General Boundary Condition Ramping

EDE16 · August 8, 2016, 16:39

Hi all,

Doing turbomachinary simulations in STAR and using stagnation inlets. When ramping pressures, can it just be ramped in the shortest number of iterations where no divergence is seen, or is it better to ramp maybe 20% then hold steady for some time before continuing in the same way until 100% of the ramp is reached? I guess, I am wondering is there anyway of saying this way is generally better because....?

Any input appreciated,

Ed

marmot · August 11, 2016, 06:55

Are you only looking for an answer at 100% the dp or do you need information for other pressure differences?

Instead of ramping a pressure difference you could try ramping relaxation factors, but to answer your question in general I prefer doing the 20% be it pressure difference, heat source, run steady for awhile and than 40%, steady, ... at least this way you have a converged answer at some levels.

August 8, 2016, 16:39	General Boundary Condition Ramping	#1
EDE16 Member Join Date: Jun 2016 Posts: 52 Rep Power: 9	Hi all, Doing turbomachinary simulations in STAR and using stagnation inlets. When ramping pressures, can it just be ramped in the shortest number of iterations where no divergence is seen, or is it better to ramp maybe 20% then hold steady for some time before continuing in the same way until 100% of the ramp is reached? I guess, I am wondering is there anyway of saying this way is generally better because....? Any input appreciated, Ed

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August 11, 2016, 06:55		#2
marmot Senior Member kevin alun Join Date: Sep 2011 Location: Germany Posts: 106 Rep Power: 14	Are you only looking for an answer at 100% the dp or do you need information for other pressure differences? Instead of ramping a pressure difference you could try ramping relaxation factors, but to answer your question in general I prefer doing the 20% be it pressure difference, heat source, run steady for awhile and than 40%, steady, ... at least this way you have a converged answer at some levels.