Numerical predictions of flow and thermal fields in an enclosure with two periodically moving walls

Abstract

SUMMARYNumerical predictions of transient ow and thermal ÿelds in a rectangular enclosure with two periodically moving vertical walls are presented. The combined in uence of the movement of the walls and the buoyancy as well on the ow pattern and heat transfer performance is evaluated. The compressibleow model is adopted, and governing equations are expressed in integral form and discretized on the moving grids, which deform in resonance with the walls to accommodate the variation in the volume of the enclosure. A two-stage pressure-correction scheme is applied for simultaneously determining the distributions of absolute pressure, density, temperature, and velocity of the compressible ow ÿeld in the enclosure during the periodically stable periods. E ects of the frequency, stroke, and the phase angle of the wall oscillations on the ow are of major concerns in this study. The frequency is ranged between 5 and 25 Hz and the dimensionless strokes (l=H ) of the wall are varied from 0.4 to 1.0. Results for Nusselt numbers on the walls as well as the dimensionless input work required to excite the wall oscillation are provided.