58 citations · 180 across the 15 of their papers we have counts for
15 papers · 1 filter
Fluctuation covariance-based study of roll-streak dynamics in Poiseuille flow turbulence
Marios-Andreas Nikolaidis, Petros J. Ioannou, Brian F. Farrell
Although the roll-streak (R-S) is fundamentally involved in the dynamics of wall-turbulence, the physical mechanism responsible for its formation and maintenance remains controvers…
A vectorized Navier-Stokes ensemble direct numerical simulation code for plane parallel flows
Marios-Andreas Nikolaidis
We present a pseudo-spectal Navier-Stokes solver for plane parallel flows (Couette/Poiseuille), that has been developed on the MATLAB programming language. The code performs direct…
Investigating nonlinearity in wall turbulence: regenerative versus parametric mechanisms
B. F. Farrell, E. Kim, H. J. Bae +2
Both linear growth processes associated with non-normality of the mean flow and nonlinear interaction transferring energy among fluctuations contribute to maintaining turbulence. H…
Mechanism of Roll-Streak Structure Formation and Maintenance in Turbulent Shear Flow
B. F. Farrell, P. J. Ioannou, M. -A. Nikolaidis
In wall-bounded shear flow the primary coherent structure is the streamwise roll and streak (R-S). Absent of an associated instability the R-S has been ascribed to non-normality me…
POD-based study of turbulent plane Poiseuille flow: comparing structure and dynamics between quasi-linear simulations and DNS
Marios-Andreas Nikolaidis, Petros J. Ioannou, Brian F. Farrell +1
Turbulence in the restricted nonlinear (RNL) dynamics is analyzed and compared with DNS of Poiseuille turbulence at . The structures are obtained by POD analysis of the two…
Synchronization of Low Reynolds Number Plane Couette Turbulence
Marios-Andreas Nikolaidis, Petros J. Ioannou
We demonstrate that a separation of the velocity field in large and small scales according to a streamwise Fourier decomposition identifies subspaces with stable Lyapunov exponents…
Cause-and-effect of linear mechanisms sustaining wall turbulence
Adrián Lozano-Durán, Navid C. Constantinou, Marios-Andreas Nikolaidis +1
Despite the nonlinear nature of turbulence, there is evidence that part of the energy-transfer mechanisms sustaining wall turbulence can be ascribed to linear processes. The differ…
Alternative physics to understand wall turbulence: Navier-Stokes equations with modified linear dynamics
Adrán Lozano-Durán, Marios-Andreas Nikolaidis, Navid C. Constantinou +1
Despite the nonlinear nature of wall turbulence, there is evidence that the energy-injection mechanisms sustaining wall turbulence can be ascribed to linear processes. The differen…
Wall turbulence without modal instability of the streaks
Adrián Lozano-Durán, Marios-Andreas Nikolaidis, Navid C. Constantinou +1
Despite the nonlinear nature of wall turbulence, there is evidence that the mechanism underlying the energy transfer from the mean flow to the turbulent fluctuations can be ascribe…
Parametric mechanism maintaining Couette flow turbulence verified in DNS implies novel control strategies
Brian F. Farrell, Petros J. Ioannou, Marios-Andreas Nikolaidis
The no-slip boundary condition results in a velocity shear forming in fluid flow near a solid surface. This shear flow supports the turbulence characteristic of fluid flow near bou…
Statistical State Dynamics Based Study of the Role of Nonlinearity in the Maintenance of Turbulence in Couette Flow
Brian F. Farrell, Petros J. Ioannou, Marios-Andreas Nikolaidis
While linear non-normality underlies the mechanism of energy transfer from the externally driven flow to the perturbation field that sustains turbulence, nonlinearity is also known…
The mechanism by which nonlinearity sustains turbulence in plane Couette flow
Marios-Andreas Nikolaidis, Brian F. Farrell, Petros J. Ioannou
Turbulence in wall-bounded shear flow results from a synergistic interaction between linear non-normality and nonlinearity in which non-normal growth of a subset of perturbations c…
Instability of the roll/streak structure induced by free-stream turbulence in pre-transitional Couette flow
Brian F. Farrell, Petros J. Ioannou, Marios-Andreas Nikolaidis
Although the roll/streak structure is ubiquitous in pre-transitional wall-bounded shear flow, this structure is linearly stable if the idealization of laminar flow is made. Lacking…
A statistical state dynamics-based study of the structure and mechanism of large-scale motions in plane Poiseuille flow
Brian F. Farrell, Petros J. Ioannou, Javier Jiménez +3
The perspective of statistical state dynamics (SSD) has recently been applied to the study of mechanisms underlying turbulence in various physical systems. An example implementatio…
Turbulence in the highly restricted dynamics of a closure at second order: comparison with DNS
Navid C. Constantinou, Adrian Lozano-Durán, Marios-Andreas Nikolaidis +3
S3T (Stochastic Structural Stability Theory) employs a closure at second order to obtain the dynamics of the statistical mean turbulent state. When S3T is implemented as a coupled…