The intensity of convection of fluids with different Prandtl number in a vertical cylinder of large aspect ratio

We study the free convection in a long vertical cylinder with constant temperature gradient on the side surface. The wall temperature does not change its value in the circumferential direction, the flow is laminar; the fluid is Newtonian; the change in the density from the temperature used in the Boussinesq approximation, the problem is stationary. The movement is simulated by means of CFD in Ansys CFX. Verification of the used model is made. The natural convection of three fluids (water, gas-saturated oil, degassed oil) is studied for aspect ratio (the ratio of height to diameter) of 60, 80, 100, 200. Types of convective motion depending on the Rayleigh number is classified as “immovable” Ra