This work reports the application of a model-free deep reinforcement learning (DRL) based flow control strategy to suppress perturbations evolving in one-dimensional linearised Kuramoto–Sivashinsky (KS) equation and two-dimensional boundary layer flows. The former is commonly used model disturbance developing flat-plate These systems are convectively unstable, being able amplify upstream distur...

The family of wake profiles formed from the Falkner–Skan boundary-layer solutions with negative pressure gradient, m, was shown in (Woodley and Peake, 1997) to be inviscidly absolutely unstable. However, due to numerical difficulties, the limit m→ 0 was not considered there, although the results that were found appeared to indicate that the double Blasius profile (m = 0) is absolutely unstable....

When a boundary layer starts to develop spatially over a flat plate, only disturbances of sufficiently large amplitude survive and trigger turbulence subcritically. Direct numerical simulation of the Blasius boundary-layer flow is carried out to track the dynamics in the region of phase space separating transitional from relaminarizing trajectories. In this intermediate regime, the correspondin...

In this paper we examine the large Reynolds number, Re, asymptotic structure of the wavenumber in the Orr-Sommerfeld region, for the Blasius boundary-layer on a semi-infinite flat plate given by Goldstein (1). We show that the inclusion of the term which contains the leading order non-parallel effects, at O(Re−1/2), leads to a non-uniform expansion. By considering the far downstream form of eac...

Synaptonemal complex (SC) chains were revealed in semisterile intraspecific F1 hybrids of Ellobius tancrei Blasius, 1884 (2n = 49, NF=56 and 2n=50, NF=56), heterozygous for Robertsonian (Rb) translocations. Chains were formed by Rb submetacentrics with monobrachial homology. Chromosome synapsis in spermatocytes of these hybrids was disturbed, apparently because of the problematic release of the...

The classical experiments on turbulent friction in rough pipes were performed by Nikuradse in the 1930s. Seventy years later, they continue to defy theory. Here we model Nikuradse's experiments using the phenomenological theory of Kolmogórov, a theory that is widely thought to be applicable only to highly idealized flows. Our results include both the empirical scalings of Blasius and Strickler ...