scholarly journals A comprehensive finite element examination of Carreau Yasuda fluid model in a lid driven cavity and channel with obstacle by way of kinetic energy and drag and lift coefficient measurements

2020 ◽  
Vol 9 (2) ◽  
pp. 1785-1800 ◽  
Author(s):  
Rashid Mahmood ◽  
S. Bilal ◽  
Ilyas Khan ◽  
Nabeela Kousar ◽  
Asiful H. Seikh ◽  
...  
Author(s):  
M. R. Meigounpoory ◽  
A. Rahi ◽  
A. Mirbozorgi

The drag and lift forces acting on a rotating impenetrable spherical suspended nano-particle in a homogeneous uniform flow are numerically studied by means of a three-dimensional numerical simulation with slip boundary condition. The effects of both the slip coefficient and rotational speed of the nanosphere on the drag and lift forces are investigated for Reynolds numbers in the range of 0.1 < Re < 100. Increase of rotation increases the drag and lift force exerted by flow at the surface of nano-sphere. By increasing slip coefficient the values of drag and lift coefficients decreases. At full slip condition, rotation of the nano-sphere has not significant effects on the drag and lift coefficient values moreover the lift coefficient of flow around the rotating spherical particle will be vanished. Present numerical results at no-slip condition are in good agreements with certain results of flow around of rotating sphere.


Author(s):  
Rajan Fernandez ◽  
Keith Alexander

Inspired by animals, flapping wing propulsion has been of interest since the early 1900s. Flapping hydrofoil propulsion has been attempted by designers of human powered watercraft because of the novelty and the apparent high theoretical efficiency, but with limited success. The earliest human powered hydrofoil, the Wasserlaufer, was invented by Julius Schuck in 1953. The first really successful human powered hydrofoil, the Trampofoil, was invented by Alexander Sahlin in 1998. While these craft function adequately the design data for flapping hydrofoils is inadequate or not available. This paper describes an experimental program and initial results for the required data. To design a vehicle with a lifting and thrusting oscillating hydrofoil the force that the hydrofoil will exert on the vehicle through its entire oscillating cycle must ideally be known. The force profiles could be estimated via quasi-static calculations based on steady flow lift and drag coefficients, but these often do not cover the full 360 degree range that can be required and there is doubt that the steady flow coefficients properly represent the dynamic situation of an oscillating hydrofoil. Hence a valuable process would be one that could determine dynamic drag and lift coefficient loops as function of the Strouhal number, heaving and pitching profiles. To work toward the collection of this information, experimental data is being recorded in a towing tank with an oscillating NACA4415 hydrofoil over a range of Strouhal numbers and types of oscillating profiles. While there are still some limitations to the experimental equipment preliminary experimental results show the limitations of using quasi-static calculations and go some way to providing the design data for the hydrofoil section tested. We conclude that quasi-static calculations based on the gliding coefficient curve for for an oscillating hydrofoil are only valid for very small Strouhal numbers (St≪0.05). We have shown that as the Strouhal number increases, the error in such calculations increases very rapidly. We also note that the lift coefficient of the hydrofoil has a strong dependence on the angle of attack and is not affected by the gliding stall.


Author(s):  
Tomasz P Stańkowski ◽  
David G MacManus ◽  
Christopher TJ Sheaf ◽  
Robert Christie

This paper describes current progress in the development of methods to assess aero-engine airframe installation effects. The aerodynamic characteristics of isolated intakes, a typical transonic transport aircraft as well as a combination of a through-flow nacelle and aircraft configuration have been evaluated. The validation task for an isolated engine nacelle is carried out with concern for the accuracy in the assessment of intake performance descriptors such as mass flow capture ratio and drag rise Mach number. The necessary mesh and modelling requirements to simulate the nacelle aerodynamics are determined. Furthermore, the validation of the numerical model for the aircraft is performed as an extension of work that has been carried out under previous drag prediction research programmes. The validation of the aircraft model has been extended to include the geometry with through flow nacelles. Finally, the assessment of the mutual impact of the through flow nacelle and aircraft aerodynamics was performed. The drag and lift coefficient breakdown has been presented in order to identify the component sources of the drag associated with the engine installation. The paper concludes with an assessment of installation drag for through-flow nacelles and the determination of aerodynamic interference between the nacelle and the aircraft.


Author(s):  
Sajjad Miran ◽  
Chang Hyun Sohn

Purpose – The purpose of this paper is to focus on the variation of wake structures and aerodynamic forces with changes in the cylinder corner radius and orientation. Design/methodology/approach – Numerical simulations were performed for flow past a square cylinder with different corner radii placed at an angle to the incoming flow. In the present study, the rounded corner ratio R/D=0 (square cylinder), 0.1, 0.2, 0.3, and 0.4 (where R is the corner radius and D is the characteristic dimension of the body) and the angle of incidence α in the range of 0°-45° were considered. Findings – The numerical model was validated by comparing the present results with results in the available literature, and they were found to be in good agreement. The critical incidence angle for the rounded corner cylinder – corresponding to the minimum mean drag coefficient (C D ), the minimum root mean square value of the lift coefficient C L,RMS), and the maximum Strouhal number – shifted to a lower incidence angle compared with the sharp corner square cylinder. The minimum drag and lift coefficient at R/D=0 were observed for the critical incidence angle αcri=12°, whereas for R/D=0.1-0.4, the minimum drag and lift coefficient were found to be within the range of 5°-10° for α. Originality/value – The presented results shows the importance of the incidence angle and rounded corners of the square cylinder for reduction of aerodynamic forces. The two parameters support the shear layer flow reattachment on the lateral surface of the cylinder, have a strong correlation with the reduction of the wake width, and hence reduced the values of C D and C L .


ROTOR ◽  
2017 ◽  
Vol 10 (2) ◽  
pp. 47
Author(s):  
Maria Margareta Zau Beu ◽  
I Putu Andhi Indira Kusuma

The 2D numerical simulation of an underwater acoustic system undergoing VIV (Vortex Induced Vibration) which is in position parallel to 5 m distance with variation of hydrophone cable position. The diameter of the hydrophone cable in use is 0.04 m, with Reynold numbers (Re) variations of 13000, 15000, 17000, 19000, 21000, 23000, 25000, 27000 and 30000. Position variations are used to determine the flow pattern characteristics that occur behind the cylinder as well the maximum value of drag coefficient (CD) and lift coefficient (CL). The simulation results show that the characteristic flow pattern around a cylinder at each Re value indicates the release of the vortex behind the cylinder with different drag and lift coefficient values.  Keywords: Vortex Shedding, Hydrophone, Acoustic System


Author(s):  
Feysal A. Adem ◽  
Dongmei Zhou ◽  
Pramod Krishnani

The flows over a pickup truck with add-on devises were studied using computational fluid dynamics (CFD) with the objective of investigating the effect of these add-no devices on the flow structures around the vehicle, aerodynamic drag, and lift coefficient. All numerical simulations were performed using commercial CFD software Fluent [8]. A generic pickup model with extended cab was used as the base model and all the flow simulations were performed at zero degree yaw angle. The pickup configurations used in the present CFD simulation include Aerocap with different rear inclination angle α, Tonneau cover, Rear Roof Garnish, and Tail-plates. Results from numerical simulations indicated that Aerocap with inclination angle α = 12° and a reduced rear width has produced the minimum aerodynamic drag coefficient. It was also shown that the wake region decrease when the rear inclination angle increases.


2021 ◽  
Vol 12 (1) ◽  
pp. 159-183
Author(s):  
Arun M. P. ◽  
Satheesh M. ◽  
J. Edwin Raja Dhas

The designing and modeling of delta wing is one of the interesting topics. A number of researchers has contributed different works on modeling the same. This paper comes out with a new delta wing modeling with the inclusion of optimization concept. The obtained data from the investigation is integrated and given as the input to the classifier for predicting the drag and lift coefficients. This paper uses neural network (NN) classifier for predicting the drag and lift coefficients. Moreover, the weight of the NN is optimized using a proposed genetic algorithm. After the implementation, the performance of proposed model is compared to other conventional methods like individual adaptive genetic algorithm (IAGA-NN), deterministic adaptive genetic algorithm (DAGA-NN), self-adaptive genetic algorithm (SAGA-NN), genetic algorithm (GA-NN), gradient descendent (GD-NN), and Levenberg masquerade (LM-NN), respectively, in terms of drag and lift coefficient.


2019 ◽  
Vol 1276 ◽  
pp. 012013
Author(s):  
G S Samy ◽  
S Thirumalai Kumaran ◽  
M Uthayakumar ◽  
M Sivasubramanian ◽  
Krishna Bhagavathi Sankar

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