Abstract
Turbulent separation in channel flow containing a curved wall is studied using a generalised form of Kolmogorov equation. The equation successfully accounts for inhomogeneous effects in both the physical and separation spaces. We investigate the scale-by-scale energy dynamics in turbulent separated flow induced by a curved wall. The scale and spatial fluxes are highly dependent on the shear layer dynamics and the recirculation bubble forming behind the lower curved wall. The intense energy produced in the shear layer is transferred to the recirculation region, sustaining the turbulent velocity fluctuations. The energy dynamics radically changes depending on the physical position inside the domain, resembling planar turbulent channel dynamics downstream.
Highlights
Most of the statistical theory of turbulence concerns the mechanisms that sustain turbulent fluctuations against dissipation, namely production and fluxes of turbulent kinetic energy in the physical space [1] and across the different scales of motion [2]
Turbulent separation was addressed by a Direct Numerical Simulation of turbulent channel flow with a lower curved wall
The presence of the bump produces a stable, fully turbulent recirculation bubble which is separated from the core flow by a strong shear layer
Summary
Most of the statistical theory of turbulence concerns the mechanisms that sustain turbulent fluctuations against dissipation, namely production and fluxes of turbulent kinetic energy in the physical space [1] and across the different scales of motion [2]. The present work investigates, through Direct Numerical Simulation (DNS), the scale-byscale energy production, transport and dissipation in a channel with a lower curved wall which is a relatively more complex geometry with respect to previous studies in homogeneous or shear flows. The asterisk denotes the mid-point average, e.g. u∗i = (ui + ui)/2, whilst the δ denotes an increment, e.g. δUi = Ui − Ui. Since the present domain has only one homogeneous direction, the span-wise one, the generalised Kolmogorov equation is defined in a five dimensions space where the independent coordinates are the two physical Xc and Yc and the three separation rx, ry and rz coordinates. Equation (4) provides a way to distinguish between the transfer of energy from production to dissipation in both physical and separation spaces as opposed to only observing one-point statistics, as, for example, in the mean flow kinetic energy and the turbulent kinetic energy equations, which provide information concerning the transport, production and dissipation only in physical space
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
