A5026607009- Fluid Dynamics and Turbulent Flows
- Seismic Imaging and Inversion Techniques
- Fluid Dynamics and Vibration Analysis
- Heat Transfer Mechanisms
- Wind and Air Flow Studies
- Seismic Waves and Analysis
- Aerodynamics and Acoustics in Jet Flows
- Geophysical Methods and Applications
- Computational Fluid Dynamics and Aerodynamics
- Vibration and Dynamic Analysis
- Solar and Space Plasma Dynamics
- Lattice Boltzmann Simulation Studies
- Particle Dynamics in Fluid Flows
- Fractional Differential Equations Solutions
- Plasma and Flow Control in Aerodynamics
- Cavitation Phenomena in Pumps
- Aerodynamics and Fluid Dynamics Research
- Combustion and flame dynamics
- Statistical Mechanics and Entropy
- Numerical methods in engineering
- Plant Water Relations and Carbon Dynamics
- Hydrology and Sediment Transport Processes
- Numerical methods in inverse problems
- Theoretical and Computational Physics
- Quantum, superfluid, helium dynamics
Beijing Institute of Technology
2024
Texas Tech University
2017-2024
Zhuhai Institute of Advanced Technology
2024
Beihang University
2007-2021
Chongqing Vocational and Technical University of Mechatronics
2021
University of Houston
2013-2017
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation
2015-2016
Southwest Petroleum University
2015-2016
Houston Methodist
2014
Jiangsu University
2011-2013
Well-resolved direct numerical simulations (DNS) have been performed of the flow in a smooth circular pipe radius $R$ and axial length $10{\rm \pi} R$ at friction Reynolds numbers up to $Re_\tau =5200$ using pseudo-spectral code OPENPIPEFLOW. Various turbulence statistics are documented compared with other DNS experimental data pipes as well channels. Small but distinct differences between various datasets identified. The factor $\lambda$ overshoots by $2\,\%$ undershoots $0.6\,\%$ Prandtl...
Well-resolved direct numerical simulations of turbulent open channel flows (OCFs) are performed for friction Reynolds numbers up to $Re_\tau =2000$ . Various statistics documented and compared with the closed (CCFs). As expected, mean velocity profiles OCFs match well CCFs in near-wall region but diverge notably outer region. Interestingly, a logarithmic layer Kárman constant $\kappa =0.363$ occurs OCF at , distinctly different from CCF. Except very thin near free surface, most vorticity...
A microburst can be modelled by releasing a volume of fluid that is slightly heavier than the ambient fluid, allowing it to fall onto horizontal surface. Vorticity develops on sides this parcel as descends and causes roll up into turbulent vortex ring which impinges ground. Such model exhibits many features naturally occurring microbursts are hazard aviation. In paper achieved experimentally salt water fresh from cylindrical dispenser. When care taken with release spreading rate surface...
Drag control using a newly developed spanwise opposed wall-jet forcing (SOJF) method is studied via direct numerical simulation of the incompressible Navier–Stokes equations in turbulent channel flow (at friction Reynolds numbers $Re_{\unicode[STIX]{x1D70F}}=180$ and 550). SOJF characterized by three parameters: amplitude $A^{+}$ , spacing $\unicode[STIX]{x1D706}^{+}$ height $y_{c}^{+}$ ( $+$ indicates viscous scaling). At notable drag reduction achieved for wide ranges with an optimal...
Accurate seismic modeling in realistic media serves as the basis of full-waveform inversion and imaging. Recently, viscoacoustic incorporating attenuation effects has been performed by solving a fractional Laplacian wave equation. In this equation, attenuation, being spatially heterogeneous, is represented partially varying power operator previously approximated global Fourier method. We have developed local-spectral approach, based on Hermite distributed approximating functional (HDAF)...
The effect of Reynolds number (Reτ) on drag reduction using spanwise wall oscillation is studied through direct numerical simulation incompressible turbulent channel flows with Reτ ranging from 200 to 2000. For the nondimensional period T+ = 100 maximum velocity amplitude A+ 12, (DR) decreases 35.3% ± 0.5% at 22.3% 0.7% frequency ω+ for DR slightly increases Reτ, i.e., ≈ 0.06 0.08 2000, DRmax=23.2%±0.6%. These results show that progressively increasing Reτ. Turbulent statistics and coherent...
Direct numerical simulations of compressible turbulent channel flows are performed for bulk Mach numbers M${}_{b}$ = 0.8 and 1.5 Reynolds Re${}_{b}$ up to 34000. It is shown that the incompressible become similar at high Re${}_{b}$. Most compressibility effects can be considered using semilocal scaling. Although streamwise stress peak continuously increases with M${}_{b}$, change decreases higher
As a fundamental topology-transforming event, reconnection plays significant role in the dynamics of plasmas, polymers, DNA, and fluids—both (classical) viscous quantum. Since 1994 review by Kida & Takaoka, substantial advances have been made on this topic. We recent studies vortex flows, including physical mechanism, its relationship to turbulence cascade, formation finite-time singularity, helicity dynamics, aeroacoustic noise generation.
Two low-frequency-modulated plasma actuators are symmetrically positioned on either side of a thin flat plate to continuously generate pairs counter-rotating vortices, with velocity fields captured using time-resolved particle image velocimetry (PIV). Convolutional neural networks U-Net architecture adopted the phase-averaged field plasma-induced vortices from single PIV snapshot eliminate requirement multiple measurements. The influence number input features and samples model accuracy is...
Coherent structures over two distinct, organized wall perturbations – a transverse sinusoidal bump with and without small-scale longitudinal grooves are studied using direct numerical simulations. Large-scale spanwise rollers (SRs) form via shear layer rollup past the peak, enveloping large separation bubble (SB) for both smooth (SW) grooved (GW). In GW, alternatingly spinning jets emanating from crests’ corners merge layer, altering SRs compared in SW. The underlying coherence of highly...
The effect of Reynolds number on drag reduction via spanwise wall oscillation (SWO) is investigated through direct numerical simulations flat plate turbulent boundary layers (TBLs) over a wide range numbers (i.e., 344≤Reθ≤2340). Five periods with fixed maximum velocity amplitude are considered. In particular, the scaled using uncontrolled friction uτ,0 at starting position control xsc=250δ0 (Reθ=344) Tsc+ = 50, 75, 100, 125, and 150, Wm,sc+=12. Drag progressively decreases increasing...
In a recent article, Canton et al. [J. al., Phys. Rev. Fluids 1, 081501(R) (2016)] reported significant drag reduction in turbulent channel flow by using large-scale, near-wall streamwise swirls following the control strategy of Schoppa and Hussain [W. F. Hussain, 10, 1049 (1998)] for low Reynolds numbers only, but found no at high friction (Reτ=550). Here we show that lack Re observed is remedied proper choice large-scale flow. this study, apply opposed wall-jet forcing to achieve same...
Spanwise wall oscillation has been extensively studied to explore possible drag control methods, mechanisms and efficacy – particularly for incompressible flows. We performed direct numerical simulation fully developed turbulent channel flow establish how effective spanwise is when the compressible also document its reduction ( ${\mathcal{D}}{\mathcal{R}}$ ) trend with Mach number. Drag first investigated three different bulk numbers $M_{b}=0.3$ , $0.8$ $1.5$ at a fixed Reynolds number...
Helicity, an invariant under ideal-fluid (Euler) evolution, has a topological interpretation in terms of writhe and twist for closed vortex tube, but accurately quantifying is challenging viscous flows. With novel helicity decomposition, we present framework to construct the differential that establishes theoretical relation between total twisting number local rate each surface. This can characterize coiling lines internal structures within – important laminar–turbulence transition,...
We propose a dynamical vortex definition (the ‘ $\unicode[STIX]{x1D706}_{\unicode[STIX]{x1D70C}}$ definition’) for flows dominated by density variation, such as compressible and multi-phase flows. Based on the search of pressure minimum in plane, defines to be connected region with two negative eigenvalues tensor $\unicode[STIX]{x1D64E}^{M}+\unicode[STIX]{x1D64E}^{\unicode[STIX]{x1D717}}$ . Here, $\unicode[STIX]{x1D64E}^{M}$ is symmetric part product momentum gradient...
Abstract
We present new results on the strong parallel scaling for OpenACC-accelerated implementation of high-order spectral element fluid dynamics solver Nek5000. The test case considered consists a direct numerical simulation fully-developed turbulent flow in straight pipe, at two different Reynolds numbers Reτ = 360 and 550, based friction velocity pipe radius. is tested several GPU-enabled HPC systems, including Swiss Piz Daint system, TACC's Longhorn, Jülich's JUWELS Booster, Berzelius Sweden....
Topological transition and helicity conversion of vortex torus knots links are studied using direct numerical simulations the incompressible Navier–Stokes equations. We find three topological transitional routes ( viz. merging, reconnection to turbulence) in evolution over a range aspect ratios winding numbers. The depends not only on initial topology but also geometry knots/links. For small ratios, initially knotted or linked tube rapidly merges into ring with complete from writhe link...