Pattern interaction effect.

Unexpected responses of physical systems to external stimuli can be observed when the stimuli are organized into spatial patterns and, especially, when stimuli of different physical origins are involved, leading to the pattern interaction problem. Combinations of weak stimuli-individually only capable of producing marginal local responses-can produce a global response without involving any bifurcations. Its existence is demonstrated by the interaction of properly tuned topography and temperature patterns.

Use of Surface Corrugations for Energy-Efficient Chaotic Stirring in Low Reynolds Number Flows.

We demonstrate that an intensive stirring can be achieved in laminar channel flows in a passive manner by utilizing the recently discovered instability waves which lead to chaotic particle movements. The stirring is suitable for mixtures made of delicate constituents prone to mechanical damage, such as bacteria and DNA samples, as collisions between the stream and both the bounding walls as well as mechanical mixing devices are avoided. Debris accumulation is prevented as no stagnant fluid zones are formed.

Droplet Splashing on an Inclined Surface.

Oblique droplet impacts onto a smooth surface at various inclination angles and at different ambient gas pressures were investigated using high-speed photography. It was found that the droplet splash can be entirely suppressed either by increasing the inclination angle or by reducing the ambient pressure. Variations of the threshold angle required for the splash suppression as a function of the impact velocity were determined, as well as the threshold pressure as a function of the inclination angle and the impact velocity.

Natural convection in a horizontal fluid layer periodically heated from above and below.

Natural convection in a horizontal slot heated from above and from below has been considered. Each heating has a certain spatial distribution. It has been demonstrated that a wide variety of convection patterns can be generated by changing the relative position of both heating patterns.

Natural convection in a fluid layer periodically heated from above.

Natural convection in a horizontal layer subject to periodic heating from above has been studied. It is shown that the primary convection leads to the cooling of the bulk of the fluid below the mean temperature of the upper wall. The secondary convection may lead either to longitudinal rolls, transverse rolls, or oblique rolls.