Abstract
When a reactive less viscous liquid is injected into a Hele-Shaw cell filled with a more viscous liquid and displaces the more viscous liquid, viscous fingering involving a chemical reaction forms. Although some experimental studies on this phenomenon have already been reported, a clear understanding of the region where and when the reaction takes place in the fingers has not yet been obtained. Here, by using a novel experimental method which involves switching the less viscous liquid that is injected into the system, we identified the reaction region at a given time under various reactant concentration conditions.
