Sean Symon

Sean Symon
University of Southampton · AeroAstro

PhD Aeronautics

About

22
Publications
5,300
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488
Citations
Additional affiliations
October 2012 - present
California Institute of Technology
Position
  • Grad RA

Publications

Publications (22)
Preprint
Full-text available
The predictions of resolvent analysis for turbulent channel flow are evaluated for a friction Reynolds number of Retau = 550. In addition to the standard resolvent operator with kinematic viscosity, a resolvent operator augmented with the Cess eddy viscosity is considered. Adding eddy viscosity significantly alters the low-rank behavior of the reso...
Article
Full-text available
p>We investigate energy transfer mechanisms for vortex shedding in the two-dimensional cylinder wake at a Reynolds number of Re=100. In particular, we focus on a comparison of the energy transfer in the true flow field to that predicted by resolvent analysis. The energy balances achieved by the true cylinder flow are first characterized - both for...
Article
p>We analyse the inter-scale transfer of energy for two types of plane Poiseuille flow: the P4U exact coherent state of Park & Graham (J. Fluid Mech., vol. 782, 2015, pp. 430-454) and turbulent flow in a minimal channel. For both flows, the dominant energy-producing modes are streamwise-constant streaks with a spanwise spacing of approximately 100...
Conference Paper
Full-text available
The objective of this article is to determine for which scales stochastic forcing of the linearized Navier-Stokes equations, recast as the resolvent operator, is sufficient to reproduce second-order statistics in turbulent channel flow. Our focus is on the large scales at a friction Reynolds number of Reτ = 2003. We consider a molecular resolvent o...
Preprint
Full-text available
Energy transfer mechanisms for vortex shedding behind a 2D cylinder at a Reynolds number of Re=100 are investigated. We first characterize the energy balances achieved by the true cylinder flow---both for the flow as a whole and for each of its most energetic harmonic frequencies. It is found that viscous dissipation balances production when each i...
Preprint
Full-text available
We analyse the inter-scale transfer of energy for two types of plane Poiseuille flow: the P4U exact coherent state of Park and Graham (2015) and turbulent flow in a minimal channel. For both flows, the dominant energy-producing modes are streamwise-constant streaks with a spanwise spacing of approximately 100 wall units. Since the viscous dissipati...
Article
Full-text available
The objective of this article is to determine for which scales stochastic forcing of the linearized Navier-Stokes equations, recast as the resolvent operator, is sufficient to reproduce second-order statistics in turbulent channel flow. Our focus is on the large scales at a friction Reynolds number of Re τ = 2003. We consider a molecular resolvent...
Article
The flows around a NACA 0018 airfoil at a chord-based Reynolds number of $Re=10\,250$ and angles of attack of $\unicode[STIX]{x1D6FC}=0^{\circ }$ and $\unicode[STIX]{x1D6FC}=10^{\circ }$ are modelled using resolvent analysis and limited experimental measurements obtained from particle image velocimetry. The experimental mean velocity fields are dat...
Article
Full-text available
A methodology is presented that exploits both data-assimilation techniques and resolvent analysis for reconstructing turbulent flows, containing organized structures, with an efficient set of measurements. The mean (time-averaged) flow is obtained using variational data-assimilation that minimizes the discrepancy between a limited set of flow measu...
Article
Full-text available
We use the feedback formulation of McKeon and Sharma [J. Fluid Mech. 658, 336 (2010)], where the nonlinear term in the Navier-Stokes equations is treated as an intrinsic forcing of the linear resolvent operator, to educe the structure of fluctuations in the range of scales (wave numbers) where linear mechanisms are not active. In this region, the a...
Article
We use the feedback formulation of McKeon and Sharma [J. Fluid Mech. 658, 336 (2010)], where the nonlinear term in the Navier-Stokes equations is treated as an intrinsic forcing of the linear resolvent operator, to educe the structure of fluctuations in the range of scales (wave numbers) where linear mechanisms are not active. In this region, the a...
Preprint
Full-text available
The flows around a NACA 0018 airfoil at a Reynolds number of 10250 and angles of attack of alpha = 0 (A0) and alpha = 10 (A10) are modelled using resolvent analysis and limited experimental measurements obtained from particle image velocimetry. The experimental mean velocity profiles are data-assimilated so that they are solutions of the incompress...
Article
We study the evolution of velocity fluctuations due to an isolated spatio-temporal impulse using the linearized Navier–Stokes equations. The impulse is introduced as an external body force in incompressible channel flow at $Re_{\unicode[STIX]{x1D70F}}=10\,000$ . Velocity fluctuations are defined about the turbulent mean velocity profile. A turbulen...
Preprint
We use the feedback loop of McKeon \& Sharma (2010), where the nonlinear term in the Navier-Stokes equations is treated as an intrinsic forcing of the linear resolvent operator, to educe the structure of fluctuations in the range of scales (wavenumbers) where linear mechanisms are not active. In this region, the absence of dominant linear mechanism...
Conference Paper
Full-text available
A flow reconstruction methodology utilizing resolvent analysis and data-assimilation is applied to flow around a NACA 0018 airfoil at an angle of attack α = 10 • and chord-based Reynolds number Re = 10250. The underlying principle of the reconstruction is to maximize the value of limited experimental measurements as the only inputs are a rough appr...
Article
We seek to quantify non-normality of the most amplified resolvent modes and predict their features based on the characteristics of the base or mean velocity profile. A 2-by-2 model linear Navier-Stokes (LNS) operator illustrates how non-normality from mean shear distributes perturbation energy in different velocity components of the forcing and res...
Article
Full-text available
Data assimilation can be used to combine experimental and numerical realizations of the same flow to produce hybrid flow fields. These have the advantages of less noise contamination and higher resolution while simultaneously reproducing the main physical features of the measured flow. This study investigates data assimilation of the mean flow arou...
Article
Full-text available
It has been recently shown that the presence of macrotextures on superhydrophobic materials can markedly modify the dynamics of water impacting them, and in particular significantly reduce the contact time of bouncing drops, compared with what is observed on a flat surface. This finding constitutes a significant step in the maximization of water re...
Article
Bouncing liquid silicone oil drops on a vertically oscillating bath of the same liquid were studied exper- imentally. The different bouncing regimes previously described in the literature were observed, with transitions depending mainly on the droplet size and the forcing acceleration of the oil bath. In a partic- ular range of forcing amplitudes,...

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Projects

Projects (2)
Project
Model incompressible, wall-bounded turbulent flows using modal decomposition techniques (e.g. resolvent analysis, spectral proper orthogonal decomposition) or modelling coherent structures.
Archived project
Study surface tension phenomena with the aim to passively control walking oil drops or water impacting superhydrophobic surfaces. These can be achieved by submerging obstacles in the vibrating oil bath or adding macro-textures to reduce the contact time of rebounding water drops.