[dewey]

Hi.

I am trying to simulate natural convection inside a pipe.

The boundary conditions are as follows:

The pipe is divided into three parts,

- The middle one has a temperature of 1300
- The others are adiabatics
- The sides are OPENINGS, can be inlet or/and outlet

How can i put this openings boundary condition in U and P_pgh?

How can i put the OPENING TEMPERATURE without force the flow, i mean, without fixed the outflow temperature on that side; like wall temperature been an opening.
On ANSYS CFX i can put this boundary condition definining an opening and one opening temperature.

Thanks for your time.

[jherb]

You are looking for the inletOutlet boundary condition.

[KateEisenhower]

Hello Alberto and Joachim,

I am not sure that this is right. With inletOutlet Alberto would have to specify the inflow temperature as a scalar. But how should he know the value?

What about zeroGradient?

Best regards,

Kate

[jherb]

Originally Posted by dewey

How can i put the OPENING TEMPERATURE without force the flow, i mean, without fixed the outflow temperature on that side; like wall temperature been an opening.
On ANSYS CFX i can put this boundary condition definining an opening and one opening temperature.

I think this is exactly, what inletOulet boundary does. For outward flow direction it behaves like zeroGradient. For inflows you set the temperature with inletValue.

[dewey]

Hi i have another question, i am trying to simulate a water in a vertical pipe as in pictures, in the middle of the pipe i have a wall some temperature hotter than the water, can you tell me what am i doing wrong? the water dosnt heat passing the wall hot, i dont know what TEMPERATURE Bc i have to put at outlet in order to dont force this.

If i put a fixed value, i am forcing the outlet temperature right? and i dont want that.i already try with zeroGradient. I want the temperature of the water heated.

thanks for you answer.

[KateEisenhower]

Hola Alberto,

have you applied fixedValue at the inlet and at the walls? What happened when you tried zeroGradient at the outlet?

Best regards,

Kate

Originally Posted by dewey

Hi i have another question, i am trying to simulate a water in a vertical pipe as in pictures, in the middle of the pipe i have a wall some temperature hotter than the water, can you tell me what am i doing wrong? the water dosnt heat passing the wall hot, i dont know what TEMPERATURE Bc i have to put at outlet in order to dont force this.

If i put a fixed value, i am forcing the outlet temperature right? and i dont want that.i already try with zeroGradient. I want the temperature of the water heated.

thanks for you answer.