Controlling Waves in Fluid

 

There is a big challenge in the physics community. Controlling traveling waves that come from the coupling of oscillations and diffusions has remained elusive. Control of these waves willl improve reaction- diffusion systems and the dynamics that defines them.

Researchers have discovered a novel approach to control waves in a type of fluid flow. This is referred to as hyperbolic flow. The scientists controlled the chemical waves via the stretching and compression of fluids. 

A team from Universite libre de Bruxelles (ULB) and Universite de Rennes released their findings in a journal called Physical Review Letters. 

Anne De Wit is the senior author of the paper. She said during a recent interview, "At a summer school in Corsica, discussions between the Brussels and Rennes team triggered the curiosity to see how chemical waves studied at ULB in Brussels would behave in hyperbolic flows analyzed in Rennes. The primary objective was to see how a non-trivial flow would influence the dynamics of waves."

De Wit's experiment manipulated fluids to reliably control the properties of chemical waves. The team subjected a reactive medium to a hyperbolic flow. Hyperbolic flows are when fluid elements are stretched in one direction and compressed in another. 

De Wit explains, "We first prepared solutions of a bubble-free recipe of the Belousov-Zhabotinsky reaction, a classical oscillating reaction known to provide nice waves and injected these solutions in a reactor on two opposite sides. In such a flow, the waves align in the center of the reactor instead of developing target patterns as in the absence of flow. Varying the injection flow rate, we could control the wave packet i.e., control its alignment and the number of waves it contains."

Using this novel method, the team was able to shape and direct traveling wave packets in a hyperbolic flow. Localized wave packets were observed emerged in the fluid. Due to the reaction, diffusion and flow induced compression were also observed. The waves were influenced by transverse flow disturbances. The waves shift from plane-like to distorted patterns in response to the disturbances.

The scientists also discovered that a singular wave packet has a preferential direction, even when the rate of compression decreased. 

De Wit explains, "A notable achievement is to be able to align waves by a flow in a given localized packet. As waves carry information embedded in their orientation and wavelength, this could have applications in sending and storing directional and quantitive information."

This new study opens up wave control in multiple fields. De Wit summarizes, "Our plan for future research is to tune the spatio-temporal distribution of the reactants to see whether we can fine tune the control of the waves."