Learning Forum

[Mae Kristine Labendia]

Hi experts,

Good day I am a new user of ansys. Would like to ask some advice on simulating projects in ansys fluent. I tried to simulate pipe composed of air fluid with inlet temperature of 575K and assume velocity of 5m/s with assumed gauge pressure of 28MPa pipe length is to be 500m. I would like to know the temperature outlet with this condition. after setting up conditions, temperature from inlet is all same going to outlet,

here are conditions i made, i used  the outlet is outflow, the inlet is pressure-inlet don`t know why nothing change with temperature. What may be other lacking data i need to input so I will know the temperature of the outlet.

 

Thank you in advance for your time and answers in advance

[Nikhil Narale]

Hello, 

On the pipe wall, make sure to assign correct thermal boundary condition. By default, it is set to zero heat flux (which is nothing but adiabatic : Insulated wall). 

[Mae Kristine Labendia]

Hi Nikhil Narale,

Thank you so much. I did set adiabatic and now it works. Thank you again

[Mae Kristine Labendia]

 

Hi Nikhil Narale

I do like to ask question, as I set my boundary conditions, it seems that what I inputted in the free stream temperature is also the outlet temperature of pipe. 

What I would like to discover is the outlet temperature of above mentioned conditions. Assuming inlet temperature of 300deg celcius 500m below ground. with assumed pressure of 28Mpa what should be the best way to discover the outlet temperature of my case.

 

Appreciate your help and to anyone who may have an idea really appreciate.

Thank you so much

 

[Nikhil Narale]

Hello, 

 

First thing, be aware that you have selected convection under thermal condition. This signifies that there is convection on the outer side of the pipe wall, and it is not for inside. Moreover, you have set the heat transfer coeff. to 0 which I think won't make any sence here. If you want to give constant temperature, select temperature under thermal condition and set appropriate value. Once the simulation is over, you can use report definitions to find out outlet temperature. 

For details, check this course on heat transfer on our AIC site: Heat Transfer Modeling in Ansys Fluent | Ansys Courses

 

Thank you! 

[Mae Kristine Labendia]

 

Hi Nikhil Narale,

Thank you so much for your help, because of that I finally got the temperature.

 

Another question I`d like to ask is I would like my contour to be displayed in a way that it will be section in the middle of my solids. Aside from creating semmetry plane in the design modeller, is there any way that I can show it.

Appreciate your help always.

Thank you.

 

[Nikhil Narale]

It is not recommended to create a plane in DM or at the CAD level. Instead, create a plane in Fluent itself and display the contour on it. To do so, navigate to Results - Surfaces - Create - Plane. Please refer to the attached image for guidance.

[Mae Kristine Labendia]

Hi Nikhil Narale,

Thank you again for your help. It works.

[Nikhil Narale]

You're welcome :) 

[Mae Kristine Labendia]

Hi Nikhil Narale,

Aside from cutting pipe, can I simulate using surface and will consider various soil sorrounds from my pipe. I take too long for the 500m length pipe, I am considering surface if this can be possible.

Thank you in advance.

[Nikhil Narale]

I am not able to understand your question completely. Do you just want to consider the fluid domain and exclude the solid pipe to save time? If so, it is possible. You can go with either the 'Thin wall thermal resistance' approach or the 'Shell conduction' approach. In either cases, you don't have to consider the solid geometry and don't have to mesh it. This will save your time. 

Check out these links for more details:

1: Thin wall thermal resistance (7.4.15.5.7. Thin-Wall Thermal Resistance Parameters)
7.4. Boundary Conditions (ansys.com)

2: Shell conduction (14.2.5. Shell Conduction)
14.2. Modeling Conductive and Convective Heat Transfer (ansys.com)

 

If you are not able to access these links, refer to this forum discussion: How to access the ANSYS Online Help

Thank you! 

[Mae Kristine Labendia]

I wanted to simulate using 2D instead of 3D. Thank you so much for these links. Will check on these.

[Nikhil Narale]

Rather than 2D, I would suggest you to go with axisymmetric condition, if it suits your problem. 

[Nikhil Narale]

Looks like you have created a separate post for this question: Surface Simulation (ansys.com)

[Mae Kristine Labendia]

 

Hi Nikhil Narale,

Thank you for your immediate reply. 

Will check on axisymmetric condition.

Yes. Recently I created with that post but I wasn`t able to receive suggestion so I decided to add in this Thread.

Thank you always for your help

 

[Mae Kristine Labendia]

 

 

Hi Nikhil Narale

Sorry for lot of questions. I always get losed since this my first ever analysis experience. Why did my simulation contour have all same color? I had the result, from inlet temperature of 573K  and inlet velocity is 5m/s flows through 10m pipe and result temperature outlet is 571.4K but the color of my simulation are all red in contours though my solution is converged. Is it reasonable or does something wrong with my input. Pipe with water vapor and assuming drysoil sorrounds pipe. Kindly see attached. Thank you always for your help.

 

[Nikhil Narale]

Hello, 

 

The temperature on the wall appears to be constant due to the boundary condition. However, you may want to check the temperature contour on the mid-plane.

The temperature drop from 573 K to 571.4 K, which is a decrease of around 1.6 K, it seems like a small drop in temperature. Is this what you expected?

[Mae Kristine Labendia]

Hi Nikhil Narale

Why is it that my land also getting red in color. I think it should not be as wide as that cause the fluid that carries hot liquid is only at the encircled one. The red one inside the yellow green circle is only the fluid that has 573K temperature

Thank you.