Adjoint based optimization and control of a separated boundary-layer flow

• Published in: European journal of mechanics, B, Fluids Vol. 41; pp. 169 - 177
• Main Authors: Passaggia, Pierre-Yves, Ehrenstein, Uwe
• Format: Journal Article
• Language: English
• Published: Issy-les-Moulineaux Elsevier Masson SAS 01.09.2013; Elsevier Masson; Elsevier
• Subjects: Adjoint-based optimization; Adjoints; Boundaries; Computational fluid dynamics; Control; Dynamical systems; Engineering Sciences; Exact sciences and technology; Flow control; Flow separation; Fluid dynamics; Fluid flow; Fluid mechanics; Fluids mechanics; Fundamental areas of phenomenology (including applications); Instabilities; Instability; Mechanics; Navier-Stokes equations; Nonlinear dynamics; Optimization; Physics; Control; Instabilities; Flow separation; Adjoint-based optimization; Actuators; Aspiration; Digital simulation; Blowing; Optimization; Boundary layer separation; Hump; Optimal control; Flow control; Modelling; Navier-Stokes equations
• ISSN: 0997-7546; 1873-7390
• DOI: 10.1016/j.euromechflu.2013.01.006

An adjoint based optimization procedure for the nonlinear Navier–Stokes system is implemented and applied to the dynamics of a separated boundary-layer flow over a bump. For this open flow configuration, boundary conditions which are compatible between the direct and adjoint system are implemented using the influence matrix technique. Beyond a critical Reynolds number, the flow is unstable and subject to instabilities with multiple time-scales. Computing iteratively optimal initial perturbations, the most sensitive regions to forcing are highlighted. Wall blowing–suction actuators are then introduced at these locations and their capability of controlling the unstable linear and nonlinear dynamics is explored, by means of the adjoint based numerical algorithm.