scholarly journals Hydrodynamics of gliding penguin flipper suggests the adjustment of sweepback with swimming speeds

2021 ◽  
Author(s):  
Masateru Maeda ◽  
Natsuki Harada ◽  
Hiroto Tanaka
Keyword(s):  
Large Eddy Simulation ◽  
Cfd Simulation ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Force Balance ◽  
Hydrodynamic Performance ◽  
Vertical Force ◽  
Sweep Angle ◽  
Eddy Simulation ◽  
Large Eddy

Hydrodynamic performance of a gliding penguin flipper (wing) considering the backward sweep was estimated with computational fluid dynamics (CFD) simulation. A flipper of a gentoo penguin (Pygoscelis papua) was 3D scanned, smoothed, and a numerical fluid mesh was generated. For accurate yet resource-saving computation, an embedded large-eddy simulation (ELES) methods was employed, where the flow near the flipper was solved with large-eddy simulation (LES) and flow far away from the flipper was solved with Reynolds-averaged Navier-Stokes (RANS). The relative flow speed was fixed at 2 m s-1, close to the typical foraging speed for the penguin species. The sweep angle was set to be 0°, 30°, and 60°, while the angle of attack was varied between -40° and 40°, both are within the realistic ranges in the wing kinematics measurement of penguins in an aquarium. It was revealed that a higher sweep angle reduces the lift slope, but the lift coefficient is unchanged at a high angle of attack. Drag coefficient was reduced across the angles of attack with increasing the sweep angles. The drag polars suggest the sweep angle may be adjusted with the change in swimming speed and anhedral (negative dihedral) angle to minimise drag while maintaining the vertical force balance to counteract the positive buoyancy. This will effectively expand the swimming envelope of the gliding penguin, similar to a flying counterpart such as swift.

scholarly journals Prediction of Pollutants Emissions in a CFM56-3 Combustor, Using Large Eddy Simulation

2020 ◽  
Author(s):  
Inês Isabel Ascensão Costa Morão ◽  
Francisco Miguel Ribeiro Proença Brojo
Keyword(s):  
Large Eddy Simulation ◽  
Cfd Simulation ◽  
Numerical Study ◽  
Jet Fuels ◽  
Cad Model ◽  
Commercial Software ◽  
Ansys Fluent ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Detailed Chemical

In the present work a CFD simulation was performed using a CFM56-3 combustor.   It was intended to simulate the combustion and emission of pollutants (CO2, CO, UHC and NOx) from the different jet fuels ( Jet A, Jet B and TS-1), when burning these through ICAO’s LTO cycle. Being this a continuity study, the CAD model of CFM56-3 made by Oliveira [5] was used. The mesh was constructed with HELYX-OS software and the numerical study was made using the commercial software ANSYS Fluent16.2. It can be concluded, amongst all the fuels simulated that increasing the power produces higher NOx. There was also an erratic behaviour in the emissions of UHC and CO results, because an empiric model was used and not a detailed chemical model. Keywords: Jet Fuels, ANSYS Fluent, Pollutants emissions, ICAO’s LTO cycle, CFM56-3

scholarly journals Convective heat transfer over a wall mounted cube at different angle of attack using large eddy simulation

2014 ◽  
Vol 18 (suppl.2) ◽  
pp. 301-315
Author(s):  
Habibollah Heidarzadeh ◽  
Mousa Farhadi ◽  
Kurosh Sedighi
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Large Eddy Simulation ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Angle Of Attack ◽  
Scale Model ◽  
Flow Angle ◽  
Eddy Simulation ◽  
Large Eddy

Turbulent fluid flow and convective heat transfer over the wall mounted cube in different flow angle of attack have been studied numerically using Large Eddy Simulation. Cube faces and plate have a constant heat flux. Dynamic Smagorinsky (DS) subgrid scale model were used in this study. Angles were in the range 0???45 and Reynolds number based on the cube height and free stream velocity was 4200. The numerical simulation results were compared with the experimental data of Nakamura et al [6, 7]. Characteristics of fluid flow field and heat transfer compared for four angles of attack. Flow around the cube was classified to four regimes. Results was represented in the form of time averaged normalized streamwise velocity and Reynolds stress in different positions, temperature contours, local and average Nusselt number over the faces of cube. Local convective heat transfer on cube faces was affected by flow pattern around the cube. The local convective heat transfer from the faces of the cube and plate are directly related to the complex phenomena such as horse shoe vortex, arch vortexes in behind the cube, separation and reattachment. Results show that overall convective heat transfer of cube and mean drag coefficient have maximum and minimum value at ?=0 deg and ?=25 deg respectively.

scholarly journals CFD Simulation of the Discharge Flow from Standard Rushton Impeller

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Bohuš Kysela ◽  
Jiří Konfršt ◽  
Ivan Fořt ◽  
Zdeněk Chára
Keyword(s):  
Large Eddy Simulation ◽  
Cfd Simulation ◽  
Laser Doppler Anemometry ◽  
Rushton Turbine ◽  
Sliding Mesh ◽  
Eddy Simulation ◽  
Large Eddy ◽  
The Mean ◽  
Rushton Impeller ◽  
Good Agreement

The radial discharge jet from the standard Rushton turbine was investigated by the CFD calculations and compared with results from the Laser Doppler Anemometry (LDA) measurements. The Large Eddy Simulation (LES) approach was employed with Sliding Mesh (SM) model of the impeller motion. The obtained velocity profiles of the mean ensemble-averaged velocity and r.m.s. values of the fluctuating velocity were compared in several distances from the impeller blades. The calculated values of mean ensemble-averaged velocities are rather in good agreement with the measured ones as well as the derived power number from calculations. However, the values of fluctuating velocities are obviously lower from LES calculations than from LDA measurements.

Large Eddy Simulation of Coflow Jet Airfoil at High Angle of Attack

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Hong-Sik Im ◽  
Ge-Cheng Zha ◽  
Bertrand P. E. Dano
Keyword(s):  
Large Eddy Simulation ◽  
Angle Of Attack ◽  
Weno Scheme ◽  
Quantitative Prediction ◽  
High Angle ◽  
High Angle Of Attack ◽  
Jet Mixing ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Lift And Drag

Large eddy simulation (LES) is conducted to investigate coflow jet (CFJ) airfoil flows at high angle of attack (AOA). The Smagorinsky model with Van Driest damping is employed to resolve the subgrid-scale stress. The fifth-order weighted essentially non-oscillatory (WENO) scheme is used for reconstruction of the inviscid flux and the fourth-order central differencing for the viscous flux. The LES results at an AOA of 0 deg, 12 deg, 25 deg, and 30 deg with momentum coefficients of Cμ = 0.15 and 0.08 are compared with the experiment to understand the flow structure of the jet mixing and flow separation. The quantitative prediction of lift and drag and qualitative prediction of vortex structures are in good agreement with experiment.

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