A conservative degree adaptive HDG method for transient incompressible flows
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arXiv
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| Format: | Preprint |
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2024
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| author | Felipe, Agustina Sevilla, Ruben Hassan, Oubay |
| author_facet | Felipe, Agustina Sevilla, Ruben Hassan, Oubay |
| contents | Purpose: This study aims to assess the accuracy of degree adaptive strategies in the context of incompressible Navier-Stokes flows using the high order hybridisable discontinuous Galerkin (HDG) method.
Design/methodology/approach: The work presents a series of numerical examples to show the inability of standard degree adaptive processes to accurate capture aerodynamic quantities of interest, in particular the drag. A new conservative projection is proposed and the results between a standard degree adaptive procedure and the adaptive process enhanced with this correction are compared. The examples involve two transient problems where flow vortices or a gust needs to be accurately propagated over long distances.
\noindent \textbf{}Findings:polynomials with a lower degree. Due to the coupling of velocity-pressure in incompressible flows, the violation of the incompressibility constraint leads to inaccurate pressure fields in the wake that have a sizeable effect on the drag. The new conservative projection proposed is found to remove all the numerical artefacts shown by the standard adaptive process.
Originality/value: This work proposes a new conservative projection for the degree adaptive process. The projection does not introduce a significant overhead because it requires to solve an element-by-element problem and only for those elements where the adaptive process lowers the degree of approximation. Numerical results show that with the proposed projection non-physical oscillations in the drag disappear and the results are in good agreement with reference solutions. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2411_06388 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | A conservative degree adaptive HDG method for transient incompressible flows Felipe, Agustina Sevilla, Ruben Hassan, Oubay Fluid Dynamics 76D05, 76M10, 35Q30, 65M12, 65M50, Purpose: This study aims to assess the accuracy of degree adaptive strategies in the context of incompressible Navier-Stokes flows using the high order hybridisable discontinuous Galerkin (HDG) method. Design/methodology/approach: The work presents a series of numerical examples to show the inability of standard degree adaptive processes to accurate capture aerodynamic quantities of interest, in particular the drag. A new conservative projection is proposed and the results between a standard degree adaptive procedure and the adaptive process enhanced with this correction are compared. The examples involve two transient problems where flow vortices or a gust needs to be accurately propagated over long distances. \noindent \textbf{}Findings:polynomials with a lower degree. Due to the coupling of velocity-pressure in incompressible flows, the violation of the incompressibility constraint leads to inaccurate pressure fields in the wake that have a sizeable effect on the drag. The new conservative projection proposed is found to remove all the numerical artefacts shown by the standard adaptive process. Originality/value: This work proposes a new conservative projection for the degree adaptive process. The projection does not introduce a significant overhead because it requires to solve an element-by-element problem and only for those elements where the adaptive process lowers the degree of approximation. Numerical results show that with the proposed projection non-physical oscillations in the drag disappear and the results are in good agreement with reference solutions. |
| title | A conservative degree adaptive HDG method for transient incompressible flows |
| topic | Fluid Dynamics 76D05, 76M10, 35Q30, 65M12, 65M50, |
| url | https://arxiv.org/abs/2411.06388 |