Laminar separation bubbles present a three-dimensional self-excited instability mechanism which leads to the appearance of spanwise-periodic structures. In incompressible flow, this mechanism was found to become active at conditions in which wave-like, two-dimensional perturbations are only convectively unstable. In the absence of continuous external excitation, the three-dimensional instability is expected to dominate the flow dynamics and initiate the laminar-turbulent transition. This work extends previous analyses by incorporating the effect of compressibility at subsonic conditions. Two-dimensional numerical simulations of a flat-plate boundary layer with a prescribed free-stream deceleration and acceleration are carried out to obtain a set of model laminar separation bubbles. A linear stability analysis is applied then, to study the influence of Reynolds and Mach numbers on the three-dimensional instability.

No abstract

No abstract

No abstract

No abstract

Coherent optical interconnects with up to 400-Gbps transmission rates and distances exceeding 80 km have been proposed to meet the increasing capacity demand of inter-datacenter communications. The interplay between the fiber Kerr effect and the receiver noise posses an upper-bound to the transmission distance. In this paper, we used numerical simulations to find the maximum achievable range of 400-Gbps unrepeated singlewavelength links with single and dual polarization. Simulations reveal that, for a forward error correction code limit of 10-3 , the maximum distance is 145 km for dual-polarization, which can be used as a benchmark to assess the transmitter/receiver-induced penalties.