scholarly journals Numerical simulation of the flow over a tubercled wing

2020 ◽  
Vol 307 ◽  
pp. 01036
Author(s):  
Mohammed Baghdad ◽  
Abdelkader Nehmar ◽  
Ahmed Ouadha
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Drag Coefficient ◽  
Turbulence Model ◽  
Numerical Study ◽  
Leading Edge ◽  
Governing Equations

The objective of the present study is to carry out a numerical study of the flow around a NACA0021 modified wing by the incorporation of sinusoidal tubercles on its leading edge at a Reynolds number equal to 225,000. The SST k-ω turbulence model is used as closure to the incompressible governing equations. Runs have been performed for several attack angles. Results show that for lower angles of attack, tubercles reduce the drag coefficient with a slight increase in lift.

Direct numerical simulation of flow past a transversely rotating sphere up to a Reynolds number of 300 in compressible flow

2018 ◽  
Vol 857 ◽  
pp. 878-906 ◽  
Author(s):  
T. Nagata ◽  
T. Nonomura ◽  
S. Takahashi ◽  
Y. Mizuno ◽  
K. Fukuda
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Mach Number ◽  
Direct Numerical Simulation ◽  
Drag Coefficient ◽  
Rotation Rate ◽  
Free Stream ◽  
Rotating Sphere ◽  
Free Stream Mach Number ◽  
Low Reynolds

In this study, direct numerical simulation of the flow around a rotating sphere at high Mach and low Reynolds numbers is conducted to investigate the effects of rotation rate and Mach number upon aerodynamic force coefficients and wake structures. The simulation is carried out by solving the three-dimensional compressible Navier–Stokes equations. A free-stream Reynolds number (based on the free-stream velocity, density and viscosity coefficient and the diameter of the sphere) is set to be between 100 and 300, the free-stream Mach number is set to be between 0.2 and 2.0, and the dimensionless rotation rate defined by the ratio of the free-stream and surface velocities above the equator is set between 0.0 and 1.0. Thus, we have clarified the following points: (1) as free-stream Mach number increased, the increment of the lift coefficient due to rotation was reduced; (2) under subsonic conditions, the drag coefficient increased with increase of the rotation rate, whereas under supersonic conditions, the increment of the drag coefficient was reduced with increasing Mach number; and (3) the mode of the wake structure becomes low-Reynolds-number-like as the Mach number is increased.

scholarly journals Numerical study of gas dynamics and heat transfer in matrix channels at various rib angles

2021 ◽  
Vol 2057 (1) ◽  
pp. 012026
Author(s):  
A V Barsukov ◽  
V V Terekhov ◽  
V I Terekhov
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Reynolds Number ◽  
Gas Dynamics ◽  
Average Velocity ◽  
Numerical Study ◽  
Reynolds Numbers ◽  
Separation Flow ◽  
Maximum Heat ◽  
Maximum Heat Transfer

Abstract The results of numerical simulation of the separation flow in matrix channels by the RANS method are presented. The simulation is performed at the Reynolds number Re = 12600, determined by the mass-average velocity and the height of the channel. The distribution of the local Nusselt number is obtained for various Reynolds numbers in the range of 5÷15⋅103 and several rib angles. It is shown that the temperature distribution on the surface is highly nonuniform; in particular, the maximum heat transfer value is observed near the upper edge facets, in the vicinity of which the greatest velocity gradient is observed.

scholarly journals Effect of Air Exchange Rate on Particle Decay in a Cleanroom: A Numerical Study

2019 ◽  
Vol 111 ◽  
pp. 01037
Author(s):  
Yunus Emre Cetin ◽  
Mete Avci ◽  
Orhan Aydin
Keyword(s):  
Exchange Rate ◽  
Turbulence Model ◽  
Recovery Time ◽  
Numerical Study ◽  
Particle Dispersion ◽  
Discrete Phase Model ◽  
Governing Equations ◽  
Air Exchange Rate ◽  
Particle Decay ◽  
Discrete Phase

In this study, particle decay in a cleanroom is investigated numerically. A commercial CFD package, FLUENT, is used in the analysis. The governing equations are solved by using the k-å turbulence model. For particle dispersion, the discrete phase model (DPM) is applied. Four different air change rates (3-10-25-43 ACH) with three particle diameters (0,5-5-10 ìm) are considered. It is shown that 10 ACH satisfies the needs in terms of recovery time.

Numerical Simulation Analysis of Car Overtaking on SST Turbulence Model

2014 ◽  
Vol 628 ◽  
pp. 270-274
Author(s):  
Yi Bin He ◽  
Qi Zhi Shen
Keyword(s):  
Numerical Simulation ◽  
Numerical Experiment ◽  
Drag Coefficient ◽  
Turbulence Model ◽  
Simulation Analysis ◽  
Turbulence Models ◽  
Force Coefficient ◽  
Side Force ◽  
Sst Turbulence Model ◽  
Side Force Coefficient

Thebased SST (shear strain transport) turbulence model combines the advantages of and turbulence models and performs well in numerical experiment. In the paper, the SST turbulence model is applied to model vehicle overtaking process with numerical simulation technology. The change graph of drag coefficient and side force coefficient are gained. Analysis of the phenomena is presented at the end.

Experimental Aerodynamic Characteristics of a Compound Wing in Ground Effect

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Saeed Jamei ◽  
Adi Maimun Abdul Malek ◽  
Shuhaimi Mansor ◽  
Nor Azwadi Che Sidik ◽  
Agoes Priyanto
Keyword(s):  
Reynolds Number ◽  
Drag Coefficient ◽  
Center Of Pressure ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Leading Edge ◽  
Ground Effect ◽  
Reynolds Numbers ◽  
Aerodynamic Characteristics ◽  
Ground Clearance

Wing configuration is a parameter that affects the performance of wing-in-ground effect (WIG) craft. In this study, the aerodynamic characteristics of a new compound wing were investigated during ground effect. The compound wing was divided into three parts with a rectangular wing in the middle and two reverse taper wings with anhedral angle at the sides. The sectional profile of the wing model is NACA6409. The experiments on the compound wing and the rectangular wing were carried to examine different ground clearances, angles of attack, and Reynolds numbers. The aerodynamic coefficients of the compound wing were compared with those of the rectangular wing, which had an acceptable increase in its lift coefficient at small ground clearances, and its drag coefficient decreased compared to rectangular wing at a wide range of ground clearances, angles of attack, and Reynolds numbers. Furthermore, the lift to drag ratio of the compound wing improved considerably at small ground clearances. However, this improvement decreased at higher ground clearance. The drag polar of the compound wing showed the increment of lift coefficient versus drag coefficient was higher especially at small ground clearances. The Reynolds number had a gradual effect on lift and drag coefficients and also lift to drag of both wings. Generally, the nose down pitching moment of the compound wing was found smaller, but it was greater at high angle of attack and Reynolds number for all ground clearance. The center of pressure was closer to the leading edge of the wing in contrast to the rectangular wing. However, the center of pressure of the compound wing was later to the leading edge at high ground clearance, angle of attack, and Reynolds number.

scholarly journals Effects of Suction and Blowing on Flow Separation in a Symmetric Sudden Expanded Channel

2008 ◽  
Vol 13 (4) ◽  
pp. 451-465 ◽  
Author(s):  
G. C. Layek ◽  
C. Midya ◽  
S. Mukhopadhyay
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Laminar Flow ◽  
Finite Difference ◽  
Recirculation Zone ◽  
Critical Reynolds Number ◽  
Governing Equations ◽  
Flow Asymmetry ◽  
Suction And Blowing ◽  
Finite Difference Techniques

A numerical simulation has been carried out to study the laminar flow in a symmetric sudden expanded channel subjected to a uniform blowing/suction speed placed at the lower and upper porous step walls. The governing equations for viscous flow have been solved using finite-difference techniques in pressure-velocity formulation. The results obtained here have been compared with the available experimental and numerical results of similar problems. It is noted that the recirculating region formed near the step walls diminishes in its length for increasing values of blowing speed applied at the porous step walls. For a suitable blowing speed, the recirculation zone disappears completely. The critical Reynolds number for the flow bifurcation (i.e. flow asymmetry) is obtained and it increases with the increase of the blowing speed. The critical Reynolds number for symmetry breaking of the flow decreases with the increasing values of suction speeds. The primary and the secondary recirculating regions formed near the channel walls are controlled using blowing.

Experimental Study of Automotive Aerodynamics in Headlamp Effect

2011 ◽  
Vol 279 ◽  
pp. 339-344
Author(s):  
Lan Fang Jiang ◽  
Hong Liu ◽  
Ai Qi Li
Keyword(s):  
Numerical Simulation ◽  
Boundary Condition ◽  
Experimental Study ◽  
Reynolds Number ◽  
Wind Tunnel ◽  
Drag Coefficient ◽  
Surface Pressure ◽  
Symmetry Plane ◽  
Automotive Aerodynamics ◽  
Inlet Boundary Condition

The effect of headlamp modeling on automotive aerodynamics was studied by wind tunnel tests. Firstly, the effect of Reynolds number on drag coefficient of automotive scaled down models was studied under different velocity of flow to verify the rationality of selecting scale for scaled down model and setting inlet boundary condition. Secondly, drag coefficient of automotive scaled down models with different headlamp modeling design were measured. Thirdly, the distribution of surface pressure on central symmetry plane and headlamp was measured and analyzed. It also validated the validity of preceding numerical simulation. It is of importance to guide the headlamp modeling design and automotive modeling design.

Effect of Sunroofs and Side Windows on Aerodynamic Characteristics of Transit Bus

2012 ◽  
Vol 224 ◽  
pp. 333-337 ◽  
Author(s):  
Xing Jun Hu ◽  
Feng Tao Ren ◽  
Bo Yang ◽  
Peng Guo
Keyword(s):  
Numerical Simulation ◽  
Drag Coefficient ◽  
Turbulence Model ◽  
Working Conditions ◽  
Working Condition ◽  
Aerodynamic Characteristics ◽  
Rear Side ◽  
Front Side ◽  
Side Window ◽  
Transit Bus

In this paper, k-Omega turbulence model is applied in the numerical simulation of the transit bus, several typical working conditions of the transit bus with windows open at a speed of 10m/s are investigated, and a custom function Q is introduced to characterize the amount of ventilation of each window. The results show that, when the transit bus travels with windows open, the air always flows into the carriage through the middle and rear side windows of the transit bus, and circulates in the carriage and then flows out of the carriage through the front side window. When the bus travels with sunroofs open in leeward mode and side windows open, the amount of ventilation is the maximum. This working condition is the best one when taking both drag coefficient and the amount of ventilation.

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