Natural convection in a partially open enclosure is encountered in many practical applications such as the cooling of electronic device

the ventilation of building and the heat transfer in chemical process.A model that was formed by adiabatic walls and three partial openings

where the density of fluid changed continuously by linear heat source

was developed based on the theories of computational fluid dynamics and heat transfer.And four different ventilation modes were discussed based on the model.The comparisons among four ventilation modes indicated that the height of neutral level depended on both the source and the ventilation modes.For a specific ventilation mode

the ventilation air-flow rate and heat transfer can be increased by increasing the heat source strength but not by lifting the height of middle opening (MO).It implied that expanding the area of openings directly made ventilation air-flow rate larger

whereas not affirmatively reinforced heat transfer because the heat transfer from the source in the enclosure with a small-area opening was sometimes more than that with a large-area opening.Some general guidelines for optimizing natural convection in practical applications with multi-opening were provided.