[AntonioCG]

Hello all,

I am trying to simulate a moving pipe, this means that I have to simulate two fluids, air and water. However, The problem I am facing is that, I know the temperature at the inlet of the pipe, so I have to activate the Energy equation. As the pipe is moving, I would like to see the temperature obtained due to the flux of the aire (for example at 305 K) as the interaction of the air with the Wall of the Pipe. My problem is that activating the energy equation I have to define the temperatures at the outlet and at the wall of the pipe.

So, I would like to simulate the temperature evolution as function of the velocity of the pipe instead of giving a Temperature (defined as constant). Is it possible to simulate it in ANSYS Fluent ? If it is possible, how can I do it ?

I attach the image of the pipe if it hepls. To specify, the inlet of the air is perpendicular to the wall of the pipe.

PipeWindTunel.PNG

Thank you in advance.

[vinerm]

You description is not very clear. Why movement of pipe requires two fluids to be used? What is the objective of the simulation? Do you already know the relation between the velocity and heat flux or temperature of the pipe wall? If there is inlet and outlet specified, then a constant velocity of pipe will not have any effect, except due to being closer to inlet or outlet. If flow is caused due to the motion of the pipe, then it would certainly affect the flow.

[AntonioCG]

Thank you for your reply.

Exactly, the flow is caused due to the motion of the pipe.

I attach exactly my problem. As I would like to see the Heat Flux in function of the Velocity of the air, I am trying to define an expression which depends on this velocity. I have been trying to think about it without succeed, can you help me with this expression please ? (I attach the image to clarify it)

DefineExpresion.PNG

[vinerm]

Then you can use the expression, however, just a mention of Velocity does not clarify anything for Fluent. You need to mention the cell zone or boundary zone whose velocity is to be used and is it a component of the velocity or the magnitude. You also need to specify the average method, i.e., area-weighted or volume weighted or other depending upon the scenario.

[AntonioCG]

Thank you again.

I have specified the velocity (as magnitude) and the boundary zone, Velocity.mag (["wall"]). However, I don't know how to specify the average method. Can you please tell me how can I do it or where can I find the information of how to do it ?

Also, I don't know why, the simulation doesn't work well. As I finish and click on calculate, Fluent closes automatically without showing a result or even an iteration. How can I solve this and why can it be ? (Can it be because I am not specifying the averge method?)

I can't find the error because it takes 1 sec to close Fluent.

[vinerm]

Following is the format for an expression

Average(VelocityMagnitude, ["cylWall"], Weight = "Area")

cylWall needs to be replaced with whatever is the name of the cylinder wall whose velocity you want to refer to. For a wall, you can either use Area based average or arithmetic average. Since it is wall, the method won't matter since whole body moves as a rigid body. To use arithmetic average, specify None in place of "Area".