In this Letter we discuss theoretically the instabilities of thermotropic freely standing smectic- A films under shear flow [3]. We show that, in Couette geometry, the centrifugal force pushes the liquid crystal toward the outer boundary and induces smectic layer dilation close to the outer boundary. Under strong shear, this effect induces a layer buckling instability. The critical shear rate i...

The paper deals with an approach to the Inverse Problems based upon their relations to the Boundary Control Theory (the BC-method). A possibility to recover a velocity c = ("") ?1=2 via response operator of the Maxwell dynamical system is discussed. The main result is that the operator (plus values of c; @c @ at a boundary) determines velocity uniquely in the maximal near-boundary layer in whic...

[1] Because of transverse pore-scale dispersion, a mixing layer develops along the interface between a lighter fluid (fresh water) that flows toward a well or sink above a heavier fluid (seawater) in a steady axisymmetric configuration. The Peclet number characterizing mixing, Pe = L/aT, where L is the aquifer thickness and aT is transverse dispersivity, is generally much larger than unity. The...

A fundamental problem in heat transfer is the convective cooling of the heated walls of a channel. We find steady two-dimensional (2D) flows that maximize the heat removed from fixed-temperature walls for a given rate of energy used to drive the flow, Pe (Pe is the Peclet number, a dimensionless flow speed). For parabolic (Poiseuille) flow, the heat transfer scales as Pe. Starting from Poiseuil...

While the computation of boundary-layer thickness is straightforward for canonical equilibrium flows, there are no established definitions general non-equilibrium flows. In this work, a method developed based on local reconstruction "inviscid" velocity profile $U_I[y]$ resulting from application Bernoulli equation in wall-normal direction. The $\delta_{99}$ then defined as location where $U/U_I...

long-throated flumes are measurement structures often used in water and wastewater systems to determine the flow discharge. the head-discharge relationship of long-throated flumes is traditionally determined following the critical flow theory and the boundary layer concept. after a review of the traditional approach and an analysis of the approximate assumptions of the boundary layer approach, ...