The Theme issue (118, March 2019) is devoted to the subject of laminar-turbulent transition prediction and flow control. Transition of flow state from laminar to turbulent is associated with significant changes in its structures and characteristics and therefore its prediction is of great interest in many industrial applications. It is a complex phenomenon and consists of different stages as receptivity (generation of perturbations), linear and nonlinear growth. The computational approaches for transition prediction are based on a wide range of methods from solution of eigenvalue problems through Large-Eddy Simulations (LES) to Direct Numerical Simulations (DNS). The increase of capacity and speed of computation resources, development of different numerical techniques allows computations of complex global modes.
The recent demand for reduction of emissions and increase of efficiency of industrial process and transport systems has also resulted in increased interest for transition control. In recent years, simple approaches like continuous boundary-layer suction has been improved by utilizing complex and sophisticated control theories. Often, the control means take advantage of flow instability mechanisms to generate a large impact from a small input energy.
The current issue of the bulletin, are partly based on the works presented at the 13th SIG33 workshop, Progress in Flow Instability, Transition and Control (held in Paraty, Brazil, March 6-8, 2018).
PREFACE: Laminar-Turbulent Transition Prediction and Control
Linear and Non-Linear Dynamics of a Micro-ramp Wake
J. Groot, J. Casacuberta, Q. Ye and S. Hickel
Recirculating Large Scale Structures Inside the Cove of a Bulb Sealed Slat
H. T. Himeno, D. S. Souza, D Rodriguez and M. A. F. Medeiros
Rossiter Modes in a Compressible Open Cavity: A Comparison between the Linear Predictions and Non-linear Simulations
S. Mathias and M. A. F. Medeiros
Resolvent Analysis: With or Without Eddy Viscosity?
P. Morra, O. Semeraro, D. S. Henningson and C. Cossu
Uncertainty Quantification of Acoustic Receptivity with an Adjoint Linear Navier-Stokes Approach
H. Raposo, S. Mughal and R. Ashworth
On the Wave-cancelling Nature of Boundary Layer Transition Control
K. Sasaki, P. Morra, A. V. G. Cavalieri, A. Hanifi and D. S. Henningson
Absolute Instability in Jets and Wakes: the Flow Physics of the α mode
E. Martin, A. V. G. Cavalieri and P. Jordan