Simulation of natural convection flow for vertical heated rod by using ANSYS/Fluent

The decay heat removal by natural convection is very important in case of Station blackout (SBO) of nuclear reactor. The computational fluid dynamic (CFD) is helpful to simulate the flow and temperature field. However, the CFD simulation models need to be validated by the experimental data. Thus, in this report, the Anslys/Fluent is applied to simulate the natural convection induced by single heater rod. The vertical heated rod with a diameter of 12 mm and a length of 225 mm is immersed at the center of a vertical pipe made of acrylic with a diameter of 146 mm and a height of 500 mm. In this simulation, the coupled scheme algorithm is also applied. Regarding to experimental method, the optical method such as Particle Image Velocimetry (PIV) was applied for 2-dimensional velocity distribution and pointwise temperature measurement. As a result, the predicted flow and temperature field are well agreed with experimental data. Accordingly, the thermal plumes are well estimated by ANSYS/Fluent, in which the buoyant plumes induced by different temperatures vertically go up along the heater rod's upper part until the container's isolated upper wall. The complicated flow occurs in the middle part of the container by mixing the downward flow on the top and the upward flow from the heater rod.