suitable outlet boundary condition

kmgraju · July 10, 2013, 02:42

Dear all
In a pipe flow (many obstructions exist inside the pipe), If I don't know the outlet pressure, velocity etc what is the suitable boundary condition.
I know the inlet velocity and pressure at t=0 s
Kindly give your suggestions

Thank you

Regards
Govind

hmasenger · July 10, 2013, 03:54

there is now way to model a problem without knowing the outlet BC!.you can simplify the model to a known situation like free discharge flow or you can use a mas flow outlet BC.if you know the inlet velocity then you know the mass flow inlet that is equal to the mass flow outlet in most problems.

kmgraju · July 10, 2013, 05:24

Quote:

Originally Posted by hmasenger

there is now way to model a problem without knowing the outlet BC!.you can simplify the model to a known situation like free discharge flow or you can use a mas flow outlet BC.if you know the inlet velocity then you know the mass flow inlet that is equal to the mass flow outlet in most problems.

Thank you for your reply

I have one more question. Is outflow boundary condition equal to mass flow rate boundary condition?

Thank you

Regards

Govind

hmasenger · July 10, 2013, 10:35

yes but pay attention to flow dimensions. mass flow rate Is in kg/sec not m3/hr or other volume flow dimensions.

July 10, 2013, 02:42	suitable outlet boundary condition	#1
kmgraju Senior Member Govindaraju Join Date: Apr 2010 Posts: 209 Rep Power: 17	Dear all In a pipe flow (many obstructions exist inside the pipe), If I don't know the outlet pressure, velocity etc what is the suitable boundary condition. I know the inlet velocity and pressure at t=0 s Kindly give your suggestions Thank you Regards Govind

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July 10, 2013, 03:54		#2
hmasenger Senior Member hamed Join Date: Apr 2009 Posts: 148 Rep Power: 17	there is now way to model a problem without knowing the outlet BC!.you can simplify the model to a known situation like free discharge flow or you can use a mas flow outlet BC.if you know the inlet velocity then you know the mass flow inlet that is equal to the mass flow outlet in most problems.

July 10, 2013, 10:35		#4
hmasenger Senior Member hamed Join Date: Apr 2009 Posts: 148 Rep Power: 17	yes but pay attention to flow dimensions. mass flow rate Is in kg/sec not m3/hr or other volume flow dimensions.