[Comi]

Hi, can any of you give me an advice regarding how to simulate open space with Fluent?

In my model I need to extract the surface temperatures of an heat exchanger in open space, the device is positioned at a certain distance from the floor and a wall. In order to reduce the number of elements I used simmetry on one side.
I placed the heat exchanger into a limited volume of air. If I assign the wall boundary condition to the walls that surround the air volume it would be like simulate the heat exchanger into a box, so is there a way to assign an open space-like B.C. to these walls?

Thanks very much

[RaiderDoctor]

Can you post a pic of your fluid domain with arrows pointing to your boundaries, and what conditions you assign them?

[LuckyTran]

Originally Posted by Comi

so is there a way to assign an open space-like B.C. to these walls?

A pressure inlet or a pressure outlet should work.

[Comi]

Originally Posted by LuckyTran

A pressure inlet or a pressure outlet should work.

Thanks, I will try that

[Comi]

I have another question: in order to use pressure inlet or pressure outlet I should set the Gauge Pressure to zero right? The operating pressure is still at default value

[LuckyTran]

Originally Posted by Comi

I have another question: in order to use pressure inlet or pressure outlet I should set the Gauge Pressure to zero right? The operating pressure is still at default value

Right... If you keep the default operating pressure (which is ~1 atm) and set a zero gauge pressure, then your boundary condition is ~1atm of absolute static pressure.

[Comi]

Originally Posted by RaiderDoctor

Can you post a pic of your fluid domain with arrows pointing to your boundaries, and what conditions you assign them?

Regarding your request here is a pick of the geometry, due to some circumstances I can't show you the details.

I have a radiator that hang on a wall, the radiator has n eletric resistance inside and i want to know what will be the surface temperature at steady state.

That is why I needed the open space like BC. Unfortunately using the pressure inlet or pressure outlet I can't reach a satisfying solution, probably i'm missing something again.

I'm using pressure based solver, the resistance is a parallelepiped that is not included into the domain, I just gave the W/m2 distribution at the surfaces that represent the resistence. The resistence is in contact both with the raditator and the air.

[Comi]

Another question: even though I impose a certain energy flux on the surfaces of the resistance the fluid fluxes are all wrong. Instead of having hot air going versus the top of the volume , air just enter from the top side of the pressure inlet and exit from the bottom. I tried to cheat by puttting a pressure outlet on the top of the volume but the direction of the flux doesn't change.
Any suggestion?
I'm using k-epsilon turbulence model, s2s, pressure based solver

Thank you