Learning Forum

[Ali Fauze]

Hello, I'm conducting a natural convection simulation using Fluent, and while I'm satisfied with most of the results, the pressure field appears unphysical. As depicted in the accompanying image, my model consists of a heated source cylinder positioned centrally in a room, which naturally heats the air. This causes the air to be drawn in at the inlet and expelled at the outlet due to density differences. I defined inlet and outlet vents with pressure loss coefficients of 0.5 for the inlet and 1 for the outlet, respectively. The fluid motion, velocity field, and the temperature and density fields all appear physically acceptable. However, the highest pressure values are observed at the outlet, as can be seen in the image below. The operating conditions and reference values are defined correctly.

 

Best regards, 

[Rob]

What did you set the operating density as? What air density model did you use?

[Ali Fauze]

Hello Rob, 

Thank you for your response,
My reference density is the rho0 defined 1.204 kg/m^3 and the air density model used is the incompressible ideal gas.

Best regards,

[Rob]

Velocity inlet or pressure? If it's the latter, what does Fluent think the density is at the external temperature?

[Ali Fauze]

hey Rob, 

Thanks for the response,

I defined an inlet vent with a pressure loss coefficient (so a pressure inlet), and the external temperature is 20°C and it's imposed in the Velocity inlet BC.

Best regards,

[Rob]

Pressure or velocity inlet? You can't have both. If you initialise at the "outside" temperature and plot density (contour, node values off to get the single value) what do you get as a value?