Numerical analysis on the effect of natural convection in pulse tube

Natural convection in a pulse tube was numerically simulated to analyze how the direction of the buoyancy force affects the flow and temperature distributions. 2D cylindrical coordinates and the Boussinesq assumption were applied in this computation for the steady natural convection. Computational result shows that when the cold end is at the bottom, the natural convection in the tube inhibits the heat exchange and helps to hold the temperature difference at the two ends. The heat to be conducted at the ends where the cold end is at the bottom is only 31% of that where the cold end is at the top. This result is in good agreement with the experiments. This analysis can be used to enhance the performances of a pulse tube refrigerator.