710 citations · 1.6k across the 23 of their papers we have counts for
23 papers
Periodic Shadowing Sensitivity Analysis of Chaotic Systems
Davide Lasagna, Ati Sharma, Johan Meyers
The sensitivity of long-time averages of a hyperbolic chaotic system to parameter perturbations can be determined using the shadowing direction, the uniformly-bounded-in-time solut…
Compressible Invariant Solutions In Open Cavity Flows
J. Javier Otero, Ati S. Sharma, Richard D. Sandberg
A family of compressible exact periodic solutions is reported for the first time in an open cavity flow setup. These are found using a novel framework which permits the computation…
New equilibrium solution branches of plane Couette flow discovered using a project-then-search method
Muhammad Arslan Ahmed, Ati Sharma
New equilibrium solution branches for plane Couette flow are reported which add to the inventory of known solution branches. The exact solutions are found by projecting known equil…
Exact coherent states for grooved Couette flows
Sabarish Vadarevu, Ati Sharma, Bharathram Ganapathisubramani
Recent progress indicates that highly symmetric recurring solutions of the Navier-Stokes equations, such as equilibria and periodic orbits, provide a skeleton for turbulence dynami…
Scaling and interaction of self-similar modes in models of high-Reynolds number wall turbulence
A S Sharma, R Moarref, B J McKeon
Previous work has established the usefulness of the resolvent operator that maps the terms nonlinear in the turbulent fluctuations to the fluctuations themselves. Further work has…
Estimation of unsteady aerodynamic forces using pointwise velocity data
F. Gómez, A. S. Sharma, H. M. Blackburn
A novel method to estimate unsteady aerodynamic force coefficients from pointwise velocity measurements is presented. The methodology is based on a resolvent-based reduced-order mo…
A reduced-order model of three-dimensional unsteady flow in a cavity based on the resolvent operator
F Gómez, HM Blackburn, M Rudman +2
A novel reduced-order model for nonlinear flows is presented. The model arises from a resolvent decomposition in which the nonlinear advection terms of the Navier-Stokes equation a…
Steady streamwise transpiration control in turbulent pipe flow
F Gómez, HM Blackburn, M Rudman +2
A study of the the main features of low- and high amplitude steady streamwise wall transpiration applied to pipe flow is presented. The effect of the two transpiration parameters,…
On the design of optimal compliant walls for turbulence control
M. Luhar, A. S. Sharma, B. J. McKeon
This paper employs the theoretical framework developed by Luhar et al. (J. Fluid Mech., 768, 415-441) to consider the design of compliant walls for turbulent skin friction reductio…
On the correspondence between Koopman mode decomposition, resolvent mode decomposition, and invariant solutions of the Navier-Stokes equations
Ati S. Sharma, Igor Mezić, Beverley J. McKeon
The relationship between Koopman mode decomposition, resolvent mode decomposition and exact invariant solutions of the Navier-Stokes equations is clarified. The correspondence rest…
Adjoint-based Optimal Flow Control for Compressible DNS
J. Javier Otero, Ati S. sharma, Richard D. Sandberg
A novel adjoint-based framework oriented to optimal flow control in compressible direct numerical simulations is presented. Also, a new formulation of the adjoint characteristic bo…
Passivity-Based Output-Feedback Control of Turbulent Channel Flow
Peter H. Heins, Bryn Ll. Jones, Ati S. Sharma
This paper describes a robust linear time-invariant output-feedback control strategy to reduce turbulent fluctuations, and therefore skin-friction drag, in wall-bounded turbulent f…
Low-dimensional representations of exact coherent states of the Navier-Stokes equations from the resolvent model of wall turbulence
Ati S. Sharma, Rashad Moarref, Beverley J. McKeon +3
We report that many exact invariant solutions of the Navier-Stokes equations for both pipe and channel flows are well represented by just few modes of the model of McKeon & Sharma…
Modelling for Robust Feedback Control of Fluid Flows
Bryn Ll. Jones, Peter H. Heins, Eric C. Kerrigan +2
This paper addresses the problem of obtaining low-order models of fluid flows for the purpose of designing robust feedback controllers. This is challenging since whilst many flows…
A framework for studying the effect of compliant surfaces on wall turbulence
M. Luhar, A. S. Sharma, B. J. McKeon
This paper extends the resolvent formulation proposed by McKeon & Sharma (2010) to consider turbulence-compliant wall interactions. Under this formulation, the turbulent velocity f…
A foundation for analytical developments in the logarithmic region of turbulent channels
Rashad Moarref, Ati S. Sharma, Joel A. Tropp +1
An analytical framework for studying the logarithmic region of turbulent channels is formulated. We build on recent findings (Moarref et al., J. Fluid Mech., 734, 2013) that the ve…
A low-order decomposition of turbulent channel flow via resolvent analysis and convex optimization
R. Moarref, M. R. Jovanovic, J. A. Tropp +2
We combine resolvent-mode decomposition with techniques from convex optimization to optimally approximate velocity spectra in a turbulent channel. The velocity is expressed as a we…
Transient growth mechanisms of low Reynolds number flow over a low-pressure turbine blade
AS Sharma, N Abdessemed, SJ Sherwin +1
A direct transient growth analysis for three-dimensional perturbations to flow past a periodic array of T-106/300 low-pressure turbine fan blades is presented. The methodology is b…
Model-based scaling of the streamwise energy density in high-Reynolds number turbulent channels
Rashad Moarref, Ati S. Sharma, Joel A. Tropp +1
We study the Reynolds number scaling and the geometric self-similarity of a gain-based, low-rank approximation to turbulent channel flows, determined by the resolvent formulation o…
Relaminarisation of Re_τ = 100 channel flow with globally stabilising linear feedback control
A S Sharma, J F Morrison, B J McKeon +3
The problems of nonlinearity and high dimension have so far prevented a complete solution of the control of turbulent flow. Addressing the problem of nonlinearity, we propose a flo…
On coherent structure in wall turbulence
A S Sharma, B J McKeon
A new theory of coherent structure in wall turbulence is presented. The theory is the first to predict packets of hairpin vortices and other structure in turbulence, and their dyna…
Predicting structural and statistical features of wall turbulence
B. J. McKeon, A. S. Sharma, I. Jacobi
The majority of practical flows, particularly those flows in applications of importance to transport, distribution and climate, are turbulent and as a result experience complex thr…
A critical layer model for turbulent pipe flow
B. J. McKeon, A. S. Sharma
A model-based description of the scaling and radial location of turbulent fluctuations in turbulent pipe flow is presented and used to illuminate the scaling behaviour of the very…