Flow visualization and skin friction determination in transitional channel flow

نویسندگان

چکیده

Abstract The present study experimentally determines the transitional Reynolds number range for plane channel flow and characterizes its state. pressure along is measured to determine skin friction coefficient as function of from laminar state, through region into fully turbulent structure was studied visualisation which shows that increases state starts showing randomly occurring spots. With increasing spots shift oblique patches bands small scale turbulence form across width, together with large-scale streaky structures found in areas between regions. An image analysing technique used intermittency factor, i.e. fraction flow, number. It reaches value before (the factor still below one). This suggests observed non-turbulent regions contribute enhancement wall-normal transfer momentum. Also above numbers where has been established features consisting irregular are found. They have an shape similar indicating transition process not complete even level. Graphic abstract

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ژورنال

عنوان ژورنال: Experiments in Fluids

سال: 2021

ISSN: ['0723-4864', '1432-1114']

DOI: https://doi.org/10.1007/s00348-020-03102-6