how to setup pressure boundary conditions?

bioman6666 · November 17, 2010, 20:43

Hello
I want to use star-ccm to simulate water flowing in a duct. One side of this duct is connected with a very larger top-openned reservoir and the other side is applied with a negtive pressure [like vacuum pump] to suck water out. What kinds of pressure type should I define in inlet side at reservoir top face and outlet side ?
Thank you !!

Gary

hx_wwj · December 14, 2010, 10:39

inlet pressure outlet
outlet pressure outlet

并且需要预定义流速，否则反流比较严重

mahbub03 · March 23, 2011, 14:14

Inlet- Velocity Inlet

Outlet: Pressure Outlet

Most convenient BC for duct flow.

bioman6666 · March 26, 2011, 23:55

So, can I set the inlet side with 1 atm total pressure as a boundary condition; and 0.95 atm static pressure pressure as outlet condition ? [reference pressure = 0 atm]
As to the pre-defined velocity, should I set it in the initial condition?
Thanks !!

ara1362 · April 1, 2011, 19:09

You can either do mass flow inlet or velocity inlet.
for outlet use stagnation inlet and choose a negative pressure.
pressure outlet does not work as well with negative pressures.

as far as initial conditions go: they are good for the first initial guess.
use the inlet conditions on the inlet boundary with no pressure.

set something for the reference pressure, i dont think ccm+ likes 0 reference pressure that much and adjust your outlet pressure accordingly.

November 17, 2010, 20:43	how to setup pressure boundary conditions?	#1
bioman6666 New Member gary Join Date: Nov 2010 Posts: 4 Rep Power: 15	Hello I want to use star-ccm to simulate water flowing in a duct. One side of this duct is connected with a very larger top-openned reservoir and the other side is applied with a negtive pressure [like vacuum pump] to suck water out. What kinds of pressure type should I define in inlet side at reservoir top face and outlet side ? Thank you !! Gary

December 14, 2010, 10:39	reply	#2
hx_wwj New Member wenjiewang Join Date: Dec 2010 Posts: 1 Rep Power: 0	inlet pressure outlet outlet pressure outlet 并且需要预定义流速，否则反流比较严重

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March 23, 2011, 14:14		#3
mahbub03 New Member Mahbub Islam Join Date: Mar 2010 Location: Bangladesh Posts: 24 Rep Power: 16	Inlet- Velocity Inlet Outlet: Pressure Outlet Most convenient BC for duct flow.

March 26, 2011, 23:55		#4
bioman6666 New Member gary Join Date: Nov 2010 Posts: 4 Rep Power: 15	So, can I set the inlet side with 1 atm total pressure as a boundary condition; and 0.95 atm static pressure pressure as outlet condition ? [reference pressure = 0 atm] As to the pre-defined velocity, should I set it in the initial condition? Thanks !!

April 1, 2011, 19:09		#5
ara1362 New Member ara Join Date: Apr 2011 Posts: 8 Rep Power: 15	You can either do mass flow inlet or velocity inlet. for outlet use stagnation inlet and choose a negative pressure. pressure outlet does not work as well with negative pressures. as far as initial conditions go: they are good for the first initial guess. use the inlet conditions on the inlet boundary with no pressure. set something for the reference pressure, i dont think ccm+ likes 0 reference pressure that much and adjust your outlet pressure accordingly.