Frequency Response and Heat Transfer of Thermal Convection Generated by Nanofluids under Microgravity Envionments with Gravity Modulation

Abstract

Three-dimensional numerical analysis was performed to clarify the frequency response and heat transfer characteristics of the nanofluid to the gravity modulation under the microgravity environment. Gravity modulation was modeled as a sinusoidal oscillation of gravity. The frequency response of the nanofluid is good at low gravity modulation frequencies, so a heat transfer rate becomes high when the gravity modulation maximizes. Also, the heat transfer rate becomes maximum when the volume fraction of nanofluid is low. On the contrary, since the frequency response is poor at high gravity modulation frequencies, the time variations of the heat transfer rate are not observed. Therefore, the heat transfer rate is constant, and always the maximum at the low volume fraction. In the low frequency range, the time averaged heat transfer rate increases as the average temperature of nanofluid increases, and then the oscillation amplitude of heat transfer rate becomes large as the diameter of nanoparticle increases.