Numerical study based on experimental datas of the active control applied to the flow past a backward facing ramp

Abstract : This work is based on Dan Hlevca and his co-authors’ experimental study [5] on the active control applied to the flow past a backward facing ramp inclined to 25°. Following the study of the mean and unsteady flow without control applied, the authors use the control technique of pulsed jets because they are interested in the influence of the variation of the duty cycle DC, keeping the blowing time constant. In their conclusion they highlight the disappearance of the recirculation bubble at the back of the body and the recovery of pressure at whatever frequency and the applied DC. An estimate of the drag coefficient is calculated by extrapolating the pressure measurements taken in a median longitudinal plane. The authors remain cautious about interpretations related to the drag coefficient, not knowing explicitly the pressure distribution on the body in the transverse dimension. The present work is the numerical portion of this study. RANS simulations with first order turbulence models were conducted to try to extract the solution on the mean flow in a relatively short time. The incapacity of RANS models of the first order classical turbulence model to determine a precise solution of the mean flow around this type of geometry imposed a mixed numerical strategy URANS-LES, also named DES (detached eddy simulation). Characteristics of the mean and unsteady flow are thus found, which made it possible to validate the numerical DES approach chosen and to consider the solution obtained as a suitable estimation of the physical problem. A restriction of the computation domain with the introduction of synthetic turbulent fluctuations at the inlet makes it possible to envisage, on the delay of this internship and with the computer means at disposal, a simulation of the controlled case. We could afterwards look at the pressure distribution of the entire body and determine the influence of the pulsed jets on the pressure drag coefficient.
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Rémy Simonet. Numerical study based on experimental datas of the active control applied to the flow past a backward facing ramp. Fluids mechanics [physics.class-ph]. 2019. ⟨dumas-02023452⟩

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