Learning Forum

[hk1234]

Hi,

 

I have a problem to simulate a developed Stream.

I wanted to simulate the forced convection by a turbulent air stream. The problem is that the stream is changing too much an I want to have just turbulent but developed stream and than the heat loss.

How can I do this.

Best regards

Hilal

[Rob]

You mean the flow field is changing with time?

[hk1234]

yess, the flow field is changing although I want developed Stream.
I just want to have the heat transfer over the time but depending on the stream by forced convection.

[Amine Ben Hadj Ali]

Do you need a velocity profile at inlet which is developed but the magnitude is changing?

[hk1234]

I simulate wind with a certain inlet velocity.

As you can in see on the pictures the turbulence increases more and more instead of getting a certain pattern after a short time like a developed stream.

[Amine Ben Hadj Ali]

I do not see any turbulence increasing: do you mean the vortex before the building/body in the second image? You have flow separation at the top, vortex at the bottom due to stagnation and probably reattachment after the body which is not shown in the pictures (I hope you modeled the region behind the body to capture the wake and the reattachment region). 

I do not understand your problem because I do not see any problems.

[hk1234]

yess, I mean the vortex before the building. And yess, I have modelled the outlet too.

I need to have the the stream developed from the beginning of the heat transfer. Maybe it is better visible here:

Best regards,

Hilal

[Amine Ben Hadj Ali]

I still do not get the question: what are you expecting? Why should we see a developed flow? You can provide a developed profile at inlet but it will end up with separation (flow past a bluff body) and some recirculation zones.

 

Run transient and do some animations: that is what I can say here.

[Rob]

You're modelling a transient system, and may have picked up eddy shedding. What does the residual plot look like? What's the plug flow residence time in the domain?

[hk1234]

the residuals look like this.

 

I now tried to have  a larger box for the flow Simulation, it looks better but somehow I can not refresh the mesh . There is always an error saying overlapping contact regions even I used the option repairing overlapping contact regions. Is it more likly for this error to have to do with the geometry than the meshing?

 

Thanks