It is well known that the instability of boundary layers is sensitive to the mean velocity profile, so that a small distortion to the basic flow may have a detrimental effect on its stability. The main interest of the present paper is in investigating the mechanisms by which a relatively weak distortion can significantly affect the instability of an otherwiseuniform Blasius flow. Specifically, ...

The introduction of a lattice converts a singular boundary-layer problem in the continuum into a regular perturbation problem. However, the continuum limit of the discrete problem is extremely nontrivial and is not completely understood. This paper examines two singular boundary-layer problems taken from mathematical physics, the instanton problem and the Blasius equation, and in each case exam...

We define turbulent-turbulent spot as a local concentration of vortices with high level of swirling strength originating from hairpin packet in a turbulent boundary layer. We also define bypass transition in the narrow sense as the breakdown of the Blasius boundary layer beneath freestream homogeneous isotropic turbulence with an initial amplitude of 1 to 4 percent. We present evidence for the ...

Non-Oberbeck-Boussinesq (NOB) effects on the flow organization in two-dimensional Rayleigh-Bénard turbulence are numerically analyzed. The working fluid is water. We focus on the temperature profiles, the center temperature, the Nusselt number, and on the analysis of the velocity field. Several velocity amplitudes (or Reynolds numbers) and several kinetic profiles are introduced and studied; th...

This paper explores the use of nonparallel adjoint methods to predict the receptivity of two and three-dimensional boundary layers. Solutions obtained from both adjoint Navier–Stokes (ANS) and adjoint parabolized stability equations (APSE) have been validated against linearized Navier–Stokes (LNS) solutions that provide a full description of the linear receptivity process. The adjoint methods a...