Energy problem in air cooled object

Fred511 · August 1, 2021, 19:03

First of all, I would like to thank anyone whoever will answer and try to help me.

I'm working on ansys fluent to simulate the air cooling of a brake disk inside its wheel assembly. The general purpose is to see how air flow (the car is moving at an X speed) will cool the disk after a strong braking, which is set in the simulation using a temperature patch after the initialization.

Now, I've already successfully achieved a transient simulation with ONLY the brake disk, getting everything work and seeing the temperature slowly decreasing each time step.

My intention is, therefore, to start adding pieces around the disk itself and so arrive to the final setup i need.

In the Geometry I imported the disk as solid and each other as frozen, worked on the assembly, created the enclosure and then substracted each piece from the enclosure with the boolean, not keeping what I want to consider just as a wall (wheel assembly, car body ecc) and keeping the disk as a solid body.

About meshing, I'm working on a 10 million cells mesh in order to just see if everything is okay. I'll do the heavy mesh once all ready.

About Fluent, from what I've read online, the issue should be in the boundary conditions; anything beside those (in where the walls are different because now there are also the "fluid walls" given from the substracts of the car body) were set like the previus semplified one. I'll post images of that also in needed.
Where do I made a mistake?

Note that the coupling between the solid disk and the fluid enclosure was recognized automatically in the mesher, and I also tried to set it manually afterwards in the "Mesh interface" -> "Contact region" option.

Here's the link of my imgur profile in where i uploaded pics of Geometry, Residuals, Temperature report and boundaries.

https://fredrich511.imgur.com/all

If there's a rule problem about using general links, i'll update the post with the single link of each pic.

Again, thanks for any answer.

EDIT:
Here's the link to the temperature report of the first simulation, brake disk alone, as comparison to see how it should act.
https://imgur.com/dtLCxUM

LoGaL · August 1, 2021, 23:54

I didn’t get what is the problem

Fred511 · August 2, 2021, 09:24

The problem is that the temperature don't decrease as it should.
The disk starting temperature is 300°C, as you can see in the report pic it jumps from 3/5000 to 0°C instead of just going down smoothly.
Here's the link of the temperature report of the control simulation, with the disk alone.

https://imgur.com/dtLCxUM

August 1, 2021, 19:03	Energy problem in air cooled object	#1
Fred511 New Member Edoardo Frinconi Join Date: Aug 2021 Location: Italia Posts: 2 Rep Power: 0	First of all, I would like to thank anyone whoever will answer and try to help me. I'm working on ansys fluent to simulate the air cooling of a brake disk inside its wheel assembly. The general purpose is to see how air flow (the car is moving at an X speed) will cool the disk after a strong braking, which is set in the simulation using a temperature patch after the initialization. Now, I've already successfully achieved a transient simulation with ONLY the brake disk, getting everything work and seeing the temperature slowly decreasing each time step. My intention is, therefore, to start adding pieces around the disk itself and so arrive to the final setup i need. In the Geometry I imported the disk as solid and each other as frozen, worked on the assembly, created the enclosure and then substracted each piece from the enclosure with the boolean, not keeping what I want to consider just as a wall (wheel assembly, car body ecc) and keeping the disk as a solid body. About meshing, I'm working on a 10 million cells mesh in order to just see if everything is okay. I'll do the heavy mesh once all ready. About Fluent, from what I've read online, the issue should be in the boundary conditions; anything beside those (in where the walls are different because now there are also the "fluid walls" given from the substracts of the car body) were set like the previus semplified one. I'll post images of that also in needed. Where do I made a mistake? Note that the coupling between the solid disk and the fluid enclosure was recognized automatically in the mesher, and I also tried to set it manually afterwards in the "Mesh interface" -> "Contact region" option. Here's the link of my imgur profile in where i uploaded pics of Geometry, Residuals, Temperature report and boundaries. https://fredrich511.imgur.com/all If there's a rule problem about using general links, i'll update the post with the single link of each pic. Again, thanks for any answer. EDIT: Here's the link to the temperature report of the first simulation, brake disk alone, as comparison to see how it should act. https://imgur.com/dtLCxUM Last edited by Fred511; August 2, 2021 at 09:25. Reason: adding informations

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August 1, 2021, 23:54		#2
LoGaL Senior Member Lorenzo Galieti Join Date: Mar 2018 Posts: 374 Rep Power: 12	I didn’t get what is the problem

August 2, 2021, 09:24		#3
Fred511 New Member Edoardo Frinconi Join Date: Aug 2021 Location: Italia Posts: 2 Rep Power: 0	The problem is that the temperature don't decrease as it should. The disk starting temperature is 300°C, as you can see in the report pic it jumps from 3/5000 to 0°C instead of just going down smoothly. Here's the link of the temperature report of the control simulation, with the disk alone. https://imgur.com/dtLCxUM