineti ◽  
K. Wittkowski
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Drag Reduction ◽  
Fuel Efficiency ◽  
Aerodynamic Performance ◽  
Flight Performance ◽  
Sweep Angle ◽  
Aircraft Flight ◽  
Induced Drag ◽  
Aircraft Performance

Abstract Traditional winglets are designed as fixed devices attached at the tips of the wings. The primary purpose of the winglets is to reduce the lift-induced drag, therefore improving aircraft performance and fuel efficiency. However, because winglets are fixed surfaces, they cannot be used to control lift-induced drag reductions or to obtain the largest lift-induced drag reductions at different flight conditions (take-off, climb, cruise, loitering, descent, approach, landing, and so on). In this work, we propose the use of variable cant angle winglets which could potentially allow aircraft to get the best all-around performance (in terms of lift-induced drag reduction), at different flight phases. By using computational fluid dynamics, we study the influence of the winglet cant angle and sweep angle on the performance of a benchmark wing at Mach numbers of 0.3 and 0.8395. The results obtained demonstrate that by adjusting the cant angle, the aerodynamic performance can be improved at different flight conditions.

Computational Fluid Dynamics (CFD) Simulation of Drag Reduction by Riblets on Automobile

2010 ◽  
Author(s):  
N. N. N. Ghazali ◽  
Y. H. Yau ◽  
A. Badarudin ◽  
Y. C. Lim ◽  
Jane W. Z. Lu ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Drag Reduction ◽  
Cfd Simulation ◽  
Computational Fluid Dynamics Cfd

Thermal Modeling of a Liquid-Cooled PM Traction Motor

2003 ◽  
Author(s):  
Edward Jih ◽  
Thomas Abraham ◽  
Stephen Stella ◽  
Roy Davis ◽  
Bert Dinger ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Permanent Magnet ◽  
Electric Motor ◽  
Hybrid Electric Vehicle ◽  
Effective Properties ◽  
Copper Wire ◽  
Critical Role ◽  
Traction Motor ◽  
Dynamics Analyses

The electric motor plays a critical role for the applications of the Hybrid Electric Vehicle and Fuel Cell Electric Vehicel. It is also well known that thermal constraints represent one of the main limitations in the performance of the electric motor. For example, the electric motor will be short-circuited if the insulation coatings of the copper wire bundles fail. Furthermore, the performance of the permanent magnet electric motor reduces significantly as the rotor magnet temperature increases. In this study, a series of Computational Fluid Dynamics analyses were performed for the design of a liquid-cooled permanent magnet electric motor to achieve better thermal performance. Several thermal tests of a partial permanent magnet traction motor assembly (stator and housing only) were also performed to determine effective properties of the stator slot and thermal contact resistance between stator and housing that may vary due to the manufacturing process. A simplified thermal network model of this system was established from the Computational Fluid Dynamics analyses. Then the critical heat transfer path of this system was identified.

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