Turbulence is a ubiquitous phenomenon in environmental and engineering flows. Turbulent flows enhance the transport and mixing of momentum, heat, or matter and also lead to the large wall-shear stress near solid walls. Consequently, turbulent flows have an essential role in predicting meteorological phenomena and in designing many engineering applications (e.g., submarines, ships, aircraft, pipelines, heat exchangers, etc.). However, understanding turbulent flows is a long-standing challenge due to the complex, chaotic, and multi-scale nature of turbulence. We study coherent structures or eddies that are crucial to understanding the multi-scale phenomena of turbulence, especially for high-Reynolds-number flows.

 

1. Coherent structures in high-Reynolds-number wall turbulence

1) Turbulent channel/pipe flow

2) Turbulent boundary layer

3) Adverse and favorable pressure gradient

4) Physical modelling of wall turbulence

5) Vortical structures and skin friction

6) Wall-pressure fluctuations and flow induced noise

7) Turbulent/non-turbulent interface

 

 

 

2. Numerical method

1) Direct numerical simulation

2) Machine learning based simulation

3) Wall-modeled large-eddy simulation

 

 

3. Drag reduction and flow control

1) Passive and active control for skin friction reduction by manipulating coherent structures

2) Superhydrophobic surface

 

 

 

4. Turbulent boundary layer over surface roughness and urban-like surface

1) Surface roughness

2) Urban-like rough surface

M. Yoon, J. Hwang, J. Yang and H. J. Sung
Wall-Attached Structures in an Adverse Pressure Gradient Turbulent Boundary Layer
Journal of Fluid Mechanics, 2020, Vol. 0, No. 0, pp. 0~ 0

J. Yang, J. Hwang and H. J. Sung
Influence of Wall-Attached Structures on the Interface of Quiescent Core region in Turbulent Pipe Flow
Physical Review Fluids, 2019, Vol. 0, No. 0, pp. 0~ 0

J. Hwang, J. H. Lee and H. J. Sung
Statistical Behaviour of Self-Similar Structures in Canonical Wall Turbulence
Journal of Fluid Mechanics, 2020, Vol. 0, No. 0, pp. 0~ 0