An Explicit Algebraic Closure for Passive Scalar-Flux: Applications in Channel Flows at a Wide Range of Reynolds Numbers

oleh: Constantinos F. Panagiotou, Fotos S. Stylianou, Elias Gravanis, Evangelos Akylas, Constantine Michailides

Format: Article
Diterbitkan: MDPI AG 2020-11-01

Deskripsi

In this paper, we propose an algebraic model for turbulent scalar-flux vector that stems from tensor representation theory. The resulting closure contains direct dependence on mean velocity gradients and quadratic products of the Reynolds stress tensor. Model coefficients are determined from Direct Numerical Simulations (DNS) data of homogeneous shear flows subjected to arbitrary mean scalar gradient orientations, while a correction function was applied at one model coefficient based on a turbulent channel flow case. Model performance is evaluated in Poiseuille and Couette flows at several Reynolds numbers for <inline-formula><math display="inline"><semantics><mrow><mi>P</mi><mi>r</mi><mo>=</mo><mn>0.7</mn></mrow></semantics></math></inline-formula>, along with a case at a higher Prandtl number (<inline-formula><math display="inline"><semantics><mrow><mi>P</mi><mi>r</mi><mo>=</mo><mn>7.0</mn></mrow></semantics></math></inline-formula>) that typically occurs in water–boundary interaction applications. Overall, the proposed model provides promising results for wide near-wall interaction applications. To put the performance of the proposed model into context, we compare with Younis algebraic model, which is known to provide reasonable predictions for several engineering flows.