3 results
Now showing1 - 3 of 3
- Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Assessment of explicit algebraic stress models in transonic flowsA class of recently developed explicit algebraic stress models (EASM) [2] is subjected to a critical assessment in transonic engineering flows. It is found that the performance and robustness of these models is hampered with inaccuracies due to an inappropriate regularization practice inherent to the stress-strain relation. The origin of the régularisation is attributed to an inadequate closure assumption for the production-to-dissipation ratio in non-equilibrium conditions. To remedy the defect, a simple approximation for an explicit representation of P/ε within the stress-strain relation is proposed. The emerging unregularized EASM satisfies the positivity requirement for the eddy-viscosity and obeys to the realizability principle. Several exemplary 2D and 3D testcases, employing different numerical algorithms, are investigated to assess the predictive capabilities of the present proposal including a linear truncation. Supplementary, the mathematical rigour of the approach is used to combine the non-linear stress-strain relation with a multiscale methodology and pressure-dilatation models. The paper aims to argue the potential advantages of an unregularized EASM methodology in transonic engineering flows.Publicationtype: Journal Article41 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Assessment of advanced transport-equation turbulence models for aircraft aerodynamic performance predictionPublicationtype: Conference Paper24 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , On the realizability of nonlinear stress-strain relationships for Reynolds stress closures(1998); ; A class of recently developed explicit algebraic stress models based on tensorially quadratic stress-strain relations [7] is subjected to a systematical realizability analysis. It is found that these models, which are of particular interest for their rigorous derivation from linear second-moment closure models, tend to produce inappropriate unrealizable results like negative turbulence energy components, even in simple shear flows. The cause of the defect is identified in conjunction with a set of realizability-furnishing constraints on the model coefficients. With the exception of the silent normal stress component in accelerated flow, the nature and rationale of the explicit algebraic stress model suggested by Gatski and Speziale [7] can be extended to maintain the realizability principle. Results obtained from the corresponding quasi-realizable quadratic eddy-viscosity model are reported in comparison with other nonlinear modelling practices.Publicationtype: Journal Article38