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-   -   how to setup pressure boundary conditions? (http://www.cfd-online.com/Forums/star-ccm/82137-how-setup-pressure-boundary-conditions.html)

bioman6666 November 17, 2010 21:43

how to setup pressure boundary conditions?
 
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 11:39

reply
 
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 15:14

Inlet- Velocity Inlet

Outlet: Pressure Outlet

Most convenient BC for duct flow.

bioman6666 March 27, 2011 00:55

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.


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