[Q] CHEMISTRY POST PROCESSING takes a long time...

Whitebear · August 5, 2014, 21:24

Does anyone have an experience that chemistry post processing takes a long time? I am solving coal combustion problem and pre processing solver takes one day but more than two days has taken for solver solves NOx calculation. How can I reduce the chemistry post processing time? I set 8 rays in radiation, upwind for advection scheme and 12 cores(hyper threading) parallel calculation for 1.2million nodes.

ghorrocks · August 6, 2014, 09:21

I presume you mean the solver time is long - the pre- and post processing should be quick regardless of whether chemistry is present.

Yes, chemistry can make the equations less numerically stable and that leads to longer run times. "CFD" and "I need a more powerful computer" are often said together.

Opaque · August 6, 2014, 10:22

Not sure what is the source of your problem; however, you should not run ANSYS CFX with hyperthreading on. Performance will suffer once you start running in parallel.

Whitebear · August 8, 2014, 10:39

Thank you very much indeed ghorrocks and Opaque.

August 5, 2014, 21:24	[Q] CHEMISTRY POST PROCESSING takes a long time...	#1
Whitebear Member Jinwhan Ryuk Join Date: Feb 2013 Location: South Korea Posts: 91 Rep Power: 13	Does anyone have an experience that chemistry post processing takes a long time? I am solving coal combustion problem and pre processing solver takes one day but more than two days has taken for solver solves NOx calculation. How can I reduce the chemistry post processing time? I set 8 rays in radiation, upwind for advection scheme and 12 cores(hyper threading) parallel calculation for 1.2million nodes.

August 8, 2014, 10:39	Thank you.	#4
Whitebear Member Jinwhan Ryuk Join Date: Feb 2013 Location: South Korea Posts: 91 Rep Power: 13	Thank you very much indeed ghorrocks and Opaque.

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August 6, 2014, 09:21		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,854 Rep Power: 144	I presume you mean the solver time is long - the pre- and post processing should be quick regardless of whether chemistry is present. Yes, chemistry can make the equations less numerically stable and that leads to longer run times. "CFD" and "I need a more powerful computer" are often said together.

August 6, 2014, 10:22		#3
Opaque Senior Member Join Date: Jun 2009 Posts: 1,873 Rep Power: 33	Not sure what is the source of your problem; however, you should not run ANSYS CFX with hyperthreading on. Performance will suffer once you start running in parallel.