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Problem with natural convection in conjugate in heat transfer
Posted Aug 31, 2010, 4:27 a.m. EDT 0 Replies
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I have a problem with convection in the "nitf" module.
I need to define some 3D models with natural convection cooling heated bodys
(Not by the "Convective cooling" boundary condition, but by solving Navier-Stokes).
So I want to build a model, where the ONLY cause for the movement of gas is the buoyancy
caused by adding a Fy= -9.81*nitf.rho(T) volume force.
For faster boundary testing I have set up a 2D model with only one heating body inside a fluid domain rectangle.
It is no problem to set up the "airbox" with stable boundary condition for an airstream with an inlet
velocity ("Symmetry" parallel to the flow, "Inlet Velocity" and "Temperature" at the inlet and "Outlet pressure" and
"Outflow" at the outlet) but I have not managed to come up with stable boundary conditions for a completely free
convection. I get some results with no buoyancy if I use the above boundaries and set the inlet velocity to 10e-10 [m/s], but I am not feeling comfortable with the "symmetry"´boundaries in this case because they distort the "free" convection field.
Anyway, no matter what the BCs are, as soon as I switch on the volume force Fy=-9.81*nitf.rho(T) I get no
convergence at all.
I also remember that I have seen a 3.5 example like "free convection around a thermos-can" but I can not find
it anymore.
I'll be grateful for any help!
Best,
Markus
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Hello Markus Berger
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