Explaining the Lack of Mesh Convergence of Inviscid Adjoint Solutions near Solid Walls for Subcritical Flows

Numerical solutions to the adjoint Euler equations have been found to diverge with mesh refinement near walls for a variety of flow conditions and geometry configurations. The issue is reviewed, and an explanation is provided by comparing a numerical incompressible adjoint solution with an analytic...

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Main Authors: Carlos Lozano, Jorge Ponsin
Format: Article
Language:English
Published: MDPI AG 2023-04-01
Series:Aerospace
Subjects:
Online Access:https://www.mdpi.com/2226-4310/10/5/392
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author Carlos Lozano
Jorge Ponsin
author_facet Carlos Lozano
Jorge Ponsin
author_sort Carlos Lozano
collection DOAJ
description Numerical solutions to the adjoint Euler equations have been found to diverge with mesh refinement near walls for a variety of flow conditions and geometry configurations. The issue is reviewed, and an explanation is provided by comparing a numerical incompressible adjoint solution with an analytic adjoint solution, showing that the anomaly observed in numerical computations is caused by a divergence of the analytic solution at the wall. The singularity causing this divergence is of the same type as the well-known singularity along the incoming stagnation streamline, and both originate at the adjoint singularity at the trailing edge. The argument is extended to cover the fully compressible case, in subcritical flow conditions, by presenting an analytic solution that follows the same structure as the incompressible one.
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spelling doaj.art-de19aae3a60a402e9ba1f559558ceba52023-11-17T23:59:34ZengMDPI AGAerospace2226-43102023-04-0110539210.3390/aerospace10050392Explaining the Lack of Mesh Convergence of Inviscid Adjoint Solutions near Solid Walls for Subcritical FlowsCarlos Lozano0Jorge Ponsin1Computational Aerodynamics Group, National Institute of Aerospace Technology (INTA), Carretera de Ajalvir, Km 4, 28850 Torrejón de Ardoz, SpainComputational Aerodynamics Group, National Institute of Aerospace Technology (INTA), Carretera de Ajalvir, Km 4, 28850 Torrejón de Ardoz, SpainNumerical solutions to the adjoint Euler equations have been found to diverge with mesh refinement near walls for a variety of flow conditions and geometry configurations. The issue is reviewed, and an explanation is provided by comparing a numerical incompressible adjoint solution with an analytic adjoint solution, showing that the anomaly observed in numerical computations is caused by a divergence of the analytic solution at the wall. The singularity causing this divergence is of the same type as the well-known singularity along the incoming stagnation streamline, and both originate at the adjoint singularity at the trailing edge. The argument is extended to cover the fully compressible case, in subcritical flow conditions, by presenting an analytic solution that follows the same structure as the incompressible one.https://www.mdpi.com/2226-4310/10/5/392adjoint Euler equationsanalytic adjoint solutionwall singularitymesh dependence
spellingShingle Carlos Lozano
Jorge Ponsin
Explaining the Lack of Mesh Convergence of Inviscid Adjoint Solutions near Solid Walls for Subcritical Flows
Aerospace
adjoint Euler equations
analytic adjoint solution
wall singularity
mesh dependence
title Explaining the Lack of Mesh Convergence of Inviscid Adjoint Solutions near Solid Walls for Subcritical Flows
title_full Explaining the Lack of Mesh Convergence of Inviscid Adjoint Solutions near Solid Walls for Subcritical Flows
title_fullStr Explaining the Lack of Mesh Convergence of Inviscid Adjoint Solutions near Solid Walls for Subcritical Flows
title_full_unstemmed Explaining the Lack of Mesh Convergence of Inviscid Adjoint Solutions near Solid Walls for Subcritical Flows
title_short Explaining the Lack of Mesh Convergence of Inviscid Adjoint Solutions near Solid Walls for Subcritical Flows
title_sort explaining the lack of mesh convergence of inviscid adjoint solutions near solid walls for subcritical flows
topic adjoint Euler equations
analytic adjoint solution
wall singularity
mesh dependence
url https://www.mdpi.com/2226-4310/10/5/392
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