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/

Zendy Plus

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

Zendy Tools

Zendy Open

The Moody diagram, a plot of friction factor versus flow rate, is awell-known engineering tool for estimating head loss in pipe flows. Itcomprises well-defined relationships between friction factor and flow rate overthe majority of parameter space, but there is a gap in the transitional regimebetween laminar and turbulent flows. It is often left hatched because in thisparameter range the friction is deemed indefinite, which Moody remarked couldat least partially be due to the different initial conditions used to establishthe flow. Here we investigate this issue and seek a systematic dependence forfriction in the transitional regime. The novel method we use is to approach thetransitional regime from above by reducing the flow speed from a turbulent flowstate. We find that in different pipe flow setups, both driven by gravity, asingle curve corresponding to a maximum density of the transitional flowstructures is found. We test the generality of this result using an alternativemethod to drive the flow through the pipe, using a mass displacement device.Our investigation of the flow driven by a syringe produces yet a differentcurve, indicating that the method of driving the flow has a significant impacton both the final states and the paths to them in the transitional regime.

Completing Moody's friction diagram in the turbulent transitional regime