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Member
E_DUMAN
Posts: 5
Registered: ‎01-05-2013

Axial fan analysis time,

266 Views, 6 Replies
11-03-2013 04:59 AM

Hello,

 

I am trying to solve Axial fan Performance analysis But its takes a long time even though I have a good computer.(2 processor ,16 core 32 three. And 64 gb ram.)

My model detail 8 rotor and 9 stator. and fan diameter 900 mm.My total element about 7 million.

 

How can i reduce analsys time ?

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Product Support
wildej
Posts: 798
Registered: ‎08-25-2011

Re: Axial fan analysis time,

11-04-2013 01:09 AM in reply to: E_DUMAN

Hi,

 

This is quite a tricky question to answer, how long is the run and what are your expectations? Did you follow the guide here: http://help.autodesk.com/view/SCDSE/2014/ENU/?url=/cloudhelp/2014/ENU/SimCFD/files/GUID-013A783C-807...

 

What does '32 three' mean?

Did you ensure that you have 16 cores enabled within 'Solver Computers' if CFD is not already using them all when it runs?

 

Kind regards,

Jon



Jon Wilde
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Member
E_DUMAN
Posts: 5
Registered: ‎01-05-2013

Re: Axial fan analysis time,

11-05-2013 02:01 AM in reply to: wildej

Hello Jhon,

 

İ tried autodesk cfd turbomachinery guide.

 

i am running until 5000 iterations with 0.0025 s time step. (for 1.point on performance curve) . and our resutls are acceptable mean (pressure ,flowrate) but its taking long time

 

my computer 16 core and 32 thread ( hyperthreading system).

 

Under the solver computers box  core value =0 is it false? and have i select "use cluster"

 

i added my cpu window.

 

Thanks,

 

Best Regards 

 

Eyyüp DUMAN

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Product Support
wildej
Posts: 798
Registered: ‎08-25-2011

Re: Axial fan analysis time,

11-05-2013 02:23 AM in reply to: E_DUMAN

Hi Eyyüp,

 

OK, best to just have 16 cores assigned then, 0 should do the same too though, it will just use what it found during installation.

No need to select cluster, as you are not running on a cluster.

 

The guide says run initially blade to blade to get the speed up fairly quickly and stably and then switch to 3deg/step for the final section. Doing this might help you run models faster.

 

Kind regards,

Jon

 



Jon Wilde
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Member
E_DUMAN
Posts: 5
Registered: ‎01-05-2013

Re: Axial fan analysis time,

11-05-2013 03:14 AM in reply to: wildej

Hi again,

 

ok you are right.i am always doing that.

 

But when my iteration get to 2000 then  pressure and flowrate convergences on monitor point .(2000 iteration =approximately 60 hours) and we bought program license since 1 years and i am working about axial flow fan simulation since 1 year so i couldnt  reduce my simulation time.

 

Thanks ,

 

Best Regards

 

Eyyüp DUMAN

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Product Support
apolo.vanderberg
Posts: 300
Registered: ‎08-31-2011

Re: Axial fan analysis time,

11-06-2013 10:36 AM in reply to: E_DUMAN
To reduce simulation time we would need to find methods of strategically reducing the mesh count, or finding methods to leverage a larger timestep size.
As Jon mentioned some run blade-to-blade and then follow with 3º per timestep.
Is it 8 rotor blades or 8 rotors (such that this is a multistage unit with 8 rotating regions) ?

What is your clock speed of the 16cores? While that is a nice number of cores if this happen to be 16cores @ 2Ghz (for example) you might find that a 4core machine at 3.4Ghz might run just as fast or faster due to the difference in clock speed
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Member
E_DUMAN
Posts: 5
Registered: ‎01-05-2013

Re: Axial fan analysis time,

11-07-2013 01:32 AM in reply to: apolo.vanderberg

Hello

 

Firstly My computer HP z820  (its consist of  two processor, liquid colling system 64 gb ram ssd harddisk...) My clock speed 3.10 Ghz Totaly 16 core 32 thread ,its mean sometimes  cpu behavior like 32 core.

my  model geometry consist of 8 rotor and 11 stator.Fan Diameter 900 mm and my air volume lenght 6 meter.İ run with 8 blade to blade time .. (3000 rpm ,900 mm  = time step size 0.0025)

 Running with  3 degree per time speed  takes more long time than 0.0025 time speed.

 

İ added my model photo.

 

Thanks

 

 

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