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vitorleiteg May 2, 2019 11:09

Server Room (phoenics2018)
 
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Hello everyone! Fellow undergrad learning to use CFD needing some help! :)


Started recently working on a CFD model for a server room and I am having some trouble on modelling the server racks and the inrow cooling machines.

I tried several different solutions.

First, modeled all server racks as heat sources (literally just boxes, since I am still a beginner I wanted to start simple) and added a fan on the front and a opening on the back (the fan pulling cold air from the cooling zone to the hot zone). This solution didn't work since the air pulled did not get any heat from the heat source.

Then, as a second try I added angle ins (one on the front of the rack and one on the back) and linked them, adding 5KW of heat on the exit. For some reason the added heat was appearing at the front of the rack, not after leaving the outlet.


Any solutions or tip on how to model a server room utilizing phoenics flair?


Here is a screenshot of what I have modeled so far.
https://imgur.com/W9BsU7o
https://imgur.com/W9BsU7o


Thank you for the help.

Shakil (CHAM) May 9, 2019 10:20

Hey Vitor,

You can try setting up the model as follows.

https://i.imgur.com/KbjRJkI.png

vitorleiteg May 14, 2019 04:59

1 Attachment(s)
Thank you for the reply Shakil,

I've made the modifications that you talked about, but in a simpler environment to be able to simulate changes faster.

So far what I did:

Created 6 plate surfaces to enclose the rack;
Created 10 small blockages inside the rack, each one with heat flux of 500W.

I already believe these change represents a big upgrade on the rack model itself but unfortunately I am still having trouble to simulate airflow through the racks.

Since fans pulls air from the front of the rack to the back, I tried adding fans (11 fans, -0.3m^3/s each / negative sign because it is pulling) in front of the rack and a opening on the back of the rack.

Strangely, no matter the value I put for the fans, they seem to not pull any air. I tried, instead of using flow rate, using velocity with a negative sign but it does not work as well.

When putting these values with positive sign it does work properly.

Next, I tried to "simulate" the fans with opening on both sides and utilize 'High and Low' object sides but it did not work as well.


Would really appreciate some extra help,
Sincerely,

Vitor Leite


*EDIT*

I finally was able to fix the problem. For some reason when creating the rack enclosure model, I kept thinking that I should create 6 plates objects to completely close the rack (2 on the sides, 2 on the front and back and 2 on the bottom and top), and add fan and opening objects on the front and back plates of the racks, respectively.

The problem with airflow was completely fixed with just removing the front and back plates of the rack model.

Thank you Shakil, wouldn't be possible to finish this model without your help :)


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