Torsional flow of a viscoelastic fluid over soft surfaces

Experiments are performed to show that the suppression of purely elastic instability for the torsional flow of a polymeric solution over soft solids is dependent on the shear modulus of the soft surface. The shear rate at which viscosity shows an increase is the critical shear rate for the onset of purely elastic instability. It was shown that in presence of a soft surface in between the top moving plate and the bottom plate there is a suppression of purely elastic instability . However those experiments were done only for a particular shear modulus of the soft surface. In the present work we perform the flow experiments by keeping soft surfaces of varying shear modulus. We explore the role of varying shear modulus on the onset of the purely elastic instability. hence we conclude that the suppression of purely elastic instability is dependent on the shear modulus of the soft surface prepared.