Effect of carrier and particle concentration on ultrasound properties of magnetic nanofluids

• Sound wave propagation studied in kerosene and transformer oil based magnetic fluid.
• Ultrasonic velocity decreases with increasing volume fraction and temperature.
• Collapsing of structures at higher temperature leads to decrease sound wave attenuation.
• Possibility of structure formation is more in transformer oil compared to kerosene.
• Field induced structure formation is more in transformer oil than to kerosene.

Ultrasound wave propagation in nanofluids and its rheological behavior has been studied as a function of solid volume fraction, temperature and magnetic field for magnetic nanofluids synthesized in kerosene and transformer oil. Ultrasonic velocity decreases while viscosity increases with increasing volume fraction. The attenuation of ultrasonic wave is explained using dipolar coupling co-efficient which favors oligomer structures with increasing number density of particles. The structure formation increases further with increase in magnetic field which is prominent in transformer oil compared to kerosene. This difference can be due to the structural difference between these two carriers.