Data-driven tools and techniques have proved their effectiveness in many engineering applications. Machine-learning has gradually become a paradigm to explore innovative designs in turbomachinery. However, industrial computational fluid dynamics (CFD) experts are still reluctant to embed similar approaches in standard practice and very few solutions have been proposed so far. The aim of the work is to prove that standard wall treatments can obtain serious benefits from machine-learning modeling. Turbomachinery flow modeling lives in a constant compromise between accuracy and the computational costs of numerical simulations. One of the key factors of the process is defining a proper wall treatment. Many works point out how insufficient resolutions of boundary layers may lead to incorrect predictions of turbomachinery performances. Wall functions are universally exploited to replicate the physics of boundary layers where grid resolution does not suffice. Widespread wall functions were derived by the observation of a few canonical flows, further expressed as a simple polynomial of Reynolds number and turbulent kinetic energy. Despite their popularity, these functions are frequently applied in flows where the ground assumptions cease to be true, such as rotating passages or swirled flows. In these flows, the mathematical formulations of wall functions do not account for the distortion on the boundary layer due to the combined action of centrifugal and Coriolis forces. Here, we will derive a wall function for rotating passages, through means of machine-learning. The algorithm is directly implemented in the NS equations solver. Cross-validation results show that the machine-learnt wall treatment is able to effectively correct the turbulent kinetic energy field near the solid walls, without impairing the accuracy of the Reynolds-averaged numerical simulations (RANS) turbulence model in any way .

A Machine-Learnt Wall Function for Rotating Diffusers / Tieghi, Lorenzo; Delibra, Giovanni; Corsini, Alessandro; Tucci, Francesco Aldo. - In: JOURNAL OF TURBOMACHINERY. - ISSN 0889-504X. - 143:8(2021), pp. 1-9. [10.1115/1.4050442]

A Machine-Learnt Wall Function for Rotating Diffusers

Lorenzo Tieghi
Primo
Methodology
;
Giovanni Delibra
Secondo
Methodology
;
Alessandro Corsini
Penultimo
Supervision
;
Francesco Aldo Tucci
Ultimo
Visualization
2021

Abstract

Data-driven tools and techniques have proved their effectiveness in many engineering applications. Machine-learning has gradually become a paradigm to explore innovative designs in turbomachinery. However, industrial computational fluid dynamics (CFD) experts are still reluctant to embed similar approaches in standard practice and very few solutions have been proposed so far. The aim of the work is to prove that standard wall treatments can obtain serious benefits from machine-learning modeling. Turbomachinery flow modeling lives in a constant compromise between accuracy and the computational costs of numerical simulations. One of the key factors of the process is defining a proper wall treatment. Many works point out how insufficient resolutions of boundary layers may lead to incorrect predictions of turbomachinery performances. Wall functions are universally exploited to replicate the physics of boundary layers where grid resolution does not suffice. Widespread wall functions were derived by the observation of a few canonical flows, further expressed as a simple polynomial of Reynolds number and turbulent kinetic energy. Despite their popularity, these functions are frequently applied in flows where the ground assumptions cease to be true, such as rotating passages or swirled flows. In these flows, the mathematical formulations of wall functions do not account for the distortion on the boundary layer due to the combined action of centrifugal and Coriolis forces. Here, we will derive a wall function for rotating passages, through means of machine-learning. The algorithm is directly implemented in the NS equations solver. Cross-validation results show that the machine-learnt wall treatment is able to effectively correct the turbulent kinetic energy field near the solid walls, without impairing the accuracy of the Reynolds-averaged numerical simulations (RANS) turbulence model in any way .
2021
rotating wall function; adaptive high Reynolds wall treatment; machine learnt CFD; OPENFOAM/PYTHON interface
01 Pubblicazione su rivista::01a Articolo in rivista
A Machine-Learnt Wall Function for Rotating Diffusers / Tieghi, Lorenzo; Delibra, Giovanni; Corsini, Alessandro; Tucci, Francesco Aldo. - In: JOURNAL OF TURBOMACHINERY. - ISSN 0889-504X. - 143:8(2021), pp. 1-9. [10.1115/1.4050442]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1545718
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