Article: Numerical investigation of a control channel behind a backward-facing step in a duct Journal: Progress in Computational Fluid Dynamics, An International Journal (PCFD) 2017 Vol.17 No.5 pp.313 - 325 Abstract: Flow control over a backward-facing step (BFS) by continuous suction/blowing is numerically investigated. This study examines the influence of blowing/suction rate, and slot size on the detachment process. Fluid flow is assumed turbulent, incompressible, 2D and steady in average. The governing equations are discretised by the finite volume method based on the k-ε RNG one point closure turbulence model. The investigations were performed for a Reynolds number of 3.5 104 with respect to the step height (h). Several blowing/suction rates are checked (-0.035 < Cq < +0.035) for four slot size cases namely (a = 0.95 mm, 2.25 mm, 3 mm and 5 mm). All results indicate that suction/blowing shortens the reattachment length and reduces the turbulence energy. The detailed flow structure suggests a way of shortening of the recirculation length with increasing the blowing/suction rate. Through different flow conditions, two correlations for reattachment length related to blowing or suction rate are proposed. The smallest slot size produces greatest turbulence kinetic energy and maximum friction all considered suction/blowing rates. Inderscience Publishers - linking academia, business and industry through research

Title: Numerical investigation of a control channel behind a backward-facing step in a duct

Authors: Houda Benlaalam Bouchtout; Amina Mataoui; Faiza Kendil Zidouni

Addresses: Theoretical and Applied Laboratory of Fluid Mechanics, Faculty of Physics, University of Science and Technology Houari Boumedienne – USTHB, Algiers, Algeria ' Theoretical and Applied Laboratory of Fluid Mechanics, Faculty of Physics, University of Science and Technology Houari Boumedienne – USTHB, Algiers, Algeria ' Theoretical and Applied Laboratory of Fluid Mechanics, Faculty of Physics, University of Science and Technology Houari Boumedienne – USTHB, Algiers, Algeria

Abstract: Flow control over a backward-facing step (BFS) by continuous suction/blowing is numerically investigated. This study examines the influence of blowing/suction rate, and slot size on the detachment process. Fluid flow is assumed turbulent, incompressible, 2D and steady in average. The governing equations are discretised by the finite volume method based on the k-ε RNG one point closure turbulence model. The investigations were performed for a Reynolds number of 3.5 10⁴ with respect to the step height (h). Several blowing/suction rates are checked (-0.035 < C_q < +0.035) for four slot size cases namely (a = 0.95 mm, 2.25 mm, 3 mm and 5 mm). All results indicate that suction/blowing shortens the reattachment length and reduces the turbulence energy. The detailed flow structure suggests a way of shortening of the recirculation length with increasing the blowing/suction rate. Through different flow conditions, two correlations for reattachment length related to blowing or suction rate are proposed. The smallest slot size produces greatest turbulence kinetic energy and maximum friction all considered suction/blowing rates.

Keywords: channel flow; backward-facing step; suction/blowing process control; vortical structure; CFD; FLUENT; turbulence.

DOI: 10.1504/PCFD.2017.086317

Progress in Computational Fluid Dynamics, An International Journal, 2017 Vol.17 No.5, pp.313 - 325

Received: 29 Sep 2015
Accepted: 26 Jan 2016
Published online: 04 Sep 2017 *

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Title: Numerical investigation of a control channel behind a backward-facing step in a duct

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