Turbulent statistics in a lubricated channel flow

Alati, Alessandro 2024. Turbulent statistics in a lubricated channel flow. MPhil Thesis, Cardiff University. Item availability restricted.

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Abstract

In this work we aim to study, through the use of Direct Numerical Simulations (DNS), the turbulent drag reduction that occurs in a lubricated channel during the transport of a fluid at a low Reynolds number. In this situation, one of the two fluids separates the second from the wall forming a thin layer in contact with it. In our configuration the thin lubricating layer is adjacent to one of the wall, which will be called lubricated side. We consider the same density (ρ1 = ρ2) for the two fluids, we change the viscosity ratio (λ = ν1/ν2) with two different values: λ = 1 and λ = 0.5. To assess the role of the surface tension we also performed an additional simulation at λ = 1 varying the We number from We = 0.055 to We = 0.5. As expected the drag reduction (DR) mechanism is strongly related to the viscosity ratio, in particular the flow rate increase when decreasing λ due to a relaminarization of the lubricated layer. Moreover, the parametric analysis on the effect of viscosity ratio and surface tension allows us to highlight very interesting modulations of the dynamics of the interface and of the turbulent kinetic budgets. To date, the latest studies in this area have been carried out using the Phase Field Method [1] for the description of the interface. One of the scopes of the present study is to confirm and extend the existing results by exploring the dynamics of the flow with the use of the Volume of Fluid (VOF) method [2].

Item Type:	Thesis (MPhil)
Date Type:	Completion
Status:	Unpublished
Schools:	Schools > Engineering
Uncontrolled Keywords:	Drag reduction multiphase flow direct numerical simulation volume of fluid turbulence
Date of First Compliant Deposit:	3 June 2025
Last Modified:	03 Jun 2025 11:29
URI:	https://orca.cardiff.ac.uk/id/eprint/178681

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