which BC for getting outlet pressure in a channel flow

josephmp · February 8, 2015, 10:43

Hi all, i have just started studying ansys fluent. what i have to find is the pressure drop in a microchannel with a specified velocity inlet and length of pipe. Nothing is known about outlet conditions. the outlet pressure need not be atmospheric. In such a case what should be my outlet boundary condition? how can i get the outlet pressure. when i m applying pressure outlet BC with zero gauge pressure i m always getting zero gauge pressure at outlet, but i need the actual pressure at outlet....somebody plz help me

lovecraft22 · February 8, 2015, 16:39

Why are you interested in the absolute pressure at the outlet if you're aiming at the pressure drop in the pipe?r

josephmp · February 9, 2015, 01:56

sorry, now i understand even my question was wrong.....when i changed the outlet pressure values with pressure outlet BC the pressure drop remained the same. i m interested only in the pressure drop. But initially i thought wen i m fixing inlet velocity and channel dimensions i m fixing inlet pressure also....thats why asked such a question....do you want to add anything more?

lovecraft22 · February 9, 2015, 15:59

Correct. You don't want to overcostrain your system. If you impose a pressure at the outlet the pressure at the inlet will be calculated in order to have a certain (imposed) velocity at that location.

February 8, 2015, 10:43	which BC for getting outlet pressure in a channel flow	#1
josephmp Member joseph Join Date: Jan 2015 Posts: 32 Rep Power: 11	Hi all, i have just started studying ansys fluent. what i have to find is the pressure drop in a microchannel with a specified velocity inlet and length of pipe. Nothing is known about outlet conditions. the outlet pressure need not be atmospheric. In such a case what should be my outlet boundary condition? how can i get the outlet pressure. when i m applying pressure outlet BC with zero gauge pressure i m always getting zero gauge pressure at outlet, but i need the actual pressure at outlet....somebody plz help me

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February 8, 2015, 16:39		#2
lovecraft22 Senior Member lore Join Date: Mar 2010 Location: Italy Posts: 460 Rep Power: 18	Why are you interested in the absolute pressure at the outlet if you're aiming at the pressure drop in the pipe?r

February 9, 2015, 01:56		#3
josephmp Member joseph Join Date: Jan 2015 Posts: 32 Rep Power: 11	sorry, now i understand even my question was wrong.....when i changed the outlet pressure values with pressure outlet BC the pressure drop remained the same. i m interested only in the pressure drop. But initially i thought wen i m fixing inlet velocity and channel dimensions i m fixing inlet pressure also....thats why asked such a question....do you want to add anything more?

February 9, 2015, 15:59		#4
lovecraft22 Senior Member lore Join Date: Mar 2010 Location: Italy Posts: 460 Rep Power: 18	Correct. You don't want to overcostrain your system. If you impose a pressure at the outlet the pressure at the inlet will be calculated in order to have a certain (imposed) velocity at that location.