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1,315 results on '"Navier–Stokes equations"'

1. Global POD-Galerkin ROMs for Fluid Flows with Moving Solid Structures

Author

Bolun Xu, Mingjun Wei, John Hrynuk, and Haotian Gao

Subjects
Direct numerical simulation, Aerospace Engineering, Reynolds number, Projection (linear algebra), Domain (mathematical analysis), Mathematics::Numerical Analysis, Physics::Fluid Dynamics, symbols.namesake, Fluid–structure interaction, symbols, Applied mathematics, Current (fluid), Galerkin method, Navier–Stokes equations, Mathematics
Abstract

Traditional proper orthogonal decomposition (POD)-Galerkin projection for reduced-order models (ROMs) of fluid flows is based on a fixed domain. The current method removes this limitation by consid...

Published
2022
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2. General Drag Coefficient for Flow over Spherical Particles

Author

Eric J. Ching, Christopher J. Hogan, Thomas E. Schwartzentruber, Chenxi Li, Michael Kroells, Matthias Ihme, and Narendra Singh

Subjects
Physics::Fluid Dynamics, Physics, Drag coefficient, Free molecular flow, Flow (mathematics), Compressibility, Aerospace Engineering, Mechanics, Navier–Stokes equations, Boltzmann equation, Heat capacity
Abstract

A generalized physics-based expression for the drag coefficient of spherical particles moving in a fluid is developed. The proposed correlation incorporates essential rarefied effects, low-speed hy...

Published
2022
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3. Dutch-Roll Stability Analysis of an Air Mobility Vehicle Using Navier–Stokes Equations

Author

Guru P. Guruswamy

Subjects
Lift (force), Lift coefficient, Lateral stability, Wing, Dutch roll, Fuselage, Aerospace Engineering, Navier–Stokes equations, Stability (probability), Geology, Marine engineering
Abstract

Dutch-roll motions caused by sudden gusts are studied for a typical advanced air mobility vehicle. The selected lift+cruise configuration consists of a fuselage with high wing powered by lifting an...

Published
2021
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4. Laminar–Turbulent Transition Reversal on a Blunted Plate with Various Leading-Edge Shapes

Author

Vladimir Evguenyevich Mosharov, Volf Ya. Borovoy, Sergey V. Aleksandrov, and Vladimir Nikolaevich Radchenko

Subjects
Physics, Leading edge, Stagnation temperature, Aerospace Engineering, Reynolds number, Mechanics, Physics::Fluid Dynamics, symbols.namesake, Mach number, symbols, Laminar-turbulent transition, Bow shock (aerodynamics), Navier–Stokes equations, Wind tunnel
Abstract

The influence of the flat-plate leading-edge shape on laminar–turbulent transition is investigated. Experiments were carried out at a Mach number of M∞=5; a unit Reynolds number Re1∞ from 1.5×107 t...

Published
2021
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5. Numerical Investigation on Combustion-Enhancement Strategy in Shock–Fuel Jet Interaction

Author

Bin Yu, Bin Zhang, Miaosheng He, Haoyang Liu, Zi’ang Wang, and Hong Liu

Subjects
Jet (fluid), Materials science, Astrophysics::High Energy Astrophysical Phenomena, Mathematics::Analysis of PDEs, Turbulence modeling, Aerospace Engineering, Mechanics, Lagrangian particle tracking, Combustion, Solid fuel, Shock (mechanics), Physics::Fluid Dynamics, Oblique shock, Physics::Chemical Physics, Navier–Stokes equations, Physics::Atmospheric and Oceanic Physics
Abstract

Multidimensional numerical simulations are performed to investigate the evolution and formation of unburned fuels for a shock–fuel jet interaction scenario. A full set of Navier–Stokes equations wi...

Published
2021
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6. Efficient One-Shot Technique for Adjoint-Based Unsteady Optimization

Author

Kivanc Ekici and Reza Djeddi

Subjects
One shot, Lift coefficient, symbols.namesake, Computer science, Lagrange multiplier, Memory footprint, symbols, Aerospace Engineering, Applied mathematics, Vorticity, Navier–Stokes equations, Broyden fletcher goldfarb shanno, Kármán vortex street
Abstract

A computationally efficient one-shot approach with a low memory footprint is presented for unsteady optimization. The proposed technique is based on a novel and unique approach that combines local-...

Published
2021
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7. Rotor-Blade Planform Design Based on an Overset Harmonic-Balance-Adjoint Optimization Framework

Author

Mark Woodgate, George N. Barakos, Thomas A. Fitzgibbon, and Richard H. Markiewicz

Subjects
Blade (geometry), Computer science, Rotor (electric), business.industry, Aerospace Engineering, Computational fluid dynamics, Planform, law.invention, Vortex, Harmonic balance, Control theory, law, Current (fluid), Navier–Stokes equations, business
Abstract

Optimization methods in conjunction with computational fluid dynamics are a key tool in advancing current rotor design. High-fidelity optimization of unsteady rotor flows in forward flight, however...

Published
2021
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8. Investigation of Transition Delay on a Wing Section by Dynamic Surface Deformation

Author

Donald P. Rizzetta and Miguel R. Visbal

Subjects
020301 aerospace & aeronautics, Materials science, Angle of attack, Turbulence, Aerospace Engineering, 02 engineering and technology, Mechanics, Deformation (meteorology), 01 natural sciences, 010305 fluids & plasmas, Natural laminar flow, 0203 mechanical engineering, 0103 physical sciences, Navier–Stokes equations, Surface deformation, Wing section, Plasma actuator
Abstract

Numerical calculations were carried out in order to investigate the delay of transition to turbulence on a wing section by means of local dynamic surface deformation. Physically, the deformation ma...

Published
2021
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9. Interpretation of Multilobe Wavepackets in Spectral Proper Orthogonal Decomposition of Supersonic Jet

Author

Seiji Tsutsumi, Satoshi Nonaka, Masahito Akamine, Susumu Teramoto, and Koji Okamoto

Subjects
Physics::Fluid Dynamics, Physics, Jet (fluid), Flow (mathematics), Turbulence, Modal analysis, Wave packet, Singular value decomposition, Aerospace Engineering, Supersonic speed, Navier–Stokes equations, Computational physics
Abstract

Spectral proper orthogonal decomposition (SPOD) is a major modal analysis that extracts a dominant structure at each frequency from complicated flow data, such as the wavepacket hidden under turbul...

Published
2021
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10. Parabolized Stability Analysis of Hypersonic Thermal–Chemical Nonequilibrium Boundary-Layer Flows

Author

Song Fu, Liang Wang, and Xianliang Chen

Subjects
020301 aerospace & aeronautics, Hypersonic speed, Materials science, Direct numerical simulation, Aerospace Engineering, Non-equilibrium thermodynamics, 02 engineering and technology, Aerodynamics, Mechanics, 01 natural sciences, Wedge (geometry), 010305 fluids & plasmas, symbols.namesake, Boundary layer, 0203 mechanical engineering, Mach number, 0103 physical sciences, symbols, Navier–Stokes equations
Abstract

In this work, the stability of Mach 20 flows past a 6 deg wedge in thermal–chemical nonequilibrium (TCNE) is studied by means of linear parabolized stability equations (PSEs) in combination with ad...

Published
2021
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12. Stabilization of the Adjoint for Turbulent Flows

Author

Scott M. Murman and Anirban Garai

Subjects
Physics, 020301 aerospace & aeronautics, Turbulence, Chaotic, Aerospace Engineering, 02 engineering and technology, Mechanics, Mathematics::Spectral Theory, Kinetic energy, 01 natural sciences, 010305 fluids & plasmas, Physics::Fluid Dynamics, Nonlinear Sciences::Chaotic Dynamics, Boundary layer, 0203 mechanical engineering, Incompressible flow, 0103 physical sciences, Shape optimization, Reynolds-averaged Navier–Stokes equations, Navier–Stokes equations
Abstract

Traditional adjoint variables grow exponentially for turbulent chaotic flows. Most proposed methods (for example. ensemble adjoint, shadow-based, and unstable-subspace-based approaches, etc.) are c...

Published
2021
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13. Numerical Simulation of Shock Tubes Using Shock Tracking in an Overset Formulation

Author

Peter Collen, Matthew Satchell, Luca di Mare, and Matthew McGilvray

Subjects
Physics, 020301 aerospace & aeronautics, Computer simulation, Astrophysics::High Energy Astrophysical Phenomena, Rotational symmetry, Aerospace Engineering, 02 engineering and technology, Mechanics, Lagrangian particle tracking, 01 natural sciences, 010305 fluids & plasmas, Shock (mechanics), Physics::Fluid Dynamics, Discontinuity (linguistics), 0203 mechanical engineering, 0103 physical sciences, Two-dimensional flow, Shock tube, Navier–Stokes equations, Astrophysics::Galaxy Astrophysics
Abstract

An axisymmetric viscous shock tube simulation code is developed that keeps the shock and the contact discontinuity stationary in suitably constructed moving frames of reference. The flowfield aroun...

Published
2021
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14. Numerical Method for Particulate-Induced High-Speed Boundary-Layer Transition Simulations

Author

Christoph Brehm, Sayed Mohammad Abdullah Al Hasnine, and Oliver M. F. Browne

Subjects
Physics, 020301 aerospace & aeronautics, business.industry, Adaptive mesh refinement, Numerical analysis, Aerospace Engineering, 02 engineering and technology, Mechanics, Solver, Computational fluid dynamics, 01 natural sciences, 010305 fluids & plasmas, Physics::Fluid Dynamics, Boundary layer, 0203 mechanical engineering, Incompressible flow, 0103 physical sciences, Laminar-turbulent transition, business, Navier–Stokes equations, Physics::Atmospheric and Oceanic Physics
Abstract

A new numerical method to efficiently simulate particulate interactions with high-speed transitional boundary-layer flows is presented. A particulate solver, employing Crowe’s correlation, is used ...

Published
2021
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17. Assessment of Low-Dissipative Shock-Capturing Schemes for the Compressible Taylor–Green Vortex

Author

Neil D. Sandham and David J. Lusher

Subjects
Shock wave, Physics, 020301 aerospace & aeronautics, ComputingMilieux_THECOMPUTINGPROFESSION, Shock (fluid dynamics), Turbulence, Direct numerical simulation, Aerospace Engineering, 02 engineering and technology, Mechanics, 01 natural sciences, Moving shock, 010305 fluids & plasmas, Physics::Fluid Dynamics, 0203 mechanical engineering, 0103 physical sciences, Dissipative system, Taylor–Green vortex, Navier–Stokes equations
Abstract

Interactions between shock waves and turbulence are ubiquitous in high-speed flows of practical aeronautical interest. Recent advances in computational power have made implicit large-eddy simulatio...

Published
2021
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18. Characteristic Scales in Shock–Turbulence Interaction

Author

Jean-Pierre Hickey, Francis Lacombe, Subhajit Roy, Sebastian Karl, and Krishnendu Sinha

Subjects
Physics, 020301 aerospace & aeronautics, Turbulence, Direct numerical simulation, Aerospace Engineering, Reynolds number, Shock thickness, 02 engineering and technology, Mechanics, Kinetic energy, 01 natural sciences, 010305 fluids & plasmas, Shock (mechanics), Physics::Fluid Dynamics, symbols.namesake, 0203 mechanical engineering, 0103 physical sciences, symbols, Mean flow, Navier–Stokes equations, Reynolds-averaged Navier–Stokes equations
Abstract

A semi-empirical estimate of the time-averaged thickness of a planar shock embedded in a turbulent mean flow is presented in an effort to quantify the characteristic time and length scales for turb...

Published
2021
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19. Single-Pixel Particle Image Velocimetry for Characterization of Dielectric Barrier Discharge Plasma Actuators

Author

Noritsugu Kubo, Hirokazu Kawabata, Atsushi Komuro, Koki Nankai, Hiroyuki Nishida, Yuta Ozawa, Taku Nonomura, Takuma Ibuki, and Kotsonis Marios

Subjects
Materials science, business.industry, Aerospace Engineering, Mechanics, Dielectric barrier discharge, Computational fluid dynamics, Pressure coefficient, law.invention, Particle image velocimetry, law, Parasitic drag, Navier–Stokes equations, Alternating current, business, Plasma actuator
Published
2020
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20. Entropy-Adjoint p-Adaptive Discontinuous Galerkin Method for the Under-Resolved Simulation of Turbulent Flows

Author

Francesco Bassi, Alessandro Colombo, G. Noventa, Antonio Ghidoni, Andrea Crivellini, Krzysztof J. Fidkowski, and Matteo Franciolini

Subjects
020301 aerospace & aeronautics, Drag coefficient, Turbulence, Mathematical analysis, Direct numerical simulation, Aerospace Engineering, 02 engineering and technology, 01 natural sciences, Pressure coefficient, 010305 fluids & plasmas, 0203 mechanical engineering, Incompressible flow, Discontinuous Galerkin method, 0103 physical sciences, Settore ING-IND/06 - Fluidodinamica, Entropy (energy dispersal), Navier–Stokes equations, Mathematics
Abstract

This paper presents an approach to mesh adaptation suitable for scale-resolving simulations. The methodology is based on the entropy-adjoint approach, which corresponds to a standard output-based a...

Published
2020
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21. Reduced-Order Modeling for Dynamic Mode Decomposition Without an Arbitrary Sparsity Parameter

Author

John Graff, Tarunraj Singh, Francis D. Lagor, and Matthew Ringuette

Subjects
020301 aerospace & aeronautics, business.industry, Computer science, Modal analysis, Aerospace Engineering, 02 engineering and technology, Computational fluid dynamics, 01 natural sciences, 010305 fluids & plasmas, Set (abstract data type), Nonlinear system, 0203 mechanical engineering, 0103 physical sciences, Singular value decomposition, Dynamic mode decomposition, Navier–Stokes equations, business, Algorithm, Selection algorithm
Abstract

Dynamic mode decomposition (DMD) yields a linear, approximate model of a system’s dynamics that is built from data. This paper seeks to reduce the order of this model by identifying a reduced set o...

Published
2020
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23. Numerical Modeling of Instability and Breakup of Elliptical Liquid Jets

Author

Ghobad Amini, M.R. Morad, and Mahdi Nasiri

Subjects
Physics, 020301 aerospace & aeronautics, Finite volume method, Computer simulation, Adaptive mesh refinement, Aerospace Engineering, 02 engineering and technology, Mechanics, Breakup, 01 natural sciences, Instability, 010305 fluids & plasmas, Physics::Fluid Dynamics, Surface tension, 0203 mechanical engineering, 0103 physical sciences, Navier–Stokes equations, Body orifice
Abstract

Numerical simulations are performed to provide an in-depth insight into the effect of instabilities on liquid jets discharging from elliptical orifices. The axis-switching phenomenon and breakup ar...

Published
2020
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24. Numerical Modeling Screen for Flow and Noise Control Around Tandem Cylinders

Author

Song Fu, Wenqing Zhu, and Zhixiang Xiao

Subjects
Physics, Noise reduction, High-lift device, Mathematics::Analysis of PDEs, Direct numerical simulation, Aerospace Engineering, Mechanics, Physics::Fluid Dynamics, symbols.namesake, Flow (mathematics), symbols, Noise control, Strouhal number, Navier–Stokes equations, Reynolds-averaged Navier–Stokes equations
Abstract

Noise reduction by screens applied to tandem cylinders was studied numerically. The screen was modeled by adding source terms to the Navier–Stokes equations. To validate the screen model, a windbre...

Published
2020
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25. Slip Flow Models for Gas Flows in Rectangular, Trapezoidal, and Hexagonal Microchannels

Author

Waqar A. Khan and M. Michael Yovanovich

Subjects
020301 aerospace & aeronautics, Materials science, Aerospace Engineering, 02 engineering and technology, Heat transfer coefficient, Mechanics, Computer Science::Numerical Analysis, 01 natural sciences, Aspect ratio (image), Isothermal process, Mathematics::Numerical Analysis, 010305 fluids & plasmas, Physics::Fluid Dynamics, 0203 mechanical engineering, 0103 physical sciences, Compressibility, No-slip condition, Fanning friction factor, Shear stress, Navier–Stokes equations
Abstract

A compact slip flow model is proposed for isothermal, incompressible gas flows in long microchannels of rectangular (square), trapezoidal (triangular), and double-trapezoidal (rhombic) cross sectio...

Published
2020
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26. Shock-Induced Flow Separation in an Overexpanded Supersonic Planar Nozzle

Author

Shashi B. Verma, Abdellah Hadjadj, B. Zebiri, and A. Piquet

Subjects
020301 aerospace & aeronautics, Materials science, Shock (fluid dynamics), Nozzle, Direct numerical simulation, Aerospace Engineering, 02 engineering and technology, Mechanics, 01 natural sciences, 010305 fluids & plasmas, Physics::Fluid Dynamics, Flow separation, symbols.namesake, 0203 mechanical engineering, 0103 physical sciences, Physics::Atomic and Molecular Clusters, symbols, Strouhal number, Supersonic speed, Navier–Stokes equations, Reynolds-averaged Navier–Stokes equations, Astrophysics::Galaxy Astrophysics
Abstract

Shock-induced flow separation in an overexpanded supersonic planar nozzle is investigated numerically by means of three-dimensional wall-modeled large-eddy simulations (LES). The objective of this ...

Published
2020
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27. Numerical Investigation of the Effects of Nonuniform Premixing on Shock-Induced Combustion.

Author

Kazuya Iwata, Shinji Nakaya, and Mitsuhiro Tsue

Subjects
*NAVIER-Stokes equations, *GAUSSIAN function, *MOLE fraction, *HYPERSONIC flow, *CHEMICAL kinetics, *MACH number
Abstract

A parametric numerical study was performed to study effects of the nonuniform premixing of a hydrogen-air mixture on the structures of oblique detonation and shock-induced combustion formed on the surface of a hypersonic spherical projectile. Axisymmetric two-dimensional Navier-Stokes equations were solved with a detailed chemical kinetic mechanism involving nine species. A smooth-front oblique detonation formed on the hypersonic projectile at a Mach number of 6.46 under a uniformly stoichiometric condition was taken as the completely premixed case. For nonuniform cases, hydrogen mole fraction was distributed at the inlet boundary based on the Gaussian function. As the nonuniformity was increased, the following occurred: 1) deformed oblique detonation, 2) oscillating shock-induced combustions with nonuniform corrugated structures, 3) steady shock-induced combustions with (and without) the minimum induction length located outside the centerline, and 4) nose-confined combustion. Analyses on distributions of induction lengths combined with zero-dimensional additional simulations demonstrated that a reactivity gradient became strongly influential on the nonuniformly premixed structures as the nonuniformity was increased, and finally the postshock flowfield became the most determinant factor. [ABSTRACT FROM AUTHOR]

Published
2016
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28. Active Flow Control for Interaction Noise Reduction of Contra-Rotating Open Rotors.

Author

Akkermans, R. A. D., Stuermer, A., and Delfs, J. W.

Subjects
*NOISE control, *WAKES (Aerodynamics), *TRAILING edges (Aerodynamics), *NAVIER-Stokes equations, *REYNOLDS number
Abstract

A possible way to decrease interaction tone noise of a contra-rotating open rotor is through the application of trailing-edge blowing by reducing the momentum deficit of the front rotor wake, and therefore its interaction with the aft rotor. In this contribution, an assessment of front-rotor trailing-edge blowing is presented for the reduction of contra-rotating open-rotor interaction noise. For this purpose, the German Aerospace Center designed a generic contra-rotating open rotor that has been modified to include trailing-edge blowing at the front rotor blades. With the German Aerospace Center computational fluid dynamics code TAU, unsteady Reynolds-averaged Navier-Stokes simulations have been made of the baseline and the trailing-edge blowing configuration. Subsequently, an aeroacoustic analysis has been performed with the Ffowcs-Williams/Hawkings tool APSIM+ for both configurations. The results show negligible differences of the aerodynamic performance, with significantly lower unsteady loading of the aft rotor when the trailing-edge blowing technique is active. The aeroacoustic results illustrate that the interaction tones are notably ameliorated; that is, a reduction over almost the complete polar angle is seen when trailing-edge blowing is active. With respect to the A-weighted overall sound pressure level, a reduction of approximately 2.5 dBA in the maximum level for the trailing-edge blowing configuration is achieved for the considered geometry. Noise reductions up to 5 dBA are displayed in the up- and downstream directions, which mainly arise from reduced interaction tones caused by the trailing-edge blowing technique. The decreased noise radiation with trailing-edge blowing mainly stems from a reduction in the first two interaction tones. [ABSTRACT FROM AUTHOR]

Published
2016
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29. Well-Balanced, Conservative Finite Difference Algorithm for Atmospheric Flows.

Author

Ghosh, Debojyoti and Constantinescu, Emil M.

Subjects
*CONVECTIVE flow, *WEATHER forecasting, *FINITE difference method, *EULER equations, *NAVIER-Stokes equations, *CONSERVATION laws (Physics)
Abstract

The numerical simulation of meso-, convective-, and microscale atmospheric flows requires the solution of the Euler or the Navier-Stokes equations. Nonhydrostatic weather prediction algorithms often solve the equations in terms of derived quantities such as Exner pressure and potential temperature (and are thus not conservative) and/or as perturbations to the hydrostatically balanced equilibrium state. This paper presents a well-balanced, conservative finite difference formulation for the Euler equations with a gravitational source term, where the governing equations are solved as conservation laws for mass, momentum, and energy. Preservation of the hydrostatic balance to machine precision by the discretized equations is essential because atmospheric phenomena are often small perturbations to this balance. The proposed algorithm uses the weighted essentially nonoscillatory and compact-reconstruction weighted essentially nonoscillatory schemes for spatial discretization that yields high-order accurate solutions for smooth flows and is essentially nonoscillatory across strong gradients; however, the well-balanced formulation may be used with other conservative finite difference methods. The performance of the algorithm is demonstrated on test problems as well as benchmark atmospheric flow problems, and the results are verified with those in the literature. [ABSTRACT FROM AUTHOR]

Published
2016
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30. Resolvent Analysis of Compressible Laminar and Turbulent Cavity Flows

Author

Lawrence Ukeiley, Qiong Liu, Yiyang Sun, Kunihiko Taira, and Louis N. Cattafesta

Subjects
Physics, 020301 aerospace & aeronautics, Turbulence, Fluid Dynamics (physics.flu-dyn), Direct numerical simulation, FOS: Physical sciences, Aerospace Engineering, Laminar flow, Harmonic (mathematics), Physics - Fluid Dynamics, 02 engineering and technology, Mechanics, Boundary layer thickness, 01 natural sciences, 010305 fluids & plasmas, Physics::Fluid Dynamics, 0203 mechanical engineering, 0103 physical sciences, Two-dimensional flow, Navier–Stokes equations, Resolvent
Abstract

The present work demonstrates the use of resolvent analysis to obtain physical insights for open-cavity flows. Resolvent analysis identifies the flow response to harmonic forcing, given a steady base state, in terms of the response and forcing modes and the amplification gain. The response and forcing modes reveal the spatial structures associated with this amplification process. In this study, we perform resolvent analysis on both laminar and turbulent flows over a rectangular cavity with length-to-depth ratio of $L/D=6$ at a free stream Mach number of $M_\infty=0.6$ in a spanwise periodic setting. Based on the dominant instability of the base state, a discount parameter is introduced to resolvent analysis to examine the harmonic characteristics over a finite-time window. We first uncover the underlying flow physics and interpret findings from laminar flow at $Re_D = 502$. These findings from laminar flow are extended to a more practical cavity flow example at a much higher Reynolds number of $Re_D = 10^4$. The features of response and forcing modes from the laminar and turbulent cavity flows are similar to the spatial structures from the laminar analysis. We further find that the large amplification of energy in flow response is associated with high frequency for turbulent flow, while the flow is more responsive to low frequency excitation in the laminar case. These findings from resolvent analysis provide valuable insights for flow control studies with regard to parameter selection and placement of actuators and sensors.

Published
2020
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31. Mechanisms for Absolute Instabilities in Uniform and Nonuniform Density Swirling Flows

Author

Anjay Kumar Mishra

Subjects
Convection, Physics, Batchelor vortex, Flow (psychology), Mathematics::Analysis of PDEs, Aerospace Engineering, Spectral density, Mechanics, Kinetic energy, Instability, Quantitative Biology::Cell Behavior, Physics::Fluid Dynamics, Incompressible flow, Navier–Stokes equations
Abstract

In this paper, transitions from convective to absolute instability in post-vortex-breakdown swirling flow with nonuniform density are investigated using linear stability analysis. Addition of swirl...

Published
2020
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32. Takeoff Simulation of Lift+Cruise Air Taxi by Using Navier–Stokes Equations

Author

Guru P. Guruswamy

Subjects
020301 aerospace & aeronautics, Angle of attack, Computation, Cruise, Aerospace Engineering, Lift (soaring), 02 engineering and technology, 01 natural sciences, 010305 fluids & plasmas, 0203 mechanical engineering, 0103 physical sciences, Takeoff, Navier–Stokes equations, Reynolds-averaged Navier–Stokes equations, Geology, Marine engineering
Abstract

Takeoff trajectory computations are made for a typical lift+cruise small transport aircraft suitable for an urban air taxi. The selected wing–body model consists of lifting and pushing propellers. ...

Published
2020
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33. Mean and Unsteady Flow Reconstruction Using Data-Assimilation and Resolvent Analysis

Author

Peter J. Schmid, Sean Symon, Denis Sipp, Beverley McKeon, Graduate Aeronautical Laboratories (GALCIT), California Institute of Technology (CALTECH), DAAA, ONERA, Université Paris Saclay (COmUE) [Meudon], ONERA-Université Paris-Saclay, Department of Mathematics [Imperial College London], and Imperial College London

Subjects
Aerospace Engineering, 02 engineering and technology, Computational fluid dynamics, 01 natural sciences, Kármán vortex street, Flow measurement, 010305 fluids & plasmas, Physics::Fluid Dynamics, [SPI]Engineering Sciences [physics], symbols.namesake, ASSIMILATION DONNEES, 0203 mechanical engineering, 0103 physical sciences, Navier–Stokes equations, Mathematics, Resolvent, [PHYS]Physics [physics], 020301 aerospace & aeronautics, Turbulence, business.industry, Reynolds number, Mechanics, STABILITE HYDRODYNAMIQUE, symbols, Reynolds-averaged Navier–Stokes equations, business
Abstract

International audience; A methodology is presented that exploits both data-assimilation techniques and resolvent analysis for reconstructing turbulent flows, containing organized structures,with an efficient set of measurements. The mean (time-averaged) flow is obtained using variational data-assimilation that minimizes the discrepancy between a limited set of flowmeasurements, generally from an experiment, and a numerical simulation of the Navier–Stokes equations. The fluctuations are educed from resolvent analysis and time-resolved data at a single point in the flow. Resolvent analysis also guides where measurements of the mean and fluctuating quantities are needed for efficient reconstruction of a simple example case study: flow around a circular cylinder at a Reynolds number ofRe = 100.For this flow, resolvent analysis reveals that the leading singular value,most amplifiedmodes, and themean profile for 47 < Re < 320 scalewith the shedding frequency and length of the recirculation bubble. A relationship between these two parameters reinforces the notion that a wave maker, forwhich the length scaleswith the recirculation bubble, determines the frequency and regionwhere an instability mechanism is active. The procedure offers away to choose sensor locations that capture the main coherent structures of a flow and a method for computing mean pressure by using correctly weighted resolvent modes.

Published
2020
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34. Shock-Stable Roe Scheme Combining Entropy Fix and Rotated Riemann Solver

Author

Xuesong Li, Chun-wei Gu, Xiaodong Ren, and Yu-Hong Li

Subjects
Finite volume method, Mathematics::Operator Algebras, Astrophysics::High Energy Astrophysical Phenomena, Aerospace Engineering, Physics::Data Analysis, Statistics and Probability, Compressible flow, Instability, Moving shock, Riemann solver, Roe solver, symbols.namesake, Mathematics::K-Theory and Homology, symbols, Mathematics::Metric Geometry, Entropy (information theory), Applied mathematics, Navier–Stokes equations, Mathematics
Abstract

The Roe scheme is an important shock-capturing scheme that is known for its good performance. However, the classical Roe scheme suffers from disastrous problems, such as shock instability for hyper...

Published
2020
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35. Stability Analysis of the Swirling Majdalani–Fist Mean Flowfield in Solid Rocket Motors

Author

Wesley A. Gibson and Trevor S. Elliott

Subjects
Propellant, 020301 aerospace & aeronautics, Materials science, Fist, Aerospace Engineering, 02 engineering and technology, Mechanics, 01 natural sciences, Stability (probability), 010305 fluids & plasmas, Chamber pressure, Burn rate (chemistry), 0203 mechanical engineering, 0103 physical sciences, Solid-fuel rocket, Navier–Stokes equations, Spinning
Abstract

Numerous studies have been performed to show the effects of spinning and swirling flows on increased flight stability characteristics, higher propellant consumption, increased burn rate, greater ch...

Published
2019
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36. Relation Between the Finite-Time Lyapunov Exponent and Acoustic Wave

Author

Han Shuaibin, Shuhai Zhang, and Luo Yong

Subjects
Physics, 020301 aerospace & aeronautics, business.industry, Mathematical analysis, Aerospace Engineering, 02 engineering and technology, Acoustic wave, Lyapunov exponent, Computational fluid dynamics, 01 natural sciences, Jet noise, 010305 fluids & plasmas, Nonlinear Sciences::Chaotic Dynamics, Flow separation, symbols.namesake, 0203 mechanical engineering, Computer Science::Systems and Control, 0103 physical sciences, symbols, Two-dimensional flow, Navier–Stokes equations, Spline interpolation, business
Abstract

The relation between different time scales of the finite-time Lyapunov exponent (FTLE) and the acoustic wave is studied. Gonzalez et al.’s proposition (“Finite-Time Lyapunov Exponent-Based Analysis...

Published
2019
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37. Convergence of Two Internal Mean Flow Solutions for Spinning Rocket Motors

Author

Orie M. Cecil and Joseph Majdalani

Subjects
Physics, 020301 aerospace & aeronautics, business.product_category, Computer simulation, Aerospace Engineering, Reynolds number, 02 engineering and technology, Mechanics, Vorticity, 01 natural sciences, Physics::Geophysics, 010305 fluids & plasmas, Physics::Fluid Dynamics, symbols.namesake, 0203 mechanical engineering, Rocket, 0103 physical sciences, symbols, Mean flow, Solid-fuel rocket, business, Navier–Stokes equations, Spinning
Abstract

In this work, two mathematical procedures are used to derive the incompressible mean flow profile in a simulated solid rocket motor that is modeled as a spinning right-cylindrical porous tube. The ...

Published
2019
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39. Adjoint-Based Optimization for Thrust Performance of Three-Dimensional Pitching–Rolling Plate

Author

Mingjun Wei, Haibo Dong, Min Xu, and Chengyu Li

Subjects
Physics, 020301 aerospace & aeronautics, Angle of attack, MathematicsofComputing_NUMERICALANALYSIS, Aerospace Engineering, Reynolds number, ComputerApplications_COMPUTERSINOTHERSYSTEMS, Thrust, 02 engineering and technology, Mechanics, Immersed boundary method, 01 natural sciences, Ellipsoid, 010305 fluids & plasmas, Physics::Fluid Dynamics, symbols.namesake, 0203 mechanical engineering, Flow velocity, Physics::Space Physics, 0103 physical sciences, symbols, High Energy Physics::Experiment, Shape optimization, Navier–Stokes equations
Abstract

An adjoint-based optimization is applied to study the thrust performance of a pitching–rolling ellipsoidal plate in a uniform stream at Reynolds number 100. To achieve the highest thrust, the optim...

Published
2019
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40. Effect of Forcing on a Supersonic Compression Ramp Flow

Author

Jonathan Poggie

Subjects
Flow control (data), 020301 aerospace & aeronautics, Materials science, Turbulence, Aerospace Engineering, 02 engineering and technology, Mechanics, Vortex shedding, 01 natural sciences, 010305 fluids & plasmas, Physics::Fluid Dynamics, symbols.namesake, 0203 mechanical engineering, Flow (mathematics), Mach number, 0103 physical sciences, Laminar-turbulent transition, symbols, Supersonic speed, Navier–Stokes equations
Abstract

Simulations were carried out of a 24° compression ramp in Mach 2.25, turbulent flow. In addition to simulations of the baseline flow, calculations were carried out with flow control applied, in the...

Published
2019
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41. Dynamic Aeroelasticity of Wings with Tip Propeller by Using Navier–Stokes Equations

Author

Guru P. Guruswamy

Subjects
Physics, 020301 aerospace & aeronautics, Wing, Mathematics::Analysis of PDEs, Propeller, Aerospace Engineering, 02 engineering and technology, Mechanics, Aeroelasticity, 01 natural sciences, 010305 fluids & plasmas, Physics::Fluid Dynamics, 0203 mechanical engineering, Flow (mathematics), Beam and Warming scheme, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Potential flow, Reynolds-averaged Navier–Stokes equations, Navier–Stokes equations, Astrophysics::Galaxy Astrophysics
Abstract

Aeroelastic computations are made for a flexible wing with a tip-propeller system designed for electric aircraft. Flow is modeled using the Navier–Stokes equations, and wing structures are modeled ...

Published
2019
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42. Combined Entropy and Output-Based Adjoint Approach for Mesh Refinement and Error Estimation

Author

Krzysztof J. Fidkowski and Kevin T. Doetsch

Subjects
010101 applied mathematics, Lift coefficient, Drag, Computer science, Aerospace Engineering, Entropy (information theory), 010103 numerical & computational mathematics, 0101 mathematics, Navier–Stokes equations, 01 natural sciences, Algorithm
Abstract

This paper presents a strategy for mesh refinement driven by a new indicator that combines two previously investigated indicators: one based on a user-specified engineering output, such as drag or ...

Published
2019
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43. Direct Numerical Simulation of Transition Control via Local Dynamic Surface Modification

Author

Miguel R. Visbal and Donald P. Rizzetta

Subjects
020301 aerospace & aeronautics, Materials science, Direct numerical simulation, Aerospace Engineering, 02 engineering and technology, Mechanics, Optimal control, 01 natural sciences, Compressible flow, 010305 fluids & plasmas, Vortex, 0203 mechanical engineering, Order (business), 0103 physical sciences, Surface modification, Navier–Stokes equations, Plasma actuator
Abstract

Direct numerical simulations were carried out in order to reproduce the generation and control of transition on a flat plate by means of local dynamic surface modification. The configuration and fl...

Published
2019
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44. New Approach to Estimate Total Jet Loads with Different Knudsen Numbers

Author

Chunpei Cai, Ruihua Zhang, Shiying Cai, and Jun Li

Subjects
Physics, 020301 aerospace & aeronautics, Jet (fluid), Computer simulation, Physics::Instrumentation and Detectors, Astrophysics::High Energy Astrophysical Phenomena, Aerospace Engineering, 02 engineering and technology, Mechanics, 01 natural sciences, Pressure coefficient, 010305 fluids & plasmas, Physics::Fluid Dynamics, 0203 mechanical engineering, Heat flux, Free molecular flow, 0103 physical sciences, Astrophysics::Earth and Planetary Astrophysics, Knudsen number, Direct simulation Monte Carlo, Navier–Stokes equations
Abstract

This short note presents a new approach to estimate coefficients for gaseous jet loads at an inclined flat plate. These load coefficients are derived at the collisionless flow limit. The plate surf...

Published
2019
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45. Viiflow—A New Inverse Viscous-Inviscid Interaction Method

Author

Maximilian Ranneberg

Subjects
Airfoil, Physics, 020301 aerospace & aeronautics, ComputingMethodologies_SIMULATIONANDMODELING, business.industry, Aerospace Engineering, 02 engineering and technology, Mechanics, Computational fluid dynamics, 01 natural sciences, 010305 fluids & plasmas, Physics::Fluid Dynamics, 0203 mechanical engineering, Flow (mathematics), Inviscid flow, 0103 physical sciences, Fluid–structure interaction, Reynolds-averaged Navier–Stokes equations, Navier–Stokes equations, business, ComputingMethodologies_COMPUTERGRAPHICS, Wind tunnel
Abstract

Viscous–inviscid interaction is the fastest method in computational fluid dynamics available for airfoil design and analysis that is able to capture viscous effects on the flow. Despite advances in...

Published
2019
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46. Experimental Model-Based Estimation and Control of Natural Tollmien–Schlichting Waves

Author

Marios Kotsonis, C.C. de Visser, and H. J. Tol

Subjects
Physics::Fluid Dynamics, Physics, Particle image velocimetry, Turbulence, Experimental model, Mathematics::Analysis of PDEs, Aerospace Engineering, Mechanics, Dielectric barrier discharge, Navier–Stokes equations, Plasma actuator, Standard deviation, Freestream
Abstract

A compensator strategy based on the linearized Navier–Stokes equations, aimed to suppress Tollmien–Schlichting waves naturally occurring in low freestream turbulence conditions, is experimentally d...

Published
2019
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47. Wall Temperature and Suction Control of Linear Modes in Compressible Corner Flow

Author

Ulrich Rist, N. Schnoebel, and J. Staudenmeyer

Subjects
Physics, 020301 aerospace & aeronautics, Suction, Prandtl number, Aerospace Engineering, 02 engineering and technology, Mechanics, Physics::Classical Physics, 01 natural sciences, 010305 fluids & plasmas, Physics::Fluid Dynamics, symbols.namesake, 0203 mechanical engineering, Flow (mathematics), Dirichlet boundary condition, 0103 physical sciences, symbols, Two-dimensional flow, Constant (mathematics), Navier–Stokes equations, Linear stability
Abstract

Linear stability behavior of self-similar streamwise corner flows is investigated under the influence of constant wall temperatures Tw and suction rates cq perpendicular to each wall. For three Mac...

Published
2019
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48. Reverse Design of Ultrasonic Absorptive Coating for the Stabilization of Mack Modes

Author

Tiehan Long, Rui Zhao, Chih-yung Wen, and X. D. Tian

Subjects
020301 aerospace & aeronautics, Admittance, Materials science, Angle of attack, Aerospace Engineering, 02 engineering and technology, Mechanics, engineering.material, 01 natural sciences, 010305 fluids & plasmas, Boundary layer, 0203 mechanical engineering, Coating, Flow velocity, Collocation method, 0103 physical sciences, engineering, Ultrasonic sensor, Navier–Stokes equations
Abstract

The effects of ultrasonic absorptive coating (UAC) admittance on the first and second modes in a high-speed boundary layer are analyzed using linear stability theory. It is shown that the growth ra...

Published
2019
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50. Dual-Actuator Disc Theory for Turbines in Yaw

Author

Dheepak N. Khatri, Matthew Bryant, Andre P. Mazzoleni, Rodney Metoyer, Kenneth Granlund, and Punnag Chatterjee

Subjects
Physics, Conservation equations, Aerospace Engineering, Two-dimensional flow, Mechanics, Kinetic energy, Actuator, Navier–Stokes equations, Conservation of mass, Fluid density, Dual (category theory)
Published
2019
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