抄録
Air distribution of ventilated room space was analyzed by numerically solving three-dimensional Navier-Stokes equations. Marker-and-Cell (MAC) method was adopted as the finite difference analogue of N-S equations, because, especially in three-dimensional flow, the boundary conditions were easier to set than those of vorticity transport equations. After brief explanation of MAC computing procedure, a cube-shaped room model was resolved into 9×9×9 cells, putting an air inflow at the center of the ceiling surface, and an air outflow at the bottom center of one of side walls. Computations were carried out from appropriate initial conditions, reaching successfully the perfect steady solutions up to 50 of Reynolds number based on the length and the velocity of the air inflow. Some descriptions of characteristic features of computed room air distribution are given below. 1) Injected jet falls straight down, and spreads radially over the bottom surface. 2) One part of flow goes out through the air inlet. The other part turns upward through the area near the side walls to the ceiling of the room model. Stronger stream can be seen at the corners of the side walls than at the centers of them. 3) Then the air is gathered slowly toward the room center, and falls down again induced by the jet stream. 4) Whole processes of recirculation are very similar to what are observed in the experiments reported on our another paper, though the experiments have been made including turbulence in larger Reynolds numbers of 1000-8000.
