pressure

hamid1 · February 6, 2012, 04:50

Hi
I understand that minus pressure in the boundary means a suction pressure, but what does minus pressure inside the domain mean?

ANTONY A R V · February 6, 2012, 09:32

A localised region having vaccuum or pressure less than atmospheric pressure

hamid1 · February 7, 2012, 12:07

what does vacuum exactly mean?
if I consider my system in vacuum (there is no pressure from outside the system) and
regarding to the simulation based on the b.c. why should we care about the atmosphere, this is my issue getting confused of many times in simulation by Fluent,
what i want to simulate is a T shaped tube (with three openings), in two openings the pressure is known (there is a pressure from outside to inside the domain),
also in the third opening there is a suction implied by a vaccume system or a syringe, (so minus pressure),...
so i put 100 pa and 100 pa for the first two openings and -100 pa for the third opening......

ANTONY A R V · February 20, 2012, 11:53

A negative pressure means pressure less than atmospheric. You may have this at the suction side of fan and pump. This gauge pressure may be negative. but absolute pressure will be positive. The negativeness is relative to atmospheric pressure.

February 6, 2012, 04:50	pressure	#1
hamid1 Senior Member hamid Join Date: Nov 2010 Posts: 185 Rep Power: 15	Hi I understand that minus pressure in the boundary means a suction pressure, but what does minus pressure inside the domain mean?

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February 6, 2012, 09:32		#2
ANTONY A R V New Member ANTONY AROUL RAJ V Join Date: Jan 2012 Location: Chennai Posts: 22 Rep Power: 14	A localised region having vaccuum or pressure less than atmospheric pressure

February 7, 2012, 12:07		#3
hamid1 Senior Member hamid Join Date: Nov 2010 Posts: 185 Rep Power: 15	what does vacuum exactly mean? if I consider my system in vacuum (there is no pressure from outside the system) and regarding to the simulation based on the b.c. why should we care about the atmosphere, this is my issue getting confused of many times in simulation by Fluent, what i want to simulate is a T shaped tube (with three openings), in two openings the pressure is known (there is a pressure from outside to inside the domain), also in the third opening there is a suction implied by a vaccume system or a syringe, (so minus pressure),... so i put 100 pa and 100 pa for the first two openings and -100 pa for the third opening......

February 20, 2012, 11:53		#4
ANTONY A R V New Member ANTONY AROUL RAJ V Join Date: Jan 2012 Location: Chennai Posts: 22 Rep Power: 14	A negative pressure means pressure less than atmospheric. You may have this at the suction side of fan and pump. This gauge pressure may be negative. but absolute pressure will be positive. The negativeness is relative to atmospheric pressure.