Surface temperature BC does not affect internal temperature

[Anonymous]

The attached model is a simple example of the problem I'm having. When forcing airflows (either velocity or mass flow rate) of different temperatures into a volume (0 psig at the exit), the flow velocity makes sense but the temperature results do not. I'm expecting some variation in temperature, but except for a small sliver at the hot inlet, the air is uniformly cool.

Experience tells me I'm missing something simple.

Thanks,

Kerry

[Anonymous]

Attached is what I'm actually trying to do: model gas turbine exhaust flow into a diffuser (the point is to keep the exposed metal cool and cool the exhaust to some extent).

The exhaust inlet at the bottom has BC's for mass flow rate (155 lbm/s) and static temperature (1051 F). The upper surface of the big air volume has BC 0 static psig and the bottom has BC 65 F static to force the temperature of whatever ambient flow is drawn into the diffuser. There may be some big style issues with how I've set this up so please advise if necessary.

The problem I'm seeing is that while the flow velocity makes sense (air flows up from the 155 lbm/s surface trhough the diffuser), the temperature is nearly constant in the volume with the exception of right at the 1051 F surface.

I've tried a few different basic setups and BC variations, but I know I'm missing something... 

[Jon.Wilde]

Hi,

Thanks for sharing this model. I am not quite sure where to start with it as the setup is not quite correct and I am not entirely sure what the correct approach should be yet. 

One problem I have is that there are some boundary conditions which are not assigned to anything T=2--C, T=400C and a 2m/s velocity. They are in the tree but not assigned.

Bear in mind that we cannot assign these to internal surfaces - perhaps this is one of the problems. You would need to have internal suppressed volumes and then you could use these.

Could you run a 1/2 or 1/4 model here? It would be faster - I think you are likely need to need a good deal more mesh than is presently assigned.

What mach numbers are you expecting? Is this a compressible study?

Kind regards,

Jon