There are many uses for natural turbulent flows around hot horizontal cylinders. If the material that flows around the cylinder is confined vertically or horizontally, it can change the way the flow behaves. When there is both horizontal and vertical confinement (rectangular enclosure), the contact between the fluid and the walls of the enclosure can still be different. To facilitate further studies, a numerical paper validation is first required. This is done based on the paper entitled “ Natural convection from horizontal heated cylinder with and without horizontal confinement”.

Simulation Process

Model geometry is erected by Design Modeler. A proper division of the zones eases the production of a structured grid. The Boussinesq model is used to consider density as a variable in the momentum equation’s buoyancy part. Sutherland’s equation is used to connect viscosity and air. As given in relations 3 & 4 in the paper, density and specific heat are variable and dependent on temperature. A user-defined function (UDF) is written to apply so.

Post-processing

For the sake of validation investigation, we concentrate on Figure 9 which plots Nusselt variation around the cylinder at Ra=4e+4 and H/D=0.3. The same parameter is exclusively exported from ANSYS Fluent, resulting in the following figure: Two curves can perfectly cover each other, showcasing a suitable precision.

Figure 1: Local Nusselt number variation around the cylinder