Vortex simulation of active control strategies for transitional backward-facing step flows

Creusé, Emmanuel; Giovannini, André; Mortazavi, Iraj

doi:10.1016/j.compfluid.2008.01.036

Cited by 17 publications

(12 citation statements)

References 27 publications

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“…It is therefore important to capture in an accurate way vorticity boundary conditions. In classical implementations of vortex methods, the no-slip boundary condition is satisfied through the creation of vortex elements [16][17][18] or by updating particle strength to account for vorticity fluxes at the boundary [2,4,7]. The no-through flow boundary conditions are implemented together with the Poisson equation to determine stream functions and potential in (5).…”

Section: Vorticity Formulation and Remeshed Particle Methodsmentioning

confidence: 99%

Vortex penalization method for bluff body flows

Mimeau

Gallizio

Cottet

et al. 2015

Numerical Methods in Fluids

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International audienceIn this work, a penalization method is discussed in the context of vortex methods for incompressible flowsaround complex geometries. In particular, we illustrate the method in two cases: the flow around a rotatingblade for Reynolds numbers 1000 and 10,000 and the flow past a semi-circular body consisting of a porouslayer surrounding a rigid body at Reynolds numbers 550 and 3000. In the latter example, the results areinterpreted in terms of control strategy

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Section: Vorticity Formulation and Remeshed Particle Methodsmentioning

confidence: 99%

Vortex penalization method for bluff body flows

Mimeau

Gallizio

Cottet

et al. 2015

Numerical Methods in Fluids

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“…To conclude this Section, let us mention that some different control strategies may also be of interest to modify the recirculation zone and the transport in the channel. Thus, in [32] two different techniques are investigated. The first one does not make use of micro-jets but is based on a pulsing inlet velocity.…”

Section: Backward Facing Stepmentioning

confidence: 99%

A penalty model of synthetic micro-jet actuator with application to the control of wake flows

Pasquetti

Peres

2015

Computers & Fluids

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International audienceA simple model of synthetic (zero-net mass-flux) micro-jet is proposed and implemented in a large-eddysimulation spectral solver of the incompressible Navier–Stokes equations. Essentially, it is simplyrequired to introduce a penalty like term in the momentum equation, with a variable penalty coefficientthat culminates during the expulsion phase. Examples of applications are considered for the control ofseveral turbulent wake flows, the backward facing step, the D-shaped body and the square backAhmed body

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“…The convective part is solved using a "Vortex-In-Cell (VIC)" method (see e.g. [15] and [21] for its application to active flow control) with a semi-Lagrangian resolution. In this fractional step a convective velocity is associated to each finite vortex element through a high order interpolation procedure, and the displacement is achieved using a Runge-Kutta method.…”

Section: Vorticity Formulation and Vortex Methodsmentioning

confidence: 99%

Passive Flow Control Around a Semi-Circular Cylinder Using Porous Coatings

Mimeau¹,

Cottet²,

Mortazavi³

2014

International Journal of Flow Control

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In this paper, the passive control of flow past a semi-circular cylinder is investigated. This control is achieved by adding a porous medium between the solid obstacle and the incompressible fluid in order to reduce drag forces and regularize the flow. A vortexpenalization method is chosen to easily model the flow in the different media. Several configurations of the porous layer are investigated and parametric studies are performed in order to determine the most efficient passive flow control devices. This control study can be considered as a first step to propose efficient strategies to regularize the flow around a side-view mirror. NOMENCLATUREC D drag coefficient D computational domain F, S fluid domain and solid domain F D drag force Re Reynolds number Z enstrophy d non-dimensional diameter h reference mesh size k intrinsic permeability l ref height of the obstacle u ref reference velocity u = (u,v) velocity field u s body rigid motion u¯mean velocity magnitude u ∞ free stream velocity Γ D computational domain boundaries Δt time step Φ porosity λ penalization parameter μ dynamic viscosity ν kinematic viscosity r density of the fluid τ porous layer thickness χ S characteristic function ω vorticity field INTRODUCTIONOn a ground vehicle, the outside mirrors, due to their spanwise position, indeed generate a nonnegligible wake which interferes with the flow past car sides. They are responsible of up to 10% of the total vehicle drag but they only represent 0.5% of the total projected surface, which accounts for a good motivation to perform flow control past these obstacles. This work is devoted to the control of flow past a two-dimensional semi-circular cylinder which can be considered as a simplified section of a sideview mirror. As it was shown in [1, 2], a flow past a square back obstacle is not dominated by longitudinal three-dimensional vortical structures, therefore a preliminary two-dimensional study can be useful to supply information and general trends for a further control study in three dimensions around a hemisphere. The aim is to use a control device easy to set up, low cost and allowing to keep the geometry unchanged. As active control devices can be hardly implemented in such a case, an efficient passive strategy seems to be a good alternative. A suitable solution has already been proposed by Bruneau and Mortazavi in [3][4][5][6][7]. It consists in adding a porous sheath on the obstacle surface in order to reduce the vorticity generation of the boundary layer. The presence of a porous medium at the solid-fluid interface indeed imposes a kind of mixed boundary condition intermediate between the noslip and the slip one on the solid boundary [8]. As a result, the shear forces are decreased and the flow dynamics is smoothed. Consequently, the problem we have to solve involves three different media, namely the solid obstacle, the porous layer and the fluid. An easy way to tackle it is to use the penalization method [9]. This method is based on a unique model, the Brinkman-Navier-Stokes equations, which ...

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Vortex simulation of active control strategies for transitional backward-facing step flows

Cited by 17 publications

References 27 publications

Vortex penalization method for bluff body flows

Vortex penalization method for bluff body flows

A penalty model of synthetic micro-jet actuator with application to the control of wake flows

Passive Flow Control Around a Semi-Circular Cylinder Using Porous Coatings

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