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# Simcenter Thermal-Flow steps and boundary conditions

Solution Partner Pioneer

Hello,

We are trying to simulate a coupled thermal-flow analysis model on a factory air conditioning system, it is a simple analysis, the air enters through a cylindric shaped conduct and it exits only from small holes located at the lateral surfaces of the conduct, the objective of the simulation is to calculate the fluid velocity in the Room where the air flows as well as the temperature values.

Later we would also like to see how the cooling influences the cylindric conduct in itself.

So far here's the steps i followed:

1) creating the cylindric conduct

2) Use of Boolean operation to create both fluid volumes (the interior fuild volume of the conduct which will be at a temperature of 14.5°C and the exterior volume which represents the Room in which the cooling will take place and at an initial Ambiant temperature)

3) Meshing of both Volumes independently (with 3D TET10 mesh) as well as messhing the cylindric conduct (with 2D TRI6 Thin Shell mesh)

4) Creating aDisjoint Fluid Mesh Pairing between the two vomules (since we couldn't use the mesh mating command)

5) Definition of the inlet and the openings (which are the 6 faces of the exterior volume)

Are those steps correct so far? if i'm missing something or doing something wrong please point it out for me.

The next step will be the introduction of the Thermal Boundary conditions  which we had troubles and which leads to my question : how to model the boundary conditions? (as a mentioned earlier the interior volume AKA the cooling volume will be at 14.5°C and the exterior volume will be at Ambiant temperature initially)

Also any insights to solver parameters? is there something specific that i need to change?

I'll attach pictures below and the files i'm working with for better understanding of the matter at hand, any help will be greately Appreciated!

Best regards!

Helmi BOUALI

Mechanical Engineer

PLM Ressources SARL

18 REPLIES 18

# Re: Simcenter Thermal-Flow steps and boundary conditions

Gears Phenom

3) Merge two volumes and therefore not do 4).

# Re: Simcenter Thermal-Flow steps and boundary conditions

Solution Partner Pioneer

Hello @Karachun

later on we'll need to set boundary conditions which are different in each volume, can i do that even after merging both volumes, and if yes can you tell me how?

# Re: Simcenter Thermal-Flow steps and boundary conditions

Gears Phenom

Boundary conditions or initial conditions?

# Re: Simcenter Thermal-Flow steps and boundary conditions

Solution Partner Pioneer

for the exterior volume (Room) it'll be an initial condition since that's the volume that'll be cooled
as for the interior volume it should always be at 14.5°C therefore it should be a boundary condition
that's how i see it, do you think it makes sense?

# Re: Simcenter Thermal-Flow steps and boundary conditions

Gears Phenom

No, you set initial temperature for all volume and temperature of cooling air for inlet in tube.

# Re: Simcenter Thermal-Flow steps and boundary conditions

Solution Partner Pioneer

@Karachun

i'm sorry i'm a bit confused, can you explain more

do you mean that i should still merge both volumes and i will only need to use initial conditions, is that right?

# Re: Simcenter Thermal-Flow steps and boundary conditions

Gears Phenom

I think better to make pause and you should explain physical boundary conditions of exterior volume.

Like "There is a room with walls, there is a vent hole at one wall and air can exit through this hole, room contain equipment that produce heat with power P, etc."

This will make some things clear.

# Re: Simcenter Thermal-Flow steps and boundary conditions

Gears Phenom

If I understand correct then you can set temperature at the openings. When flow enter domain it will have specified temperature.

If you perform steady state analysis then initial conditions don’t effect on result (flow time is infinite) and you can set constant initial conditions in whole volume.

# Re: Simcenter Thermal-Flow steps and boundary conditions

Solution Partner Pioneer

there's a cylindric conduct in a room, the air enters from one side and it exits from small holes located on the lateral surfaces of the conduct and then spreads in the room, the cooling air temperature is 14.5°C and the Room's temperature is Ambiant

we want to calculate the temperature of the room in its steady state

do we use initial or boundary conditions?