On the combined effect of internal and external intermittency in turbulent flows
Orateur : Michael Gauding
Abstract : The edge of a free turbulent shear flow is characterized by a turbulent/non-turbulent interface (TNTI) which is a distinct and highly contorted layer that separates turbulent from irrotational flow regions. Transfers of mass, momentum and scalar quantities, such as species or heat, occur over the thickness of this layer, which renders its physical understanding crucial for a variety of engineering and environmental applications. Moreover, strong fluctuations occur in the vicinity of the TNTI and are transported by the mechanism of entrainment into the turbulent core of the flow. These fluctuations are known as external intermittency. First, the impact of external intermittency on small-scale turbulence is investigated in a turbulent jet flow. It is shown that external intermittency breaks the self-similarity of structure functions and invalidates the classical scaling relations proposed by Kolmogorov. Second, the coupling between internal and external intermittency is investigated in a turbulent non-premixed flame. It is demonstrated that external intermittency creates local gradients that are significantly more intense compared to those created by internal intermittency alone. Third, a general framework is developed to study the dynamics of interfaces in turbulent flows and to provide a link to morphological content, such as surface density, curvature and fractal dimension.
Date et lieu : le mercredi 29/09 à 10h30, Salle de séminaire IRPHE.
Le port du masque est obligatoire. Le nombre de personnes dans la salle doit être inférieur à 65% de la capacité, soit environ 50 personnes.
Voir en ligne : plus d’informations concernant l’orateur