579 citations · 952 across the 24 of their papers we have counts for
24 papers
An objective vortex identification method
Yifei Yu, Yiqian Wang, Chaoqun Liu
Generally, the vortex structures should be independent of the observers who are moving, especially when their coordinates are non-inertial, which may result in confusions in commun…
New Governing Equations for Fluid Dynamics
Chaoqun Liu, Zhining Liu
There are several questions with NS, which include: 1. Both symmetric shear terms and stretching terms in strain and stress are coordinate-dependent and thus not Galilean invariant…
Principal Decomposition of Velocity Gradient Tensor in the Cartesian Coordinates
Chaoqun Liu, Yifei Yu, Yisheng Gao
Traditional Cauchy-Stokes decomposition of velocity gradient tensor gives a symmetric and an anti-symmetric subtensors which are called the strain-rate and vorticity tensors. There…
A mathematical study on the local fluid rotation axis
Charles Nottage, Yifei Yu, Chaoqun Liu
As widely recognized, vortex represents flow rotation. Vortex should have a local rotation axis as its direction and angular speed as its strength. Vorticity vector has been consid…
Liutex-based Modified Navier-Stokes Equation
Yifei Yu, Jianming Liu, Yonghua Yan +3
The Navier-Stokes (NS) partial differential equations, as the governing equation of fluid dynamics, are based on particles with zero volume. In such a condition, conservation law o…
Correlation Analysis among Vorticity, Q method and Liutex
Yifei Yu1, Pushpa Shrestha, Oscar Alvarez +2
Influenced by the fact that vorticity represents rotation for rigid body, people believe it also works for fluid flow. However, the theoretical predictions by vorticity do not matc…
Stretching and Shearing Contamination Analysis for Liutex/Rortex and Other Vortex Identification Methods
Pushpa Shrestha, Charles Nottage, Yifei Yu +2
Although traditional vortex identification methods such as Q, Delta, Lambda2, Lambdaci remain popular in the identification and visualization of vortices, these methods count on sh…
Vortex Core and POD Analysis on Hairpin Vortex Formation in Flow Transition
Sita Charkrit, Chaoqun Liu
In this study, the new concept of vortex core line based on Liutex definition is applied to demonstrate that vortex ring is not part of the Lambda-vortex and the generation of ring…
Letter: Modified normalized Rortex/vortex identification method
Jianming Liu, Chaoqun Liu
In this paper, a modified normalized Rortex/vortex identification method named Omega_R is presented to improve the original Omega_R method and cure the bulging phenomenon on the is…
Letter: Mathematical Foundation of Turbulence Generation-Symmetric to Asymmetric Liutex/Rortex
Jian-ming Liu, Yue Deng, Yi-sheng Gao +2
Vortex has been considered as the building block and muscle of turbulence for long time. A new physical quantity called Liutex (previously named Rortex) has been defined as the rig…
A Liutex based definition of vortex axis line
Chaoqun Liu, Yi-sheng Gao, Jian-ming Liu +1
Eulerian local region-type vortex identification criteria, including the criterion, the criterion and the criterion et al., are widely used for vortex identification due to the sim…
Physical meaning of vorticity based on the RS decomposition and an explicit formula for the Liutex vector
Yiqian Wang, Yisheng Gao, Chaoqun Liu
In the present study, the physical meaning of vorticity is revisited based on the RS decomposition proposed by Liu et al. in the framework of Liutex (previously named Rortex), a vo…
DNS Study on Vorticity Structures in Late Flow Transition
Xiangrui Dong, Shuling Tian, Chaoqun Liu
Vorticity and vortex are two different but related concepts. This paper focuses on the investigation of vorticity generation and development, and vorticity structure inside/ outsid…
Rortex and comparison with eigenvalue-based vortex identification criteria
Yisheng Gao, Chaoqun Liu
Most of the currently popular Eulerian vortex identification criteria, including the Q criterion, the Delta criterion and the Lambda_ci criterion, are based on the analysis of the…
Rortex A New Vortex Vector Definition and Vorticity Tensor and Vector Decompositions
Chaoqun Liu, Yisheng Gao, Shuling Tian +1
A vortex is intuitively recognized as the rotational/swirling motion of the fluids. However, an unambiguous and universally-accepted definition for vortex is yet to be achieved in…
A Definition of Vortex Vector and Vortex
Shuling Tian, Yisheng Gao, Xiangrui Dong +1
Vortex is ubiquitous in nature. However, there is not a consensus on the vortex definition in fluid dynamics. Lack of mathematical definition has caused considerable confusions in…
DNS Study on Physics of Late Boundary Layer Transition
Chaoqun Liu, Ping Lu
This paper serves as a review of our recent new DNS study on physics of late boundary layer transition. This includes mechanism of the large coherent vortex structure formation, sm…
DNS Study for the origin of the flow Randomization in Late Boundary Layer Transition
Manoj Thapa, Ping Lu, Chaoqun Liu
This paper is devoted to the investigation of the origin and mechanism of randomization in late boundary layer transition over a flat plate without pressure gradient. The flow rand…
Numerical Study on Mechanism of Small Vortex Generation in Boundary Layer Transition
Ping Lu, Chaoqun Liu
The small vortex generation is a key issue of the mechanism for late flow transition and turbulence generation. It was widely accepted that small length vortices were generated by…
Numerical and Experimental Studies on the Separation Topology of the MVG Controlled Flow at M=2.5
Qin Li, Yonghua Yan, Ping Lu +3
In this paper, the implicitly implemented LES method and fifth order bandwidth optimized WENO scheme are used to make comprehensive studies on the separation topology of the MVG co…
LES Study on the Mechanism of Vortex Rings behind Supersonic MVG with Turbulent Inflow
Yonghua Yan, Caixia Chen, Ping Lu +1
In this study, we investigate the interaction between vortex rings behind MVG and the oblique shocks in the MVG controlled ramp flow at M=2.5 and Req=5760. Implicit large eddy simu…
Improvement of Mixing Function for Modified Upwinding Compact Scheme
Huankun Fu, Ping Lu, Chaoqun Liu
The compact scheme has high order accuracy and high resolution, but cannot be used to capture the shock. WENO is a great scheme for shock capturing, but is too dissipative for turb…
Numerical Study on Randomization in Late Boundary Layer Transition
Ping Lu, Manoj Thapa, Chaoqun Liu
The mechanism of randomization in late boundary layer transition is a key issue of late boundary layer transition and turbulence theory. We studied the mechanism carefully by high…
Numerical Study on Mechanism of Multiple Rings Formation
Ping Lu, Yonghua Yan, Chaoqun Liu
In this paper, the flow around each ring-like vortex is investigated by high order DNS including first sweep, first ejection, second sweep, second ejection, positive spike, momentu…