Effect of electric field chirality on the unpinning of chemical waves in the Belousov–Zhabotinsky reaction

Abstract

We investigate the unpinning of chemical spiral waves attached to obstacles in the Belousov–Zhabotinsky (BZ) reaction using a Circularly Polarized Electric Field (CPEF). The unpinning is quantified by measuring the angle at which the spiral leaves the obstacle. Previously, we had found that the wave can unpin when the electric field along the direction of the spiral is above a threshold value. When we apply a DC field, this condition can be satisfied for a range of spiral phases, which we call the unpinning window (UW). With a CPEF, this UW moves either along the direction of the spiral (co-rotating) or against the spiral (counter-rotating). We find that when the field is co-rotating, it can take several rotations of the spiral to get unpinned. With a counter-rotating field, the spiral always unpins during the first rotation. We analyze how unpinning with CPEF depends on the electric field's relative speed, chirality, and strength using experiments and the Oregonator model. Our work helps to understand and control chemical waves. © 2024 Elsevier Ltd