Investigation into ferrofluid magnetoviscous effects under an oscillating shear flow

► Extension of the magnetoviscous effect of ferrofluids to the oscillatory shear flow. ► Influence of magnetic field level, shear stress amplitude and frequency is studied. ► Ferrofluid viscosity is lower for oscillatory than for steady flow shearing. ► Ferrofluid viscosity is not sensitive to shear rate amplitude. ► Negative-viscosity effect occurs even for a null magnetic field.