Third generation of vortex identification methods: Omega and Liutex/Rortex based systems

Journal of Hydrodynamics, Journal Year: 2019, Volume and Issue: 31(2), P. 205 - 223

Published: Feb. 20, 2019

Language: Английский

---

New normalized Rortex/vortex identification method

Physics of Fluids, Journal Year: 2019, Volume and Issue: 31(1)

Published: Jan. 1, 2019

A new vortex identification criterion, named ΩR, is proposed for the normalization of Rortex, using idea Omega method (Ω). ΩR a normalized function from 0 to 1, which measures relative rotation strength on plane perpendicular local axis. The advantages can be summarized as follows: (1) 1 and further used in statistics correlation analysis physical quantity. (2) distinguish rotational vortices shear layers, discontinuity structures, other non-physical structures. (3) quite robust always set 0.52 capture structures different cases at time steps.

Language: Английский

---

Explicit formula for the Liutex vector and physical meaning of vorticity based on the Liutex-Shear decomposition

Journal of Hydrodynamics, Journal Year: 2019, Volume and Issue: 31(3), P. 464 - 474

Published: April 2, 2019

Language: Английский

---

A review on flow-induced vibration of offshore circular cylinders

Journal of Hydrodynamics, Journal Year: 2020, Volume and Issue: 32(3), P. 415 - 440

Published: June 1, 2020

Language: Английский

---

Investigations on the performance and wake dynamics of a tidal stream turbine under different yaw-offset conditions

Physics of Fluids, Journal Year: 2025, Volume and Issue: 37(1)

Published: Jan. 1, 2025

The misalignment between flow and rotor can significantly alter the efficiency of tidal stream turbine (TST), therefore, it is vital to predict in field performance TST under yaw-offset conditions. First, this paper implements a high-precision Lagrangian dynamic sub-grid-scale model based on large-eddy simulation (LES) method. A classical computational fluid dynamics benchmark case selected validate accuracy LES (DLES) results indicate that newly implemented method exhibits reduced dissipation effectively captures local effects non-uniform fields, including vortex structures. Second, an efficient high-fidelity numerical (AL-DLES) for forecasting wake presented by integrating actuator line (AL) code with aforementioned DLES framework. After comparing experimental results, was discovered developed AL-DLES coupling approach, which addresses issues challenging meshing, rapid dissipation, insufficient fidelity previous methods, accurately simulate forces acting while also capturing detailed characteristics field. Furthermore, study will be extended investigate various conditions, exploring mechanisms instability evolution meandering. Meanwhile, latest third-generation (Ωnew) identification program successfully applied visualization Through comparative analysis three distinct approaches, demonstrated Ωnew superior system located behind rotor, eliminating need manual threshold selection. In addition, capable simultaneously both strong weak vortices, aspect future research.

Language: Английский

---

Bubble dynamics and its applications

Journal of Hydrodynamics, Journal Year: 2018, Volume and Issue: 30(6), P. 975 - 991

Published: Nov. 23, 2018

Language: Английский

---

Dynamic mode decomposition of cavitating flow around ALE 15 hydrofoil

Renewable Energy, Journal Year: 2019, Volume and Issue: 139, P. 214 - 227

Published: Feb. 12, 2019

Language: Английский

---

Evolutions of flow patterns and pressure fluctuations in a prototype pump-turbine during the runaway transient process after pump-trip

Renewable Energy, Journal Year: 2020, Volume and Issue: 152, P. 1149 - 1159

Published: Jan. 22, 2020

Language: Английский

---

Optical and simulation investigation of effect of jet-wall interaction on combustion performance of methanol pre-chamber turbulent jet ignition system

Applied Energy, Journal Year: 2025, Volume and Issue: 385, P. 125533 - 125533

Published: Feb. 17, 2025

Language: Английский

---

Vortex and energy characteristics in the hump region of pump-turbines based on the rigid vorticity and local hydraulic loss method

Physics of Fluids, Journal Year: 2025, Volume and Issue: 37(3)

Published: March 1, 2025

With the climate change hazards and implementation of pumped-storage hydropower units in power grid increases, maintaining hydraulic stability hump region is primordial for energy transition yet presents a significant challenge. This study investigates loss characteristics instability pump-turbine during operation using both model testing computational fluid dynamics methods. The results indicate that predominantly occurs guide vane (GV) passage draft tube (DT), more with flow reduction. Specifically, vaneless space linked to shear vorticity, while rigid vorticity plays prominent role GV DT. Analysis Rortex enstrophy transport equation shows pseudo-Lamb term dominant factor influencing vortex evolution. Additionally, combining Reynolds-averaged Navier–Stokes equations particle image velocimetry experiments reveals near zero-velocity gradient region, effects are concentrated core on runner side, primarily wake direction motion.

Language: Английский

---