A Dynamic Thermal Insulator: Inducing Resonance within a Fluid Saturated
Porous Medium Enclosure Heated Periodically from the Side
B. V. Antohe and J. L. Lage
Internatinal Journal of Heat and Mass Transfer ,
Vol. 37, pp. 771-782, 1994
Abstract
This theoretical and numerical study investigates the natural
convection flow within a fluid saturated porous medium enclosure
subjected
to intermittent heating from the side (hot wall). A theory for predicting
the natural convection frequency of the flow wheel circulating inside the
enclosure is developed from the general porous medium equations on scaling
basis . Physical insight indicates that heat flow resonance might occur
when the input heat frequency matches the flow wheel circulating frequency.
Numerical simulations confirm the existence of a preferred (resonance
)
input heat pulsating frequency. They also reveal that at the resonance
frequency the fluid saturated porous medium system behaves as a dynamic
thermal insulator
in which the strong natural convection activity within the
system, characterized by high amplitude heat flow oscillations, coexists with
a damped oscillatory heat flux at the isothermal (cold) wall.