In the first part, the stability of two-dimensional parallel flow is discussed. A more restrictively general stability criterion for inviscid parallel flow is obtained analytically. First, a sufficient criterion for stability is found as either −μ1 < U ′′ U−Us < 0 or 0 < U ′′ U−Us in the flow, where Us is the velocity at the inflection point, and μ1 is the eigenvalue of Poincaré’s problem. Seco...

one of the main architectural characteristics in the central area of iran is the relation between life and climatic conditions; e.g., the four-seasonal house which is a typical kind of the central-yard house. as the climate of isfahan is more pleasant than other desert regions in the central part of iran, wind towers are replaced with skylights to ventilate the pool area of hoze-khane. so far, ...

Synoptic eddy–mean flow interaction has been recognized as one of the key sources for extratropical lowfrequency variability. In this paper, the underlying dynamics of this interaction are examined from the perspective of a synoptic eddy-induced dynamic instability. To delineate this instability, a barotropic model is used that is linearized with respect to a stochastic basic flow prescribed wi...

We present an experimental investigation of viscoelastic fluid flow in a cross-slot microgeometry under low Reynolds number flow conditions. By using several viscoelastic fluids, we investigate the effects of the microchannel bounding walls and the polymer solution concentration on the flow patterns. We demonstrate that for concentrated polymer solutions, the flow undergoes a bifurcation above ...

We consider the local convective and absolute instabilities of the boundary layer on a rotating sphere located in a uniform axial flow, extending our previous work, which considered still outer fluid. Axial flow is seen to stabilise the convective instabilities, and our predicted onset of the spiral vortices is in good agreement with existing experimental data. The vortex angle is found to incr...