Wyniki 1-2 spośród 2 dla zapytania: authorDesc:"Abdelkader MEKRI"

Numerical modeling of plasma Actuator at high pressure DOI:10.15199/48.2018.04.07

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Flow control plasma actuator has been widely studied over the past two decades as a means to reduce drag and improve performance of aerodynamic bodies [1][2][3]. Recently, the most commonly used plasma actuator has become the sliding-dielectric barrier-discharge (SDBD). A typical configuration of the SDBD is indicating the geometrical parameters of interest for its operation. Plasma actuator consists of two electrodes attached to opposite sides of a dielectric sheet. When high voltage pulse sufficient amplitude is applied between the electrodes, the intense electric field partially ionizes the surrounding air producing no thermal plasma on the dielectric surface. The collisions between the neutral particles and accelerated ions generate a net body force on the surrounding fluid leading to the formation of an “ionic wind" [4]. The body force can be used to impart the desired flow control outcome on a given fluid system. The numerical modeling of the plasma produced by a SDBD actuator to which a short high voltage pulse is applied is described in this work. This numerical model offers the advantages of a detailed description of the plasma, providing the spatial and temporal evolution of the charged species and allowing the computation of electrohydrodynamic forces. However, these outputs are meaningful only if the model is able to describe the physics accurately. This last point is the main challenge with the numerical modeling of the plasma at atmospheric pressure, since the experimental validation is difficult to perform for other than very global characteristics of the plasma, such as the velocity of streamers or its spatial extent. In this paper, we outline a numerical simulation methodology for plasma actuators. The transport equations and Poisson's equation formed self-consistent model [5]. We use Scharfetter and Gummel schemes SG and SG0 [6] [7] [8]. Coupling at time splitting method [5] [8] [9] to resolve the [...]

Two-dimensional modeling positive and negative streamer discharge at high pressure DOI:10.15199/48.2018.06.05

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The simulation of a streamer in electric discharge is not a new problem. Indeed, for many years authors have proposed first the simulations in one dimensional considering only the phenomena on the axis. These onedimensional models remain limited and do not fully account for the physics of discharge. This is why many authors have focused on two-dimensional modeling. The basics of the streamer theory were developed by Raether [1], Loeb and Meek [2]. In their model, we explain the movement of the discharge by that of an ionization front that propagates within space between two electrodes. Once the discharge is initialized, we notice that its propagation is assured without the help of any outside agent. Since the propagation of a streamer depends only on its own space charge field, it can propagate towards the cathode or towards the anode. This possibility makes it possible to define two types of streamers: negative streamer (also called Anode-Directed Streamers) and positive streamer (also called Cathode-Directed Streamers) [3]. We describe the results of numerical calculations of negative and positive streamer propagation based on a fully two-dimensional algorithm, which apply of fluxcorrected scheme names ADBQUICKEST to correct and follow the strong density gradients [4]. The development of this algorithm has allowed us to investigate problems in streamer propagation of considerable interest [5][19]. This work presents the results of the algorithm application to questions including the streamer propagation on ionization ahead of the streamer, on applied photoionization and ionization term, on applied field, on initial and boundary conditions for both case of streamer. 2. Model formulation 2.1 Studied configuration The computational domain is a cylinder of radius R = 0.5 cm (Figure 1) [6]. This domain is limited by two metallic electrodes parallel, planes and circular separated by a distance d equal to 0.5 cm. The applied[...]

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