Effects of reactant concentrations on reactive miscible viscous fingering

Effects of reactant concentrations on the characteristics of reactive misci ble viscous fingering in a Hele-Shaw cell at low finger-growth velocity wer e studied both experimentally and theoretically. The product distribution v aries with the variations in the initial reactant concentrations and depend s on the location of a reaction zone. When the reaction zone is located in the more-viscous-liquid region the product concentrates at the fingertips, but when it is located in the less-viscous-liquid region, the product sprea ds in a relatively broad area inside the fingers. This significant differen ce in the reaction pattern resulting from variations in the reactant concen trations is caused by the large difference of molecular diffusivity in the two liquids, that is, of viscosity which is one of the important factors fo r viscous fingering. These results are confirmed theoretically by one-dimen sional diffusive-reactive analysis.