English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We investigate the role of the bulk eddy-viscosity variation on thewell-known log-layer mismatch problem. An analysis of the mean momentum-balanceshows that the modeled stress term close to the wall can dominate because ofthe bulk eddy-viscosity. Consequently, the momentum-balance equation lacks adegree-of-freedom and the mean velocity conforms to an incorrect profile tosatisfy the momentum-balance. We show that zonal enforcement of the target massflow-rate can be an effective strategy to introduce an additional degree offreedom to the mean momentum-balance, which led to a significant reduction inthe log-layer mismatch. When the mass flow-rate is enforced zonally, thefiltered velocity field attains its own constant velocity-scale above theReynolds-averaged field, supporting the hypothesis that there exists anartificial boundary layer above the Reynolds-averaged region. We simulateturbulent channel flows at friction Reynolds numbers of 2000 and 5200 on coarsemeshes that would put the first point away from the wall well into thelogarithmic layer. Second-order turbulence statistics and one-dimensionalvelocity spectra agree well with the direct numerical simulation benchmark datawhen results are normalized by the velocity-scale extracted from the filteredvelocity field. Additionally, the error in the skin-friction coefficient forfriction Reynolds numbers of 2000 decreased from $14.1\%$ to $2.5\%$ when weenforced the mass flow-rate zonally.

The role of bulk eddy-viscosity variation on the log-layer mismatch observed in wall-modeled large-eddy simulations