Steady Fluid Flow (internal with external fluid)

[lmnpontes]

Hi to everyone

I need to simulate something like a heat convector with ventilation. 

I created a tube to do something more easily. The tube is on the air and it has a fan in one of the border and in the other don’t has nothing. I created the internal and external fluid, and i deactivated the initial tube part. I started to try just simulate the fluid flow, to the next stage simulate fluid and heat transfer. I have 2 equal warnings: “Converge with stagnation due to oscillation”, and the output doesn’t seems good because the velocities. The gradient of velocity is to much equal!! 

If someone could help me with this.....

thank you

[Joey.X]

From your attached first picture, a velocity boundary condition was applied on the surface of the tube; however, the second picture shows the whole pipe is in an enclosure.

It needs to note that the velocity boundary condition is valid on external boundary, but not appropriate for any internal surfaces like in this case. To take care velocity BC on internal surface, one needs specify internal fan boundary condition on the surface. Internal surface always has surface pairs which have two surfaces in contacted parts, user can pick either one of them, then right click to select fan boundary condition and select type to "Internal" and Operation to "Fixed velocity", finally specify the wanted velocity magnitude and direction.

(Refer to attached image for internal fan/vBC settings)

For the warnings of “Converge with stagnation due to oscillation”,  it is common and acceptable that the real fluid has some oscillations if it turns in relative complicated geometries.

[lmnpontes]

thank you for your answer

i will try that solution. When i get results i update you