Influence of a baffle on cell convection in superimposed fluid-porous domain

• Main Authors: Chu-Hung Lee, 李祖宏
• Other Authors: Falin Chen
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/cy6x2d

碩士 === 國立臺灣大學 === 應用力學研究所 === 106 === This paper simulates and analyzes the impact of an insulated baffle to cell convection in both the fluid layer and the porous layer. In addition, this paper introduces the basic theory and the flow motion of the fluid in the porous medium and further elaborates the most commonly used plastic foam in current building insulation and cooling system. We utilize the commercial software package—COSMOL to begin numerical simulation using the finite element method, and we observe the flow pattern structure and the change of structure after implementing the insulated baffle. Much research has been conducted in the area of applying porous medium in building insulation and cooling system. Therefore, the model discussed in this paper allows us to understand the changes of convection effect and to track its pattern. Additionally, this superimposed fluid-porous domain structure improves its suitability in industrial designing. In this research, we adjust the depth ratio between the porous layer and the fluid layer to observe the structural change of the flow. We also change the location of the insulated baffle in the bottom as well as the height of the baffle. First, based on the simulation result, when depth ratio is higher, fluid layer dominates. In this scenario, the velocity of flow is higher, and the influence of baffle on flow pattern is more obvious. In contrast, if depth ratio is lower, porous layer dominates. In this case, the velocity of flow is lower and the influence of baffle on flow pattern is less obvious. Second, the location of insulated baffle also has a huge impact on flow pattern. When the baffle is placed in the central bottom, the baffle has the largest impact to flow pattern. This impact on flow pattern decreases as the baffle moves away from the central bottom location. Finally, the height of the baffle is another important factor. Based on the simulation result, when a baffle is lifted up to a certain height, the baffle almost has no impact on the flow pattern even if we keep increasing the height. This research conclusion offers more possibilities and convenience to future insulation system design. In building insulation system, plastic foam is the most widely used material due to its low cost and durability. In this research, we mainly analyze plastic foam in all the simulation scenarios, and the parameter is also set up based on plastic foam.