POD analysis on vortical structures in MVG wake by Liutex core line identification

Journal of Hydrodynamics, Journal Year: 2020, Volume and Issue: 32(3), P. 497 - 509

Published: June 1, 2020

Language: Английский

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Liutex-based vortex dynamics: A preliminary study

Journal of Hydrodynamics, Journal Year: 2020, Volume and Issue: 32(6), P. 1217 - 1220

Published: Dec. 1, 2020

Language: Английский

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Liutex-based vortex control with implications for cavitation suppression

Journal of Hydrodynamics, Journal Year: 2021, Volume and Issue: 33(1), P. 74 - 85

Published: Feb. 1, 2021

Language: Английский

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New governing equations for fluid dynamics

AIP Advances, Journal Year: 2021, Volume and Issue: 11(11)

Published: Nov. 1, 2021

The difference in the governing equation between inviscid and viscous flows is introduction of terms. Traditional Navier–Stokes (NS) equations define stress based on Stokes’s assumptions. In NS equations, supposedly proportional to strain, both strain tensors are symmetric. There several questions with which include following: 1. Both symmetric shear terms stretching coordinate-dependent thus not Galilean invariant. 2. physical meaning diagonal off-diagonal elements clear, coordinate-dependent. 3. It hard measure quantitatively, viscosity really measured by vorticity, strain. 4. no vorticity tensor plays an important role fluid flow, especially for turbulent flow. newly proposed dynamics use only, anti-symmetric. advantages anti-symmetric, invariants independent coordinate rotation. anti-symmetric stress. Viscosity coefficients obtained experiments, vorticity. term can be further decomposed into rigid rotation shear, turbulence research. 5. computation cost reduced half as all zero six three. Several computational examples tested, clearly demonstrate new have exactly same results. As shown below, identical mathematics, but one has lower mentioned above, including possibility study flow better. recommended instead equations. unique definition operation vectors matrix also discussed this paper.

Language: Английский

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Influence of Blade Type on the Flow Structure of a Vortex Pump for Solid-Liquid Two-Phase Flow

Machines, Journal Year: 2021, Volume and Issue: 9(12), P. 353 - 353

Published: Dec. 15, 2021

Vortex pumps have good non-clogging performance owing to their impellers being retracted into retraction cavities, but they are much less efficient than ordinary centrifugal pumps. In this paper, numerical simulations were performed on a model of the 150WX200-20 vortex pump for four different blade types, and influence structure was determined. The revealed existence axial vortices in flow passage between blades impeller region. geometric characteristics these more regular two-phase solid-liquid single-phase liquid flow. presence solid phase reduced strength compared with suppressed increase size secondary circulation vortex. It found, however, that shape had greater circulating phase. state medium flowing out domain direct effect related law governing channel blades. found front-bent best curved worst. This type internal used further explain relationship external pump, understanding which is crucial selection hydraulic optimization.

Language: Английский

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Direct numerical simulation and in-depth analysis of thermal turbulence in square annular duct

International Journal of Heat and Mass Transfer, Journal Year: 2019, Volume and Issue: 144, P. 118590 - 118590

Published: Sept. 6, 2019

The thermal turbulence in an infinitely-long square annular duct (SAD) was studied by the direct numerical simulation with Reynolds (Re) number Reb≈6400 based on bulk velocity. isothermal boundary condition applied to side walls SAD higher and lower temperatures outer inner walls, respectively. As one of most fascinating features for corner turbulence, turbulent-driven secondary flow (TDSF) presented twin counter-rotating vortex pairs symmetrically located at concave convex corners. TDSF found significantly increase spatially-averaged Nusselt (Nu) comparing laminar flow. instantaneous structures were visualized third-generation vortex-identification method Liutex. budget analyses governing-equation turbulent layer (TBL) distinguished balancing mechanisms from traditional flat-plate TBL, which justified necessity classify generic TBLs into their sub-categories Type-A, B C TBLs. Moreover, current study focused a issues such as effects TBL law formulations. For present SAD, it that buffer between semi-log layers tended be wider than linear conduction was, first time, Type-B temperature TBL. Based indicator function, quantitative sublayer partitions conducted both velocity then applicable ranges sublayers rigorously determined. Further, profound damping mechanism introduced laws derive more accurate analytical formulations entire sublayers.

Language: Английский

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Numerical simulation of turbulent thermal boundary layer and generation mechanisms of hairpin vortex

Aerospace Science and Technology, Journal Year: 2020, Volume and Issue: 98, P. 105680 - 105680

Published: Jan. 9, 2020

Language: Английский

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Correlation analysis among vorticity, Q method and Liutex

Journal of Hydrodynamics, Journal Year: 2020, Volume and Issue: 32(6), P. 1207 - 1211

Published: Nov. 23, 2020

Language: Английский

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Secondary instability of channel-confined transition around dual-circular cylinders in tandem

International Journal of Mechanical Sciences, Journal Year: 2021, Volume and Issue: 208, P. 106692 - 106692

Published: July 28, 2021

Language: Английский

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Research on complex wake interference of aligned rotors considering the precone variation of the upstream wind turbine

Frontiers in Marine Science, Journal Year: 2022, Volume and Issue: 9

Published: Dec. 6, 2022

To understand the interaction wake effects of aligned horizontal-axis wind turbines, a refined and low-cost simulation framework is developed by combining actuator line (AL) with local dynamic Smagorinsky (LDS) model. Firstly, published performance NREL-5MW turbine used to corroborate accuracy AL-LDS coupling Secondly, research extended predict interference between two tandem rotor wakes. The influence precone characteristics on overall power output turbines explored modifying upstream introducing latest third-generation Ω vortex identification method in post-processing procedure. According results, have complex interference, angle variation always reducing global power, leading an unstable downstream wake. This detrimental system lifespan due high fluctuation stress as well may ecological implications sediment alteration. From upwind (negative) can lead higher but lower performance, compared non-tilted turbine. Despite optimal 0°, -2.5° proves more advantageous owing large flexible deformation wingtips. findings serve continuous incentive for improving farm numerical simulation.

Language: Английский

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